Field Update – 6/15/20

Statewide

The video below is from Vegetable Weed Specialist Matt Cutulle. It shows a flame weeder attachment killing weeds around the edges of a field. The person walking behind the tractor is using a flame weeder with a propane tank on his back. These are good options for weed control in organic fields.

Coastal

Zack Snipes reports, “It’s the time of year when crops are starting to look ugly.  We are in the middle of tomato harvest and it seems to be a pretty good crop this year.  Bacterial spot is starting to spread up the plants due to a heavy fruit set, perfect weather, the inability to spray, and constant handling by pickers. Keep up with spray programs as the last few weeks of development are critical to size and taste.  Rabbiteye blueberries are coming in strong right now and look really good with the occasional berry having Exobasidum. Stink bug pressure has been very high this year and I’m seeing damage on a multitude of crops.”

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It is critical to know the difference between Southern Blight and Bacterial wilt when managing tomato diseases.  Southern Blight will have a white fungal mat with small “BBs” on the stem. Photo from Zack Snipes.

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Bacterial wilt shows up in the same fields year after year. Photo from Zack Snipes.

Rob Last reports, “In our area, we are seeing some good quality watermelons and cantaloupes coming to harvest.  We are seeing some manganese toxicity related to low pH in both crops.  Also given the sporadic storms we have seen leaf potassium levels have been lower than ideal.  It would be recommended to monitor tissue nutrient levels and adjust fertilizer applications accordingly.”

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Manganese toxicity on cantaloupe leaves appears as round, tiny, tan spots, sometimes with a yellow halo.  This symptom can be misdiagnosed as early downy mildew. Foliar analysis can be used to diagnose Mn toxicity. Photo from Dr. Tony Keinath.

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 On the leaf underside, the halo appears water-soaked (“greasy”). This symptom can be misdiagnosed as early downy mildew. Foliar analysis can be used to diagnose Mn toxicity. Photo from Dr. Tony Keinath.

Midlands

Justin Ballew reports, “We got a little much-needed rain last week. Crops are developing quickly and growers have started harvesting the oldest planted sweet corn as well as squash, zucchini, cucumbers, beans, and what’s left of spring brassicas. Cucurbit downy mildew has not yet been found in the midlands, but it probably won’t be long. Keep applying preventative fungicides.”

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Zucchini almost ready to be picked. Photo from Justin Ballew.

Sarah Scott reports, “Peach season is in full swing. Bacteriosis and brown rot continue to show up in many fields. Warm temperatures during an extended bloom period as well as rain and cold at critical times in the early season are likely the culprits for these issues.”

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Bacteriosis on ripening peach. Photo from Sarah Scott.

Pee Dee

Bruce McLean reports, “Cucumbers are being harvested in good numbers. Squash and zucchini yields are increasing. Sweet corn will be ready to begin harvest in a few days. Disease pressure is increasing in cucumbers, primarily Cucurbit Downy Mildew (CDM). CDM has caused significant damage and severely reduced the crop in two locations. Forecasted rains for the next 7-10 days will make it extremely difficult to spray fungicides (as well as applying insecticides, herbicides, and fertilizer). Fruit crops are being negatively impacted by the weather, as well. Reduced fruit quality is caused by increased disease pressure and wet field conditions. And, the forecast over the next 7-10 days is for more rain.”

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Checkerboard pattern indicative of Cucurbit Downy Mildew on cucumbers. Photo from Bruce McLean.

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Purplish-brown sporulation on the underside of cucumber leaves confirms that it is Cucurbit Downy Mildew. Photo from Bruce McLean.

Tony Melton reports, “Cucurbit downy mildew is increasing rapidly with the rain, glad we started spraying Ranman or Orondis 2 weeks ago. With the rain, ponds have returned to our fields. As one of my vegetable farmers said “Not a good year to be in the Pee Dee vegetable business.” Hundreds of acres of beans, squash, cucurbits, and peas have drowned. Farmers are probably tired of me saying “Potassium Phosphide will help.” Regretfully, on brassicas, the yellowed margined beetle has become established in the Pee Dee, and downy mildew is awful. However, sweet potatoes are growing like a weed (its close kin morning glories).”