20: Role of planting date on yellow squash and zucchini growth and yield during the whitefly season in Georgia

Georgia is the fifth largest state in the U.S. for yellow squash and zucchini production. However, an increase in the whitefly population and Cucurbit Leaf Crumple Virus (CuLCrV) appearance have resulted on yield reductions and loss of fruit quality. Alternative practices for integrated pest management is required. The objective of the study was to evaluate five planting dates for yellow squash and zucchini during the whitefly season in Georgia. Field experiments were conducted in the Tifton Vegetable Park at the University of Georgia in 2019. A factorial experimental designed of planting date (i.e., Aug. 16, Aug. 30, Sep. 16, Sep. 30, and Oct. 16) was arranged in a randomized complete design for yellow squash and zucchini. Whitefly population, and CuLCrV and silver leaf severity were weekly monitored during crop development. Yield and fruit quality were recorded. Although CuLCrV and silver leaf were observed for all planting dates, the whitefly population picked in early September. Consequently, early planting dates (i.e., Aug. 16 and Aug. 30) had 100% of plant mortality. Late planting dates were less affected by whitefly and CuLCrV; however, the cool temperatures of late Nov. and early Dec. reduced flowering and plants did not produce. The highest yellow squash and zucchini yields were measured for Sep. 16 and Sep. 30. In conclusion, early planting dates were severely affected by whitefly population, late planting dates were affected by weather conditions. Nevertheless, whitefly population varies from year to year and an additional year of study is undergoing to validate results.