Weekly Field Update – 9/21/20

Posted on September 21, 2020 by Justin Ballew

Coastal

Zack Snipes reports, “Cooler temperatures have finally arrived in the Lowcountry! We had a good bit of rain in certain areas last week and some fields are soggy. I saw lots and lots of silverleaf disorder in squash this past week. Silverleaf disorder is caused by whiteflies. The nymphs of the whitefly feed on the newly developing tissue which causes the upper epidermis of the leaf to separate thus giving the plant a silver appearance. I am still seeing heavy whitefly pressure in most crops throughout the Lowcountry so keep up with spray programs and remember to ROTATE chemistries. For more information on the whitefly, click here.

Silverleaf of squash is a symptom of whitefly feeding. Photo from Zack Snipes.

Whitefly feeding damage on collards. Photo from Justin Ballew.

Midlands

Justin Ballew reports, “These cooler temperatures that have arrived following the rain feel great, but they are going to slow crop development some. Folks are already picking fall brassicas, though some may be a little small. Just trying to keep up with demand. There are plenty of caterpillars out there. I’m seeing diamondback moths (of course) as well as cabbage loopers and a few corn earworms. Be sure to rotate your insecticides when spraying for caterpillars. Folks are continuing to prep fields for the rapidly approaching strawberry season.”

Cabbage loopers are showing up. Loopers frequently rear up like a cobra when disturbed. Photo from Justin Ballew

Sarah Scott reports, “Heavy rains, in some areas totaling near 6 inches, fell around Aiken and Edgefield Counties last week. Rain was definitely welcome, however, the downpours led to some erosion issues as well as waterlogged soils in low spots. Brassica crops are benefitting from the cooler temperatures. Peach season has ended and post-season cleanup has begun. Plastic has been laid for fall plantings of strawberries.”

Eggplant is looking good. Photo from Sarah Scott.

Pee Dee

Tony Melton reports, “Rain, rain, rain. It came quickly, so most drained off quickly, if drainage was adequate. Need to dig sweet potatoes as quickly as possible to keep down the amount of rot. Greens, pickles, and peas are struggling to survive the rain – some are drowned. Ponds are back in the fields. Some strawberry plastic is already down but the rest of the folks are just beginning this week. Transplants are scarce and most likely will be late getting here this year.

Upstate

Kerrie Roach reports, “There has been a significant rise in wine grape production interest over the last month or two in the Upstate. Each week seems to bring another caller asking for recommendations. While climates here are relatively good for grape production overall, high humidity and heat make disease control difficult. Pierce’s Disease is one of the deadliest to deal with; prevention requires intense insect vector control and control means the complete removal of the affected plant. Recent studies have brought new cultivars to the forefront which are helping southern growers become more successful in this niche industry.

‘Traminette’ with leaf scorch symptom of Pierce’s Disease. Photo from Kerrie Roach.

‘Traminette’ with a dead leaf petiole still attached to the vine. Another symptom of Pierce’s Disease. Photo from Kerrie Roach.

‘Traminette” with Pierce’s disease showing islands of green tissue surrounded by brown. This specific grower has already disposed of the affected vines, and will be replacing with newer more resistant cultivars. Photo from Kerrie Roach.

Field Update – 5/20/19

Posted on May 20, 2019 by Justin Ballew

Statewide: Dr. Guido Schnabel reports, “Green fruit rot is starting to show up in commercial peach orchards. This disease is caused by the fungus Monilinia fructicola. In spring we had an extended period of bloom with lots of rain. That led to blossom blight caused by the same fungal pathogen. Growers must take this disease very seriously as it can cause significant preharvest and postharvest fruit rot. Many take advantage of our lab service to determine potential weaknesses in fungicide spray programs. For more information contact your local county agent or Dr. Schnabel directly at schnabe@clemson.edu.”

Green fruit(*Monolinia fructicola*) rot on a peach. Photo from Dr. Guido Schnabel.

Coast: Zack Snipes reports, “We have had nice warm weather that is helping the development of irrigated crops. We are starting to get dry and could use some rain for dry land crops and to settle dust. We are in the middle of squash and cucumber harvest. We are starting to see powdery mildew show up on cucurbit crops. The tomato crop looks promising this year despite the usual bacterial wilt common in fields. To test for bacterial wilt, select a wilting plant, cut it through the stem, and put into a jar of water. If the pathogen responsible for bacterial wilt is present (Ralstonia solanacearum), you will get what’s known as bacterial streaming which is a milky white stream coming from the cut end of the plant.

Bacterial wilt ( *Ralstonia solanacearum*) on tomato. Photo from Zack Snipes

Powdery mildew on squash leaf. Photo from Zack Snipes.

Midlands: Justin Ballew reports, “The weather this past week was pretty mild, but dry. Thrips have become a problem in strawberries in some areas, but we are so close to the end of picking that most growers would not benefit from a treatment. Production has really decreased and some growers have already begun redirecting picking labor to other crops. Spring planted squash and peppers are starting to come into production and everything is looking pretty good. Keep an eye out for spider mites on tomatoes as it gets hot and stays dry this week.

Peppers are developing well in the midlands. Photo from Justin Ballew

Sarah Scott reports, “We have begun picking early varieties of peaches across the Ridge. Things are looking good for a nice crop this year. Green fruit rot (Monilinia fructicola), also known as brown rot, has shown up in a few spots around the Ridge. We are continuing to monitor stink bug populations in orchards. Traps have shown high numbers of insects but damage has been scattered in this area.