Field Update – 6/29/20

Coastal

Rob Last reports, “In our area crops are generally looking good with watermelons and cantaloupes coming to harvest.  From a pest perspective, we are finding some early pickleworm and melon worm damage occurring. In addition, cucumber beetles and squash bugs remain active. Cucurbit downy mildew is being found in the area and as such protectant fungicide applications remain viable options. If in doubt scout.”

Zack Snipes reports, “Last week was full of heavy rain and heat. It finally feels like June.  Crops are either going one of two ways right now:  they either look great or they are succumbing to disease. Tomatoes are picking great and I’ve seen some really nice watermelons finish up this week. Peppers are loving this heat but I have seen an uptick in bacterial leaf spot (BLS) in the crop. Keep up with spray programs (copper and Manzate) for BLS in pepper. Tomatoes are also starting to look rough with all the heat and rain. If your tomato crop dies, please identify the culprit so we can better manage it next year. Soilborne diseases such as bacterial wilt and southern blight will not go away next year. I will be more than happy to work with folks on crop planning, cover crops, and rotation on their farms so we can avoid crop failures.

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A quick cut of the stem of a wilting plant and a dip into water can help to positively identify Bacterial Wilt in tomato. The presence of the pathogen will yield a clear to white ooze coming from the plant after a few minutes in the water. Photo from Zack Snipes.

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Bacterial Leaf Spot is spreading in pepper due to the heavy rains and increased heat. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “We finally got some widespread rain mid-week and it has rained in places most days since. Some areas received enough rain to cause temporary flooding in lower-lying fields. Remember, according to produce safety guidelines, any produce that was flooded may not be harvested. We should expect diseases to worsen in the coming weeks. Powdery mildew in cucurbits and bacterial spot in tomatoes has certainly increased in the past week. Crops are still developing very rapidly and we are picking lots of squash, zucchini, cucumbers, tomatoes, eggplant, sweetcorn, greens, beans, etc.”

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This field of cucumbers was temporarily flooded by the heavy rain last week. Photo from Justin Ballew

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A crew picking squash in Lexington. Squash and zucchini are growing like wildfire in the midlands. Photo from Justin Ballew.

Pee Dee

Tony Melton reports, “Raining almost every day some storms causing downed trees.   Root rot bad applying a lot of potassium phosphide. A few strawberry growers still picking around rains. Downy mildew bad but Ranman and Orondis are doing a good job of control. Peas are maturing and will not be too long until harvest. We need to hurry to get the second crop planted on the same land. Still planting sweet potatoes. Okra and tomatoes just started to bare. Southern stem blight is bad and we’re spraying Fontelis. Some first crop butterbeans are being harvested.”

Downy Mildew Found on Watermelon in SC

Downy mildew was found yesterday, June 17, 2020, in one watermelon field in Bamberg County, South Carolina. All growers should immediately spray watermelon with Ranman, Revus, or Gavel to protect their crops from downy mildew. In addition to direct yield loss, loss of vine cover can expose fruit to sunburn (when the sun comes out again). Growers who find downy mildew in a field should apply Orondis Ultra or Orondis Opti in a weekly rotation with Ranman or Gavel. For more information on downy mildew, see the updated Cucurbit Downy Mildew Management for 2020.

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Downy mildew symptoms on watermelon foliage. Photo from Dr. Tony Keinath.

Field Update – 8/19/19

Coastal Region

Dr. Tony Keinath reports, “Phomopsis blight is showing up on eggplant at the Coastal REC. On susceptible cultivars, like ‘Black Beauty,’ the disease starts as leaf spots; later in the season stem cankers and fruit rot appear. Although several fungicides are registered on eggplant, none are specifically labeled for Phomopsis blight. Aprovia Top and Priaxor might give some control; more testing is needed before a definite recommendation can be made.”

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Phomopsis blight on eggplant foliage. Photo from Dr. Tony Keinath.

Midlands

Justin Ballew reports, “Last week we had some scattered rains, but some areas remain bone dry.  Irrigation is running a lot in those areas.  Muscadine harvest has started and so far, this is the largest yield we’ve seen in recent years.  Squash, zucchini, eggplant, cucumbers, and tomatoes are also being harvested. Quality looks good, but volume is down a bit in some areas.  More fall brassicas are being planted and strawberry growers are just starting the process of prepping their fields.”

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Great crop of muscadines in the midlands this year. Photo from Justin Ballew.

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Good looking eggplant harvested in the midlands. Photo from Justin Ballew.

Pee Dee Region

Bruce McLean reports, “Much of the upper Pee Dee Region received beneficial rains late last week. This helped to drop temps back to about normal, following the excessive heat from a few days earlier. On most crops, the rain really helped to push production again. Late season cucumbers, squash, zucchini, and okra are looking good. Canary melons are looking excellent. Volumes on these crops are good. Last week’s heat did take a toll on watermelons, though. Volumes are significantly down from the prior week and are likely winding down for the season. Muscadines are a bit varied across the region. In some locations, ‘Carlos’ and ‘Noble’ (wine and juice varieties) are getting very close to harvest, while other vineyards are ripening a bit slower. Harvest on the most mature wine and juice muscadines could begin as soon as next week.

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Fall cucumbers were showing some downy mildew earlier on. Fungicide applications seem to have held down further development. Photo from Bruce McLean.

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Canary melons are looking excellent. Photo from Bruce McLean.

Tony Melton reports, “Heavy rain in certain area but none in others.  Some fresh market sweet potatoes are ready for harvest.  Processing sweet potato harvest will begin end of August.  Pickling cucumbers for machine harvest are still being planted most growers are favoring the parthenocarpic varieties.  Brassica planting has begun – seeds and transplants.  Fall bearing blackberries are yielding well.”

Upstate

Mark Arena reports seeing pecan scab. “Pecan Scab fungus is a weather dependant disease. There are varieties/cultivars that exhibit tolerance to this disease as shown below in the photos. Observed in Picture #1, we see both the nuts and foliage are showing signs of infection (the brown lessions). Picture #2 shows no sign of disease on either the nuts and/or foliage at the present time. Pecan scab can go undetected for days before the lessions appear, therefore, it is imperaitive to use a preventitive fungicide program to insure nut production.

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Nuts and leaves infected by pecan scab. Photo from Mark Arena.

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Nuts and leaves appear free of pecan scab. Photo from Mark Arena.

 

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.