Heavy disease pressure is being seen this spring in greenhouse-grown vegetable transplants in Georgia, says David Langston, University of Georgia Extension plant pathologist.
“What generally happens is that transplant growers will try to hold back plants because they are ready to transplant before growers can use them, usually due to wet field conditions,” says Langston.
Wet field conditions correspond to heavy disease pressure in greenhouses because high relative humidity and overcast skies don't allow for the proper drying of foliage and plant media, he says.
“Another issue is the lack of effective, legal pesticides for use in the greenhouse,” says Langston. “Generally, if a pesticide is labeled in the field for a certain crop, it can be used in the greenhouse unless the label specifically prohibits its use.”
Langston recommends that growers use fans to promote air circulation and reduce humidity in the greenhouse.
“Also, use fungicides that are labeled for greenhouse use. And, thirdly, if bacteria are present, send a sample to the Tifton Plant Disease Clinic to determine if the disease will result in field losses, as would be the case with fruit blotch.”