Based on our degree-day (DD) model for Sparganothis fruitworm, flight initiation and first eggs laid events are expected at around 596 and 681 DD, respectively (see chart). As of June 18, Sparganothis has accumulated 661 DD (using April 15 as biofix; a biofix more realistic to New Jersey practices). Based on the April 15 biofix, flight has been initiated and eggs should start to be laid soon. However, we do not expect peak flight and those eggs to start hatching until the end of next week. Larval injury to fruit usually begins after the eggs hatch. If treatment is required (based on pheromone trap counts), sprays should be done 10-14 days after peak moth captures, ca. 7-11 July. If Sparganothis pressure has been high, it may be advisable to treat 3 weeks after the moth flight began (i.e., around 1-4 July) and again 10 days later. When bees are present your option is to use an insect growth regulator such as Confirm or Intrepid. Our “standard” recommendation has been, however, to wait until bees are removed to apply an insecticide. Your post-bloom options include Diazinon, Altacor, Delegate, Exirel, or Intrepid. Timing of insecticide application is critical; so, if needed, do not wait too long to manage this pest. I will continue to provide weekly updates to see if these estimated dates change as the season progresses.
Sparganothis fruitworm degree-day model
