Beware of Bacterial and Fungal Pathogens in Increased Rainfall

By Breanna Kendrick

Nicholas Dufault, assistant professor and Extension agent in the Plant Pathology Department at the University of Florida, researches management of diseases affecting vegetable crop production in Florida.

“With all the rainfall, the biggest thing we want to pay attention to is the movement of fungal and bacterial pathogens,” said Dufault. “Fungal and bacterial pathogens will be a big issue, especially for seedlings that were just planted. For instance, in peanuts and cotton that are going into the ground now, we might see more seedling disease issues.”

According to Dufault, seed treatments usually will take care of most disease issues, but sometimes when there is a lot of stress from moisture, the treatments do not last long enough. There are applications that can be applied, which vary depending on the crop. “It’s great to consult local Extension agents about specific crops and what you are interested in and what you can apply to them,” said Dufault.

For other crops that are already planted — like watermelon, corn and other forage crops —fungal and bacterial issues can appear after rainfall. Maintaining management programs could be very useful before and after the rain.

The biggest issue right now in watermelons has been downy mildew, which tends to take up a lot of Dufault’s focus. “Probably one thing that a lot of people don’t think about is our cooler season pathogens may still show up a little bit more than what we’ve seen in the past,” he said.

Fusarium wilt in watermelons could still be a problem because of the cloud coverage and lack of sunny days, added Dufault.

“With corn crops, we also need to pay attention to what is going to happen with some of our foliar pathogens and see if they show up earlier or not,” said Dufault. “Just because we’ve had rain doesn’t necessarily mean that the foliar pathogens will be there. Scouting is going to be key for everybody. Going out and scouting and making sure you know what’s going on out in the field and what’s present before you make a decision on what you want to do for management will be very key.”

Dufault said growers should stay ahead of the diseases; don’t let them get ahead of you. “The main thing everyone should be doing is scouting and striving to stay one step ahead of issues that may arise,” he said. “Getting the right diagnosis and the right products out is vital to assuring you take control of your crops. Missing management applications anywhere from five to 14 days could lead to a significant increase in disease if the environment is right for those pathogens.”

Besides scouting for diseases, growers should keep an eye out for stressed plants, advised Dufault. He said stressed plants can sometimes look like diseased plants. Growers who need assistance should contact a local Extension office.