Fog and Downy Mildew on Collards

From Clemson Plant Pathologist Tony Keinath.

Foggy fall mornings are nature’s warning that conditions are favorable for brassica downy mildew to get started on collard and kale.

Downy mildew sporulation (white masses) on the underside of a collard leaf. Photo from Dr. Tony Keinath.

Remember that because downy mildew affects the harvested, edible portion of the crop, control practices must be very effective to increase yields. Use the following practices to maximize control:

1. Rotate crops to new fields every year. Brassica downy mildew is believed to survive in soil.

2. Check lower, older leaves for angular yellow downy mildew spots on the top of the leaves and black lesions with white downy mildew growth on the bottom of the leaves. Even lesions 1/8-inch in diameter can produce spores.

Yellow downy mildew lesions on the top side of a collard leaf. Photo from Dr. Tony Keinath.

3. Make the first fungicide spray when the first foggy morning is predicted. Fog means the leaves will stay wet all night and a good part of the morning. The lack of sunshine on foggy mornings also allows downy mildew spores to stay alive longer than on sunny mornings, when UV light will kill them in about 24 hours.

4. Potassium phosphite is a very effective, economical alternative fungicide against brassica downy mildew. It is probably “good enough” by itself during sunny periods without rain. Note that it is not labeled for certified organic production.

5. During rainy periods, rotate effective conventional fungicides, like Zampro or Presidio, with potassium phosphite. Fungicide rotation is critical for leafy brassica greens left in the field for more than 2 months when leaves are cropped repeatedly. Zampro may be applied only 3 times per crop. Presidio may be applied 3 times at the 4-ounce rate or 4 times at the 3-ounce rate.

For more info on brassica downy mildew, see Dr. Keinath and Tim Bryant’s article in the latest issue of the Clemson IPM Newsletter.

Weekly Field Update – 10/11/21

Statewide

There are some reports that anthracnose may be issue in strawberries this year. In addition, we are continuing to look out for the new disease, Neopestalotiopsis. Clemson Plant Pathologist Guido Schnabel has recommended applying Zivion S (natamycin) via preplant dip to help prevent these diseases. Dr. Schnabel provided the following instructions:

Mixing Instructions. Add Zivion S while stirring to the volume of water to be applied, or to a smaller volume that is then added to more water to make the expected final volume. Continuously stir the treatment solution unless it is to be applied immediately.
Application Time. Apply prior to plant as a preplant transplant root or whole plant dip treatment. Do not apply after or to harvestable commodities.
Application Rate. Root or whole plant dip: mix 6-12 fl. oz. (0.04 – 0.08 lbs a.i.) of Zivion S per 10 gallons of water. Dip plants for a minimum of 2 minutes, but no more than 5 minutes. Plant treated plants after dip application.

To find Zivion contact Nelson Jameson at 800-826-8302.

Coastal Region

Rob Last reports, “We are progressing well with preparations for strawberry planting. Some Plants are due to be delivered this week. Remember, if fumigants have been used, check to ensure the products have dissipated to prevent damage to the transplants. The same is true to make sure planting restrictions on any pre-emergence herbicides applications are observed. Always refer to the label. Finally, remember to check your plants carefully for pest and disease inoculum from the nursery. Planting any disease or pest-infected plants will lead to a more challenging. If you require any help, please reach to Extension Agents.”

Zack Snipes reports, “I thought I had moved to Seattle last week with all the rain and dreary weather. We have a good week of weather coming up and I expect that everyone will be busy in the fields transplanting greens, finishing laying plastic, and continuing the harvest of fall crops. Watermelons, squash, and winter squash are being harvested this week. Downy mildew is loving this weather and is on basil, squash, cucumbers, winter squash, and cantaloupe. I have seen many freshly transplanted fields with black rot in brassica. This disease shows up every time we plant brassica. It is essential to transplant quality transplants. If your transplant supplier is sending you diseased plants, then visit our Seed and Transplant Supplier list to find a new supplier. You might be surprised how big of a difference it makes. Carolina Farm Stewardship Association is having a webinar this week on Tuesday, October 12 at 12pm on Ginger and Tumeric production in a high tunnel. Please email zbsnipe@clemson.edu for link and passcode.

Black rot with its characteristic yellow “V” shaped lesion. Photo from Zack Snipes.
Transplants that are yellow and have black rot symptoms will not yield like healthy plants. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “We finally saw some sunshine this past weekend after a pretty rainy week. Caterpillar pressure has been high and lots of treatments have been going out. I’ve been seeing a decent amount of pathogenic fungi developing on diamondback moth caterpillars due to the wet conditions creating the perfect conditions for development. We’ve had a couple acres of strawberries planted and ordinarily we would be planting full steam ahead now, but strawberry plants are late coming in this year. Lots of folks are being told it will be next week before their plants come in. I’m also hearing reports that anthracnose may be a problem from nurseries this year. As a result, we are strongly recommending a fungicide dip on transplants before planting to combat this and any potential infections from the new disease Neopestalotiopsis. See Dr. Schnabel’s comments about Zivion above.”

This diamondback moth caterpillar’s corpse is covered in white fungal growth. The recent wet conditions have provided the perfect environment for entomopathogenic fungi development. Photo from Justin Ballew.

Phillip Carnley reports, “Cucumbers are finished in Orangeburg and Calhoun counties. Fall greens are in full swing with some pressure from DBM with the occasional looper. Growers are bedding strawberry fields and applying their pre’s. We have seen heavy infestations of gummy stem blight in fall watermelons, as well as spider mite damage in blackberries.”

Gummy stem blight has been bad in watermelons this fall. Photo from Phillip Carnley.
Yellowing from spider mite feeding in blackberry. Photo from Phillip Carnley.

Sarah Scott reports, “Tree removal and field prep for new peach installations are happening around the ridge. Strawberry plants are being planted now and got a good watering in with last weeks rain. Fall vegetables are looking good, growers should keep up with scouting for disease issues in the field following the week of wet and humid weather.

Tree removal and preparations for new planting are going on now along the Ridge. Photo from Sarah Scott.
Fall tomatoes are looking great. Photo from Sarah Scott.

Upstate

Andy Rollins reports, “I am busy scouting new strawberry plantings this past week. Be on the look out for leaf diseases of plants but also check roots thoroughly for discoloration. When planting make sure crowns are still visible after planting. We are also preparing ground for new peach production going in. We are still picking a few muscadines, but that will be finishing pretty soon.”

Fungal infection on a newly planted strawberry leaf. All plantings need to be looked after carefully for the new disease Neopestalotiopsis. Photo from Andy Rollins.

Weekly Field Update – 10/4/21

Coming up this Thursday (10/7/21) is the Farm Safety Day for Women hosted by the SC Women’s Ag Network (SCWAgN). Topics will include chainsaw, electrical/fire, pesticide, tractor, and trailer safety. Click here to register.

Coastal Region

Zack Snipes reports, “We had near perfect conditions for working in the fields this week compared to past weeks. Muscadine harvest is near complete and watermelons are beginning to be harvested.  I sampled a good many blueberry fields this week with red foliage and weak plants.  We have identified some bacterial leaf scorch in a few orchards and are hoping other farms don’t have this pathogen as well.  There are currently no management options once this disease is found in blueberry.  I also saw some herbicide injury on plants this week as well.” 

Atypical symptoms of bacterial leaf scorch in blueberry seen this season. Photo from Z. Snipes.
Dual Magnum injury on cucumbers. Photo from Z. Snipes.

Rob Last reports, “As planting season is well underway for fall crops, I am getting calls about suspected herbicide damage to sensitive crops.  Symptoms include stunting of the plants; discoloration, be that yellowing or bleaching.  There are several steps to preventing issues associate with herbicide damage. Firstly make sure your spray application equipment is cleaned carefully according to the product’s label to be applied.  The process could be as simple as a triple wash or may need to wash out using a tank cleaner, again following directions on the label. Secondly, be sure of the plant back restrictions for herbicides applied to the previous crops.  Many residual (soil acting) herbicides can have significant effects on sensitive crops. Remember always follow the label and if you are in doubt, ask an Extension Agent for help.”  

Midlands

Justin Ballew reports, “It was a little warmer this past week and it has gotten dry. Lots of irrigation has been running lately. Caterpillar populations remain high in brassica crops and growers are making treatments. Remember, it is important to use a surfactant with caterpillar insecticides when spraying brassica crops like collards, kale, cabbage, broccoli, etc. The waxy leaf coating makes water bead up and roll right off the leaves. A surfactant helps the spray droplets spread out and stick to the leaves. Forgetting a surfactant can make insecticides appear to have poor efficacy even when the insect population is in fact sensitive.”

Without a surfactant to help droplets spread out and stick to the leaf, water readily beads up and rolls off the waxy leaf coating of collards, kale, cabbage, broccoli, etc. Video from Justin Ballew.

Upstate

Andy Rollins reports, “Fall blackberry production on Primeark 45 has been exceptional this year.  Spring crop was killed out and seemed to force better than normal fall production.  Muscadine picking is also in full force still and quality is excellent.   
We are finished bedding for strawberry and some growers already have their plants in the ground.  Close inspection of plug plants for blackened roots is extremely important.  Also please make sure plants are properly planted.  This is especially true for cutoff and bareroot plantings.  
We are also getting new ground ready for peach plantings in 2022.  Incorporation of lime and phosphorus at this time is critical for longterm success in this instance.  Many times lime recommendations need to be doubled to achieve the desired pH.” 

Blackberry on-farm new varieties in trial. Photo by A. Rollins.
‘Galaxy’ is a thornless, semierect high-quality blackberry with firm, large dark fruit suited for fresh market. Photo by A.Rollins.

Kerrie Roach reports, “With a significant loss in the apple crop from the late April cold event in the Upstate, growers have had to work together to keep things available for customers. The reduction in spray applications throughout the season has shown through on the crop that remained on the trees. This tends to be a pay for it now, or pay for it later kind of situation. End of season and dormant applications are going to be that much more important for the 2022 growing season. Muscadines are really starting to come in strong, and figs are just about to finish in the next week or so. Last week was beautiful, but this week looks to be filled with rain and cooler temperatures. Keep an eye on fall planted crops and monitor closely for disease activity.”

Weekly Field Update – 9/27/21

Coming up this Saturday (10/2/21) is a Waste Pesticide Collection Event held by the SCDA in York. Take a look at their news release here and take advantage of this event if you have any pesticides sitting around that you don’t expect to use.

Coastal Region

Zack Snipes reports, “We have had plenty of rain as of late in the Lowcountry. Many growers could not get in the fields due to fields being soggy. We have some beautiful weather coming this week so I expect a good bit of ground to be prepped and planted. We have plenty of moisture in the soil so those preemergent herbicides should have great efficacy if put down properly. I am seeing some odd yellowing symptoms of watermelon vines that lead to a collapse in the plant. We sent off samples to the Plant Diagnostic Lab. If you are suspicious of a plant disease, we can identify the disease for you. I also received a few calls this week about greenhouses. Before buying a greenhouse, consider retrofitting a shipping container. Thousands of transplants can be grown in a very small space which saves you money on your heating and cooling bill.”

A retrofitted shipping container for growing vegetable transplants at the CREC. Photo from Zack Snipes.
Thousands of transplants can be grown in near optimal conditions in a container. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “We’ve really been enjoying the fall weather here in the midlands. We got some rain and the high temperatures have been in the upper 70s/low 80s. The majority of folks got their beds formed and plastic laid for strawberries last week. I’m getting some reports that strawberry nurseries are facing a tight supply this year. Hopefully, everyone got their orders in early. On brassicas, we’ve seen a significant increase in caterpillar population levels over the last week. That makes now a great time to run a field bioassay to screen for insecticide resistance in diamondback moth populations. Contact your local agent to schedule one.”

Tiny, oval, yellow-colored, diamondback moth eggs on the underside of a leaf of a week-old collard plant. Scout carefully as soon as plants go in the ground. Photo from Justin Ballew.

Phillip Carnley reports, “Brassica production is ramping up in Orangeburg and Calhoun and Clarendon counties. Diamondback caterpillar is making itself known in brassica crops, especially in collards. Make sure to scout early and treat in a timely fashion. If your insecticide program is not showing the desired level of control, talk with your local agent about scheduling a bioassay to assess your population’s resistance to different insecticides. Also, be on the lookout for black rot and other fungal problems in early transplants. Loopers seem to be a non-issue currently but stay vigilant in monitoring. I am still getting plenty of calls for pecans and the majority of the issues are pecan scab and yellow aphid damage, causing nut drop and premature defoliation. Also be mindful to monitor/ test for nematodes, in my area I am seeing population loading due to lack of cultural and chemical control. On blackberries, make sure to harvest in a timely manner and maintain a high level of sanitation, as there is plenty of spotted wing drosophila to go around.”

African Fig Flies (AFF)(with the white stripes) can invade small fruit crops simultaneously with spotted wing drosophila (SWD). Once the SWD cuts a hole in the fruit to lay an egg, the AFF comes along and lays an egg in the same hole. AFF can also invade strawberries and blackberries independent of SWD. Photo from Phillip Carnley.

Pee Dee

Bruce McLean reports, “Last week’s rainfall really helped to moisten dry soils around the Pee Dee. Fall vegetable crops are coming along. Disease activity is low and insect activity is light to moderate. Surprisingly, diamondback moths have not been observed yet. Looper activity has been light to moderate on brassicas and cabbageworms have been observed in some fields. Aphids have been seen, as well. Stink bug activity has been moderate on okra. Okra harvest has begun to slow down, but decent volumes are still being harvested. Wine and juice muscadine harvest is complete, but some fresh market muscadines are still being picked in limited volumes. Most folks have bedded and fumigated for strawberries (… or will be this week). Talking to growers, it sounds like strawberry plants (plug and bare root) are getting a bit scarce… more so than normal for this time of the year. If you’re looking for some plants, you may have to go with varieties that you might not familiar with. Be sure to order early next year to get the varieties and volumes you need.”

Weekly Field Update – 9/20/21

Coastal Region

Rob Last reports, “Fall cucurbit crops, including cantaloupes, and watermelons are ripening and approaching harvest. Disease pressure from powdery mildew and gummy stem blight have really increased significantly over the last week. Maintaining a tight spray program will be key to managing disease. As we look forward to strawberry planting land is being prepared. If you are planning to fumigate, make sure the plant back interval between fumigation application and planting is maintained. A good test can be to plant some lettuce seed in the treated area. When lettuce germinates, the risk of damage from fumigation is reduced. Finally, on any remaining fall plantings, consider using a labeled pre-emergent herbicide to help with weed management. Once the crop and weeds emerge, options are drastically reduced.

Zack Snipes reports, “Land is being prepared and fall crops are going in around the Lowcountry. Early fall crops look better with the slightly cooler temperatures and periodic rain. We are wet in some parts. I am seeing lots of bacterial spot in the fall tomato crop. We have good herbicide management plans for greens, but folks will need to take advantage of pre-emergents now.”

Bacterial spot is bad this fall due to the consistent rain. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “This past week was fairly rainy. There are several fields that are pretty soft, even some sandy fields. Folks are still planting brassicas for the fall and they are looking really nice right now. Strawberry growers are also getting prepped to fumigate and lay plastic. We’ve been seeing a lot of damping off (Pythium) in young cucurbits and some brassicas lately. The wet weather is definitely creating the perfect conditions for this. A few things that can be done to help minimize damping off include planting on plastic beds, planting at the proper depth (just deep enough to cover the plug with native soil), rotating fields wisely (tomatoes are a host for Pythium), and using a fungicide at planting may also make sense when environmental conditions are right for Pythium development.”

When transplants are set deep like the one pictured here, the moisture in the soil creates favorable conditions for Pythium to develop all the way up the stem. Instead, set transplants just deep enough to cover the plug with native soil. Photo from Justin Ballew.

Phillip Carnley reports, “Cucumber production is in its final stages here in Orangeburg and Calhoun counties with most growers close to or in the process of harvesting. There is still a noticeable amount of cucurbit downy mildew, but due to the dryer weather it has been easier to keep in check. Sweetpotatoes are currently being dug with yields looking to be fairly good. There have been a few issues with wireworm damage in sweet potato fields with the majority of damage being seen on the lighter colored tubers. Diamondback caterpillar is ramping up in brassica crops, especially in collards. Make sure to scout early and treat in a timely fashion, if your insecticide program is not showing the desired level of control talk with your local agent about scheduling a bioassay to screen your population’s resistance to different insecticides. Also be on the look out for black rot and other fungal problems in early transplants.”

Holes bored into sweetpotato tubers by wireworms. Photo from Phillip Carnley.

Sarah Scott reports, “We received some heavy rain in areas throughout Edgefield and Aiken Counties last week, up to 2 inches in spots. In preparation for October planting, plastic has been laid in strawberry fields. Brassica crops are being planted as field conditions allow. Late summer plantings of broccoli are starting to get some good size on them. Pepper plants that were put out in August are setting fruit that is starting to size up nicely.”

Strawberry plastic laid and ready to go. Photo from Sarah Scott.
These broccoli plants were put out on September 2. Photo from Sarah Scott.
Fall peppers are sizing up nicely. Photo from Sarah Scott.

Weekly Field Update – 9/13/21

Coastal Region

Zack Snipes reports, “We had a heavy downpour of rain last week surpassing 2.5 inches in some spots. I am seeing downy mildew in cucumbers and lots of gummy stem blight in winter squash and pumpkins. The worm pressure has lessened in the past few weeks. I am seeing lots and lots of black rot in transplanted brassicas. Inspect your plants before planting them to make sure the disease is not coming from the nursery. Once a brassica is planted in the field, there is not much we can do to slow the spread except hope that environmental conditions (rain, humidity) are not conducive to spread the disease. I am also seeing lots of early weed pressure in fall planted crops on both bare-ground and plastic. We have some very good herbicide options to apply preplant. Once you plant the crop, we have very few herbicides that can be used over the top of the crop. Right now is the time to get down strawberry herbicides before the season starts. As the old proverb goes: an ounce of prevention is worth a pound of cure.”

Black rot on collard transplant (V-shaped lesion on the margin) just waiting for the right environmental conditions to decimate your yields. Photo from Zack Snipes.
A healthy stand of sunnhemp shades out most, if not all, summer weeds reducing the weed seed bank. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “We received about an inch of rain (at my house), which we really needed. The temperatures over the last week have been very mild and it has started to feel like fall. Fall crops are doing well. We’re still planting brassicas and keeping an eye on caterpillars. Muscadines are being harvested now. Growers are reporting good fruit quality, but lower yields than last year. This is most likely due to the late cold weather that affected muscadine growers across the state. On pecans, black aphid populations and scab incidence are both high. It appears both of these pests are going to significantly reduce yield on sensitive varieties if growers didn’t stay on top of sprays.”

Pecan scab is severe this year. This disease can cause the tree to abort infected nuts. Photo from Justin Ballew
Black aphids are very small, but their damage is easy to see on the leaves. Photo from Justin Ballew

Weekly Field Update – 8/23/21

If you haven’t already done so, please take a few minutes to fill out a survey share your thoughts with us on Extension meetings. We’ll be using the information collected to help plan meetings over the next year. It will take less than 10 minutes and is anonymous. Click here to get started. Thanks!

Midlands

Justin Ballew reports, “Last week was warm and humid again. Some of our sandier fields got dry enough early in the week that crops were wilting in between waterings. We got a bunch of rain over the weekend, though (a little over 2 and a half inches at my house). Overall, fall planted crops are coming along nicely. Some of the earliest planted fall squash and zucchini is being picked now. We’re still seeing the same disease problems that have plagued us all summer, though growers seem to be managing them fairly well. As far as caterpillars go, I’m seeing mostly diamondback moth and armyworms with a few loopers here and there. Get ready. This could be a high pressure fall for caterpillars.”

Even though we’ve had lots of recent rain, it doesn’t take long for the sandy soil in Lexington to dry out and let the plants wilt. Photo from Justin Ballew.

Phillip Carnley reports, “Not much has changed here in Orangeburg or Calhoun Counties. Its been hot and humid and we’ve had a few untimely showers delaying cucumber harvests. There is still plenty of downy mildew to go around. We are seeing loopers on pickling cucumbers that are ready for harvest. At that stage the loopers should be treated prior to harvest with Coragen, Harvanta, or Radiant. Fall brassica, peas, and tomatoes are just now being planted.  We are seeing increased amounts of scab in pecans this year, due to the rain and humid weather. For insect and disease management in pecans, have a look at the UGA Commercial Pecan Spray Guide.”

Caterpillar damage to fall cucumbers. Photo from Phillip Carnley
Loopers are causing some damage to fall cucumbers in the Orangeburg area. Photo from Phillip Carnley.

Upstate

Andy Rollins reports, “Excessive rains have caused cracking of fruit at several upstate muscadine farms. Powdery mildew is also present but I’m not sure how much of a role it is playing on the cracking part. The powdery is damaging the skin of the fruit. Topsin M is labeled and recommended with Captan but have to wait 7 days to pick so have to watch your PHIs. Also finding some insect pests in peach. Oriental fruit moth and sap beetles have been found last week but only a small amount of affected production. Herbicide control has been difficult this year because all the rain has caused excessive grass growth, especially in new orchards.”

Seeing some cracking of the skins in muscadines in the upstate. Photo from Andy Rollins.
This new grower has done a good job of keeping his understory clean. This will pay off for him in the spring of next year if he can keep up the diligent work. Photo from Andy Rollins.

Weekly Field Update – 8/9/21

Coastal Region

Rob Last reports, “Generally speaking, we are in the change over period from spring to fall crops, with some fumigants being applied to next year’s strawberry plantings. If fumigants are to be used, make sure soil moisture is good and beds are firm to gain maximum efficacy. One thing we have observed in blackberries and blueberries in the area is the emergence of bark scale. Bark scale is a new pest to South Carolina and has previously been noted in ornamentals. However reports for Asia, where the pest is native, indicate the bark scales can survive on Rubus species.

Bark scale egg sacks and adults. Photo from Rob Last.

The images show the egg sacks and adults of the bark scale. The insects appear white and are very waxy, similar in appearance to mealybugs. The wax coatings can make management complex, preventing insecticides from penetrating the layer to be effective against the insects. The addition of crop oils to the pesticide solution may enhance efficacy by helping to strip off the waxy coatings. In blueberries, adults can be found underneath the exfoliating bark, again making contact with the insecticides more difficult. When crawlers emerge, they will be pink and barely visible to the naked eye, and monitoring will be easier with the aid of a hand lens. We will find crawlers hatching in April or May, with a second flush emerging in late summer. An excellent way to detect crawler movement is to wrap the branches in double-sided sticky tape to help to catch the crawlers. Contact insecticides can be very effective against the crawlers. Insect growth regulators may also be effective for management. Unfortunately, systemic materials such as imidacloprid appear to have little effect. Please get in touch with an Extension Agent to help with identification and management options.”

Bark scales have a waxy coating that helps protect them from insecticides. Photo from Rob Last.

Zack Snipes reports, “It’s wet in the Lowcountry. We are getting heavy rain showers what seems like everyday. This is making it hard to get equipment in fields to spray or prepare for fall plantings. I have seen some watermelon and tomato fields and they look ok considering the rain and soggy conditions. I saw some bacterial spot on pepper and expect to see the same on fall tomato with the rain and humidity we’ve had. Get out your preventative fungicides, if you can. I also saw some leafminer damage on these crops which is unusual in my tenure. It seems plants were impacted a few weeks ago but the new growth looks to be unaffected. Melonworms were found in cucumbers, so get ahead of them.”

Leafminers are showing up on tomatoes on the coast. Photo from Zack Snipes.
Melonworms were found in cucumbers this week. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “This past week was a relatively nice, mild week compared to the week before. We had some rain to start the week and more to finish it out. Planting of fall crops continues and what’s been planted seems to be growing well. I looked at a few fields this week of seedling brassicas and I’m already seeing diamondback moth caterpillars and armyworms feeding. Remember to start scouting as soon as plants go into the ground. It doesn’t take many caterpillars to eat up seedlings and small transplants. Don’t forget we can run field bioassays to screen for insecticide resistance, so call us when you start seeing worms.

Diamondback moth caterpillars are already showing up on fall brassicas. Photo from Justin Ballew
It doesn’t take many caterpillars to eat up these small plants. Photo from Justin Ballew.

Pee Dee

Bruce McLean reports, “Vegetable crops are still harvesting well, for the most part. Other than cucurbit downy mildew affecting cucumbers and some powdery mildew affecting squash, there are no widespread vegetable diseases seen in the fields. Cowpea curculio is still widespread on peas and must be intensively managed (starting prior to bloom) to minimize damage. Spotted Wing Drosophila is still very active in late-season blueberries, with trap counts showing very high capture numbers. Grape root borers (GRB) emergence is starting to increase in muscadines. Trap captures for GRB is on the rise. Much of the state is outside the window of Chlopyrifos application for GRB… except on late harvesting cultivars (more than 35 from application to harvest) and maybe some wine grape cultivars in the Upstate. Pecan weevil emergence is just getting started (in pecans). Ground and lower canopy application of Carbaryl and/or a trunk application of Tanglefoot are effective methods of control. Monitor traps and weevil movement through September (especially after rains). Re-treatment of Carbaryl will be necessary and can be reapplied at (up to) 7 day intervals. Pecan scab is becoming more evident in pecan orchards. Also, fall armyworm numbers have exploded over the last two weeks. This is a pest that can affect a wide variety of crops.

Who is spitting in my muscadine vines? That is not actual spit. It is a sticky, frothy substance produced by the spittlebug for protection from predation. Photo from Bruce McLean.
This tiny insect is the spittlebug (what is inside the frothy spittle on muscadines and other plants). They feed upon the foliage of the muscadine vine and do not cause any noticeable damage to the plant. Photo from Bruce McLean.
Grapevine aphids populations on muscadines can be quite significant in late summer. They feed primarily on the foliage and late flower clusters. They seldom require chemical management except when present during spring bloom. Heavy rains and natural predation usually keep them in check. If extended periods of dry weather occur and their feeding does lead to noticeable problems (or if honeydew and sooty mold become evident on fruit and leaves) an insecticide application may be necessary. Photo from Bruce McLean.

Weekly Field Update – 8/2/21

Coastal Region

Zack Snipes reports, “Summer crops like okra are still coming in and looking good. We’ve had a lot of rain and some fields are soggy. More rain is coming. Some growers have started planting peppers and tomatoes. Remember to get out in the fields and destroy spring crop residue. Nematodes and other pests can really thrive on that old residue.”

Root knot nematode infestation on tomato roots. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “Last week was by far the hottest week we’ve seen so far this summer. It’s been a very mild summer, so last week was actually a reminder of what “normal” is here. Tomatoes, squash, zucchini, cucumbers, and sweet corn are still being harvested. More fall brassicas, cucurbits, and some tomatoes were planted this past week. I haven’t heard of any reports of serious caterpillar activity yet, but remember to start scouting as soon as you plant. It doesn’t take long for caterpillars to significantly damage brassica seedlings.”

We’re still picking some good looking sweet corn in the midlands. Photo from Justin Ballew.

Upstate

Kerrie Roach reports, “Things in the Upstate, like much of the rest of the state, have been particularly hot and dry this last week. Irrigation has been of utmost importance as well as mitigation of disease and insects. As we move later in the season, things are starting to slow down, but now is the time to start prepping and planning for any of those fall plantings. For our smaller market growers, season extension by utilizing fall crops can be a great addition. Many farmers markets are looking for growers to sell in the early fall, and competition is slim, often making sales easier. Do your homework BEFORE plating and start looking now at local markets ending dates, vendor loads, customer preferences, and plan accordingly. Check out the SE Veg Crop Handbook for fall planting dates from many of your favorite crops. 

Weekly Field Update – 7/26/21

Statewide

The SC Specialty Crop Association is offering a new grant opportunity, the Enhancing Crop Packaging Cost-share Program. With this new cost-share program, growers can receive reimbursement up to $1,800 per grower for packaging needs. All that is required in addition to the application are copies of receipts used for purchasing packaging materials. You will also be required to fill out two surveys, one initially and one 12 months after submitting the application. All information is confidential. For more information, contact LauraKate McAllister. The application can be downloaded below.

Coastal

Zack Snipes reports, “We are in a summer weather pattern with warm, muggy days and occasional thunderstorms. Most crops have finished up or are in the process. Now is a great time to sit down and do some crop planning and field rotation planning. I collected many soil and root tissue samples lately and had them analyzed for nematodes. I was surprised at how many nematodes were present in the fields. Nematodes can interfere with growth, cause stunting, and lower overall yields. Sometimes the symptoms of nematodes can be very discrete so sampling right now is the best way to get a baseline of your populations and how to properly manage and rotate fields. If left unchecked, thousands of dollars are wasted before the first seed is planted into a field.”

Significant galling from root knot nematodes on a cucumber seedling. Photo from Zack Snipes.

Midlands

Justin Ballew reports, “It was another fairly mild week with high humidity and some pretty decent rain. Not much has changed on the disease front. We’re still seeing plenty. Growers are still prepping fields for planting fall crops. Some fall cucurbits and brassicas have been planted already. More are on the way. As soon as brassicas go in the ground, start scouting for worms. Remember, we can perform bioassays to screen for insecticide resistance in diamondback moths populations. Reach out to your local fruit and vegetable agent when you start seeing worms to schedule one.”

Bacterial spot is common on tomatoes right now. Photo from Justin Ballew.
Recently planted kale is growing well. Start scouting for worms as soon as you plant brassica crops. Photo from Justin Ballew.

Pee Dee

Bruce McLean reports, “Vegetable crops are harvesting well, with good volumes of squash, zucchini, cantaloupe, watermelon, cucumber, butterbeans, peas, tomatoes and okra. Sweet corn is beginning to wrap up. Late season blueberries are still being harvested in some volume, but will be finishing soon. Muscadines are sizing well. Vineyards that were only slightly affected by the Easter freeze are looking good and should have a good crop. Vineyards that were more significantly affected by the freeze are very short on crop this year. Grape root borer traps in muscadine vineyards are starting to catch moths in all locations. Spotted wing drosophila (SWD) trap captures (in blueberries) have dramatically increased over the past few weeks, showing that even in late season when fruit is becoming less and less plentiful, the fly is still very active and must be managed.”

Bucket trap baited with the Grape root borer (GRB) pheromone lure in muscadines. Photo from Bruce McLean.
Where we did not see significant damage from the Easter freeze, there is a good looking crop of muscadines. Photo from Bruce McLean.

Upstate

Andy Rollins reports, “I identified a major scale problem on peaches. A grower from middle part of state called about red spots on peaches. Earlier in the year across the whole state we had red spots on leaves. We found prunus necrotic ring spot on all of those samples last year but we are still unsure of the origin. In this case, it is something much different. This is an insect that feeds on the fruit and the tree itself. The adult stage of this insect doesn’t move but the crawlers do. After consulting with Dr. Brett Blaauw, regional entomologist for Clemson, the grower decided to go ahead and treat now. On Friday, he sprayed Movento at the label rate. There is great concern because with this high of a population, the life of the entire trees at risk. The plan is to follow that application with chlorpyrifos and oil at low rates after the leaves drop. You have to be careful when doing this as the oil can damage the next years bud crop if temperatures are too hot. We will be trapping using black electrical tape wrapped around the limbs then double sided scotch tape around that. We will then look for the crawlers on the scotch tape. This ensures money isn’t wasted killing a pest that has already been controlled.”

Red spots have been common on peaches this year. Photo from Andy Rollins.
In this close up of the bark on a peach tree, you can see the tiny, black and grey colored scales. Photo from Andy Rollins.