Field Update – 10/7/19

Statewide

Dr. Tony Keinath reports, “Growers who have “slacked off” on fungicide applications during the dry spell should resume biweekly or weekly fungicide sprays in areas that are or have received rain. For most fungal diseases, the amount of rain determines how severe the disease becomes. The more rain, the more fungicide sprays are needed. Note that many fungicide labels now state that the product may only be applied once every 7 days; 5-day spray schedules are going away.

Coastal Region

Zack Snipes reports, “Another hot and dry week in the Lowcountry. Non irrigated crops are really starting to suffer.  Many farms are waiting on rain to plant fall crops.  We are beginning to prepare for strawberry season but dry conditions are making it hard to lay plastic. Festivals, corn mazes, pumpkins, and haunted trails are in full gear in the Lowcountry.”

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Sunflowers can add extra income to the farm during the summer and fall seasons. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “Last week was hot, but temperatures finally dropped over the weekend. It finally feels like fall.  Dry weather remains, though.  A few areas got some light showers, but it didn’t amount to much.  Growers have laid their plastic for strawberries and planting is approaching quickly.  Caterpillars are still very active in brassica crops and we are seeing some whiteflies as well.  Keep scouting and stay on top of the insects.”

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Plastic laid for strawberries. Planting will start soon. Photo from Justin Ballew.

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Whiteflies are showing up on brassica crops in the midlands. Photo from Justin Ballew.

Sarah Scott reports, “We have had spotty rain throughout the Ridge but conditions are still very dry. Cooler night temperatures are bringing some relief. Field preparation for new peach tree plantings are underway including soil fumigation.  With the recent discovery of the root knot nematode, Meloidogyne floridensis, in fields in Edgefield County, growers can request a PCR test if nematode samples test positive for root knot nematodes.

Lalo Toledo reports, “Phytophthora blight on bell peppers has been found in Clarendon and Orangeburg County. Phytophthora blight on peppers is extremely damaging and can result in total loss of the crop prior to the first harvest. Proper fungicide applications and resistant cultivars can be used to suppress this disease. Sweet potatoes are being harvested, as well as eggplants. White-fly populations have been found in broccoli and mustard.

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Phytophthora blight on pepper. Photo from Lalo Toledo.

Field Update – 8/26/19

Coastal Region

Dr. Tony Keinath reports, “Phytophthora crown rot was observed on bronze fennel in a home landscape (mine) in Charleston. Fennel apparently is a new host for Phytophthora  (species not identified). Foliar symptoms include a progressive yellowing, starting with the older leaves. Symptoms on the lower stem and leaf sheath are a water-soaked, “greasy” rot. It is very likely that Florence (green, edible) fennel also is susceptible. Potassium phosphite products are the only fungicides registered for post-transplant applications on the leafy vegetables crop group that includes fennel.”

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Yellowing of fennel foliage from Phytophthora crown rot. Photo from Dr. Tony Keinath.

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Water-soaked, greasy rot symptom on the lower sheaths. Photo from Dr. Tony Keinath.

Midlands

Justin Ballew reports, “We got some much-needed rain over most of the midlands this week and temperatures have been a little cooler over the last few days.  Planting continues with fall brassicas and diamond back moth caterpillars are showing up already.  We need to be scouting weekly for those and using the treatment threshold of 5 worms per 10 plants at this stage of the season.  The recent moisture is causing an increase in disease pressure, so stay on your regular spray schedules.”

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Diamondback moth pupa on the underside of a collard leaf. Photo from Justin Ballew.

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Diseases like anthracnose could increase following with past week’s rain. Photo from Justin Ballew

Sarah Scott reports, “Peaches are wrapping up around the ridge. Broccoli plants are still going in for fall harvest. We have had rain in the last week which has been a nice break on irrigation systems.”

Pee Dee Region

Tony Melton reports, “Last of pickling cucumbers have been planted.  Collard, kale, turnips, mustard, etc. planting in full swing with both transplants and direct seeding.  Bed prep for strawberries has begun.  Getting late to order strawberry plants. Fall blackberry harvest is continuing.   Sweet potato harvest will begin soon.  Double cropped processing peas are starting to flower.  Butterbeans planted for fall production are starting to flower.”

Upstate

Kerrie Roach reports, “The last few peaches are being picked this week in Oconee County. The apple harvest is coming along nicely, ‘Early Fuji’ and ‘Golden Delicious’ apples will start to be picked this week. A spotty hail storm in Long Creek last week has caused some damage across the orchards, but is very localized. Summer market vegetable growers are wrapping things up with some of the Farmers Markets closing at the end of August. With rain & cooler weather forecasted, disease and weed management will be a continued battle for growers.”

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Early Fuji apples from the Upstate. Photo from Kerrie Roach.

Alternaria Leaf Blight Common This Year

From Clemson Extension Plant Pathologist Tony Keinath.

During the 2019 Cantaloupe Disease Survey, Alternaria leaf blight has been found in several fields. It was more common in fields that had not been sprayed recently than in fields sprayed on a regular schedule. It also was found in a field rotated only one year out of cantaloupe.

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Alternaria leaf blight lesions on cantaloupe leaf.

The FRAC Group 11 fungicides (Cabrio, Quadris, Flint) are the recommended fungicides. Although the gummy stem blight fungus is resistant to this group of fungicides, they still are very effective against Alternaria leaf blight on cantaloupe and anthracnose on watermelon.

Downy Mildew found in SC

From Clemson Plant Pathologist Dr. Tony Keinath:

The first SC report of cucurbit downy mildew this year came on June 6 from a crop consultant, who found it on cucumbers in Bamberg County. Growers should spray all cucumber and cantaloupe crops to prevent or manage downy mildew. The cheapest downy mildew fungicide is Ranman. It can be tank-mixed with chlorothalonil, mancozeb, or tebuconazole to add protection against fungal leaf spots, like gummy stem blight and anthracnose, that will start to spread with the rain. Another option is Orondis Opti, a pre-mix of Orondis and Bravo (chlorothalonil). Watermelon growers should be spraying with protectants, as downy mildew has been spotted on watermelon in south Georgia.

Downy mildew lesions on cucumber leaf. Note how they are delineated by the veins in the leaf. Photo from Dr. Tony Keinath.

For more info on downy mildew management in cucurbit crops, refer to this fact sheet.