Weekly Field Update – 5/22/23

Registration is now open for the Coastal REC Field Day on 6/7/23. Come to see and hear updates on vegetable weed, disease, and insect research. Register here.

Check out other upcoming meetings on the Upcoming Events tab, and don’t forget to look at our Resources tab for links to crop handbooks, helpful websites, and related blogs. Also, check out the latest episode of the SC Grower Exchange Podcast.

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.

Coastal Region

Zack Snipes

  • We got some much needed rain last week to settle the dust and push crops forward.
  • Growers should be aware of the possibility of increased disease pressure this week with the rain and increased humidity. We have great spray programs for melons and tomatoes in the SE Crop Handbook (pages 220 and 288).
  • I found a good number of squash bugs (adults, juveniles, and eggs) last week on melons and squash. We need to be on top of this pest and spray accordingly. These insects will hide at the base of the plant and down in the plastic or leaf litter. Directed sprays at the base of the plant are recommended to target this pest.
  • I also found ant damage on young melon transplants (tunneling into the stem). The plant will wilt and collapse.
Squash bugs are out and about partying and reproducing.  Manage them now instead of dealing with the issue all season. (Z. Snipes)
Ants boring into the stems of transplants has become a problem due to the dry weather as of late. (Z. Snipes)


Phillip Carnley

  • We’re seeing residual signs of pythium in cucumbers, but overall establishment looks great.
  • Cucurbit downy mildew has been found in SC, so be on the lookout and ready to treat. 
  • Blueberries are coming on strong. We are still finding some effects of the cold from earlier in the year, coupled with a lack of irrigation. 
  • Gummy stem blight (GSB) in watermelon is picking up as vines grow and start bearing fruit. Make sure to choose fungicides specific to GSB and rotate modes of action. 
  • In tomatoes, bacterial wilt is appearing, but not at great frequency. Nutrient management has also been an issue, with magnesium often being low in my area. 
  • Squash is still producing quite well.
  • A few growers are now picking their first harvest of okra. 
Blueberries are coming on strong in the Orangeburg area. (P. Carnley)
Blueberries are suffering in fields without irrigation. (P. Carnley)

Rob Last

  • Some welcome rain has been received over the last few days, which could lead to increased disease pressure in many crops. Sanitation will be crucial for many crops.
  • Wind damage and abrasion are present in many crops characterized by twisted plants or dry scarring.
  • Strawberries are loading up well with fruit. Monitor crops for spider mites and thrips. Remove any water-soaked berries to manage gray mold and anthracnose fruit rots. Maintain fungicide applications and rotate modes of action.
  • Blackberries are beginning to ripen. Monitor crops for early gray mold infections. Maintain fungicide applications and rotating modes of action.
  • Blueberries are yielding well with excellent quality. Monitor for fruit rots. Maintain fungicide applications and rotating modes of action.
  • Cucurbits are developing well, with some good fruit set being seen. As a rule of thumb, switch from chlorothalonil to mancozeb once we have softball-sized fruit. Cucurbit downy mildew has been confirmed in butternut squash in Charleston, so now is the time to add a specific downy mildewcide as per the post last week. Watch for squash bugs in cucurbit crops. Damage is seen in squash, cucumbers, watermelon, and cantaloupes. Given the rainfall, low levels of gummy stem blight are being observed in watermelon, which will likely take off. Remember to limit the number of applications of tebuconazole to one per crop, applied early, to help to manage developing resistance. Some excellent products for gummy stem blight include Inspire Super, Miravis Prime. Fusarium wilt is showing up in some fields. The best management options are varietal resistance or grafted plants onto Carolina Strongback.
  • Brassica disease pressure is currently low, but monitor crops following the rainfall to protect crops. Diamondback moths are active with increasing populations. Remember to rotate modes of action to prevent resistance. Ask your agent about bioassays for diamondback moth.
Strawberries were still loaded up before the rain. There is a salt marsh caterpillar checking this berry out. (R. Last)
Now that we have softball sized melons, make sure the right fungicides are being used. (R. Last)

Pee Dee

Bruce McLean

  • This May, so far, has shaped up to be a fruit growers’ delight with cooler than usual conditions and mostly dry weather.
  • The strawberry crop looks really good for the most part, with good quality, size, and quantity. However, many growers are seeing a drop off in sales. Folks, get out and support your local growers, especially with the quality of the strawberries coming out of the field right now. If the cooler temperatures continue, there may still be a good bit of season left.
  • Spotted wing drosophila (SWD) is starting to show up in some strawberry fields. If you are starting to see their presence, plan on maintaining insecticide cover sprays on the crop for the remaining season. This early buildup of SWD is a concern due to the early start to the strawberry season. Other susceptible small fruits, like blueberries and blackberries, should be maintained under a high risk SWD threat for this season. Maintaining weekly insecticide cover sprays will be necessary this year.
  • Blueberries are looking good. There is still some lingering cold injury on some of the early fruit, but it is not posing a significant issue with harvesting. The upcoming mid-season blueberries look amazing. They are starting to size well with tremendous volumes.
  • Blackberries are coming into harvest. Brazos is starting to harvest with some volume. Ponca, Caddo, Osage, and Ouachita are just starting to color black. Even with the cold damage to the primocane varieties, the blackberry crop is looking good for the upcoming season.
  • Muscadine flowering and fruit set is looking good. Thrips and grapevine aphid activity are pretty high. Scout your vineyard and spray accordingly.
  • Summer vegetable crops are looking good and are still being planted heavily. Thrips activity is very high. Scout your fields. Don’t let thrips set you back on crop development. They are relatively easy to kill, as most insecticides are very effective. But you need to be vigilant and not allow re-infestation. 
Cranberry fruitworm in rabbiteye blueberry. Fruitworms (both Cranberry fruitworm and Cherry fruitworm) are very common in blueberry production. Affected fruit usually prematurely color (blue). So be careful eating that early blue fruit. Cranberry fruitworms create a lot of silk webbing and frass around a cluster of fruit, whereas the Cherry fruitworm will glue adjacent fruit together with silk webbing and tunnel through to the next fruit. (B. McLean)
Exobasidium fruit spot on blueberry fruit. Exobasidium causes the affected portion of the fruit to not ripen, leaving it as a hard, bitter spot in the fruit. This disease also causes a white spot on the foliage. Exobasidium is controlled by a dormant season application of Calcium polysulfide (lime sulfur or Sulforix). (B. McLean)
Frost ring cold damage to Star (variety) blueberry. (B. McLean)


Andy Rollins

  • Strawberry production has improved with the recent warm nights. Be careful of corn earworms in the fruit this time of year. Normally, insecticides are not needed regularly for this crop, but may be needed on your farm now. Intrepid and Coragen are both excellent for caterpillar control if needed. 
  • Warmer weather has caused root rot to show up in some blueberries plants. While digging up a blueberry plant recently, some roots in the bed were growing properly, but heavy clay underneath was allowing root rot in the center of the crown to move up into the stem tissue, causing collapse.  
  • The blackberry crop looks great, with some early varieties showing color (like PrimeArk45) while later varieties (like Von) are still blooming.  The new variety Horizon has huge blooms. We’re still looking forward to the first taste of this one.
Discolored roots of blueberry plant suffering from root rot. (A. Rollins)
Discolored internal tissue of blueberry plant with root rot. (A. Rollins)

Question of the Week

What is the white-colored stuff on this beet leaf?

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

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