Dealing With Plant Stress in the Garden
Most any garden plant will ‘wilt’ in the sun or shade during periods of extreme high temperatures in this part of the state, but is this a sign of something more than the heat?
“The cooler temperatures of the early morning and late afternoon will not alleviate stress signs from disease.” Explains Duplin/Sampson Area Horticulture Extension Agent Tom Hroza. “In a diseased plant, wilting usually occurs suddenly and to the whole plant, one day it looks just fine and the next day its completely wilted. Disease can also cause leaves to roll up and this will usually occur over a few consecutive days.”
When wilting occurs soil diseases (fusarium or verticullium wilts) are usually the reason. These diseases clog up the parts of the plant that transport water and nutrient between the leaves and the roots. Unfortunately there is usually nothing we can do about it except to pull up the infected plant and dispose of it. Horza stressed not to compost disease plant matter as this serves to help spread such viruses. Most of these soil diseases have developed over the years because of the long history of tobacco production in eastern North Carolina.
“Tomatoes, peppers, potatoes, okra and eggplants are in the same family as tobacco. These diseases last for a long time in the soil so we need to practice a long crop rotation (4-6 years) This means we are to plant a crop other than the tomato family for 4-6 years before we come back with tomatoes,” Hroza said. Suggested rotation examples might be beans, corn, sweet potatoes, cabbage, collards, etc.
“Another way to help control these diseases are to plant resistant varieties. These may include Bella Rosa, Amelia, Primo Red, and BHN varieties. Unfortunately most stores do not carry these varieties, so you will have to grow them from seed.” Explained Hroza. Better Boy, Celebrity, Rutgers are varieties that usually have no resistance to our soil diseases, he added and encourages gardeners to read the seed catalogs and talk to successful tomato gardeners to find out what varieties they grow and where or how they get their plants.
“If your tomato leaves start rolling up, the cause could be cultural or environmental, meaning something to do with water, fertilizer, cultivating and wind or it could be an insect that is doing damage to the plant such as sucking or chewing,” Hroza said. “This action could also lead to a virus being transmitted to the plant by the insect. The other cause could be herbicide damage from either drift or absorption through the roots. The easiest way to avoid this is to spray at the correct time of day when the wind is as close to calm as possible with the least amount of pressure and the lowest boom setting to accomplish the job.”
In conclusion, Hroza encourages gardeners to plant their favorite varieties, but also make room for newer, more resistant varieties each year, too and keep gardening.