The Sparganothis Moth (Sparganothis sulfureana) is an important pest of cranberries in the Northern United States. Overwintered larvae emerge in spring and begin to feed on foliage, before developing into adults and reproducing. Typically, the second generation of Sparganothis moth larvae cause the most economic damage to cranberries, because in addition to leaves, these larvae feed on developing fruit which directly decreases yield. Larvae are also able to protect themselves from sprays by getting inside the developing fruit, making the timing of insecticide sprays very important, to coincide with emergence from eggs. The Sparganothis Moth Growing Degree Day Model, developed by University of Wisconsin-Madison researchers, and available on the Pest Prophet app, is a very useful tool for timing insecticide treatments to target but first and second generation larvae.
Sparganothis Moth Life Stages
March 1st is typically used as the biofix (starting point) for Sparganothis Moth growing degree day accumulation. Using this day as a starting point, cranberry growers are able to predict when overwintered larvae will reach different life stages. To calculate the Sparganothis Moth growing degree days, a lower threshold of 50 F, and an upper threshold of 86 F is used. this can be calculated from daily high and low temperatures on a field, or the Pest Prophet app can be used to determine hourly temperature data and automatically calculate and track the GDD accumulation. Using Mar 1st as a biofix the following life stages can be estimated using GDD:
Life Stage Events:
- Flight Initation – 596 GDD (F)
- First Eggs Laid – 681 GDD (F)
- Peak Flight – 884 GDD (F)
- First Eggs Hatched – 896 GDD (F)
- End of Egg Laying – 1634 GDD (F)
- Last Egg Hatched – 1890 GDD (F)
Based on this, the best time for insecticide applications to control second generation larvae during egg hatch is between 895 and 1,890 GDD (F). Spraying earlier may result in low amounts of larvae being affected, and spraying too late could result in larvae being protected inside fruit.
Adjusting the Biofix Date
For improved accuracy, the Sparganothis Moth growing degree day model can be used in conjunction with regular scouting and trapping with pheromone lures. The results of trapping and scouting should be used to re-calibrate and adjust models, which will provide better accuracy and precision over using March 1st as the biofix date, especially during years with abnormal winter weather.
Traps should be placed in spring and checked regularly. When adult moths are consistently caught, the date of the first consistent catch should be used as the new biofix date. From this point it will be about 85 GDD (F) until the first eggs are laid and between 299 and 1294 GDD (F) will be the optimum window for insecticide sprays to control the second generation larvae.This can be adjusted automatically in the Pest Prophet app by choosing “Flight Initiation” as the corresponding stage for the biofix using the first sustained adult catch date.
English 
Spanish