Host resistance and applied practices against whitefly-transmitted virus complex in the southeastern US

The abundance of host crops and optimal weather conditions during the fall growing season allow for the buildup of sweetpotato whitefly populations (Bemisia tabaci) and viruses transmitted by them in squash in Georgia, USA. Although not sustainable, growers rely extensively on insecticides for managing whiteflies and, indirectly, whitefly-transmitted viruses. Field experiments were conducted from 2019 to 2021 to assess the effect of cultural practices: type of squash (zucchini or yellow), UV-reflective plastic mulch, planting dates, and insect exclusion netting (IEN) on whitefly abundance and virus incidence. In multiple field trials, whitefly abundance and virus incidence between zucchini versus yellow squash were compared. While whitefly abundance did not vary between squash-type, the virus incidence was lower in zucchini than in yellow squash. Further field trials indicate that whitefly abundance and virus incidence were lower in yellow squash planted on UV-reflective mulch than on white plastic mulch. Yellow squash planted between mid-August to mid-September had higher virus incidence compared with squash planted before or after this period. The use of IEN resulted in significantly lower whitefly abundance and lower virus incidence compared to squash plants that were not protected. These findings demonstrate the importance of cultural practices in reducing whitefly populations and viruses transmitted by them in squash in Georgia.