David Owens, Extension Entomologist, owensd@udel.edu
Plum Curculio
Plum curculio has been active. If you have had problems with them in the past, consider scouting for them and treating for them at peach shuck split. Branches can be jarred and jostled over a white sheet to knock beetles off. This may have the added advantage of dislodging stink bugs which can also be a significant pest of small fruit. If you treat for plum curculio, Avaunt is a good material that is also active on worms, but it needs to be ingested. The neonicotinoids are also extremely effective, but have anti-feedant properties, thus they should be used after Avaunt (or Avaunt should not be used after neonics). Organophosphate insecticides and Neonics can destroy larvae already present in fruit.
There are several other materials that have efficacy on plum curculio but are probably best used when targeting other pests. These (and the above notes) are discussed in great detail in this Michigan State University article: https://www.canr.msu.edu/news/effectively_controlling_plum_curculio_in_stone_and_pome_fruits.
San Jose Scale
Apples began blooming a week to a week and a half ago. In years past, this would be when we would have caught our first San Jose Scale in pheromone trap. This year, we do not have any San Jose Scale pheromone traps out. If you had the red spots indicative of scale feeding on the fruit, or if you see large numbers of scale on the branches, you may want to consider scale management later this spring, especially if they were not treated with dormant oil before now. The pheromone traps help kick off a degree day model for timing when crawlers should be active. Using a base temperature of 51F, maximum temperature limit of 90F, and a hypothetical start date of April 15, crawlers should be active in 600-700 degree days. You can use NEWA’s weather tools to easily calculate and forecast the degree day target: https://newa.cornell.edu/crop-and-pest-management/