Target Trees: Peaches, Nectarines, Plums, and Cherries

Post-harvest is the critical timing window for borer control. Most adult flights have peaked; eggs are laid, and newly emerged larvae feed near the surface before tunneling deep into the cambium.

Biology & Key Differences

• Peachtree Borer (PTB): 1 generation per year. Attacks the trunk from a few inches above the soil line to slightly below ground.
• Lesser Peachtree Borer (LPTB): 2 generations per year. Attacks upper scaffold limbs and branches, often invading areas compromised by Cytospora canker.

Application Essentials

• Timing: Apply immediately post-harvest. Waiting longer allows larvae to penetrate deep into wood, where sprays cannot reach.
• Volume & Coverage: High volume is essential. The lower trunk and soil line (or scaffold limbs with cankers for LPTB) must be thoroughly saturated/drenched, usually requiring a dilute handgun application.
• Management Options:
  • Chlorpyrifos: Historically, the standard drench, restricted strictly to post-harvest to avoid fruit residue. Note: Due to regulatory phase-outs, availability is limited. Warhawk is one trade name that may still be available. If a dormant or delayed-dormant application is made, an additional trunk application in the same year is prohibited.
  • Pyrethroids: Various pyrethroids are labeled for borer control as alternatives, though high spray volume directed to the trunk and lower limbs remains key to efficacy.
  • Mating Disruption: Mating disruption (applied in spring) is highly recommended as an effective alternative to pesticides.
  • Trunk Painting: White latex paint applied to the lower trunk before egg laying can reduce infestations. This can also help reduce southwest injury and control injury caused by fluctuating temperatures.

Target Trees: Peaches & Nectarines

Taphrina deformans overwinters as spores on bark and bud scales. Infection occurs during bud swell in late winter when rain washes spores into expanding buds.

Management Strategy

• Timing: A single fungicide spray applied either in fall after 100% leaf drop OR in late winter strictly prior to bud-swell.
• High-Efficacy Recommendations:
  • Chlorothalonil (Bravo, Echo) or Ziram: Provide near 100% control in research trials (e.g., RAREC studies in Bridgeton, NJ). Ferbam is also highly effective.
• Fixed Coppers & Dual-Purpose Strategy:
  • Standard fixed coppers (e.g., Champ) provide fair-to-moderate leaf curl control on their own. Newer copper formulations (Kocide 3000, Nordox, Cueva, Badge X2) are also widely used.
  • Dual-Action Tip: On varieties susceptible to Bacterial Spot, use copper/bactericide formulations applied pre-bud-swell in spring (rather than fall). This timing leaves copper residue to reduce epiphytic bacterial spot inoculum right as trees enter bloom while still controlling leaf curl.

Target Trees: Plums & Cherries

Bacterial canker invades trees through leaf scars, pruning wounds, and trunk damage during cool, wet fall weather, causing dark sunken cankers and amber gumming.

Spray Schedule & Efficacy

• Application Timing: Apply sprays targeting leaf drop events when open leaf scars leave the tree vulnerable.
  • Standard Program: 2 sprays applied at 10% leaf drop and 80% leaf drop.
  • High-Pressure Orchards: If canker has been a severe problem in the block, apply up to 4 sprays at 14-day intervals through the leaf drop window.
• Recommended Products:
  • Bordeaux Mixture (M1 + M2): Rated ++ (Fair) for bacterial canker.
  • Fixed Copper (M1): Rated ++ (Fair) at labeled rates.
  • REI: 12 to 48 hours, depending on product formulation.

Target Trees: Tart, Sweet, and English Morello Cherries

Cherry Leaf Spot attacks leaves, stems, and fruit. It overwinters in diseased leaves fallen on the orchard floor, discharging sexual spores (ascospores) around bloom before spreading exponentially via rain-splashed conidia.

Key Symptoms & Risks

• Early Signs: Small red-to-purple circular spots (1/8–1/4 inch) on the upper leaf surface, developing whitish, felt-like spore patches on the undersides during wet weather.
• Defoliation Risk: Severe infections turn leaves yellow and cause premature drop. Defoliation before or during late summer starves the tree, leaving buds and wood highly susceptible to winter injury, dead spurs, and limb dieback the following spring. Goal: Trees must retain leaves through September.

Fall & Post-Harvest Management

• Mechanical Sanitation (Fall Action): Rotary mow orchard floors after leaf drop. Flail or rotary mowing hastens the decay of fallen leaves, significantly reducing overwintering inoculum levels for the upcoming spring.
• Fungicide Program: While primary spray programs begin at the bract leaf stage during bloom, two post-harvest fungicide sprays are recommended to protect the green canopy into early autumn and prevent premature defoliation. Captan 80WDG, Indar 2F, Rally, and fixed Copper.

Target Tree: Apple

Apple scab begins attacking leaves and young fruitlets during the primary scab phase in early spring. If infection has taken hold, further infections can occur as secondary scab throughout the entire growing season during wetting events. If you have noticed scab infections in your orchard this season, it is a good idea to consider sanitation practices to reduce inoculum heading into next season.

Fall Management

• Mechanical Sanitation: Rotary mow orchard floors after leaf drop. Flail or rotary mowing hastens the decay of fallen leaves, significantly reducing overwintering inoculum levels for the upcoming spring.
• Urea Foliar / Ground Application: Apply urea at 40 lb/A in 100 gal of water to accelerate leaf litter breakdown:
  • On-tree Application: Can be applied directly to trees via airblast sprayer if leaves are expected to drop within 7 days.
  • Ground Application: Apply to dropped leaves using an herbicide strip sprayer or an airblast sprayer directed toward the ground.
  • Combined Approach: Combining urea applications with post-drop rotary mowing yields the maximum reduction of spring scab inocula.
• Organic & Homeowner Cultural Controls:
  • Mowing & Compost: Raking or mowing leaves and spreading a light layer of compost accelerates natural decomposition.
  • Canopy Pruning: Pruning to open the canopy improves sunlight penetration and air movement, speeding drying times and reducing fungal infection windows.

Target Trees: Apple & Pear

Even if spring fire blight pressure was low, inspecting orchards for overwintering cankers in late fall and winter is critical to prevent bacterial outbreaks next spring.

Symptoms & Biology

• Visual Identification: Look for dead, darkened shoots with dried brown leaves that remain firmly attached to the branches long after normal leaf drop.
• Overwintering Threat: Cankers appear as dark, sunken, or cracking “scorch marks” on the bark. The Erwinia amylovora bacteria overwinter at the margins of these active cankers. In spring, warm rain causes these cankers to ooze bacteria, which insects and rain splash spread to open blossoms.

Management Strategy

Fire blight cankers are easiest to spot in late fall after normal leaf drop, but actual cutouts should be conducted during late winter dormant pruning while the trees and bacteria are inactive.