Weekly Field Update – 9/26/22

Coming up this week, there are a couple more waste pesticide collection events: Lexington on 9/27 and York on 9/28. See more details on the Upcoming Events page.

Be sure to scroll all the way to the bottom to see this week’s Question of the Week and check back on Thursday for the answer!


Extension Entomologist Tom Bilbo asks, “Do you grow cole crops? Do you have diamondback moth in your fields? Have you experienced reduced efficacy of insecticides to manage them? We are looking for cole crop farms throughout SC to collect diamondback moth larvae from. We will test these larvae in the lab against a range of common insecticides to determine if resistance has developed. The results will help us provide better recommendations on insecticide sprays and rotations. Studies conducted over the last several years in GA and FL found diamondback moth resistance to a number of commonly used insecticides (Avaunt, Lannate, Intrepid, Knack, Rimon, Warrior II, Brigade, and Coragen) and it is important we determine where else these resistance issues are occurring. If you grow kale, collards, cabbage, broccoli, or other cole crops and have diamondback moth in your field please send an email to tbilbo@clemson.edu and we will plan a visit to collect diamondback moth larvae from your farm. All results will be kept confidential and reported only in aggregate. We greatly appreciate your help, and thank you in advance!”

Diamondback moth larvae and pupa (left) and the adult moth (right). (T. Bilbo)

Coastal Region

Rob Last reports, “Sweet potatoes in the area are coming to harvest along with fall watermelons, squash, and zucchini. Diseases are present in the cucurbits, particularly downy mildew in cucumbers and gummy stem blight in watermelons. Please remember to keep fungicide applications up to date until the last harvest. As our thoughts turn to fall cropping, I am finding imported cabbageworm and diamondback moth on transplants. Remember to rotate modes of action of insecticides to get good control. Where brassica are to be transplanted, carefully consider an application of herbicide. The herbicides will make life easier but choose carefully based on your rotation and expected following crop.”

Zack Snipes reports, “Things have finally dried out enough to work the ground in many areas. Now is a great time to get out pre-plant herbicides for fall brassicas. I’m hearing many reports of weak and diseased brassica transplants coming from the plant houses. Starting with clean, healthy plants is the only way to get optimal yields. Scouting plants for disease AND insect pests (particularly diamondback moths) before you set plants in the field is highly recommended. If you have fall cucurbits planted, be on the lookout for both melonworms and pickleworms. I saw both of these pests decimate crops last week.”

An application of Treflan preemergent herbicide was applied and rototilled in. Broccoli was planted 2 days later.  (Z. Snipes)


Justin Ballew reports, “The first day of fall was very warm, but we’ve been enjoying beautiful weather since. It is quite dry here in the Midlands, but it appears we may have a significant rain event headed our way this weekend. Lots of strawberry plastic has been laid. With the ground as dry as it is, folks may need to overhead water a little before laying plastic to help the beds keep their shape. Fall crops are looking great right now. There is a little black rot present in brassicas in some overhead irrigated fields, but for the most part, diseases are very low. Pecans are looking great right now also. It appears we are going to have a good crop in the Midlands this fall.”

There is a little black rot present in brassicas, but overall disease pressure is low right now. (J. Ballew)
Pecans are progressing well in the Midlands, and we expect to have a good crop. (J. Ballew)

Sarah Scott reports, “Cooler temperatures have been enjoyable the last week here in Aiken and Edgefield, but we are pretty dry and could use a bit of rain. Hoping for some moisture from the tropical systems expected to come through later this week. Land is still being prepped for new peach plantings. We are getting close to putting strawberries in and continuing field prep for that. Fall crops are looking healthy with no real significant pest or disease issues at the moment.”

Pee Dee

Bruce McLean reports, “The nighttime temps have dropped back quite a bit, and the air is a less humid… fall is upon us. Summer vegetable crops are starting to wind down. Okra production is dropping back, as are squash and zucchini. Pickling cukes are still being picked in good volumes. Some tomatoes and peppers are being harvested. Well-managed pumpkins are looking really good. Fall vegetables are still being planted. We’re seeing some fields of really good-looking brassicas (collards, cabbage, mustard, turnips, and broccoli). Muscadines are wrapping up. Doreen (muscadines) are at peak ripeness right now. Carlos and Noble should be completely harvested. Some late fresh pick muscadines are still being harvested. Strawberry beds are just about ready for planting, but it looks like strawberry plants may be a little delayed from the nurseries due to production issues. Growers that may be forced to plant late would benefit from talking to your local Extension Agent on strategies for maximizing vegetative growth this fall. Also, be sure to actively look your plant over for disease and possible mites. Root dip (of your strawberry plants) with fungicide would be advised to ensure as clean a start as possible (from disease).”

Doreen muscadines showing what appears to be some ripe rot (sunken and shriveled grapes with pinkish color spores) and macrophoma rot (small sunken black lesions). (B. McLean)
Lynx spiders have a voracious appetite. This one just caught a hapless bumblebee. (B. McLean)

Question of the Week

For this week’s question, take a look at the photo below. Why is a portion of this squash leaf discolored (lighter green/yellow)?

Answer in the comments below and check back on Thursday to see the answer.

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