The Olive Lace Bug (Froggattia olivina) is an Australian native sap-sucking insect posing a significant threat to olive groves. It specifically targets olive trees (Olea europaea), potentially reducing yields and causing tree death if left unmanaged. Olive lace bug infestation is considered a serious threat to the olive industry in Queensland, New South Wales, Victoria and across Australia.

Olive Lace Bug (Froggattia olivina) infestation on the underside of an olive leaf, showing multiple life stages 

nymphs, adults, and characteristic black excrement spots.

STAGES OF OLIVE LACE BUG 

Lifecycle

Female Olive Lace Bugs insert eggs into the tissue on the undersides of leaves, usually along the midribs. Eggs hatch into nymphs, which pass through five moults before reaching adulthood. Olive Lace Bug overwinters as eggs, with hatching typically occurring in early spring (September to October). Adults may also overwinter in protected locations on trees. Depending on climate conditions, there may be one to four generations per year, with a lifecycle ranging from 12-23 days in warm weather to up to 7 weeks in cooler conditions.

Distribution and Spread

Originally native to New South Wales and southern Queensland, olive lace bugs have spread throughout Australia, excluding the Northern Territory. The movement of olive plants and industry activities has facilitated this spread. Juvenile bugs, relatively immobile, cluster on leaf undersides and are easily spread through planting materials, workers, and tools. Adults disperse via short flights or wind

Identification and Monitoring

• Regularly inspect leaf undersides from early spring. 
• Early infestations appear as rusty-yellow spots about half the size of a pinhead on the upper surface of leaves, contrasting clearly with the dark green leaf surface. 
• Severe infestations result in leaf browning, premature drop, and twig dieback.

Damage and Symptoms

Heavy infestations significantly affect tree vigour, delaying flowering and fruiting, reducing yields for up to two seasons, and potentially causing young tree death. Mature trees can also be severely affected, with death observed in extreme cases.

Host Plants

Known hosts include native mock olive (Notelaea longifolia) and cultivated olives (Olea europaea).

Integrated Pest Management (IPM) Strategies

• Regular Monitoring: Check frequently to detect early infestations. 
• Cultural Practices: Keep trees healthy through adequate fertilisation, irrigation, systematic pruning, and canopy management. Avoid stress caused by poor soil preparation, proximity to large eucalypts, or nutrient deficiencies.
• Biological Control: Support beneficial predators such as lacewing larvae, ladybird beetles, and predatory mites. Note: Biological controls require a continual supply of the pest to be effective, which can be difficult to achieve in the long term.
• Spray Controls: Apply proven products known to be effective in the control of OLB.  See more:  Olive Lace Bug Products

Effective Spray Regime

• Spray soon after initial detection. Severe infestations may require a second treatment 10-14 days later. 
• Apply thorough coverage on leaf undersides. 
• Prune regularly to open the canopy, improving spray effectiveness and reducing pest habitat.

Long-term Sustainability

• Maintain optimal tree health with regular nutrient checks and soil testing. 
• Remove dead or unwanted branches. 
• Educate staff on proper pest identification and management techniques.

By proactively managing olive lace bug, you safeguard the health and productivity of your olive groves, ensuring sustained profitability.

Marcelo Berlanda’s “Pruning for Production” guide highlighted why olive pruning is vital to sustain yields. This article builds on that foundation, focusing on how to encourage the growth of productive fruiting wood in Australian olive groves.

Why Productive Fruiting Wood Matters 

Olive trees bear fruit on one-year-old shoots – the growth produced in the previous season. Ensuring a steady supply of these young, fruitful shoots each year is critical for consistent yields. Without renewal, canopies fill with aging wood that carries fewer leaves and buds, leading to lower productivity. Pruning is therefore geared toward a few fundamental objectives : 

• Maintain a high leaf-to-wood ratio: An olive canopy should have abundant healthy leaves for each unit of wood. Excessive old wood with sparse foliage is unproductive. Pruning removes overly woody, leafless limbs to optimise the leaf/wood and leaf/fruit balance that drives fruiting. In practice, growers aim to leave enough leaves to support developing fruit (often discussed as an optimal leaves-per-fruit ratio) while eliminating wood that no longer bears productive shoots. 
• Promote new fruiting shoots: By cutting back old branches, the tree’s energy is redirected into new shoot growth. When these new shoots receive enough light and nutrients, they will form next year’s flower buds. Regular renewal pruning prevents the canopy from “running out” of fruitful wood. As olive expert Shimon Lavee noted, a strong flush of vegetative shoots in an “off” year provides the well-developed buds that form the next year’s heavy crop. Conversely, if few new shoots grew (for example, after an exhausting “on” year), the following crop will be light. Pruning helps balance this biennial tendency by stimulating fresh shoots each cycle. 
• Maintain light penetration and airflow: Productive fruiting wood needs sunlight. Olive flower buds are more likely to differentiate (turn from vegetative to reproductive) when exposed to adequate light. A dense, shaded interior will have blind wood with dormant buds that never fruit. Pruning opens the canopy so that sunlight reaches inner shoots, enhancing their fruiting potential. Research shows that flower bud induction is improved by light - “opening the trees for effective light penetration... increases fruiting potential by enhancing flower bud differentiation”. Along with light, better air movement helps keep foliage dry and healthy (as discussed later in pest management). 
• Prevent aging and sustain vigour: As olive wood ages, it can become less fruitful and more prone to dieback. Pruning is a form of controlled rejuvenation - removing limbs showing age or senescence to stimulate new growth (renewal). This keeps the tree in its productive prime longer. A well-pruned tree “does not lose its vitality or prematurely age”. Olive trees are long-lived and capable of sprouting new shoots from old wood, so with skilful renewal pruning, even very old trees can be reinvigorated. 
• Optimise tree structure for management: Pruning also shapes the tree for efficient harvest and orchard operations. By managing height and width, growers improve harvest efficiency (whether by hand or machine) and reduce branch breakage from heavy crops. An open managed structure lets sprays penetrate and workers/equipment access the tree. All these benefits tie back to nurturing productive wood - a compact, sunlit canopy zone where fruitful shoots thrive.  

Physiology of Shoot Growth and Bud Formation

Understanding how and when olive fruiting buds form helps refine pruning practices. Unlike deciduous fruit trees, olives do not have a true winter dormancy – their buds remain in a state of quiescence and will grow when conditions permit. Flower buds initiate relatively late: studies have shown that olive buds begin differentiating into inflorescences about 2 months before bloom (around late winter/early spring in the local climate). This means the buds on this year’s spring flowering shoots were formed in the late summer or autumn of last year, on the previous year’s wood. Crucially, those buds needed sufficient resources and light while they were forming.

Several physiological factors influence fruitful bud development: 

• Last year’s shoot vigour: Shoots that grew the previous spring and summer tend to have more nodes with flower buds. Very short, weak shoots often have fewer buds, but paradoxically, excessively vigorous shoots (“water sprouts”) often remain vegetative. Research in Tunisia (2025) found that thinner, moderately vigorous shoots carried higher inflorescence numbers than very thick shoots. This suggests that extremely strong vegetative growth (often caused by heavy winter pruning or excess fertilisation) can actually reduce floral initiation, whereas controlled, moderate shoot growth produces the best fruiting wood. Growers should aim for new shoots of medium length (e.g. ~20–40 cm, depending on cultivar) with good leaf cover – these are the shoots most likely to bear olives. Very long shoots can be tip-pruned in summer to encourage lateral fruiting spurs, but excessive heading should be avoided as it may induce unwanted branching that doesn’t flower. 
• Light exposure of buds: Olive buds need light to differentiate into flowers. Buds heavily shaded by an overgrown canopy often remain latent or become vegetative. A classic recommendation is to ensure sunlight can filter to all bearing shoots, including those in the lower and inner canopy. Connor et al. (2014) emphasised that all foliage must receive at least ~20–30% of full sunlight for the critical steps of shoot growth, floral initiation, and fruiting to occur. In hedgerow orchards, the lowest parts of the canopy wall are often the limiting factor for light – if those interior shoots get below-threshold light, they won’t set fruit. Pruning strategies like thinning out dense upper branches or narrowing the canopy can increase light to these shaded buds, thereby activating more fruitful sites. As one guide succinctly puts it, “remove any part that shades other younger parts of the tree” to keep the fruiting zone vigorous. 
• Resource allocation and alternate bearing: Olives are prone to alternate (biennial) bearing, partly due to resource competition between one year’s crop and the next year’s buds. A heavy fruit load (“on” year) not only uses up carbohydrates but also produces hormones (gibberellins from seeds) that can inhibit floral bud initiation for the following year. This is why a tree laden with fruit often grows fewer new shoots and may bloom poorly the next season. Pruning can mitigate this by adjusting the crop and stimulating vegetative growth at the right time. Strategic pruning in an “on” year (e.g. immediately after harvest) helps divert some resources to new shoot development, balancing the tree. In an “off” year, lighter pruning or none may be needed so as not to remove too much of the vigorous growth that will form next year’s inflorescences. The goal is to even out the boom-bust cycle: moderate pruning annually or biennially, rather than severe pruning at long intervals, tends to promote more regular yields.        
• Bud dormancy and chilling: Unlike many fruit trees, olive buds do not require deep winter chilling to break dormancy – they can grow if conditions are favourable (hence olives can fruit in warm climates with mild winters). However, cool winter temperatures are still important to induce olive floral buds. Insufficient chilling or an excessively warm winter can lead to delayed or incomplete flower differentiation. This is more relevant to certain Australian regions (e.g. subtropical areas) where winters are mild. While growers cannot change the weather, they should be aware that a healthy complement of buds might still fail to bloom if winter conditions are suboptimal. Good orchard practices (nutrition, pest control, pruning) ensure the tree has plenty of viable buds ready; the weather then decides how many of those convert to flowers. If a spring shows poor bloom despite many new shoots, lack of chilling or even a heat shock could be factors. In such cases, focus on tree health and wait for next season – overreacting with drastic pruning is not advised.

Takeaway: Productive fruiting wood arises from a balance – neither too vegetative nor too weak – and it needs sunlight. Pruning is the tool to create that balance by removing what’s unproductive and making space for fruitful shoots under the right environmental conditions.

Pruning Techniques to Promote Renewal Wood

Having set the physiological context, we now turn to pruning methods that encourage renewal of fruiting wood. The approach will vary with the age of the tree and the orchard system (traditional vs. high-density), but several general principles apply: 

• Prune after harvest during dormancy: In Australian conditions, this usually means late autumn to late winter (e.g. June–August, depending on region). Pruning right after harvest is a common practice – for oil cultivars harvested in autumn, growers often prune in winter before the next spring growth. This timing allows the tree to heal cuts before spring sap flow, and any stimulated shoot growth will occur as the weather warms (when it can actually develop). It’s important not to prune so early that a warm spell triggers regrowth in mid-winter, which could be damaged by frost. Generally, prune by late winter, after the risk of heavy rain or frost, if possible. For table olive varieties harvested earlier, pruning might begin in early winter (June/July in Australia). Always avoid pruning in wet conditions – cutting on a rainy day can spread diseases like bacterial olive knot to fresh wounds. 
• Use mostly thinning cuts, minimise heading: A thinning cut removes a branch at its origin, opening space but not excessively stimulating regrowth. A heading cut (tipping a branch) can trigger multiple shoots at that point. While some heading is useful to lower height or induce laterals, indiscriminate heading leads to bushy water-sprout growth at the canopy tops. These vigorous shoots often won’t fruit the next year and just consume resources. The best practice is to thin out entire limbs or large shoots that are unproductive or overcrowding, and lightly head only where necessary for shape. A rule of thumb: “cut to a lateral” – i.e. remove a branch back to a fork where a healthy lateral branch can take over, rather than stub-cutting it mid-way. Thinning cuts preserve the natural balance and direct growth into existing shoots that have better light. This results in more fruitful wood and less wasted vigour. 
• Renew in stages – avoid stripping all old wood at once: Particularly on older trees, do renewal pruning gradually. Remove one major old limb (or a few) each year rather than all in one year. Avoid severe, total canopy pruning whenever possible, as it causes a huge flush of vegetative suckers and a loss of a cropping year. Research confirms that severe pruning drastically reduces the next crop and prompts excessive regrowth. Instead, practice selective renewal: identify 20–30% of the canopy (by volume) that is oldest or least productive and remove that, leaving younger wood intact to fruit. The tree will channel energy into emerging new shoots near the cuts while still fruiting on the remaining wood that year. Over 2–3 seasons, this phased approach can completely refresh an old canopy with minimal yield loss in any given year. Even in low-density traditional orchards, renewal of aged trees is commonly done piecemeal because old olive wood can still sprout if some foliage is left to “pull” sap into the limbs. In very extreme cases where trees must be cut hard (storm damage, disease recovery, or neglected groves), expect a 1–2 year recovery period before normal yields return. Fortunately, olives are resilient – with adequate water and nutrients, they can refoliate and produce on new wood by the second or third year after even a brutal topping.
• Alternate pruning zones or sides: In hedgerow (SHD/HD) systems and even large free-standing trees, it’s wise not to prune the entire tree uniformly in one go. In hedgerows, an established practice is alternate-side pruning: trim one side of the hedgerow (or every other row) in one year and the opposite side the next year. This way, each side always has some younger fruiting shoots while the opposite side is regenerating. The same concept can apply to big trees – for instance, prune some main branches this winter, and others next winter. The unpruned parts will bear fruit to compensate, while the pruned parts regrow. Never “lion-tail” a tree (stripping out all interior branches and leaving a tuft at branch ends) – instead, maintain a balance of interior and exterior growth. By alternating pruning areas, you optimise production while renewing wood. Ferguson et al. (2012) reported that this method in SHD orchards led to better annual yields versus pruning both sides in one year. 
• Remove water sprouts and suckers judiciously: After pruning (especially if heavy), olives respond with vigorous shoots from latent buds – these can be watershoots (upright epicormic shoots along trunk or branches) or suckers from the rootstock/base. These are generally nonproductive in their first year and compete with desirable growth. It’s advisable to remove most of them in summer when they are green and soft (“summer pruning” or suckering). However, note that not all watershoots are bad – if a large limb was removed, some of the resulting watersprouts near the cut can be selected and managed to become the next fruiting branches. Typically, you’d thin out the excess shoots, leaving a few well-placed ones (avoid clusters of shoots all in one spot) and maybe pinch their tips to encourage them to harden and form flower buds. A study in Argentina found that thinning vigorous watersprouts about 3 months after winter pruning improved return bloom and yield compared to just heading them. By removing the most rampant suckers and keeping moderate shoots, you tame the regrowth flush into productive wood. Root suckers (from below the graft or ground) should usually be removed entirely, as they are often from the rootstock (if grafted) or will not form part of the canopy. 
• Aim for a vase or hedgerow form with open centres: In traditional trees, the classic shape is a vase (open-centre) with 3–5 main scaffold limbs. Keeping the centre free of clutter ensures light can reach the middle of the tree. The same logic applies to hedgerows – though they are a “wall” of foliage, they must be kept porous. A Spanish study on olive crown porosity showed that different pruning treatments did not always change overall porosity dramatically, but removing inner branches and lowering canopy density are key to light penetration. An open canopy also reduces disease (more on that below). Therefore, prune with the mindset of creating windows for light and air. One practical tip is to stand inside the tree’s canopy (for big trees) or look through a hedgerow wall – you should see patches of daylight through the canopy. If you can’t, more thinning is needed. Conversely, if you can see too much daylight (the tree looks skeletal), you pruned too much, which can lead to sunburn on bark and excessive suckering. Strive for a balanced canopy – about 50% interior light interception as a rough guide, meaning a mix of sun and dappled shade internally. 

By applying these pruning techniques, growers encourage a continuous supply of young fruiting wood while avoiding the pitfalls of over-pruning. The result is a tree that renews itself gradually: always plenty of 1-year shoots ready for the next crop, and no big shocks to the tree’s system. 

Tailoring Practices to Different Orchard Systems

Olive orchards in Australia range from traditional low-density plantings to modern high-density (HD) and super-high-density (SHD) groves. The principles of fruiting wood renewal apply to all, but the methods and intensity of pruning are adjusted to each system’s needs :

• Traditional (low-density) groves: These are widely spaced trees (e.g. 6m × 6m or more) often grown as large vase-shaped forms. Here, the challenge is managing tree size and rejuvenation over decades. Typically, traditional trees are pruned lightly every year or two, with a more severe renewal pruning maybe every 5–10 years on very old wood. The focus is on opening the centre, removing dead wood, and keeping height reachable (often below ~5–6m for ease of harvest). Growers might remove a few big limbs each winter (to stimulate new shoots inside), but avoid depleting the canopy too much in one go. Because these trees can get very large, sometimes entire sections are “stumped” in rotation – e.g. cut one scaffold back to a low knob to force new shoots, while leaving other scaffolds untouched that year. Over a cycle, the whole tree gets renewed. Traditional hand-pruning is labour-intensive, so it’s done strategically where needed. In these systems, sunlight is usually not a limiting factor around the outer canopy due to wide spacing; the main shading concern is the tree’s own interior. Thus, pruning concentrates on thinning the inside and top. Also, older trees may have hollow or leggy interiors – one objective is to populate those with new shoots by cutting back into those areas (“bringing the tree back in”). This not only produces fruiting wood closer to the trunk (improving harvest efficiency) but also reduces reliance on long, drooping peripheral branches that can break. 
• High-Density (HD) orchards: These are intermediate (e.g. 200–400 trees/ha, perhaps 5m × 3m spacing). Trees are smaller than traditional but larger than SHD hedgerows. Often a central leader or vase hybrid form is used, sometimes trained to ~3–4m height. Pruning in HD systems seeks to maximise light to all sides of the tree while controlling vigour. Mechanical aids may be used (like topping or skirt pruning with saws), but hand pruning is still important to thin out centres. One practice is selective limb removal every couple of years to prevent crowding between trees. In hedgerow-like HD plantings (if trees are aligned in rows but not a continuous hedge), you ensure each tree has its space: branches extending into tractor alleys or too close to neighbours are cut back. Prune to a cone shape (wider base, narrower top) so that lower branches aren’t heavily shaded. If mechanical harvesters like trunk shakers are used, maintaining some clear trunk and strong primary branches is important (so pruning off low suckers and very weak branches that won’t withstand shaking). HD systems might adopt some SHD techniques, like mechanical topping annually to a set height, combined with periodic hand thinning. The key is regular moderate pruning – because these trees are managed for efficiency, you can’t afford the massive alternate bearing swings or overgrowth. In fact, studies suggest annual light pruning in small orchards yields better cumulative production than infrequent heavy cuts. 
• Super-High-Density (SHD) hedgerows: These are very tightly spaced rows (e.g. 4m between rows × 1.5m between trees, ~1600+ trees/ha) pruned into narrow hedges ~2.5–3m tall. Cultivars like Arbequina, Koroneiki, and Leccino are common for SHD due to their naturally compact habit. Mechanical pruning is standard – typically, oscillating blade machines trim the sides and tops annually or biennially to maintain a harvestable “wall” for over-the-row harvesters. While mechanical hedging is efficient, it can lead to shaded interior wood and a decline in fruitful shoots deep in the canopy if done improperly. To counter this, SHD management includes: alternate-side pruning (don’t cut both sides of the hedge in the same year), and occasional, more severe “skimming” or renewal. For example, some growers, every 3–4 years, will do a heavy hedge cut on one side of the row (or remove every second tree, then replant) to renew the wall of foliage. Research by Gómez-del-Campo et al. noted that horizontal canopy porosity in tightly spaced hedges can be as low as 15% in mid-canopy, versus ~37% in the less crowded upper canopy. This highlights how dense these hedges can get. Maintaining porosity (gaps for light) through pruning is thus crucial. Connor et al. (2014) advise that both sides of an SHD hedgerow should never be heavily pruned simultaneously, and that light, frequent pruning is preferable to avoid big yield losses. In practice, this might mean yearly trimming plus a rotational renewal (e.g. flail pruning one side or topping lower than usual, but staggered). SHD groves also put a premium on controlling vegetative vigour – since trees are so close, excessive growth quickly leads to shading. Growers often use regulated deficit irrigation (RDI) and moderate nitrogen regimes to keep shoot growth in check. The pruning then accentuates this, ensuring the hedge doesn’t exceed the bounds (commonly hedged to ~2m wide at base, 1m at top, like an inverted “V”). The reward for this intensive care is early and high yields, but it requires disciplined pruning to sustain. 
• Very old or neglected trees: A note on abandoned or oversized trees (sometimes found in older groves): rejuvenating these requires a special plan. Often, the best course is heavy structural pruning in stages. For instance, cut back extremely tall trees to ~3m height by removing the top third of the canopy (one portion each year over 2–3 years). Simultaneously, thin out interior suckers and apply fertiliser and water to stimulate new shoot formation. This process can essentially “reset” an old tree into a productive, smaller framework. As pointed out in the literature, renewal of olive trees is a traditional practice even in low-density orchards – old wood retains sprouting capacity if given a chance. Farmers in the Mediterranean have for centuries rehabilitated ancient trees by pollarding or scaffold replacement, proving the olive’s remarkable ability to bounce back. Just remember to sanitise tools and perhaps apply protective copper spray on large cuts (to prevent disease in those big pruning wounds, especially important in older trees that may have existing infections). 

In summary, the pruning strategy must fit the system: gentle but regular for intensive hedges, somewhat heavier but less frequent for large traditional trees, and always aimed at keeping enough young wood in the pipeline. Regardless of system, the fundamentals remain: capture sunlight, encourage new shoots, and remove what’s unproductive. 

Integrated Pruning and Pest Management 

Pruning not only influences yields – it also plays a significant role in Integrated Pest and Disease Management (IPDM). A well-pruned olive canopy is generally healthier and easier to protect. Here’s how encouraging productive wood ties in with pest and disease considerations:

• Canopy density and fungal diseases: Many olive diseases thrive in dark, moist environments. Opening up the canopy allows better air movement and faster drying of foliage, which can substantially reduce disease incidence. For example, fungi like peacock spot (Fusicladium oleagineum) and anthracnose (Colletotrichum spp.) require periods of leaf wetness to infect. A dense canopy that stays humid after rain creates an ideal microclimate for these pathogens. By pruning to increase light and airflow, leaves dry quicker, interrupting fungal spore germination. The Best Practice IPDM Manual notes that speeding up evaporation of rain or dew through improved aeration can directly reduce fungal infections. Indeed, researchers observed higher anthracnose severity in very dense SHD plantings compared to more open canopies – underscoring that porosity matters. Growers are advised to prune out overly crowded branches and perhaps even lower canopy height to what their local climate can accommodate (e.g. in humid coastal regions, a shorter tree with a very open centre will suffer less disease than a tall, bushy tree). Additionally, better light penetration enhances bud health – weak, shaded buds are more susceptible to infections like botryosphaeria (which can cause dieback). Thus, a pruning program that keeps fruiting wood in the light not only improves fruiting but also inherently defends against disease. 
• Scale insects and other pests: Pests such as black scale (Saissetia oleae) and olive lace bug (Froggattia olivinia) often reach higher populations in dense, shady canopies. The IPDM manual explains that the immature “crawler” stages of scale and lace bug survive better in cool, humid microclimates inside unpruned trees. Hot, dry conditions are detrimental to these pests (many scales desiccate in sun-exposed positions). By pruning the inner canopy and letting sunlight in, growers create less hospitable conditions for scale infestations. In effect, judicious pruning is a cultural control method: it can significantly cut down pest survival rates, reducing the need for chemical intervention. Similarly, good pruning reduces the hiding spots for other insects and allows natural enemies (parasitoid wasps, lady beetles, etc.) to move more freely through the tree. Spray penetration is also vastly improved – when you do need to apply an oil or insecticide for scale, an open canopy lets the spray reach inner leaves and branches where pests harbour. Many organic or soft pesticides (like soaps, oils, copper, and pyrethrum) rely on contact action, so coverage is critical. Pruning ensures that sprays can “cover” the target surfaces. 
• Olive knot and wound management: One downside of pruning is the creation of wounds, which can be entry points for pathogens – notably olive knot disease, caused by the bacterium Pseudomonas savastanoi. Olive knot can invade fresh pruning cuts, especially during wet weather, forming galls on limbs. To mitigate this, avoid pruning in the rain and consider protective measures for large cuts. A common practice is to spray copper-based bactericide/ fungicide right after pruning or before the next rain. Some growers also apply tree wound dressing or a latex paint on big limb cuts as a physical barrier. These precautions help limit infection. It’s also wise to sanitise pruning tools between trees (a quick dip in disinfectant) if diseases like knot or Verticillium wilt are present, to avoid spreading them. In an IPM context, pruning is timed and executed carefully: e.g. in high rainfall areas, prune in late winter when rains are easing, and treat wounds. Fortunately, productive fruiting wood tends to be smaller diameter cuts (when you renew regularly), which heal faster and pose less risk than chopping massive old limbs. So keeping up with pruning not only fosters new fruit wood but also means you’ll have fewer huge wounds at any one time.  
• Linking pruning to disease management strategies: Some cultural IPM tips explicitly involve pruning. For instance, with anthracnose, aside from fungicides, recommended actions are early harvest (to avoid autumn rains) and pruning trees to a more open canopy. With peacock spot, pruning to allow sunlight on leaves helps because UV light can suppress the fungus, and dry leaves don’t get infected as easily. Even bacterial diseases like olive knot are indirectly suppressed by faster drying (the bacteria thrive in moisture on plant surfaces). Thus, a grower focusing on productive wood (which implies a less crowded canopy) gains a double benefit: better fruiting and fewer disease issues. The Connor et al. review (2014) notes that in traditional low-density orchards, free air movement helps prevent humid microclimates, whereas hedgerow systems require careful pruning/irrigation control to avoid humidity-related disease buildup. They highlight that “narrow and porous hedgerows” achieved by pruning plus controlled water can reduce fungal problems like peacock spot and anthracnose. This aligns perfectly with IPM advice – integrate your pruning program with your pest/disease monitoring. If you notice heavy scale or sooty mould inside trees, it’s a signal to thin those canopies. If fungal outbreaks occur, consider that a sign to increase porosity and maybe lower tree density or height during the next pruning cycle. 
• Pruning and beneficial insects: Keeping some openness in the grove (and not having a tangle of watershoots) also aids beneficial insects and mites. They can navigate and locate pests more effectively in a well-structured tree. Some predators, like lacewings, prefer slightly open trees. Additionally, if you combine pruning with cover crops or intercrops for natural enemies (as mentioned in IPDM manuals ), you create an overall environment where pests are less likely to flare up. 

In summary, a sound pruning regimen is a cornerstone of IPM in olives. It reduces pest and disease pressure naturally by altering the micro-environment and improving the efficacy of other controls. Always balance the need for opening the canopy with the tree’s productive capacity – a healthy medium density (not too sparse) is the target, so that you don’t invite sunscald or stress. With those caveats, pruning is one of the most cost-effective pest management tools a grower has.

Environmental and Management Factors Affecting Wood Renewal

Beyond pruning itself, several environmental and cultural factors influence how well an olive tree can produce new, fruitful wood. Understanding these helps growers create conditions that favour the continual renewal of fruiting shoots: 

• Water availability and irrigation strategy: Olive is drought-tolerant but will not grow new shoots well under severe water stress. Adequate soil moisture during the spring and summer is necessary for shoot extension that becomes next year’s fruiting wood. However, too much water (or untimely irrigation) can fuel overly vigorous vegetative growth that, as noted, may be less fruitful. Modern orchard practice often employs Regulated Deficit Irrigation (RDI) – deliberately stressing the trees mildly at certain times – to manage vigour. For example, some SHD groves impose a dry period during early summer (pit hardening stage of the olive) to slow shoot growth and encourage floral induction. Then, irrigation is increased later to sustain the crop. This technique can result in shorter internodes and more flowering points. Connor et al. (2014) write that sustained or regulated deficit irrigation is useful to ensure high yields without excessive vegetative growth. In essence, water management and pruning go hand in hand: pruning sets the stage for how much the tree will try to regrow, and irrigation fine-tunes that regrowth. In rain-fed groves, the principle is similar – in a very dry year, the tree may barely replace lost wood, so pruning should be lighter; in a wet year (or if supplemental water is available), pruning can be a bit heavier since the tree can respond. Irrigation can also be used post-harvest to boost new shoot growth if needed (e.g. after a heavy crop year, watering after fruit removal can help push some late shoots before winter if the climate allows). 
• Nutrient status: Proper nutrition, especially nitrogen, is crucial for shoot growth and bud formation. Nitrogen applied in late winter through spring supports the development of new shoots and leaves (which ultimately carry next year’s fruit). Nitrogen deficiency will result in short shoots with fewer nodes (hence fewer potential inflorescences). On the other hand, excess nitrogen can cause rank vegetative growth and poor fruiting as the tree stays in a “growth” mode. A balance is needed – typically, commercial growers use foliar and soil tests to guide fertilisation. Phosphorus and potassium are also important for overall tree health and flowering, but N is the main driver of shoot vigour. If heavy pruning is done, a small increase in nitrogen fertiliser can help the tree refill its canopy, but it should be carefully timed (supply N during active growth, not just before dormancy). Zinc and boron foliar spraysare micronutrients worth mentioning: zinc is involved in shoot elongation (zinc deficiency leads to stunted shoots and rosette leaves), and boron is critical for flowering and fruit set. Ensuring these micronutrients are sufficient (via Heat and sunburn if needed) can improve the quality of fruiting wood and subsequent bloom. In short, a well-fed tree can better renew its fruiting wood, but avoid over-fertilising to prevent vegetative bias. Always integrate fertilisation with pruning severity – e.g., after a significant prune, don’t heavily fertilise with N immediately, or you’ll get water sprouts; feed modestly and let the tree rebuild gradually. 
• Climate stress (temperature extremes): Environmental stresses can affect both current fruiting and future wood. For instance, a severe frost can kill one-year-old shoots (either outright or by damaging their cambium), effectively destroying that fruiting wood. If a late spring frost hits just as buds burst, it can wipe out that year’s inflorescences and even the shoots, forcing the tree to push new secondary shoots (which may or may not have time to set buds for the next year). In frost-prone areas, the pruning strategy might include leaving a bit of extra wood as a “backup”. Some growers delay pruning until late winter specifically to assess frost risk – any frost-damaged twigs can then be pruned out, and some fruitful wood might be left untouched to allow a partial crop if frost was light. Mechanical harvesting (shakers or harvesters) are another concern: suddenly exposing older shaded limbs to intense summer sun (through heavy pruning) can scald the bark. This can girdle branches or invite disease. That’s why gradual opening is preferred. If a tree is pruned hard, doing it in winter helps because the summer sun intensity on the new shoots is mitigated by those shoots themselves growing and shading the bark. Also, a whitewash or spray-on kaolin clay can be used on exposed branches to reflect sunlight in the first summer after a hard prune. Wind can break vigorous new shoots if they are too long and unprotected; sheltered orchard design or windbreaks help prevent losing the very shoots you pruned to create. 
• Pests and diseases affecting wood: We’ve touched on how pruning helps prevent pests, but pests can also reduce the formation of productive wood. Defoliation by pests (e.g. a severe peacock spot infection causing leaf drop, or heavy olive lace bug feeding) will weaken shoots and often cause them to die back or fail to form flower buds. For example, if scale insects heavily infest young shoots, the sooty mould and sap loss may stunt those shoots. This reduces fruitful nodes and may require pruning out those damaged twigs. Additionally, wood-boring pests (like olive wood-borer or even trunk diseases) can kill branches, necessitating more renewal. Good IPM to control these problems means the tree retains more healthy shoots to become next year’s fruiting wood. Nutritional disorders (like acute copper deficiency, which can kill shoot tips, or boron toxicity, which can cause twig dieback) similarly affect wood renewal and should be managed via soil and leaf analyses. 
• Cultivar differences: Some olive cultivars naturally produce more or fewer new shoots. For instance, vigorous varieties like Frantoio or Koroneiki tend to sprout readily and may need extra thinning, whereas a slow-growing variety like Manzanillo might require lighter pruning to avoid reducing too much foliage. Cultivars also differ in how strongly they alternate bearing. Research has shown cultivar architecture (branching pattern, shoot length distribution) influences how we should prune. Recognise your cultivar’s habits – a weepy cultivar (drooping branches) might need cuts to upward laterals to prevent all fruit wood from hanging downward and shading itself; an erect cultivar might need opening in the interior. Tailor the pruning severity to how the variety responds. If unsure, trial different pruning levels on a few trees and observe the regrowth and fruiting. 
• Harvest method and timing: Interestingly, how and when you harvest can impact fruiting wood. Mechanical harvesting (shakers or harvesters) can cause some damage to shoots – for example, trunk shakers might break off fruiting twigs, and over-the-row harvesters may knock off branch tips. Pruning can compensate by stimulating regrowth where breakage occurred, but be mindful of harvest injury (make cleaner cuts around damaged areas). Early harvesting (picking fruit earlier in the season) is often recommended to mitigate anthracnose; it can also benefit the tree by giving it a longer post-harvest period to grow new shoots before winter. Late-harvested trees (say, very late May or June picks) have a short window to initiate new growth before cold weather, potentially limiting the next year’s fruit wood. So there’s a trade-off: waiting for maximum ripeness vs. tree recovery time. Many commercial growers find a sweet spot where they harvest as soon as oil accumulation is adequate, then immediately prune and fertilise to maximise the “rest” period for the tree to rebuild. Over the long term, this can increase the consistency of production. 

In summary, productive fruiting wood is not just about cutting branches – it’s the outcome of the whole orchard management system. Pruning is the mechanical stimulus, but water, nutrients, and overall tree stress levels determine how the tree responds. The best results come when pruning is synced with these factors: prune to shape the growth, irrigate and fertilise to support it (but not overdo it), and protect the tree from stresses that could derail the process. By doing so, growers in Australia can maintain olive canopies that are youthful, vigorous, and laden with fruitful shoots year after year.

Conclusion: Practical Takeaways for Growers

Encouraging productive fruiting wood in olives is both an art and a science. The art lies in “reading” the tree – knowing which branches to remove and which to spare – while the science lies in understanding olive physiology and applying evidence-based practices. In this follow-up to Marcelo Berlanda’s pruning guide, we have underlined the key strategies:

• Keep it light and frequent: Regular, moderate pruning (rather than drastic cuts at long intervals) keeps the tree in balance and minimises alternate bearing shocks. Little and often beats all at once. 
• Maximise light, optimise canopy: Ensure every fruitful shoot gets sunlight. Open the centre, manage tree height, and avoid thickets of unproductive wood. A rule: if a bird can’t fly through your tree, it’s too dense! 
• Renew systematically: Remove a portion of old wood each year to stimulate new shoots. Don’t wait until the tree is a solid mass of old branches. Proactive renewal is easier and more productive than drastic rejuvenation. 
• Adapt to your system: Use appropriate techniques for your grove type – whether it’s hand-pruning a gnarly 100-year-old tree or mechanically hedging a super-intensive row. The end goal is the same: a canopy architecture that supports new growth and fruiting. 
• Integrate health with pruning: Remember that pruning is also a sanitation and IPM tool. Dispose of pruned material that contains diseases or pests (don’t leave it on the orchard floor if it’s infested). Consider timing pruning after major disease periods (e.g., prune after the wet season to remove fungus-infected twigs). Always make clean cuts and protect the tree as needed. 
• Monitor and adjust: Finally, observe how your trees respond. If you pruned a block and next spring you see an overly vegetative response (excess watershoots, low flowering), adjust by pruning a bit lighter or later, or try a growth regulator on vigorous shoots, as researchers have tested (e.g., some use plant growth regulators like paclobutrazol or mepiquat chloride experimentally to temper regrowth ). If you see the opposite – weak regrowth – it might mean the tree lacked resources (perhaps it was an “on” year and depleted, or needs more nutrition/irrigation). By following these guidelines, Australian olive growers can improve the productivity and longevity of their groves. The essence of Berlanda’s message, now enriched with current scientific insights, is that pruning for production is about forward-thinking – cultivating next year’s crop wood while harvesting this year’s crop. With a sound renewal strategy, your olive trees will reward you with consistent yields of high-quality fruit and remain robust against pests, diseases, and the vagaries of climate. As always, combine advice with on-ground experience, and happy pruning for productive wood! 

Sources: This article integrates findings from peer-reviewed studies and reputable industry publications, including research by Gómez-del-Campo et al. on light and yield distribution, Tombesi and Connor on pruning and olive physiology, Rousseaux et al. on bud dormancy and flowering, and Australian olive industry resources (NSW DPI, AOA IPDM manual) on best practices. These sources reinforce the recommendations above and ensure advice is aligned with the latest understanding of olive tree management. 

Queensland fruit fly (Bactrocera tryoni), commonly known as Q-fly, is Australia’s most economically significant horticultural pest. Its widespread impact on the stone fruit, citrus, and vegetable industries is well documented. However, its interactions with olives are less widely understood and often underestimated.

For olive growers, Q-fly occupies a grey zone i.e. it is not a primary pest, yet it can cause issues in olives. Under the right conditions, it can shift from a background risk to a notable issue affecting both production and fruit quality. This article explores the current scientific understanding of Q-fly in olive systems and outlines practical implications for commercial growers.

A Highly Adaptable Pest

Q-fly is a native Australian species with an exceptionally broad host range, attacking more than 200 fruit and vegetable species. Its success stems from high adaptability and it thrives across varied climatic zones, readily shifts between host crops, and persists in mixed agricultural and peri-urban environments.

Female flies lay eggs directly into fruit, where larvae feed on the pulp. This internal feeding leads to fruit breakdown, premature drop, and entry points for secondary fungal pathogens. Population build-up is strongly driven by temperature, humidity, and host availability, with rapid increases occurring during warm, wet conditions.

Where Do Olives Fit?

Olives (Olea europaea) are generally considered a minor or occasional host for Queensland fruit fly. However, this label can be misleading.

Australian research and field observations show that:

Q-fly females can and do oviposit in olive fruit.

Larval development can occur when conditions are favourable.

Damage tends to be sporadic but can become locally significant.

Importantly, olives often serve as a late-season host. When preferred summer fruits are no longer available, olive groves can help sustain fruit fly populations into autumn, integrating them into the wider ecological landscape supporting Q-fly.

When Risk Increases

For most olive growers, Q-fly is not a constant threat, but risk escalates under certain conditions:

Olives frequently remain on trees after stone fruit and other summer crops have finished. Residual fly populations may then target olives as an alternative host.

High Population Pressure

Seasons with above-average rainfall and humidity can trigger significant Q-fly surges, increasing attacks on less-preferred hosts like olives.

Variety and Fruit Size

Larger-fruited table olive varieties tend to be more susceptible than smaller oil cultivars, likely due to greater suitability for oviposition.

Regional Context

Groves located near stone fruit orchards, citrus blocks, or unmanaged backyard hosts face substantially higher pressure. Because Q-fly is highly mobile, isolated on-farm management has limited impact.

The Real Issue: Quality, Not Just Yield

Direct yield losses from Q-fly in olives are usually modest. The more serious consequences relate to fruit quality.

Physical Damage

Egg-laying punctures (“stings”) and larval feeding cause premature softening, fruit drop, and internal breakdown.

Disease Interaction

Q-fly entry wounds create ideal infection sites for fungal pathogens such as anthracnose. This can accelerate fruit decay, increase rot incidence, and compromise outcomes during oil extraction.

Oil Quality

Infested fruit can elevate free fatty acids (FFA), introduce oxidative defects, and shorten shelf life. Even low levels of damaged fruit can affect overall oil quality in premium production systems.

Biosecurity and Market Access

Management in Olive Systems

Q-fly is opportunistic, management in olives should be integrated, cost-effective, and scaled to actual risk.

Monitoring

Start with reliable monitoring using:

• Cue-lure traps for male populations
• Protein-based traps for female activity
  
• Regular visual inspection of fruit for sting marks
  

Orchard Hygiene

Sanitation remains one of the most effective tools:

• Prompt removal and destruction of fallen fruit
• Minimising residual fruit after harvest
  
• Managing nearby alternative host plants where practical
  

Baiting and Control

Protein bait sprays targeting female flies are a proven option, especially in higher-risk areas. Their efficacy increases markedly when applied as part of coordinated area-wide programs rather than isolated efforts.

Area-Wide Approaches

Research demonstrates that Q-fly is best managed regionally through:

• Community-wide baiting
• Sterile Insect Technique (SIT) programs
  
• Biological control with parasitoids
  

Olive growers benefit significantly from participating in these broader initiatives.

Looking Ahead With A Changing Risk Profile

Climate variability is likely to reshape Q-fly dynamics. Warmer temperatures and shifting rainfall patterns may extend the fly’s active season, improve overwintering survival, and increase pressure in regions previously considered lower risk. Combined with expanding horticultural plantings that provide continuous host availability, Q-fly is expected to remain a persistent secondary consideration for the Australian olive industry.

Final Perspective

Queensland fruit fly is not the primary pest challenge for olive growers, but it is a highly adaptable opportunist within the same production environment. In most seasons, it remains in the background; in challenging seasons, it can contribute to quality downgrades, disease pressure, and market complications.

The recommended approach is not alarm, but informed awareness: monitor early, manage regionally, and recognise that olive groves form part of the broader fruit fly ecosystem rather than existing outside it.