North Jersey Tree Fruit and Vegetable Twilight Meeting 

Apple phenology continues to progress across New Jersey. Observations indicate that northern counties are primarily at tight cluster, while southern counties are at pink bud in early varieties.

This stage marks a critical transition in disease management, particularly for apple scab, powdery mildew, and cedar apple rust, as well as key insect management timings.

Phenology Dates by County (earliest varieties)

Figure 1: Pink Lady apple variety in pink bud. Gloucester County, NJ. Photo by Katrina DeWitt

Ambrosia Beetle:

• Ambrosia beetles have been detected in Burlington, Salem, Gloucester, and Middlesex counties
• Activity has not yet been observed further north at this time
• Observed activity is low and is not a concern

Continue monitoring traps, particularly in stressed or newly planted blocks, as activity may increase with warming temperatures.

Mating Disruption Timing:

• Codling moth (CM) mating disruption should be applied around pink
• Growers should begin preparing materials and planning applications now

• Apple phenology is progressing across New Jersey, with northern counties at tight cluster and southern counties at pink bud in early varieties
• This stage marks a critical period for apple scab and powdery mildew management, as well as key insect timings
• Apple scab ascospore maturity is increasing (~13–15%) and is forecasted to reach 25–40% over the next several days, increasing infection risk
• Fungicide applications should be applied prior to infection events, with materials selected to target both scab and powdery mildew
• In southern counties at pink, begin targeting cedar apple rust

Pear phenology has advanced rapidly across southern New Jersey over the past week. Observations made on April 2 indicate that most European pear varieties are now at early white bud, following cluster separation but prior to petal show, with some blocks progressing into popcorn stage.

Asian pear varieties are more advanced, with many blocks at popcorn stage and approaching bloom.

Figure 2. White bud/popcorn. Asian pear variety phenology. Salem County, NJ. Photo by Katrina DeWitt.

Pear psylla activity has been variable across southern New Jersey. Observations from April 2 indicate differences by county:

• Salem County: adults and eggs observed
• Gloucester County: none observed
• Burlington County: no activity observed to date
• Mercer County: no activity observed to date

Overall pressure remains relatively low in many orchards. This is likely due, in part, to recent oil applications, particularly where oil was combined with materials such as Esteem, which can suppress egg laying and early population development.

At this stage (white bud to popcorn):

• Continue monitoring for adults, eggs, and the onset of nymph hatch
• Use beating trays to assess adult activity
• Examine developing shoots and leaves for egg presence

Management considerations:

• In blocks without prior applications, or where psylla is present, consider a pre-bloom insecticide application
• Consider applying particle films such as dormant oil or Surround to deter egg laying
• With pre-bloom insecticide applications, softer materials should be used to avoid harming pollinator or beneficial insect populations
• In blocks where adults are present at low pressure, insecticide options include Esteem (up to 2 applications 14 days apart), Centaur, or Aza-Direct
• In blocks where adults are present at high pressure (more than 4 adults per beating tray), insecticide options include Apta, Assail, or AgriMek
• Insecticides should be applied prior to bloom, as use during bloom is restricted due to pollinator protection

As bloom approaches (particularly in Asian pears):

• Avoid applications that may impact pollinators
• Management focus will shift to early nymph control post-bloom

• Observations from April 2 indicate most European pears are at early white bud, with some at popcorn stage
• Asian pears are at popcorn and approaching bloom
• Pear psylla activity remains variable across counties, with adults and eggs observed in Salem County
• Reduced pressure in some blocks is likely due to oil applications, with or without Esteem
• Where oil was not applied, or psylla is present, pre-bloom insecticide applications should be considered
• Insecticide applications must be completed prior to bloom to protect pollinators
• Recent and continued rainfall is increasing disease pressure, particularly for pear scab and fire blight
• Fungicide programs should be actively maintained, with reapplication needed after significant rainfall (2 inches or more)
• Fire blight risk will increase rapidly as bloom approaches, so antibiotic programs should be prepared

Continued scouting is critical over the next 7–10 days as phenology and pest pressure accelerate.

Peach varieties across New Jersey were observed at the pink bud stage this week. Nectarines are more advanced, with the majority observed near or in bloom in South Jersey. Development is progressing steadily and will continue as temperatures warm.

Blossom infections from the brown rot fungus can occur whenever pistils are exposed, and favorable environmental conditions are present.

Infections can occur during any wetting period when temperatures are between 41 and 86°F. Optimum conditions occur with wetting and temperatures in the mid-70s. During extended wetting periods (several days or more), blossoms can be infected regardless of temperature. Infections under suboptimal conditions are generally less severe.

Blossoms and fruitlets remain susceptible until the pistil desiccates, which occurs sometime between petal fall and shuck split.

Management Considerations

• Fungicides used for control at the blossom blight stage should not overlap with fungicides used in the pre-harvest stage of brown rot
• Try to save fungicide options with low pre-harvest intervals for later in the season
• Bravo Weather Stik + single-site fungicide
• Vangard (applied at pink stage)
• Rovral (applied at full bloom)
• Flint Extra (applied at petal fall)

Initiate coverage for blossom blight starting at pink for short-petaled varieties and at 5–10% bloom for showy flowers. Refer to the NJ Commercial Tree Fruit Production Guide for recommended materials and rates.

Mating Disruption Timing:

• Oriental fruit moth mating disruption should be applied at pink
• Growers should begin preparing materials and planning applications now

Scale:

• Oil applications may be safely applied up to pink on peach
• Oil can be applied alone or in combination with insecticides, including Centaur, Sivanto Prime, and Esteem

Green Peach Aphid:

• Scouting should begin at pink stage
• Thresholds for treatment are 1 colony/tree in nectarines or 2–3 colonies/tree in peaches

• Observations indicate peaches are at pink bud across New Jersey, with nectarines more advanced and approaching or in bloom in South Jersey
• Development is progressing steadily and will accelerate with warming temperatures
• Brown rot infection risk is present whenever blossoms are exposed under wet conditions, particularly between 41–86°F
• Blossoms remain susceptible through petal fall to shuck split
• Fungicide programs should be initiated at pink to early bloom, depending on flower type, while avoiding overlap with pre-harvest materials
• Oriental fruit moth mating disruption should be applied at pink; growers should prepare materials now
• Oil applications for scale can be made up to pink and may be tank-mixed with labeled insecticides
• Green peach aphid scouting should begin at pink, with treatment thresholds of 1 colony/tree in nectarines and 2–3 colonies/tree in peaches

Continued scouting and timely applications will be critical over the next 7–10 days as phenology advances.