Cranberries are starting to bloom. If insects have been effectively managed prior to bloom, we recommend no sprays at this time. A reminder: when bees are present your only choices of insecticides are insect growth regulators (IGRs) such as Intrepid 2F or Bt products such as DiPel.
During bloom we recommend monitoring insect populations using pheromone traps. Pheromone traps should be used particularly to monitor activity of Sparganothis fruitworm and blackheaded fireworm, two key pests in New Jersey.
Degree-day model for Sparganothis fruitworm
Figure 1 shows life history benchmarks of interest for Sparganothis fruitworm and associated degree-day (DD) estimates from March 1(Shawn Steffan, USDA-ARS/University of Wisconsin-Madison). Flight initiation is predicted around 595 DD, at a lower temperature threshold of 50°F. Based on this model, Sparganothis has accumulated (starting April 15) 521 DD, meaning that flight should start in about 3 days in our region.
Fig. 1. Sparganothis fruitworm degree-day model
