What is Phytophthora Root Rot?

Phytophthora root rot is a destructive soil-borne disease of olive trees caused by Phytophthora species (water-mould pathogens). At least seven Phytophthora species have been identified attacking olives in Australia . These pathogens infect roots and can extend into the lower trunk, causing root decay and crown cankers that girdle the tree. If left untreated, Phytophthora root rot can kill olive trees, either through a rapid collapse or a slow decline over several seasons . The disease has been observed in many olive-growing regions worldwide, often linked to periods of excessive soil moisture. 

Symptoms: Infected olive trees typically show a loss of vigour and drought-like symptoms even when soil moisture is adequate. Foliage becomes sparse as leaves wilt, turn yellow, and drop prematurely . Shoot dieback starts at the tips of branches and progresses downward. In advanced cases, entire limbs or the whole canopy may wilt suddenly, especially under stress conditions like hot weather, flowering or heavy fruit load . Root and trunk symptoms include soft brown rot of feeder roots and lesion-like cankers at the crown or lower trunk; peeling back bark at the base often reveals reddish-brown discoloration of the wood. Affected trees may respond by shooting new suckers from the lower trunk or roots as the upper canopy dies back . Over time, the trunk can exhibit cracks or distortions due to the underlying canker damage . In some cases, trees can decline gradually over years, whereas in other cases they collapse quickly when the compromised root system can no longer support the canopy (for example, during a heatwave or late summer) . 

       

 An olive tree showing branch dieback and defoliation due to Phytophthora root rot. Infected trees often wilt, develop yellow leaves that drop, and can either die suddenly or decline over several years. These symptoms frequently manifest when the tree is under stress (e.g., during flowering, fruit development, or hot weather) and correspond to extensive root damage and crown cankers in the lower trunk.    

Contributing Factors and Disease Spread

Waterlogging and Poor Drainage: Excess soil moisture is the single biggest contributing factor to Phytophthora root rot in olives. Phytophthora thrives in saturated, oxygen-deprived soils. Australian conditions have consistently found Phytophthora outbreaks correlated with waterlogged conditions, claypan soil layers, or generally poor drainage in groves. Even a short period of waterlogging (as little as 24 hours) in warm temperatures can kill fine olive roots and predispose trees to infection. Low-lying orchard areas, heavy clay soils that drain slowly, or sites with a high water table create ideal conditions for the pathogen. It’s important to note that while waterlogging is a common trigger, Phytophthora can sometimes cause problems even in well-drained soils if the pathogen is present and environmental conditions (temperature, soil moisture) become favourable. In high-rainfall climates or during unusually wet seasons, otherwise well-drained olive blocks may still experience Phytophthora issues if drainage cannot keep up with prolonged rainfall. 

Susceptible Rootstocks: Most olive trees in Australia are grown on their own root stock (i.e., not grafted), but in cases where different rootstocks or wild olive (Olea europaea subsp. africana) seedlings are used, susceptibility can vary. Caution is advised when using feral/wild olive trees as rootstocks or nursery stock. These plants can originate from areas where Phytophthora is present in the soil and may introduce the pathogen or be less tolerant to it. There is currently no widely available Phytophthora-resistant olive rootstock, so all varieties should be assumed susceptible. Research by Spooner-Hart et al. noted that the emergence of Phytophthora problems in Australian olives has coincided with the expansion of plantings into non-traditional (non-Mediterranean) climates and heavier soils. This underscores the role of environment and rootzone conditions in disease incidence.

Warm, High-Rainfall Climates: Olives are traditionally adapted to Mediterranean climates (winter rain, dry summers). In parts of Australia with warm temperatures and summer-dominant rainfall (e.g., coastal Queensland and northern New South Wales), the risk of Phytophthora root rot is higher. The pathogen is widespread in soils and waterways in these regions and can easily infect olive roots when wet, warm conditions persist. Growers in such climates must be especially proactive with prevention measures. High humidity and frequent rain not only favor the pathogen but can also mask early drought-stress symptoms - an infected tree might not show obvious distress until a dry period or heat event reveals the extent of root loss.

Disease Spread: Phytophthora produces motile spores (zoospores) that swim in free water, so the pathogen spreads with water movement through soil and runoff. It can be introduced or spread in a grove via infected nursery stock, contaminated soil on equipment, flood irrigation water, or even the boots of workers moving from an infested wet area to a clean area. Once in the soil, Phytophthora can persist for years in root debris or as resilient spores. Thus, any practice that moves soil or water (e.g., tractor(s) and farm equipment, drainage flows) from an infected zone to an uninfected zone can facilitate the dissemination of the disease. Growers should avoid transferring mud and material from known infested blocks and ensure any new trees planted are from disease-free sources (pathogen-free). 

       

 PC: Root systems of wild olives at the end of soil infestation trial of healthy roots.

Best Practices for Managing Phytophthora in Olives 

Successful management of Phytophthora root rot in olives relies on an integrated strategy. This includes preventative chemical treatments, supportive nutritional therapies, and cultural practices to improve soil conditions and reduce pathogen spread. The goal is to protect healthy roots from infection, eradicate or suppress the pathogen in soil where possible, and help affected trees recover. Below are the current industry best practice:

Preventative Use of Phosphorous Acid (Phosphonate) Fungicides

Caption.

Phosphorous acid (also known as phosphonate or phosphite) is a key fungicide for mana PhozGuard 620 Phytophthora in many tree crops and is a cornerstone of preventative treatment in olives. Phosphonate does not act like a typical fungicide that directly kills the pathogen on contact,  instead, it works by inhibiting Phytophthora growth and stimulating the tree’s own defense mechanisms. This dual mode of action makes it most effective as a preventative treatment, applied before or at the very early stages of infection, to help the plant resist invasion. Phosphorous acid is available under various trade names (e.g., Phosguard620) with different concentrations of active ingredient. Always confirm that the product is permitted for use on olives and follow the label or permit directions. 

Application timing and rates: On woody perennial crops like olives, foliar sprays of phosphonate are typically applied approximately every 6 weeks during the growing season for ongoing protection. This ensures a consistent level of the fungicide within the plant, as it is systemic and will move into the roots. Label rates depend on product concentration; for example, products with around 600 g/L a.i. are used around 2.5 mL/L, 400 g/L formulations at 5 mL/L, and 200 g/L formulations at 10 mL/L (when applied with an air-blast sprayer to fully cover the foliage). For young or small olive trees, high-volume spraying to runoff ensures good coverage. Crucial timing is just before periods of high risk - e.g., before winter rains or summer wet spells - so that the roots are protected in advance. 

In situations where an olive tree has very little foliage left (severe defoliation from root rot), phosphonate can be applied as a bark spray or trunk injection. Spraying a ~10% phosphorous acid solution directly on the trunk or injecting the solution into the lower trunk can deliver the fungicide to the vascular system when leaves are insufficient. Trunk application is usually done in autumn or spring when the tree is actively translocating, to maximise uptake. Always exercise caution with concentrated trunk sprays to avoid phytotoxicity and adhere to recommended concentrations carefully.

Mode of action and benefits: Once absorbed, phosphonate is translocated downward with the sap flow, reaching the roots and inhibiting Phytophthora in infected tissues. It also primes the tree’s immune response. Treated trees often show not only disease suppression but also improved new root development in some cases. Phosphonate is valued for being relatively inexpensive and having low toxicity to humans and non-target organisms, making it a practical choice for routine preventative use. In warm, high-rainfall regions of Australia where Phytophthora is endemic, applying phosphonate prophylactically to young olive trees can protect them until their root systems establish. Many agronomists recommend an initial phosphonate spray or injection soon after planting in such regions, followed by periodic treatments during the wet season.

It’s important to remember that phosphonate is a suppressive, not an eradicant, treatment. It significantly reduces Phytophthora levels and activity in the tree but does not eliminate the pathogen from the soil. Therefore, repetitive or at least annual reapplications are needed to maintain protection. If treatments are stopped, Phytophthora can rebound if conducive conditions return. Also, phosphonate works best on preventing new infections and halting early disease - severely diseased trees (with the majority of roots already rotted) may not recover with fungicide alone. In those cases, phosphonate can only prevent further spread while other measures support the tree’s regrowth.

Other fungicides: Another chemical option is metalaxyl-M (e.g., Ridomil Gold), a systemic fungicide specifically targeting oomycete pathogens like Phytophthora. Ridomil can be applied as a soil drench or via injection to kill Phytophthora in the root zone. It has shown effectiveness in olives, but similar to phosphonate, it does not sterilise the soil and must be reapplied periodically to keep the pathogen in check. Phosphonate is often preferred for long-term management due to lower cost and resistance risk, but Ridomil drenches can be useful as a curative kick-start in heavily infested soils or to protect newly planted high-value trees. Always rotate or mix chemical modes of action as allowed, to prevent the development of fungicide resistance in the Phytophthora population. 

As an example for conventional application... Calcium nitrate at 10 g/L plus Solubor (boron) at 1.5 g/L, mixed in water, applied as a fine foliar spray every 6 - 8 weeks. Calcium nitrate provides a readily absorbed form of calcium (along with some nitrogen to spur growth), and Solubor is a common soluble borate fertiliser that assists to correct boron deficiency. These can be tank-mixed and sprayed to cover the foliage; ideally, apply in the cooler part of the day (morning or late afternoon) to reduce the risk of leaf burn.  Liquid boron applications like Agrodex Boron are usually recommended.   

Foliar Calcium and Boron to Aid Recovery 

In addition to fungicides, nutritional support plays a critical role in managing Phytophthora root rot - especially for helping infected trees recover. Two nutrients in particular, calcium (Ca) and boron (B), have been observed to assist olive trees suffering from root rot. Calcium and boron are closely associated with the growth of new shoots and root tips; they are essential for cell wall strength (Ca) and cell division/floral development (B). Some olive varieties have relatively high requirements for Ca and B compared to other fruit trees, and deficiencies of these nutrients often manifest as dieback of shoot tips (boron deficiency can cause tip death and poor new leaf growth, while calcium deficiency leads to weak stems and twig dieback).

When roots are compromised by Phytophthora, the tree’s ability to uptake nutrients from the soil is severely impaired. Ailing roots mean even if fertilisers are in the soil, the tree may still suffer from nutrient deficiencies. Foliar feeding can bypass the damaged root system and deliver nutrients directly to the leaves and young shoots. Foliar sprays of calcium and boron have shown positive results in reducing twig dieback and stimulating new growth on moderately affected olive trees. The recommended practice (from field experience in Australia) is to apply calcium and boron together on a regular schedule during the active growing season:

Growers have observed that olive trees showing moderate dieback will flush new healthy shoots after a couple of rounds of Ca+B foliar nutrition, as opposed to continuing to deteriorate. By maintaining an every 6 - 8 weeks program through spring and summer, the recovering tree has a better chance to rebuild its canopy and even some root mass (because improving the canopy’s health allows the plant to allocate energy to root regrowth). This approach is a supportive therapy - it does not attack the pathogen, but rather helps the tree tolerate the infection and outgrow the damage. Calcium also contributes to disease resistance by strengthening cell walls, making it a bit harder for Phytophthora to advance through tissues, while boron is crucial for the healing of damaged tissues and the growth of new meristems.

Complete Foliar Nutrient Programs for Impaired Roots

Beyond calcium and boron, a complete foliar nutrient program is advised for olive trees with significantly impaired root systems. Because root rot limits uptake of both macro- and micro-nutrients, foliar applications of a balanced fertiliser can supply the tree with essential nutrients until roots recover. Many agricultural suppliers offer soluble foliar fertiliser blends (NPK plus Trace Elements) that can be sprayed on the canopy. These blends often contain nitrogen, phosphorus, and potassium, as well as micronutrient like zinc, manganese, iron, copper, molybdenum, etc., in plant-available forms. Applying such a foliar feed can green up a chlorotic, declining tree and promote new leaf and root development while bypassing the diseased root system.

A suggested regimen is to spray a complete foliar fertiliser (for example, an NPK 20-20-20 with trace elements, or a product formulated for orchard foliar feeding) on a monthly or bi-monthly schedule during the growing season. This can often be done in conjunction with the calcium nitrate and boron sprays - either by alternating them or, if compatibility is confirmed, combining them in one tank mix. Be cautious when mixing fertilisers with fungicides: phosphonate is generally compatible with many fertilisers, but always jar-test combinations or consult product labels.

Foliar nutrient programs should be tailored to the grove’s specific deficiencies. If leaf analysis or visual symptoms indicate particular nutrient shortages (e.g., yellowing between veins might indicate magnesium or iron deficiency, small, distorted new leaves could indicate zinc deficiency), include or emphasise those nutrients in the foliar mix. Maintaining good overall nutrition will improve the tree’s resilience. Stronger, well-nourished olive trees have a better chance to compartmentalise Phytophthora infections and resume normal growth once conditions improve. Remember that these sprays supplement but do not replace soil fertilisation; once roots recover function, reinstating a normal soil fertiliser program (adjusted for any residual soil fertility and the tree’s regained capacity) is important for long-term production.

Improving Soil Drainage and Grove Management 

Cultural controls that improve the soil environment are fundamental to managing Phytophthora - no chemical or nutrient can fully substitute for a well-drained root zone. Growers should evaluate their grove for any conditions that contribute to waterlogging or poor root health and take corrective action:

• Improve drainage: Ensure that water is not pooling around olive roots for extended periods (see image right PC Australis Plants - water pooling around olive trees). For new plantings, select well-drained sites or use raised beds/mounded rows in heavier soils. Building the planting rows as mounds (for instance, 30 - 40 cm above the aisle) allows water to drain away from root zones more quickly. In existing groves, consider installing drainage solutions such as surface drains, French drains, or deep ripping between rows to break up hardpans. If a hard clay subsoil (clay-pan) is identified, deep rip or auger planting holes through it and backfill with a more friable soil mix before planting, to prevent perched water tables. Also, maintain grassed inter-rows or gentle slopes to channel excess rainwater off the orchard rather than letting it stagnate. After heavy rain, inspect the orchard to identify any spots where water stands and address those with drains or by regrading the soil. 
• Optimise irrigation: Over-irrigation can be just as harmful as poor natural drainage. Adjust your irrigation scheduling and method to prevent waterlogging. Use soil moisture sensors if possible to guide irrigation, and err on the side of “drier” rather than “wetter” when Phytophthora risk is high. For example, instead of one long irrigation set, you might split it into shorter, more frequent sets that allow more oxygen into the root zone between waterings. Microsprinklers or drip emitters should be placed such that they wet the root zone adequately but do not create continuously soggy conditions. Make sure emitters are functioning correctly and not leaking excessively in one spot. If at high risk, avoid irrigating just before evenings or periods of cool, humid weather - it can extend soil wetness duration. Proper irrigation management is part of integrated Phytophthora control, as noted by Queensland’s Department of Agriculture: avoid both over- and under-watering, since stress from drought can also predispose trees to infection or make symptoms worse.
  
• Soil amendments: Increasing soil organic matter can improve structure and drainage in the long term. Using mulch or cover crops in the inter-row can enhance soil porosity and microbial activity (which can sometimes suppress pathogens). Apply organic mulches under the dripline of olive trees to help soil structure, but keep mulch a few inches away from the trunk to avoid creating a perpetually moist collar around the base. In clay soils, the addition of gypsum can help flocculate clay particles and improve permeability. Gypsum (calcium sulfate) applied under the canopy can also provide calcium to the soil profile, which some studies suggest may reduce Phytophthora spore formation or activity (noting that very high soil pH can actually favor the disease, so use gypsum (pH-neutral) rather than lime unless you need to correct acidity). Always test soil pH before adding lime.
  
• Grove hygiene and design: Treat Phytophthora-affected sections of the grove almost as a biohazard area to prevent spread. Do not move soil from infected areas to clean areas - for example, if you dig out a dead tree, dispose of that soil away from the orchard or sterilise it. Clean farm machinery, tools, and footwear after working in a muddy, suspect area. Restrict access to the orchard when the soil is wet (to avoid picking up mud on tires). If using surface water (from dams or creeks) for irrigation, be aware that it could harbor Phytophthora spores from upstream sources - consider water treatment or use of drip irrigation that limits soil splash. In windbreaks or nearby vegetation, note that some ornamental or wild plants can be hosts for Phytophthora; controlling weeds and alternative host plants may reduce inoculum reservoirs. When replanting where an olive tree died of root rot, it’s wise to improve the site drainage and possibly leave the hole fallow or treat the soil (some growers solarise the soil or apply fungicides like metalaxyl pre-plant) before putting a new olive in the same spot
  
• Adjusting grove practices: Other cultural adjustments can reduce stress on at-risk trees. For instance, avoid heavy pruning of diseased trees (they need as much healthy leaf area as possible to regenerate roots) - only remove dead wood and lightly shape to balance the canopy. Do not remove those water shoots or suckers that often appear on the lower trunk of sick trees; as recommended by Australis Plants, allow these shoots to grow (pruning them back only moderately so they don’t become dominant branches) because they help the tree regain foliage and vigor. They can always be pruned off later once the tree fully recovers. Likewise, be cautious with fertilising a tree with a severely compromised root system - small, frequent doses or foliar feeds are safer than a heavy soil fertiliser application, which the damaged roots cannot absorb (and which could burn them or leach away). Finally, monitor Phytophthora-affected trees closely. If a tree is not responding to treatments (fungicide + nutrients) and continues to decline, it may be better to remove it and focus efforts on protecting surrounding trees. A rotting stump or roots can continue to harbor the pathogen, so in some cases, stump removal or fumigation might be warranted in patch areas of severe infection.

Phosphorous Acid vs. Calcium - Boron Treatments: Efficacy and Limitations

Both phosphonate fungicides and calcium-boron foliar feeds are important tools in managing Phytophthora root rot, but they serve different purposes and have distinct advantages and limitations. It’s not an either/or choice - in fact, they are complementary in a comprehensive management program. Below is a comparison to clarify their roles for growers:

• Phosphorous Acid (Phosphonate) Fungicide: This is a direct disease-control agent. Its primary benefit is its proven efficacy in suppressing Phytophthora within the tree. Phosphonate is currently the most effective chemical for slowing root rot in olives; it can arrest the progression of the pathogen and protect new growth when applied properly. Advantages of phosphorous acid include its systemic action (it reaches roots from foliar or trunk application), relatively low cost, and safety profile (no significant residue issues in fruit, and safe to handlers when used as directed). It also has some plant health benefits, like promoting new root initiation. However, phosphonate has limitations: it is preventative and works best if in the plant before heavy infection occurs. It will not revive roots that have already been killed, nor eliminate the pathogen from the soil. Continuous use is needed to maintain protection, and over-reliance on any single fungicide mode of action can risk the pathogen developing reduced sensitivity (though Phytophthora resistance to phosphonate has been reported only in a few cases, it’s still a consideration). Also, for certified organic olive production, synthetic phosphonate use is usually not allowed - organic growers have extremely limited options beyond cultural controls and perhaps some biofungicides (which have lower efficacy). So, phosphonate is a powerful tool, but it addresses the cause of the disease (the pathogen) rather than the tree’s weakened condition.
• Calcium-Boron Foliar Nutrition: This is a supportive treatment aimed at the tree’s health, not at killing the pathogen. The calcium nitrate + boron sprays help the olive tree by supplying critical nutrients to emerging shoots when roots cannot do so. The key advantage of this approach is that it tackles the symptoms (tip dieback, stunted new growth) and helps the tree to produce new foliage and roots despite the disease. By strengthening cell walls (Ca) and improving meristem growth (B), the foliar nutrients can reduce twig dieback and fruit drop, thus maintaining yield potential better than if the tree were left to decline. Calcium and boron applications are relatively inexpensive and can be easily combined with other foliar feeds. Crucially, they can improve a tree’s vigor, which indirectly makes it more resilient and better able to recover once the pathogen is suppressed. The limitation, of course, is that calcium and boron do not target Phytophthora at all. If used alone, they would not stop the root rot from spreading; a tree might look momentarily better as new leaves flush, but the disease could still be advancing in the roots unabated. Therefore, relying solely on nutritional sprays would be insufficient in a moderate to severe Phytophthora outbreak. Another limitation is that foliar uptake of nutrients can be affected by weather (rain can wash sprays off, very hot days can cause foliar burn or poor absorption), so timing and repetition are important. Finally, one must ensure that other nutrient needs are met - Ca and B address a specific issue, but a tree might also need nitrogen or potassium, etc., which is why a complete foliar nutrient program is recommended alongside Ca+B. 
  

In summary, phosphorous acid vs. Ca-B foliar feeds are not competing remedies but complementary ones. Phosphonate fungicide is your frontline defense to reduce the pathogen load and protect the roots. Calcium and boron sprays (as part of a broader foliar nutrition plan) are a means to nurse the tree back to health by encouraging new growth and mitigating dieback symptoms. Phosphonate keeps the disease in check, giving the tree a chance to regenerate; the CaB and other nutrients give the tree the resources it needs to actually do that regeneration. Growers have found that using both in tandem yields far better outcomes than either approach alone - phosphonate without nutritional support may stabilize the tree but leave it languishing, whereas nutrition without phosphonate lets the disease continue to destroy roots. An integrated approach is essential.

It’s also worth comparing phosphonate with the other fungicide option, metalaxyl (Ridomil). Phosphonate and Ridomil both suppress Phytophthora, but in different ways. Ridomil is more of a curative, directly toxic to the pathogen, whereas phosphonate has those immune-boosting properties. Ridomil can knock back an active infection faster, but it has a higher cost and a risk of resistance development in the pathogen population with overuse. In practice, phosphonate is often used for regular protection, and Ridomil (if used at all) might be reserved for spot-treating severe cases or as a pre-plant soil drench in known infested sites. Both chemicals require reapplication; neither provides permanent protection. Always follow an Integrated Disease Management philosophy when using these tools - they are most effective when combined with the cultural and nutritional strategies described above.

Integrated Disease Management (IDM) in Australian Olive Groves

Managing Phytophthora root rot requires an Integrated Disease Management approach, especially in Australia’s warm, high-rainfall olive-growing regions. No single intervention is a silver bullet; instead, growers should implement a suite of preventive and remedial measures that together minimise disease impact. Below is a summary of IDM practices for Phytophthora root rot in olives: 

• Start with healthy, disease-free planting material: Only source olive trees from reputable, Phytophthora-free nurseries. Inspect the root systems of new trees (if possible) - healthy roots should be white and fibrous, not brown or foul-smelling. Avoid planting olives that show any signs of root rot or cankers. This prevents introducing the pathogen to your grove.
• Select and prepare sites wisely: Prioritise well-drained sites for new olive blocks. If you must plant in a heavier soil, invest time in soil preparation (deep ripping, adding gypsum/organic matter) to improve drainage. Form planting mounds or raised beds to keep root zones high and dry. Identify any low spots in the field and address them (through drainage tiling or by simply not planting olives in the very wettest spots). Good site selection and preparation are the most cost-effective long-term defense.
  
• Optimise water management: Design irrigation systems and schedules to meet olive water needs without creating waterlogged conditions. Use drip or micro-sprinklers to localise water and avoid overspray. Regularly check that irrigation is not contributing to puddling. During rainy periods, turn off irrigation entirely. Remember that olives are drought-tolerant compared to many fruit trees; slight under-watering is safer than over-watering in Phytophthora-prone areas. Also, avoid planting cover crops or pasture in the orchard that require frequent irrigation - keep the inter-row groundcover something that can survive on minimal water.
  
• Monitor and act early: Train yourself and staff to recognise early symptoms of Phytophthora (e.g., leaf yellowing, tip dieback, unusual leaf drop or wilting that isn’t explained by heat alone). Mark suspects trees and considers taking soil or root samples for lab testing to confirm the Phytophthora species. Early detection allows for prompt phosphonate treatment and targeted drainage fixes before the problem spreads or the tree is too far gone. If one tree in an area shows symptoms, proactively treat neighboring trees - they may be infected but not yet showing severe symptoms. 
  
• Apply chemical controls as part of a program: Use systemic fungicides like phosphorous acid as preventative sprays during high-risk periods (e.g., before and during the wet season). Follow up with repeat applications as per the label to maintain protection. If a tree is identified with active root rot, consider a curative treatment (such as a high-rate phosphonate injection or a metalaxyl drench around the root zone) to immediately reduce pathogen load, then continue with routine phosphonate. Always check the APVMA permits and registrations to ensure the product and method you choose are allowed in olives, and observe any withholding periods if the grove is in production. Rotate chemical modes of action if possible to prevent resistance - although options are limited (essentially phosphonates and phenylamides like metalaxyl), do not rely on just one product year after year without guidance. 
  
• Nutritional and soil health management: Maintain adequate nutrition in the grove to avoid stressing trees. Ensure soil pH and fertility are in the optimal range for olives (pH ~6.5 - 8, adequate but not excessive nitrogen, and sufficient phosphorus and potassium based on soil tests). Stressed or malnourished trees are more susceptible to infection and less likely to recover. After flooding or waterlogging events, consider applying a broad-spectrum foliar fertiliser to give trees a boost, as waterlogging can leach nutrients and damage roots. Incorporate organic matter through mulching or cover cropping (with species that do not harbor Phytophthora) to improve soil structure and microbial diversity, which can create a more hostile environment for the pathogen. Some growers also introduce biological controls like Trichoderma or mycorrhizal fungi into the soil, aiming to outcompete or antagonise Phytophthora - while scientific results on these are mixed, a healthy soil biota generally benefits root health.
  
• Hygiene and quarantine practices: Treat Phytophthora like you would a contagious disease. Clean pruning tools between trees (a bleach or alcohol dip can kill Phytophthora on tools). After removing dead trees or doing any excavation in an infected area, disinfect equipment and even shoes - soil clinging to a shovel or tractor tire can carry zoospores across the orchard. Avoid moving water from a known infested block to other blocks (for example, don’t pump runoff water from a sick block into your irrigation dam). If possible, keep a footbath or a brush station at the entry to a sensitive grove so that visitors don’t inadvertently bring in mud. Avoid sharing equipment with other farms known to have Phytophthora issues, or insist on thorough cleaning. If you yourself have multiple orchards, visit your Phytophthora-free orchard before visiting the infested one on the same day (not after), to reduce the chance of carrying soil back. These biosecurity measures may sound tedious, but they can save you from turning a localised problem into a farm-wide one. 
  
• Resistant varieties and rootstocks: As of now, there are no olive cultivars immune to Phytophthora, but research is ongoing into relative tolerance. Some anecdotal reports suggest that certain olive varieties handle wet feet slightly better than others - for instance, hardy traditional cultivars vs. some high-oil, fast-growing cultivars - but all will succumb if conditions are bad enough. If establishing a new grove in a high-risk site, consult local olive experts or nursery suppliers about any available rootstock or clone bred for Phytophthora resistance. The olive industry internationally is exploring grafting onto rootstocks of closely related species (like wild olive) for disease resistance, but these are not yet common practice. In the future, planting resistant rootstocks could become part of IDM (as it is in the avocado industry), but for now, Australian growers must focus on the other measures. 
  

By combining these strategies, growers create multiple layers of defense against Phytophthora. Integrated disease management means you are never relying on just one method. For example, good drainage and careful irrigation make the soil less conducive to the pathogen; phosphonate treatments reduce the pathogen’s ability to infect; nutritional sprays help the tree recover faster; and hygiene stops the spread to new areas. Each component reinforces the others. This holistic approach is particularly essential in Australia’s summer-rainfall regions, where Phytophthora pressure can be high -  growers in these areas have learned that only vigilant, year-round management will keep Phytophthora root rot at bay and their olive trees productive.

Conclusion

Managing Phytophthora root rot in olives is challenging, but with vigilant management, it is possible to minimise losses and even restore affected groves to health. The keys are prevention (through site selection, drainage, and preventative fungicides) and support (through nutrition and careful cultural care for stressed trees). Australian olive growers should view Phytophthora management as an ongoing part of grove management, much like pruning or pest control, especially in regions prone to heavy rainfall. By implementing the integrated strategies outlined above, growers can significantly reduce the impact of Phytophthora root rot, protecting their trees and investment. Remember that every grove is different - monitor your olive trees closely and adapt these recommendations to local conditions, and always reference current guidelines from olive industry research and local agricultural authorities. With a proactive, informed approach, even the threat of “root rot” can be managed, and olive trees can continue to thrive and produce in the Australian landscape.

Sources: 

• Spooner-Hart, R. et al. (2005). Sustainable Pest and Disease Management in Australian Olive Production. RIRDC Publication No. 05/080. 
• Spooner-Hart, R., Tesoriero, L., & Hall, B. (2007). Field Guide to Olive Pests, Diseases and Disorders in Australia. RIRDC (eds.).
  
• Australis Plants Nursery. (2007). Phytophthora Root Rot in Olive Trees - Practical guidelinesPhytophthora Root Rot in Olive Trees
  
• Fruit Tree Lane (Australis Plants). (2023). Managing Phytophthora Root Rot in Olive Trees.
• Bailey, A., Hall, B., & Tesoriero, L. (2017). Symptoms and management of Olive diseases and disorders. The Olive Centre Blog.  
  
• Business Queensland, Dept of Agriculture. (2022). Phytophthora Root Rot – Integrated Management.
  

AgroBest is an Australian manufacturer with a wide range of crop protection and liquid fertiliser products to help keep your olive trees healthy and productive. This guide gives you a practical overview of the AgroBest range available through The Olive Centre and how they can fit into your nutritional grove program across the season. We’ll walk through foliar feeds, soil conditioners, pest and disease support products, spray adjuvants and biostimulants, explaining when to use, and how to help with common olive problems. Whether you’re dealing with nutritional needs or tired trees that just aren’t performing, this guide is designed to help you quickly match the right AgroBest product to the needs of your grove.  A soil and leaf analysis are recommended to narrow down the correct product(s).

Foliar Nutrition Products (NPK & Trace Elements) 

Foliar nutrition is critical for addressing immediate nutrient needs and boosting olive tree productivity. AgroBest offers several NPK foliar fertilisers and trace element sprays designed for quick uptake through leaves. These products provide balanced macronutrients (nitrogen, phosphorus, potassium) often enhanced with micronutrients or biostimulants to improve efficacy.

• QuickStart - A fully soluble NPK liquid fertiliser with added trace elements, formulated to support flowering and fruiting stages. QuickStart delivers a blend of nitrogen, phosphorus, and potassium along with micronutrients to ensure olive trees have the nutrition needed for abundant bloom and fruit set. It’s typically applied as a foliar spray pre- and post-bloom. (Available in 20L, 200L, and 1000L sizes.)

• Beyond Foliar - A balanced N-P-K foliar feed enriched with seaweed extract and micronutrients, aimed at improving fruit fill, tree vigour, and overall yield and quality. This liquid concentrate supplies a moderate NPK ratio along with natural growth promotants from seaweed. Olive growers use Beyond Foliar after fruit set to enhance olive size, colour, and flavour development. (Common pack sizes: 20L, 200L)

• Plant Food - A liquid NPK concentrate tailored as a young plant starter fertiliser. With a gentle, balanced nutrient profile, Plant Food encourages healthy early growth in newly planted olive trees or nursery stock. It ensures seedlings and young groves establish strong roots and foliage without the risk of burn. (Available in 5L, 20L, etc.)
  

• Agro NK - A highly available liquid combination of nitrogen, potassium, and phosphorus designed for rapid uptake. Agro NK delivers these macronutrients in readily absorbed forms, making it ideal for mid-season foliar feeding when olive trees demand extra nitrogen (for canopy growth) and potassium (for fruit development). Growers apply Agro NK to correct general nutrient deficiencies quickly and to sustain growth during critical periods. (Available in 20L, 200L, 1000L) 
• AgroCal N - A specialty foliar nutrient focusing on calcium and nitrogen for crops with high Ca demand (like olives during pit hardening). Calcium is vital for cell wall strength and fruit firmness, while nitrogen fuels vegetative growth. AgroCal N provides a chelated calcium source together with nitrogen to address Ca deficiencies in olive foliage or developing fruit, improving tissue strength and reducing problems like tip burn or fruit drop. (Available in multiple sizes, e.g. 20L, 200L)
  

• High PK - A liquid phosphorus and potassium booster formulated to stimulate flowering and fruit set in olives. High PK supplies a surge of P and K right when olive trees transition to the reproductive phase, promoting abundant flowers and supporting early fruit development. It’s typically sprayed at pre-bloom and again during fruit sizing. Adequate phosphorus ensures strong bloom and root support, while potassium enhances flowering, fruit retention, and oil synthesis in olives. (Available in 20L, 200L) 

• Green N42 - A 42% nitrogen foliar fertiliser for fast correction of nitrogen deficiency and to drive vigorous canopy growth. Green N42 is a high-analysis N solution containing urea, ammonium, and nitrate forms of nitrogen for both immediate and sustained uptake. This multi-form formulation ensures rapid greening of yellowed olive leaves and prolonged feeding to support extended vegetative growth. Growers use Green N42 in spring or after heavy rain leaching to restore N levels, resulting in lush foliage and improved shoot growth in high-yield groves. (Offered in 20L drums, 200L drums, and 1000L IBCs)

• Green N32 + Humic - A high-analysis nitrogen (32%) fertiliser blended with humic acids. This product not only provides a quick nitrogen supply but also incorporates organic humic substances to improve soil nutrient retention and microbial activity. Foliar or fertigated use of Green N32+Humic gives the dual benefit of boosting immediate growth while also enhancing soil health and nutrient efficiency. It’s especially useful in olive orchards on sandy or low-organic-matter soils, where humics aid in holding nitrogen and other nutrients in the root zone. (Available in 20L, 200L, 1000L)

• Extra Cal - A unique calcium supplement with cytokinin (plant hormone) carrier. Extra Cal delivers calcium in an organically complexed form along with natural cytokinins that help drive calcium into fruit and leaf tissues. This foliar spray is used to correct calcium deficiencies (e.g. preventing pitless olives or soft fruit) and to improve fruit firmness. The cytokinin component stimulates cellular activity and nutrient mobilisation, so Extra Cal is ideal during olive fruit sizing - ensuring better calcium uptake into developing olives for stronger skin and reduced incidence of disorders. (Typically available in 5L, 20L quantities.) 
• Trace Element Sprays (AgroBest AgroDex Range) - In addition to NPK feeds, AgroBest provides a full suite of micronutrient foliar sprays under the AgroDex line. These are chelated trace element solutions that address specific nutrient deficiencies quickly via foliar application. For example, AgroDex Boron is a high-analysis boron (B) formula complexed with organic acids for efficient uptake, used at flowering to improve pollen viability, fruit set, and aid calcium mobility in olives. AgroDex CaB combines calcium with boron and nitrogen to support fruit quality, shoot growth, and reproductive development - helpful in preventing calcium-related fruit drop and improving olive size. There are also single-element sprays like AgroDex Fe (EDTA-chelated iron) to correct iron chlorosis and boost chlorophyll production for greener leaves, AgroDex Mg for magnesium deficiency to improve photosynthesis and leaf colour, AgroDex Mn for manganese needs (critical for enzyme activation and carbohydrate production), and AgroDex Moly (molybdenum with phosphorus) to enhance nitrogen conversion and protein synthesis in the tree. For potassium, growers can choose AgroDex K-Fill, a clear non-staining potassium solution that enhances fruit colour, size and uniform ripening, or the concentrated AgroDex K35 / K45 formulas, which supply high K with organic acids to boost fruit sweetness, oil content, and crop finishing. These trace element products are typically used as foliar sprays during periods of known deficiency or high demand (e.g. postflowering for boron, summer for magnesium, etc.). All are available in convenient liquid form (usually 20L drums up to 200L and 1000L for large operations).  This range is great for dealing with specific deficiencies.

Many of the foliar nutrient products above are compatible for tank-mixing with each other or with pest control sprays, allowing olive growers to address multiple needs in one pass. By using AgroBest’s foliar nutrition range, growers can rapidly correct nutrient shortfalls and fine-tune the olive tree’s diet throughout the season, leading to healthier canopies, improved flowering/fruiting, and ultimately better yields.

Soil Conditioners & Soil-Applied Fertilisers 

Healthy soil is the foundation of productive olive groves. AgroBest offers products that improve soil fertility, structure, and microbiology - ensuring roots have access to nutrients and water. These soil conditioners and granular/liquid fertilisers are applied to the soil (via drench, fertigation, or banding) rather than sprayed on foliage. 

• Kickstart Bio 25 - A soil-applied NPK fertiliser with added trace elements and humic compounds. Kickstart Bio 25 is a humic-based starter fertiliser formulated to promote robust root development and early crop growth when establishing orchards or during spring flush. It provides a balanced mix of nutrients (including nitrogen, phosphorus, potassium and micros) in a carbon-rich humate matrix, which improves nutrient uptake and soil structure. Olive growers often use Kickstart at planting or at the start of the season to “kick start” root systems - the humic acids enhance nutrient availability and stimulate soil microbial activity, leading to stronger root biomass and better early vigour. (Available in granular or liquid form; common sizes 20L liquid or 25kg bags if granular.)

• GroMate 5-5-5 - An organic liquid fertiliser (N-P-K 5-5-5) designed for building soil health and general crop nutrition. GroMate’s balanced 5-5-5 analysis comes entirely from organic inputs, making it ideal for improving soil fertility naturally. It contributes organic matter, feeds soil microbes, and releases nutrients slowly to the olive trees’ roots. Regular applications of GroMate can improve soil structure and root strength over time. This product suits groves aiming for organic certification or simply looking to enhance soil carbon and biological activity. It’s often applied via fertigation or as a soil drench around the root zone. (BFA certified organic; available in 20L, 200L, 1000L IBC.) 

• Fish Emulsion - A classic organic bio-stimulant fertiliser made from fish extracts, rich in nitrogen, phosphorus, trace elements, amino acids, and oils. AgroBest’s Fish Emulsion is formulated to boost soil microbial life and provide a gentle nutrient release to crops. In olives, fish emulsion can be applied to the soil to feed beneficial microbes and improve nutrient cycling, or even foliar-sprayed at low concentrations as a mild feed. Growers appreciate that it improves soil tilth and root health while also supplying minor nutrients naturally. Fish Emulsion is especially useful for correcting general nutrient deficiencies in an organic-friendly way and for mitigating transplant shock in young trees. (Available in 5L, 20L, 200L; has an organic certification.) 

• CalMate - A humic acid solution designed to be compatible with calcium fertilisers. CalMate is essentially a soil conditioner that can be combined with calcium sources (like lime or gypsum, or liquid Ca) to enhance calcium availability and uptake by plants. When olive orchards have calcareous soils or when applying calcium, adding CalMate helps chelate the calcium, keeping it soluble. This results in better Ca absorption by olive roots or leaves and can improve the efficiency of calcium fertilisation. CalMate also contributes humic substances that improve overall nutrient efficiency and bolster plant resilience under stress. Olive growers might add CalMate to their fertigation mix, especially if tissue tests show calcium deficiency or if they want to ensure maximum benefit from a foliar Ca spray (the humic acid prevents tie-up and enhances translocation). (Liquid concentrate; typical size 20L.)

• Soil pH & Structure Amendments: While not a separate product per se in the AgroBest range, it’s worth noting that some AgroBest nutritionals assist indirectly with soil structure. For example, CarboCal (though often foliar) can also be applied via drip irrigation; its organic acid-rich formulation can help flocculate soil particles and improve calcium levels in the root zone. CarboCal supplies plant-available calcium coupled with over 50 organic acids, which not only feed microbes but can help open up clay soils. Improved calcium in soil leads to better soil aggregation and drainage - crucial for olives, which don’t like waterlogging. Additionally, Green N32 + Humic (mentioned earlier) contributes humic matter that conditions the soil and reduces nitrogen leaching. In summary, many of AgroBest’s products have dual roles, acting as both fertilisers and soil conditioners due to their organic components. 

Using these soil-oriented products, olive growers can address issues like poor soil fertility, low organic matter, or imbalanced nutrients in the root zone. For instance, if an olive grove is suffering from nutrient lock-up or weak root growth, a combination of humic-enriched Kickstart and organic GroMate can rebuild soil life. If soil calcium or pH is an issue, products like CarboCal can supply calcium in a plant-accessible form that strengthens soil and trees alike. Healthier soil translates to stronger, more resilient olive trees with better uptake of nutrients and water. 

Control Aids 

While AgroBest’s focus is on nutrition, some of its products also play a role in crop protection - either by directly deterring stresses or by strengthening the plant against pests and diseases. Olive growers face challenges such as black scale insects, fungal diseases like peacock spot and anthracnose, as well as environmental stresses (frost, heat) that can predispose trees to problems. AgroBest products can be part of an integrated strategy to tackle these issues.

• Envy Frost & Sunburn Protectant - A unique anti-transpirant spray that creates a protective barrier on plant surfaces. Envy is formulated with natural compounds (e.g. pine resin) that shield crops from frost, heat, and sunburn stress by reducing transpiration and forming a micro-film on leaves and fruit. In olives, late spring frosts or extreme summer heat can damage developing fruit and foliage; applying Envy beforehand helps mitigate this. For example, spraying Envy before a forecasted frost can significantly reduce ice nucleation on olive buds and leaves, preventing frost burn. It’s equally useful ahead of heatwaves to minimise sunscald on olive fruit or desiccation of leaves. While not a pesticide, Envy falls under crop protection because a less-stressed tree is more resistant to pests and disease. (This product is used in low concentrations - e.g. 1:15 or as directed - and comes in small volumes like 1L or 5L that can treat large areas given the high dilution.)

• Spraytech OIL (Organic Adjuvant) - Primarily an adjuvant (see next section), Spraytech Oil is a vegetable oil-based spraying oil that may also have some effect for  improving pesticide efficacy. Spraytech OIL is a certified organic non-ionic oil.  Additionally, if chemical control is needed (for example, mixing an insect growth regulator for scale), adding Spraytech OIL improves that insecticide’s coverage, duration, uptake, and rainfastness. This means better pest knockdown with lower risk of spray drift. In short, Spraytech OIL can assist  with spray efficacy to boost the performance of fungicide or insecticide sprays application targeting olive diseases/pests.

• Nutritional Strengthening for Disease Resistance - A key strategy in disease management is ensuring the olive tree has sufficient nutrients to maintain strong defensive structures. Several AgroBest products indirectly help with diseases like anthracnose or peacock spot by fortifying the plant. For instance, CarboCal (the calcium organic supplement) markedly improves cell wall strength and fruit robustness. Adequate calcium in plant tissues leads to stronger cell walls, greater resistance to disease and insect attack, and reduced post-harvest damage. By regularly using CarboCal or the combined Ca-B sprays (AgroDex CaB), growers can reduce incidences of anthracnose on fruit - the pathogen finds it harder to penetrate calcium-rich, sturdy fruit skin. Calcium also helps minimise olive fruit cracking and bruising, which in turn lowers infection entry points. Another example: Fuze Copper is AgroBest’s EDTA-chelated copper micronutrient spray for correcting copper deficiency. While its main role is to fix pale leaves or dieback due to a lack of copper, it can also contribute to disease management. Copper is a well-known fungicidal element; ensuring olives have sufficient copper in their tissues can bolster their natural defence against fungal diseases like Peacock Spot (leaf fungus) or Cercospora. Growers might use Fuze Copper foliar sprays post-harvest or in spring - not only to green up the foliage but also as part of their regime to keep fungal diseases at bay (complementing any copper-based protectant sprays they may use). In general, the MultiTrace products, such as Titan (with zinc, iron, copper, etc.) help “heal” a nutritionally stressed tree; a healthier olive tree will better resist pest infestations and disease outbreaks.

It’s important to note that AgroBest does not produce synthetic pesticides or fungicides - instead, their offerings focus on prevention and plant strength. For active infestations like a severe black scale attack or an anthracnose epidemic, growers would still use specific registered pesticides (e.g. a petroleum spray or an IGR for scale, or a copper fungicide for anthracnose/fungal issue). However, integrating AgroBest products could mean fewer such interventions are needed. By using nutritionals and protectants like Envy and Spraytech Oil proactively, olive growers can reduce stress and pest pressure on their groves. This integrated approach leads to a more sustainable pest and disease management, leveraging plant health to fight off challenges naturally.   Always test product compatibility before mixing.

Adjuvants and Spray Aids 

Adjuvants are “helper” products that improve the performance of agrochemical sprays - ensuring that nutrients or pesticides stick  as intended. AgroBest’s adjuvants are especially valuable in olive production, where the undersides of leaves and the waxy surfaces of olive foliage can make spray coverage difficult. Using the right adjuvant means more of your spray actually reaches the target and stays there, rather than bouncing off or drifting away. Two key adjuvant products in the AgroBest range are: 

• Spraytech OIL - This was mentioned earlier for pest control, but as an adjuvant, it’s a game-changer for spray applications. Spraytech OIL is an organic, non-ionic surfactant/oil blend derived from vegetable oil, approved for organic use. It has a unique mode of action: it encapsulates spray droplets and pesticide molecules, reducing their evaporation and protecting them from degradation (e.g. by UV light). For olive growers, this means when you mix Spraytech OIL into your fungicide, insecticide, or foliar feed tank, you get better adhesion of the spray to olive leaves (which are notoriously slick). It greatly minimises drift and off-target losses by reducing fine droplet formation. It also buffers poor-quality water - if your spray water is slightly alkaline or hard, Spraytech OIL helps stabilise the pH and prevents things like phosphates from precipitating. In practical terms, adding 0.5 - 2.0 litres of Spraytech OIL per 1000L tank can improve the coverage of a foliar nutrient spray (ensuring the tree actually absorbs those nutrients) and can enhance pesticide uptake through the leaf cuticle. This adjuvant also confers some rainfastness; sprays are less likely to wash off in the next rain event. And because it’s made from natural oils, it’s softer on beneficial insects than harsh synthetic surfactants. (Spraytech OIL is available in a wide range of sizes - from 0.5L and 1L bottles for backyard growers, up to 20L drums and 200L for large orchards .)

AgroBest AgroChelate - An organic acid concentrate used as a water conditioner, compatibility agent, and nutrient uptake enhancer. Agro “Chelate” is essentially a blend of organic acids and amino acids. When added to a spray tank or fertigation system, it acidifies the solution slightly (bringing pH to a plant-friendly level), chelates micronutrients (preventing them from reacting with other chemicals or getting locked up), and improves the mixing of otherwise incompatible inputs. For example, olive growers often want to tank-mix calcium with phosphorus fertilisers or combine multiple trace elements - this can cause precipitation or antagonism. AgroBest’s Chelate product helps keep such mixes stable and ensures the nutrients remain in a form the plant can absorb. It also acts as a mild biostimulant due to its amino acid content, so foliar feeds with AgroChelate might show improved uptake into leaves. In summary, Agro Chelate is used as an adjuvant to condition spray water (especially if it’s alkaline or hard), to prevent clogging and leaf burn, and to facilitate smooth absorption of nutrients through the leaf cuticle. It’s particularly useful in foliar trace element programs and fertigation systems. (Available in liquid form; e.g. 5L and 20L containers.)

Using adjuvants like these is highly recommended in olive spray programs. Olives have small, waxy leaves and a dense canopy; getting sprays to penetrate and stick can be challenging. By using Spraytech OIL, growers report more uniform coverage and better results from both pest control and foliar feeding efforts (the improved uptake means you might achieve desired results with lower application rates, saving cost). Similarly, with AgroBest’s chelating adjuvant, complex tank mixes become more stable - meaning you can, for instance, mix your zinc, boron, and magnesium foliar feeds with confidence that each will remain available to the tree. In sum, AgroBest adjuvants ensure you get the maximum benefit from every spray, an important consideration given the time and cost involved in spraying an olive grove. 

Biostimulants and Growth Enhancers 

Biostimulants are products that don’t fit the traditional “fertiliser” mould of simply providing N-P-K, but instead contain natural compounds (like seaweed extracts, humic acids, beneficial microbes, etc.) that enhance plant growth and resilience. AgroBest has embraced this technology by offering several biostimulant products that can give olive trees an extra edge - improving root growth, boosting stress tolerance, and increasing nutrient uptake efficiency. These are especially relevant to olives, which often face stresses like drought, high salinity, and poor soils.

• SeaFil - A fermented seaweed extract biostimulant (derived from kelp) that boosts root development, photosynthesis, and overall plant resilience. SeaFil is rich in natural growth hormones (auxins, cytokinins), trace minerals, alginates, and amino acids from seaweed. When applied to olives (either as a foliar spray or via fertigation), it acts as a general tonic - stimulating root growth, improving leaf chlorophyll content, and helping the tree cope with stress. For example, SeaFil is often used after harvest or during spring bud-break to reinvigorate olive trees, as well as in summer to help them tolerate heat and limited water. Fermented seaweed products like this have been shown to trigger defensive mechanisms in plants; an olive tree treated with SeaFil may be better prepared to resist fungal infections or recover from pest damage. The product is 100% natural and can be used in organic groves. (SeaFil comes in powder or liquid concentrate; available in small 1kg packs for making solutions, or liquids in 20L and even bulk 1000L IBC for large farms .) 

• Fulfil - An 85% seaweed ferment biostimulant fortified with plant growth regulators (PGRs). Fulfil is another seaweed-based product, but with a higher concentration of active compounds and possibly added hormones or vitamins to really drive plant responses. In olives, Fulfil is used to enhance root mass, improve flowering and fruit set quality, and increase the tree’s tolerance to stress (like drought or heavy crop load). The auxins in Fulfil encourage new root hair formation (great for nutrient uptake), while cytokinins from the seaweed promote new shoots and can improve fruit size and quality. This product might be applied at key stages like pre-flowering (to improve inflorescence health), at fruit development (to size up olives), or after any stress event (to help recovery). Growers have observed more uniform olive fruit and healthier canopies after using Fulfil, thanks to its stress-mitigating properties. 

• Trapeaze - A seaweed-based trace element and growth promotant formula. Trapeze stands out by combining seaweed extract with essential micronutrients and natural growth stimulants like betaines, auxins, and cytokinins. It’s essentially a biostimulant + foliar feed hybrid, which makes it very convenient. When you spray Trapeze on olive trees, you are both feeding them minor nutrients and triggering growth responses. The product improves crop vigour and yield by addressing any subtle micronutrient deficits (it contains a broad spectrum of trace elements) and simultaneously encouraging the plant’s own growth processes. Olive growers might use Trapeze during mid-season to keep trees in peak condition - the micronutrients prevent hidden deficiencies that could limit yield, and the seaweed hormones keep the trees actively growing and filling fruits. It’s also used post-harvest to help trees store reserves and set up buds for the next season. (Liquid product; usually in 5L, 20L sizes; can be tank-mixed with other foliar sprays.)

• Fish Emulsion & Humate Products - In addition to SeaFil and other seaweed products, recall that Fish Emulsion (described in Soil Conditioners) also acts as a biostimulant. Its content of amino acids and organic matter feeds soil biota and can improve plant immune responses. Many olive growers use fish emulsions as part of biostimulant programs, not just as fertiliser. Similarly, humic acid products like CalMate or the humic component in Kickstart have biostimulant effects - humics can stimulate root enzymes and improve nutrient uptake. These help olive trees, especially in stress conditions (e.g. a humic foliar spray during drought can help leaves retain water and keep stomata functioning). 

By integrating biostimulants into their regime, olive growers can tackle challenges like nutrient-poor soils, irregular bearing, or climate stress in a more natural way. For example, facing a scenario of “off-year” in an alternate-bearing olive grove, one might apply SeaFil or Fulfil to reinvigorate the trees and potentially improve the next bloom. In drought-prone areas or saline irrigation conditions, biostimulants help olive trees maintain growth and yield where they otherwise might suffer. These products do not replace standard NPK fertilisers but rather supplement the nutrition program by ensuring that the plant can make the most of nutrients and overcome growth hurdles. They are akin to vitamins and probiotics for your olive trees - not absolutely required, but when used properly, they often lead to healthier, more productive plants.

Product Sizes & Usage Note: Most AgroBest biostimulants are available in various sizes to suit different scales of operation - from 1-5 L bottles for small groves up to 200 L drums for large farms. They are generally applied at low concentrations (e.g. a few litres per hectare as a foliar spray). It’s important to follow recommended timing - many biostimulants show best results when applied at specific growth stages (like root flush, pre-flowering, or stress events). 

Leaf and Soil Analysis

In Australian agriculture, understanding the hidden nutrients in your soil and plants can make the difference between an average harvest and a thriving one. Leaf and soil analysis give farmers, agronomists, olive growers, and even hobby gardeners a scientific window into their crops’ health. By regularly testing both the soil and the leaves (foliage) of your olive trees or other plants, you gain precise data to fine-tune fertiliser use, correct deficiencies, and boost overall productivity. The result is healthier olive groves, higher yields of quality fruit, and more sustainable soil management - an investment that pays off in both the short and long term through improved crop performance and soil health.

• Maximise yields and quality with targeted nutrition: Soil testing takes the guesswork out of fertilising by revealing exactly which nutrients your soil is lacking (or has in excess). This allows you to apply the right type and amount of fertiliser for optimal growth and olive production, rather than relying on assumptions. With a clear nutrient report in hand, you can boost fruit yields and oil quality by ensuring trees get precisely what they need. For example, a balanced foliar fertiliser like Beyond Foliar can supply a tailored blend of NPK and micronutrients to match those needs. In short, leaf and soil analysis translates into more productive crops and better-quality harvests for you as a grower.
• Detecting hidden deficiencies through leaf analysis: A leaf tissue analysis is essentially a “health check-up” for your olive trees, showing which nutrients the plant has actually absorbed. It can uncover silent nutrient deficiencies or toxicities in the tree that might not be obvious from a soil test alone. For example, a lack of boron or calcium will never be obvious just by looking, yet it may lead to poor flower pollination, low fruit set, or reduced olive oil quality if unaddressed - issues that can be remedied once identified through testing. Applying targeted foliar solutions like AgroDex BORON (a high-analysis liquid boron fertiliser) or CARBOCAL (an organic calcium supplement) can correct these hidden deficiencies. Regular leaf analysis lets you catch these problems early and correct them before they impact your crop’s yield or quality.
  
• Protect soil health and tree vigour for the long run: Soil analysis provides a comprehensive snapshot of your soil’s fertility, measuring pH, salinity, organic matter, and essential macro- and micro-nutrients (like nitrogen, phosphorus, potassium, calcium, magnesium, iron, zinc, and more). This holistic soil health assessment highlights imbalances that can silently undermine tree growth - for instance, excessive salts or the wrong pH can lock up nutrients and damage roots. By testing regularly, you’ll spot issues like nutrient deficiencies or adverse soil conditions in time to fix them. Armed with this information, you can apply targeted soil conditioners to rebalance the field - for instance, using a natural bio-stimulant such as Fish Emulsion to stimulate beneficial soil microbes and improve overall fertility, or a humic-acid concentrate like CalMATE to enhance nutrient uptake and plant resilience under stress. In turn, your olive trees will grow in a balanced environment, leading to stronger roots, better disease resistance, and overall improved vitality in the grove.
  
• Save money and farm more sustainably: Using leaf and soil analysis can actually reduce your input costs while benefiting the environment. The data from these tests helps you avoid wasting money on unnecessary or excessive fertiliser applications. Instead of blanket-feeding your crops (which risks over-fertilising), you can target only the nutrients that are truly needed. For example, AgroBest’s own Olive Leaf Analysis and Total Soil testing services pinpoint specific deficiencies, allowing you to remedy them with a precise input - such as a quick-release foliar blend like Quickstart (a fully soluble NPK fertiliser enhanced with trace elements for flowering and fruiting) - rather than a one-size-fits-all approach. This precision not only saves you dollars, but it also prevents nutrient runoff into waterways and minimises other environmental impacts from over-fertilising. In short, you’ll be fertilising smarter - doing more with less and keeping your land and local ecosystem healthier.
  

In Summary, AgroBest’s range of products on The Olive Centre spans everything from core fertilisers to innovative biostimulants, all geared toward improving plant nutrition and resilience. By grouping products into foliar feeds, soil conditioners, protection aids, adjuvants, and biostimulants, we see that each category addresses different aspects of olive grove management: 

• Foliar Nutrition: ensures quick correction of nutrient deficiencies and fuels key growth phases (with products like QuickStart, Beyond Foliar, High PK, and the AgroDex micronutrient line). This directly tackles issues like yellowing leaves or poor fruit set due to nutrition, and indirectly helps with disease by keeping trees vigorous. 
• Soil Conditioners: improve root environment and long-term soil health (e.g. Kickstart for root establishment, GroMate and Fish Emulsion for organic matter, humic acids for structure). Healthy soil leads to stronger trees that can better withstand pests like root rot or scale infestation. 
  
• Pest & Disease Control Aids: though not pesticides, products like Envy and Spraytech Oil protect olives from abiotic stress and make pest control more effective, while nutritionals like CarboCal and Fuze Copper build the tree’s own defences. 
  
• Adjuvants: ensure every spray counts, reducing waste and enhancing uptake. Spraytech OIL and AgroChelate improve the performance of both AgroBest’s own nutrition products and any other sprays a grower uses, thereby safeguarding investment and environmental safety by reducing drift. 
  
• Biostimulants: act on the plant’s physiology to promote growth and stress tolerance naturally. Seaweed extracts and humates help olive trees cope with challenges like salinity, drought, and alternate bearing, leading to more consistent production.
  

By selecting the right AgroBest product for the right challenge, olive producers can address specific problems (like boron deficiency causing poor flowering, or scale insect outbreaks) with targeted solutions, all while improving the overall health of their groves. The technical formulations - such as chelated micronutrients, hormone-enriched seaweed, or multi-form nitrogen - ensure that these products work efficiently in the field, yet the tone of their use is conversational and grower-friendly: they integrate easily into existing programs. All products come in practical sizes (from small packs for trials to bulk containers for large orchards) and include guidance on optimal use. In a competitive olive market, maximising tree health and yield is paramount; AgroBest’s product suite provides growers with flexible tools to nourish their trees and protect their investment from some of the most common challenges like nutrient deficiencies and nutritional needs. Armed with this range of foliar feeds, soil boosters, protectants, adjuvants, and biostimulants, olive growers can craft a comprehensive, season-long program to keep their groves thriving. The result is stronger olive trees, bigger and more abundant fruit, and a more resilient orchard ecosystem - a win-win for producers aiming for both quantity and quality in their olive oil or table olive production.