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StumbleUponCalifornia Red Scale Degree Days
Biofix: 1st male flight (early March)
Lower developmental threshold: 53oF
|
Stage of Development |
Degree-days from male flight biofix |
|
Crawler emergence |
550 |
|
Third instar virgin females |
800 |
|
Beginning of next male flight |
1100 |
Current CRS Degree-Day Accumulations
DD as of May 20, 2013
Kern County: 896
Biofix: March 11, 2013
Tulare County: 815
Biofix: March 18, 2012
Fresno County: 797
Biofix: March 18, 2013
Madera County: 714
Biofix: March 25, 2013
Degree-Days to Complete a Generation: Approximately 550 degree-days after the males fly (the biofix) and mate with the females, the first generation of crawlers (1st instar scale) will begin to emerge. The crawler stage is most susceptible to pesticides and 1 to 3 weeks after they first begin to emerge is the optimal time to apply most pesticides. As the season progresses, the scales continue to molt and develop into 2nd instars, then at approximately 800 degree-days the females become virgin 3rd instars. This point in time is optimal for releasing Aphytis wasps because this is the growth stage that they prefer to parasitize.
Approximately 1100 degree-days after the first generation of males begin to fly, the 2nd generation of males begin fly. Each of the next three crawler generations will emerge 550 degree days after the preceding male flight. Thirty-year temperature data can be used to approximate when these events are likely to occur. Current temperature readings can then be used to adjust the model. Weekly pheromone trap counts and crawler tapes can be used to confirm that these events are happening as predicted.
Generations per year: 4 to 5 generations per year.