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.”

IMG_0756

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.”

20200618_105935

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.”

l1

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.”

Downy Mildew Found on Watermelon in SC

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

2015-07-13 DM on WM

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

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.”

IMG_0619

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.

IMG_0637

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.”

IMG_0295[1]

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.

IMG_0296[1]

 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.”

20200608_135601

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.”

20200603_114105

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.”

b1

Checkerboard pattern indicative of Cucurbit Downy Mildew on cucumbers. Photo from Bruce McLean.

b2

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.

20200604_142857

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.

20200604_142847

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.”

IMG_0489

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

IMG_0499

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.”

20200603_095629

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

20200603_093954

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.”

lalo

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.”

bruce 1

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

bruce 2

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.”

ED27C93C-C296-4F56-BCB0-6DE7AC6082EE

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

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.”

IMG956628.jpg

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

IMG956617.jpg

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.”

20190807_142457.jpg

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

20190805_145339.jpg

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.”

20190812_093934.jpg

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

20190812_081355.jpg

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.”

fw.jpg

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.

IMG_0157.JPG

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

IMG_0216.JPG

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.

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.