Weekly Field Update 8/24/20

Statewide

Dr. Tony Keinath reports, “For the past few years, Orondis Opti on cucumber and cantaloupe and Orondis Ultra on pumpkin and watermelon have been the best fungicides to manage downy mildew. Based on results from a spring 2020 cucumber experiment at Coastal REC, Orondis is no longer the “silver bullet” it was 2 years ago. In my experiment, Orondis Opti rotated with Bravo controlled downy mildew in the early part of the season, but disease increased significantly during the latter part of the season and ended up higher than expected. Part of the shortcoming of the Orondis Opti/Bravo spray program was the Bravo rotation. Bravo sprayed by itself every other week did not control downy mildew at all, so spraying Orondis Opti/Bravo acted like Orondis Opti sprayed every other week, which was not enough. The labels for Orondis Opti and Orondis Ultra say they must be rotated with another fungicide. For the rest of the 2020 season, use Orondis Opti/Ranman + chlorothalonil on cucumber and cantaloupe, and Orondis Ultra rotated with Gavel or Ranman + chlorothalonil on pumpkin and watermelon. Always use the high rate (2.5 pints/acre) of Orondis products. Note that the mancozeb in Gavel or adding chlorothalonil helps to manage other foliar diseases like gummy stem blight and anthracnose. Yield data and input costs from my experiment are being analyzed to see if spraying Orondis leads to a higher net return despite the higher cost of this fungicide. Results will be presented at the virtual Cucurbit meeting in February 2021 to help growers plan downy mildew fungicide programs for the 2021 season.”

Cucurbit downy mildew continues to spread across the state.

Coastal

Rob Last reports, “Fall crops continue to grow well in the area.  Given the current weather patterns pests and disease are active in some crops particularly where there are volunteers remaining from previous crops.  Vigilance will be required in scouting an pesticide management programs.  If In doubt scout.”

Midlands

Justin Ballew reports, “It’s been cool, cloudy, and kind of pleasant outside this past week, though that has the vegetable crops growing a little slower. We’ve gotten some decent rains in most areas around the midlands as well. Bacterial spot is really showing up on fall tomatoes as a result of all the recent rain. It could be a bad fall for bacterial spot if the weather stays like this. Caterpillars are already out there on fall brassicas. It doesn’t take long once they’re planted. Start scouting, scout often, and rotate insecticides. Remember to contact one of us about screening your farm for insecticide resistance in diamondback moths once you start seeing populations build up.”

Bacterial spot and speck start on the bottom of the plant and can be splashed onto higher leaves and fruit by rain drops. Photo from Justin Ballew.
Start scouting for caterpillars as soon as your fall brassicas are planted. Photo from Justin Ballew

Pee Dee

Bruce McLean reports, “Both fruit and vegetable development has slowed a bit due to cloudy conditions. Sunny conditions needed. Sweetpotatoes are sizing well and will be ready for harvest soon. Fall cucumbers and squash should soon be ready to start harvesting. Fall brassicas are being planted now. Muscadine crop is getting close to harvest. Noble is around 90% ripe; Carlos is around 60%; Doreen is still around 25%. Brix (sugar content) is off due to rain and cloudy conditions. Noble and Carlos brix are averaging around 11% with a low of 9.2% and a high of 15.0%. Doreen is averaging less than 10%. Did find a few Doreen that brix was over 19%… candy. Sunny conditions definitely needed.”

Noble muscadines around 90% ripe. Photo from Bruce McLean.

Tony Melton reports, “Beginning to harvest processing sweet potatoes but some have been stunted and delayed by excessive rain.  Spraying processing peas for cowpea curculio.  Starting to plant processing greens by seed.  Even though lots of rain and having to mud through fields cucumbers for pickles are being harvested and still being planted.”

Upstate

Andy Rollins reports, “Blueberry pruning is best served for the dormant time of year late January-late February.  I met with a commercial grower who was anxious about getting started early partly because he has many plants completely unproductive for the second year in a row. I like to call this revenge pruning as that is the primary motivation. Be careful, you could end up hurting yourself more in the long run. In his case, it was all about light and proper pruning to encourage light down through the canopy. The orignial spacing of Rabbiteye type varieties was very close so we also considered killing every other plant to get more light into the bushes but this would not replace the need for properly selectively removing a few of the oldest canes each year, spacing them out so there is better light penetration. For a detailed explanation, please see NCSU Blueberry specialist Bill Cline’s presentation.”

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.”

Field Update: 6/22/20

Coastal

Zack Snipes reports, “A week of unseasonably mild temperatures and damp conditions slowed things down a bit. The warmer weather this past weekend and this week should put things in gear again. Starting to find some armyworms on smaller farms particularly the southern armyworm. Tomato spotted wilt virus has been showing up on tomato fruit in the Lowcountry. The disease is vectored by thrips. Early and mid-season symptoms include stunted plants that will never make fruit and brown/purple mottling on the leaves. Some plants are asymptomatic, meaning that they show no symptoms of the disease. I have been finding plants that are asymptomatic until they fruit and then symptoms appear on the fruit. Using tomato varieties that are resistant to the disease is the best management technique. The Crop Handbook has a list of varieties that have resistance. Using silver reflective mulch will also help with disease management as the mulch will repel thrips which vector the disease.”

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Characteristic symptoms of Tomato Spotted Wilt Virus on tomato fruit. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “Last week was very cool and cloudy. Though there was a decent chance of rain most days, we got very little and it remains dry in the midlands. The cool, cloudy weather really slowed things down and growers weren’t able to harvest crops as often as usual. Since there was little sunlight to dry up the dew each morning, powdery mildew really started showing up in cucurbits. It warmed back up over the weekend and plants seem to be growing faster already. Downy mildew still has not shown up here. Keep scouting and applying protective fungicides.”

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Powdery mildew growing on acorn squash foliage. Photo from Justin Ballew.

Lalo Toledo reports, “Squash bugs are active and laying eggs. Please scout for eggs on the underside of leaves and spray as soon as signs are visible. Squash bug nymphs, are gray and have black legs. Refer to the vegetable handbook for proper chemical control. Downy Mildew has been diagnosed in Orangeburg County. Please refer to the vegetable handbook regarding fungicide applications. It’s recommended to stay on a fungicide schedule and to apply protectants even before we start seeing symptoms.”

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Squash bug eggs laid on the underside of a squash leaf. Photo from Lalo Toledo.

Pee Dee

Tony Melton reports, “Cool temperatures making everything late especially peas and okra. Most sweet potatoes are planted. Things are drying out quickly with the heat.”

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).”

Field Update – 6/8/20 (Downy Mildew Arrives in SC)

Statewide

Downy mildew was found in Charleston, SC late last week on cucumbers. This is the first confirmed report of the 2020 season. If not already doing so, all cucumber and canteloupe growers should begin applying protective fungicides to help prevent or manage downy mildew. Ranman tank-mixed with a protectant such as chlorothalonil, mancozeb, or Zampro is a good option for protecting plants prior to symptom development. For more info, see Dr. Tony Keinath’s CDM Management publication.

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Downy mildew symptoms on the top side of a cucumber leaf. Note that the spots are angular in shape and are delineated by the veins in the leaf. Photo from Justin Ballew.

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Dark-colored downy mildew spores developing on the underside of a cucumber leaf. Photo from Justin Ballew.

Coastal

Zack Snipes reports, “It is a very busy time out in the fields. Every crop is coming in right now and folks are busting it to get crops out and keep the remaining crops healthy.  Keeping up with fertility, fungicide, insecticide, and herbicide programs can really help with the bottom line as now is when our crops need a little help. With the mild temperatures and cloudy, wet days last week, I saw some diseases appear and spread.  On tomato, I am finding increased bacterial spot that is starting to make plants turn yellow. This will cause a yield drag and the spots can be found on the fruit if the infection is not slowed down. Downy mildew was found in cucumber last week so be sure to be proactive and keep an eye out for that. I saw some other cucurbit diseases last week including gummy stem blight and Alternaria. The stink bug population has also increased in the past week or so with some damage showing up on tomato. Please refer to the 2020 Southeastern Crop Handbook for details on management programs for insects, diseases, and weeds.”

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Bacterial spot is increasing causing yellowing of the plants. Bacterial spot can reduce yields and develop spots on the fruit. Photo from Zack Snipes.

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Downy mildew found in cucumbers last week. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “Last week was warmer and actually a little dry. Lots of irrigation has been running. Crops are progressing quickly. Strawberries are mostly done now. The silks on the earliest planted sweetcorn are browning and harvest isn’t far off. Tomatoes, peppers, eggplant, squash, beans, and cucumbers are also progressing well. Downy mildew has been found in the state, so be sure to start preventative fungicide sprays on cucumbers.  Let us know if you’d like help scouting fields for downy.  Collards, cabbage, and kale are still being harvested and are looking good.”

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Silks are turning brown on the earliest sweet corn plantings. Photo from Justin Ballew.

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Tomatoes are developing well. It won’t be long before harvest starts. Photo from Justin Ballew.

Lalo Toledo reports, “Downy Mildew has been diagnosed in Charleston County. However, Downy Mildew has not been found in Orangeburg county.  Please be advised that it is a matter of time before we start seeing symptoms. Please refer to the vegetable handbook regarding fungicide applications. It’s recommended to stay on a Fungicide schedule and to apply protectants even before we start seeing symptoms. Bacterial Wilt on tomatoes is present in many fields in Orangeburg county. Please contact your local extension office for proper recommendations.”

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It’s only a matter of time before downy mildew shows up in cucurbits in Orangeburg County. Photo form Lalo Toledo.

Pee Dee

Bruce McLean reports, “Field conditions really improved this past week. Cucumbers are being harvested in good volumes. Overall, quality is good. Downy mildew is starting to show up in cucumber fields that were affected by recent heavy rains. Squash and zucchini are beginning to be harvested, as well. Snap beans and southern peas are flowering heavily. Some acreage of snap beans were lost due to ponding caused by recent heavy rains. Many fields of sweet corn are tasseling well and beginning to silk. Watermelon, cantaloupe, and peppers are growing very well. Blueberry quality is beginning to improve. Much of the rain-damaged fruit has been removed. Currently, the blueberry crop looks good. Muscadine fruit set is good, but thrips and aphid activity is high, which could cause problems in yield. Scouting is necessary to determine pest presence and necessary insecticide application.”

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Downy mildew really showing up in rain-stressed fields. Photo from Bruce McLean.

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Snap beans affected by ponded water from recent heavy rains. Photo from Bruce McLean.

Tony Melton reports, “Some areas got 10 inches of rain in one day. Hundreds of acres of beans and cucumbers are drowned. Cucurbit downy mildew is here on cucumbers. Weeds are awful.”

Upstate

Kerrie Roach reports, “With heavy rains a few weeks ago, high humidity and heat this past week, we are seeing some disease problems pop up across the board… make sure you are following prevention practices that fit into your growing style. Conventional, organic, or somewhere in between, all growers should be managing disease through preventative measures. Crop rotation is arguably one of the most important strategies in an Integrated Pest Management (IPM) program. If you’re a grower that hasn’t moved crops around within your site in years, now is that time!”

Andy Rollins reports finding black knot of plum. “Prune out these galled up branches as quickly as possible before they begin to sporulate. I also recommend sterilizing or at least sanitizing the pruners as much as is possible between cuts.  Treat with 2 lbs of Captan foliarly as soon as possible after pruning to try and keep those wounds free from other problems.  This problem can come in on the purchased trees, but can also come in from wild cherry trees or wild plum surrounding the orchard.  It is always a good thing to kill any and all wild cherry and plum trees directly adjacent to a commercial orchard.  Penn State has some good information here.”

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Black knot on plum branches should be pruned out before sporulation begins. Photo from Andy Rollins.

Field Update – 5/18/20

Statewide

Dr. Tony Keinath reports, “With the cooler-than-normal spring weather, two cool-season pathogens also may be active longer than normal. Downy mildew on brassicas, especially kale and collard, mainly affects the lower leaves. Sometimes it will move up onto the larger leaves in the middle of the plant. With a hand lens, you can see white mildew growth in lesions on the bottom of the leaves. In my spring 2020 trial, Presidio, potassium phosphite, and Zampro rotated with potassium phosphite worked well. Organic growers can use Badge X2 copper, which also performed well.

Fusarium oxysporum f. sp. niveum, the soilborne fungus that attacks watermelon, infects roots when soil temperatures are below 82F. At Coastal REC, I am still seeing new plants showing wilt symptoms. Remember that all control measures, and I want to stress all of them, must be applied before or at transplanting. There is nothing that can be done at this stage of crop growth. It is too late to apply fungicides, which will be a waste of money.”

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Tiny dark flecks of downy mildew on the bottom of ‘Blue Dwarf’ kale. Photo from Dr. Tony Keinath.

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Sporulation of downy mildew on the underside of ‘Tiger’ collard. Photo from Dr. Tony Keinath.

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Wilting and yellowing of lower leaves due to Fusarium wilt on watermelon 6 weeks after transplanting. Photo from Dr. Tony Keinath.

Coastal

Zack Snipes reports, “Things are coming along in the Lowcountry.  It has been very windy and I’ve had several farmers tell me that crops are using more water now because of the wind than if it were hot and humid.  Squash, zucchini, cukes, potatoes, and greens are coming off in good volume right now. Tomatoes are just a few weeks away and are in the sizing up stages right now. I have not seen any major pests or diseases as of late.  The conditions are ripe for the development of Powdery Mildew so be on the lookout when scouting watermelon, squash, brassica, and tomato.”

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Tomatoes are looking good and are just a few short weeks away. Photo from Zack Snipes.

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Powdery mildew on the shaded side of a collard leaf. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “It’s dry in the midlands. It’s been great because we haven’t seen much disease lately (especially on strawberries), but we need some rain. The forecast looks like we may get some this week. Strawberries are still yielding fairly well, though we’re starting to see fewer blooms. Fruit size is getting smaller, but taste has still been great. The first few plantings of sweet corn are tasseling now. Brassicas are still growing well, though there is some black rot out there.  Tomatoes, peppers, and cucurbits have been growing fast the last few days also.”

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The earliest plantings of sweet corn are tasseling. Photo from Justin Ballew.

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Black rot symptoms on the margins of cabbage leaves. Photo from Justin Ballew.

Sarah Scott reports, “Peach season is here! Picking several early varieties now and running packing lines. The crop looks good for this season. Bacteriosis started to show up on leaves and fruit in fields. Still picking strawberries. Summer crops like bell pepper and squash are progressing nicely.”

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Phomopsis or twig blight in a peach orchard. Lesions on twigs cause dieback, gumosis and curling at tips. Remove damaged wood and burn. Photo from Sarah Scott.

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Twig dieback from Phomopsis twig blight. Photo from Sarah Scott.

Lalo Toledo reports, “Cool temperatures have slowed down the growth of many vegetables, but most vegetable plants are looking great. Please be aware of possible diseases coming in this week. Wet and hot conditions will be conducive for pests and diseases. Please spray accordingly and scout every two days, if possible.”

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Grasshopper damage on eggplant. Photo from Lalo Toledo.

Pee Dee

Tony Melton reports, “Hail has destroyed at least 10 A squash, 200 A peaches, 30 A strawberries, 8 A blackberries, many acres of field corn, tobacco, rye, and wheat.  Damaged another 35 A strawberries, 300 A peaches.  Thank goodness that the wind has let up for a while and temperatures have risen on tomatoes, peppers, peas, beans, and sweet potatoes.  Thrips have been awful and imidacloprid is only partially controlling them. If labeled use dimethoate, acephate, etc.   More herbicide damage than usual this year because of cool temperatures and wind, even on labeled crops and drift to non-labeled crops has been awful.”

Upstate

Kerrie Roach reports, “With a week of good growing conditions, things are looking great in the Upstate for fruit & vegetable producers. In higher elevations, there were some losses of young tender plants during isolated frost events early last week. With rains expected most of this coming week, things should start to really push for our market vegetable growers. Peaches and apples are on track for a good season.

Field Update – 8/12/19

Coastal Region

Zack Snipes reports, “We are in the middle of muscadine and scuppernong harvest right now. Okra and mixed peppers are still pushing out despite the heat. We had a great Strawberry Production Meeting in Charleston last week. If you have any questions on strawberry production now is the time to ask before planting.”

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Muscadines and scuppernongs from Ravenel, SC. Photo from Zack Snipes.

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Great strawberry production meeting in Charleston (8/6/19). Photo from Zack Snipes.

Midlands

Justin Ballew reports, “We had a storm come through Saturday night that brought a little rain to some parts of the midlands, but overall we are still quite dry. More fall brassicas are going in the ground and there is already some caterpillar pressure on those that are up. Downy mildew is showing up on cucumbers and pumpkins on a more widespread scale now.  Stick to fungicide programs if you’re growing fall cucurbits.”

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Fall collards in Lexington County are already seeing diamond back moth caterpillar pressure. Photo from Justin Ballew.

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Downy mildew in fall cucumbers. Photo from Justin Ballew.

Sarah Scott reports, “We have had hot and dry conditions along the Ridge with hit and miss showers. Running irrigation heavily.  Late cherry tomatoes, eggplant, peppers and broccoli are being planted.  Leaf footed bugs on late season tomatoes causing minimal damage.  Peaches still producing through late August, possibly into early September. Field work is still being done to prepare for fall planting of new orchards.”

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September Sun peaches are nearing harvest. Photo from Sarah Scott.

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Leaf footed bugs causing minor damage to late tomatoes. Photo from Sarah Scott.

Upstate

Mark Arena reports fall webworms and tent caterpillars are showing up on pecans. “This is truly a nuisance pest and generally does not influence nut production. Proper control may be challenging since the webbing should be broken apart prior to spraying. Once the webbing is broken apart, the insecticide can make contact with the caterpillars and offer effective control. Any insecticides labeled for caterpillars will work.”

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Fall webworm in the canopy of a pecan tree. Photo from Mark Arena.

Pee Dee Region

Bruce McLean reports, “Temps have been soaring and rain has been scarce across the Pee Dee Region. Most crops are looking good though. Watermelon, cantaloupe, canary melons, cucumber, zucchini and yellow squash volumes are still up and quality is good. Okra volumes are really starting to pick up and the quality is very good. Okra is flowering heavy, so volumes should be good for the foreseeable future. Muscadines are continuing to ripen. Muscadine brix levels (sugars) are rather high for this time of the season. Harvest should be very good this year. Fresh market muscadines should be available starting this week.

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“Noble” muscadines are getting close to harvest. Photo from Bruce McClean.

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Okra is rolling along in the summer heat. Photo from Bruce McLean.

Tony Melton reports, “Fall pickling cucumbers are being planted.  Pythium is still prevalent on pickling cucumbers and may need to be controlled.  Fall peas and snap-beans are up and growing and need thrips control, but I have found thrips are in low numbers this fall and they may grow out of damage. I have found some beet armyworms on peas in some locations – scout.  Also, lesser cornstalk borers are bad on both peas and snap-beans mainly due to the dry conditions; therefore, irrigate if possible or apply Coragen or similar systemic product.  Loopers are present on sweet potatoes but doing mostly very little economic damage.  I have found some striped armyworms in certain locations which need to be controlled.  Starting to plant fall processing greens.

Field Update – 6/10/19

Statewide

Dr. Tony Keinath reported downy mildew being found on cucumbers in Bamberg County this past week. He cautioned all cucumber, cantaloupe, and watermelon growers to begin preventative sprays, if they are not already doing so. Refer back to this post for more info.

Downy mildew on cucumber leaves.

Coastal Region

Zack Snipes reports, “We finally got some much needed rain in the Lowcountry. I expect to see some disease to show up this week. Growers should be scouting all crops and spraying when needed. Downy mildew was found on cucurbits this week so be aware that you may see it in your fields as well. We had a great field day this week at the Coastal Research and Education Center.”

Clemson Plant Pathologist Tony Keinath discussing watermelon diseases at the Coastal REC Field Day. 6/5/19. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “We had thunderstorms come through late in the week and it’s rained every day since. We needed it badly. Sweet corn and tomato picking has begun and they are looking good. We’re seeing a few stink bugs in sweet corn, but nothing severe. Powdery mildew is showing up on some cucurbits now that moisture has returned. Downy mildew could show up at any time here, so keep an eye out for that and stay on a good preventative spray schedule.

Sweetcorn ready for harvest. Photo from Justin Ballew
These tomatoes will be harvested soon. Photo from Justin Ballew

Sarah Scott reports, “Rain fall amounts range from 1 inch to over 5 throughout Aiken,Saluda and Edgefield Counties which will give irrigation systems a much needed break. Flea beetles are showing up on peppers.”

– Adult flea beetle and damage to pepper plant. Photos from Sarah Scott

Pee Dee Region

Tony Melton reports, “Pythium has been awful with all the heat.  Bad on snapbeans, cucumbers, etc.  Southern stem blight has been awful on tomatoes and peppers with the heat.  Black rot has taken over some kale, cabbage, collard fields.  Sensation strawberry has had very poor yields this spring but is still bearing in the heat.  Pickleworm is hear and is worse in yellow squash, then cucumbers, and then zucchini.  The heat caused the flowers to fall on the early planted butterbeans causing all the early plantings to come together with the later planting then with the rain and cooler temperatures all plantings are setting now.  It appears we may have butterbeans but all plantings will come in at the same time causing problems with marketing.”

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.

Testing What Controls Downy Mildew in Cucumbers – and What Doesn’t

From Clemson Plant Pathologist, Dr. Tony Keinath.

Small growers can manage downy mildew on slicing cucumber and increase yields by growing a partially resistant cultivar, like Bristol, and spraying weekly with moderate-cost fungicides, like chlorothalonil rotated with Ranman. Trellising doesn’t help manage downy mildew. Read Dr. Keinath’s full article about testing cultural and chemical controls for downy mildew here.

The cucumbers ‘Speedway’ (front) and ‘Bristol’ (back) in non-trellised plots with foliage yellowing due to downy mildew on June 23, 2017. Photo by Anthony P. Keinath