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 – 7/27/20

Coastal

Zack Snipes reports, “It has been a hot week in the Lowcountry. Most spring and summer crops have finished up. Ground is being prepared and planted for fall crops. I have received a few texts from growers that have yellow dots on their zucchini plants, which is downy mildew. Even in this heat downy can still be an issue. I have also had some reports of green-colored squash in fields which is an indication of a viral pathogen. The crop handbook has recommendations for cultivars that are resistant to these viruses that cause this discoloring. Fall is notoriously bad for cucurbit viruses so plan accordingly.  I have also seen some flea beetle damage on crops as of late.”

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Downy mildew looks a little different on zucchini and pumpkin than it does on cukes. Photo from Zack Snipes.

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Flea beetle feeding damage on blackberry foliage. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “It’s been hot in the midlands and we’ve gotten to the point where there isn’t much relief at night. We had some scattered rain throughout the week, but overall we’re still quite dry. Lots of land is still being prepped for fall crops. We’ve had some fall brassicas and cucurbits planted already and they’re looking good so far. Last week I got to watch a pecan grower in Lexington thin some pecan trees. Without thinning, he would have seen a massive yield this year, which would result in a significantly diminished yield next year. Pecan growers aim for nuts on just 70% of the terminal buds.”

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Fall squash seedlings just beginning to emerge. Photo from Justin Ballew

Thinning pecans with a mechanical shaker. You can see the nuts fall as the tree vibrates.

Pee Dee

Tony Melton reports, “Pickles are still being harvested and planted. We still have hundreds of thousands of bushels in contract to be planted and harvested.  Peas for processing are being rapidly harvested and replanted, some seed is short.  Sweet potatoes are starting to swell and size.  Processing peppers are being harvested but we have a shortage of labor and multi-millions of lbs. left to harvest.  Processing tomatoes will be finished harvest this coming week.  Spring planted fresh market butterbeans and peas are mostly harvested but seed is short to plant the fall crop. Still have some flooded fields and drowned crop.”

Upstate

Kerrie Roach reports, “Spotty rain across the county again last week has led to continued issues for growers without irrigation. Fall planting for vegetables is in full force. Peaches are looking good, and apples are coming along. Most growers will be putting on a fungicide cover spray this week before significant rains are forecasted.”

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Reverted apple rootstock (believed to be M7) volunteer tree with aborted fruitlet. Photo from Kerrie Roach.

Andy Rollins reports, “Bacterial speck and bacterial spot of tomato are major problems in plum tomato varieties in the upstate right now.  They were not able to control this disease even with a vigorous spray program using mancozeb + copper on several farms.  In nearby plantings of large fruit varieties, the disease is present but not a problem.  Samples have been sent to researchers at Auburn University where the have confirmed the presence of copper resistant isolates from other farms.  Call on your extension agent for assistance with identifying and controlling this problem.”

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Bacterial speck on a tomato leaf from the upstate. Photo from Andy Rollins.

Field Update – 7/20/20

Statewide

Dr. Matt Cutulle reports, “It is always good to control goosegrass even if it is past the critical period for competition with the crop. Lack of late-season control made hand-harvesting tomatoes difficult in the field pictured below. Also, there will be a huge deposit of goosegrass seeds into the soil seed bank for next year unless the seeds are destroyed after the harvest.”

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Late season goosegrass growth can make harvest difficult and contribute lots of seed to the seed bank, which will have to be dealt with in future crops. Photo from Dr. Matt Cutulle.

Coastal

Zack Snipes reports, “We experienced a nice hot week of weather in the Lowcountry.  Most crops are finishing up with the heat and recent rains.  On later season tomato I have seen bacterial leaf spot on the fruit which makes fruit unmarketable.  I am seeing this on the second cluster of fruit set and not on the first or third clusters.  Hemp seems to be off to the races and looking pretty good so far.  There are within every hemp field occasional wilted, stunted, and yellowed plants.  These plants always have a weak root system and most of the time have girdling and interveinal discoloration.  Peppers and eggplants are loving this heat and are producing in high volumes.”

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Bacterial leaf spot showing up on the second set of fruit on the tomato plant. Photo from Zack Snipes. 

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Wilting of hemp is very common and often sporadic throughout fields. Photo from Zack Snipes

Midlands

Justin Ballew reports, “Last week was hot and mostly dry, though we did have some scattered thunderstorms come through over the weekend. Field prep for fall crops continues. We’ve had some fall tomatoes, peppers, and brassicas transplanted already and more to come this week. Everything is growing pretty fast right now and we’re still picking spring crops. Keep an eye out for spider mites, as they love the hot, dry weather we’ve had lately.”

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Fall tomatoes transplanted in Lexington this past week. Photo from Justin Ballew

Sarah Scott reports, “We are still ahead of schedule on peach varieties being harvested.  Early August Prince and August Prince are being picked now which is over a week earlier than usual. The fruit quality is still good with slightly smaller than ideal fruit.  With the extreme heat and lack of rain in the past week, summer crops like tomatoes and cucumbers are looking rough. Bell peppers are doing well.”

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An Edgefield County grower assessing his Early August Prince orchard. Photo from Sarah Scott.

Pee Dee

Bruce McLean reports, “Sweet potatoes are looking good. Establishment seems to be very good for the most part. Long green cucumbers, yellow squash, zucchini, cantaloupe, peas, okra, and sweet corn are harvesting well. Condition is good to very good. Sweet corn will be wrapping up shortly. Blueberries are pretty much finished, with only a few remaining fruit on Powderblue. Fruit condtion is fair to good. Muscadines are coming along nicely and appear to have an excellent crop. Fresh muscadines should be beginning harvest soon, with wine/juice grapes still a few weeks from harvest. Be on the lookout for Grape root borer moths. They are starting to emerge. They were being caught in traps placed in vineyards in Marion and Horry counties.

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Grape root borer moths being caught in a bucket-style trap. Photo from Bruce McLean.

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No, this is not a paper wasp. It is a grape root borer moth. Photo from Bruce McLean.

Tony Melton reports, “Harvested first crop of processing peppers. Continuing to pick and plant pickles. Processing greens are over for the spring crop. Harvesting the first crop of processing and seed peas and planting fall crop.  Getting processing tomatoes out of the field as quickly as the plant can take them.  Things are drying out, hope we don’t go into drought with the heat.”

Upstate

Kerrie Roach reports, “Spotty rain and high temperatures have left many small growers scrambling for irrigation options throughout the Upstate. Peaches and nectarines are still being harvested. Blueberries are just about finished, and farmers’ market produce is starting to wind down with the heat. Apples should begin next week with early varieties like ‘Ginger Gold’  and ‘Golden Supreme’.”

Andy Rollins reports, “Plenty of early blight, bacterial spot/speck on tomatoes this season, but some of the more troublesome problems have been various tomato virus problems. When diagnosing virus problems it is important to get lab verification because herbicide injury can look very similar when just going by visual symptoms. If you suspect herbicide drift from a neighboring farm. Look for damage to other broadleaf plants in the area in between the suspected source and the damaged plants. Follow the wind direction.  You should have more severe damage on the leading edge. Also, herbicide residual from a previous crop like sunflowers can also give you herbicide damage that you did to yourself. Read and follow all pesticide label directions. There are plant back restrictions on some herbicides so be careful. If this is the case the damage should be fairly consistent/uniform throughout the area that was planted in the other crop.

Unlike both of these other situations, virus problems may come from your seed source, the greenhouse where plants were grown, or from weeds in the field. Pokeweed is commonly a source, as are many other broadleaf weeds. Thrips, aphids, and whiteflies are all known to vector viruses into plants. Symptoms are what you see below with “shoestring” looking leaves, leaves with distorted veins, and mosaic yellow and green coloration. There are many viruses that infect plants. Each of them can show different symptoms and also they can each look different on other plants as well. It’s even possible for a healthy-looking plant with no symptoms to be infected with several viruses.”

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“Shoestring” type leaf distortion may be a symptom of a virus or herbicide damage. Get confirmation from the plant disease lab. Photo from Andy Rollins.

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 – 5/4/20

Coastal

Zack Snipes reports, “We have had a very wet spring with some places receiving over 13 inches of rain this month.  Crops look surprisingly good considering the excess rain and cooler nights.  I have seen an increase in worm activity on brassicas, particularly the cabbage looper.  With all the rain, I have seen some hot spots of bacterial spot in tomato.  If you scout from your truck or tractor, you will not find bacterial spot until much later in the growing season.  The disease starts on the bottom leaves of your tomatoes and works its way up throughout the season.  Preventative products such as copper, mancozeb, and plant activator products are the only control measures we have. Get out and scout and look very closely, as the disease is very difficult to see in the beginning stages.”

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Cabbage looper on a cabbage leaf. Photo from Zack Snipes.

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Bacterial spot starts on the bottom leaves and works its way up the plant throughout the season. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “The weather was really nice this past week. We got about an inch of rain early Thursday morning and it has been breezy since, so all the water dried up fast.  The weather conditions have been perfect for grey mold in strawberries and it is showing up in areas where folks are falling behind in sanitation. It looks like there are more blooms on the plants this week, but with temperatures in the 80’s for a few days, that may slow down some.  Thrips are still an issue in places and treatments are going out, so keep scouting. If you need to make an application for thrips, do it early in the morning or late in the day to avoid spraying foraging pollinators. Keep looking for spider mites as well.”

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Rotting berries covered in Botrytis spores can go unnoticed in between plants.  Every time the wind blows, spores from these berries will be dispersed to other areas of the field. Photo from Justin Ballew.

Sarah Scott reports, “Peaches are progressing nicely in the Ridge area. Growers started harvesting early varieties. Some issues of bacterial canker are still becoming more noticeable in later varieties. The first sprays for scale crawlers have been applied and growers are continuing weed and orchard management sprays. Still picking strawberries. Crops for summer harvest are being planted still such as tomatoes and cucurbits. We’ve had some nice rainfall over the past week to keep soil moisture up but we have had high winds that have caused some limb breakage in orchards and stress on young vegetable transplants in the field.”

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Russetting on peach, possibly from earlier thrips damage. Photo from Sarah Scott.

Pee Dee

Tony Melton reports, “Winds are awful and damaging crops (sandblasting, wringing off plants, leaving spots on leaves and stems, causing wounds where disease like damping off can start and enter plants), stunting plants, and causing early flowering in tomatoes and peppers.  Insects are awful, including grasshopper, thrips, diamondback moth, yellow-margined beetle, and false cinch bugs.  Rains and irrigation to keep down sand blowing are causing leaching of nitrogen. In combination with decreased plant growth due to wind, we are adding extra nitrogen to get the plant size needed to get yields.  Hopefully, we can keep the processing tomatoes and peppers in the growth stage a little longer before the fruiting stage really kicks-in and further reduces plant growth.”

Upstate

Kerrie Roach reports, “While some have been hesitant, many Upstate Farmers Markets opened for the season this past weekend. Utilizing revised set-ups, handwashing stations, and promoting social distancing people still came out to support growers. Strawberries in Pickens and Anderson Counties are producing well and growers are selling out quickly. Weather conditions have been great for growing the last few weeks, and many of our market growers will be starting to move into the production stage over the next few weeks.”