David Owens, Extension Entomologist, owensd@udel.edu
The week of April 21-28 saw our first captures of male San Jose scale in pheromone traps in all three orchards in which we have traps. Trap captures are used to set a ‘biofix’ to begin accumulating degree days. First generation crawlers emerge between 300-350 degree days, base 50. This is generally around 30 days after male trap capture. If you had San Jose scale spotting on 1% or more of fruit last season, control measures are recommended. Exact timing can be achieved by monitoring for crawlers using dark double-sided tape on infested branches twice per week. Crawlers are bright yellow.