Plum Curculio Phenology Model

Plum Curculio Biology and Management in New Jersey Peaches

Dr. Anne Nielsen, Tree Fruit Entomologist

Dr. Clement Akotsen-Mensah, Postdoctoral Research Associate

Plum curculio (PC)continues to be a major pest of peach, apple, plum, cherry and blueberry, and can cause significant crop losses through early season scarring of the fruit. Untreated peach blocks in NJ can have >90% injury through scarring, direct fruit loss, and larval contamination of the fruit. In recent years, we have observed that more applications are needed for control to bring PC populations to manageable levels, particularly in peaches. This is because of 1) extended period of PC activity, 2) less effective insecticides, or 3) presence of the Southern population which has at least 2 generations per year.

There is a lot of seasonal variations in major plant phenological events like time of bloom and petal fall within NJ, we can use degree-day accumulation and plant phenology to better predict activity and injury. We present results from series of research conducted in the laboratory and in research plots to help unravel the population structure and (unbaited) trap based degree-day model of PC in NJ peaches. Also, pest phenological events have been determined and a degree-day model developed which is being validated in peach orchards.

Table 1. Phenological events recorded in experimental peach orchard in 2017 and 2018 peach seasons in New Jersey

Plum Curculio Management

Insecticide treatments continue to be the main management tool for plum curculio. Insecticides are applied to the whole block targeting critical phenological events such as petal fall, peak of oviposition, and emergence of the second generation. Insecticides used (Table 2) will target the adults migrating from overwintering or egg laying. The model predicts plum curculio will start migrating from overwintering sites into peach orchards at a degree-day of 88-100DD using January 1 as biofix and 10°C as lower development temperature threshold (Table 1). The peak trap capture of the overwintering population occurs within 113-176DD. The peak egg lay in peach occurs in a range of 379-402 DD.

Growers typically begin insecticide applications against plum curculio in peach at petal fall and repeat every 7 to 14 days as long as new damage appears or until 400DD in apple (post golden delicious petal fall).

Our model provides additional decision making using pyramid trap numbers and degree-day accumulations. We predict the first application (whole block) using a plum curculio adulticide (Imidan, Avaunt, Asana, Harvanta, or Apta) to occur before the peak trap capture at 113-176 DD. This application should be made as long as the phenology of the plant permits (after petal fall). A second application (using Actara, Belay, Rimon (apples)) should be made before the peak egg laying (379-402 DD) to kill eggs. Applications should continue on 7-14 day schedule if activity and pressure warrant management. If needed, application using Imidan, Avaunt, Asana, Harvanta or Apta at the peak of the second generation 900-1317 DD.

Table 2: List of insecticides that are used to control plum curculio on pome and stone fruit (Rutgers Cooperative Extension Commercial Tree Fruit Production Guide 2016)

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