By Ashley Robinson
Fusarium wilt is one of the most serious and difficult diseases to manage in watermelons and occurs in most production regions worldwide. The fungal disease can be seedborne and has great longevity in the soil, allowing the infested soil to also serve as a source of infection.
FUSARIUM WILT
Fusarium wilt has been a recurring issue for watermelon growers in the Southeast. While there is no cure, management is possible. The most successful way to manage the disease is to begin management before planting or transplanting the plant. Thankfully, there are several ways that researchers have found to control fusarium wilt.
It is important that growers start with disease-free transplants. Because the disease is seed-transmitted, it can be easily spread through infected plant trays. New or sterilized transplant trays should always be used to prevent the spread of disease.
Another effective management strategy that researchers have been looking at is using grafted seedlings. Grafted seedlings, an intentional fusion of plant parts, are resistant to fusarium wilt and tolerable to lower soil temperatures.
Other management options include fumigation programs, crop rotation, delayed planting and using varieties with resistance when possible.
WHITEFLIES
Whiteflies have been a rising concern for South Florida watermelon producers, making the pest’s management a top priority for researchers.
There are now three viruses that are transmitted by whiteflies, says Pamela Roberts, professor of plant pathology at the University of Florida Institute of Food and Agricultural Sciences Southwest Florida Research and Education Center. “They can be particularly devastating, particularly the squash vein yellowing virus (SqVYV),” she says.
In the past, freezes seemed to knock down some of the whitefly diseases. However, whitefly diseases are starting to show up again from South Florida to Georgia with more intensity.
Whitefly diseases, SqVYV in particular, have the ability to kill the entire watermelon planting.
According to Roberts, insecticide are all growers really have for SqVYV management, although researchers are trying to identify other means to manage SqVYV. “When it comes down to it, it’s hoping for a low whitefly population during the growing season and trying to keep spraying for the whiteflies to keep them off the plants,” she says.
Labeled insecticide recommendations for the management of whiteflies can be found in the Vegetable Production Handbook of Florida.