Regular rain continued throughout the state last week. Summer officially begins later this week. We’re well into harvest now for most warm-season crops, and disease is a major concern. See details below.
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Coastal Region
Zack Snipes
- We complained about the lack of rain and are now getting our fair share. It rained every day last week, creating lots of humidity. Normally, I wouldn’t complain about the rain, but we are in the prime harvest season, and the quick showers make it extremely hard to pick, as we don’t want to pick in wet fields. In some spots, we are having a hard time getting equipment in to pick. In others, we don’t want to run the risk of spreading disease while picking wet produce.
- The rain is causing lots and lots of tomatoes to split, which makes them unmarketable. It is also causing some issues with rotting in melons. We could certainly use a few days of dry weather. I visited several farms last week, and the plants didn’t have the vigor I thought they should have at this time of year. On multiple farms, I pulled plants up and found galled roots, a tell-tell sign of root-knot nematode infestation. It would be good to check tomato, okra, squash, and watermelon plants at the end of the season to see if you have galling. If roots are galled, then we can begin to manage the issue for next season.
Galling on the roots of a young cucumber leads to stunting and poor yields.
Zack Snips, ©Clemson Extension
These tomatoes just didn’t have the right color despite the grower being dialed in on their fertility program. Upon inspecting the roots, we found that the roots were severely impacted by root-knot nematode.
Zack Snips, ©Clemson Extension
Midlands Region
Rob Last
- Summer is here in the Midlands with increasing temperatures, rainfall, and humidity. Given the propensity for thunderstorms in the afternoons and high humidity, we are in the perfect environmental conditions for many plant pathogens to thrive. Scouting crops remains crucial to detect changes in crop health early in the disease cycle. Any thunderstorms can lead to physical damage to plants, such as bruising or split leaves, creating a potential entry point for pathogens.
- Cucurbit crops are looking good, with good volumes being harvested. Downy mildew is present and active in many crops, and levels of gummy stem blight are increasing also. Fungicide applications should be rotated to prevent resistance buildup. For organic producers, options are more limited to fixed copper.
- Tomatoes are looking great. I am seeing some bacterial spots on the lower leaves. Typically, these leaves are infected through the rain splash of soil, bringing the pathogen onto the crop. Given the current weather patterns, rain splashes can quickly transfer bacteria up through the canopy and bring pathogens into contact with the fruit. Fixed copper with or without mancozeb may help in management.
- Peppers are looking good with a great fruit set. I am seeing some anthracnose rots in bell peppers. Anthracnose symptoms show as a dark sunken lesion, often with the presence of salmon-pink spores. Mancozeb, QoI, and group 3 fungicides may help to manage the disease.
- Eggplants are looking good with few disease options, be mindful of Phomopsis blight. Spider mites are also very active in many crops. It may be worth considering a predatory mite release into some situations, where eggplant, tomatoes, pepper and strawberries are produced.
- Brassicas continue to be produced in the area with a gradual reduction in crops as the weather continues to heat up. As we move further into summer, prompt destruction of harvested crops can help to reduce inoculum levels for fall crops and also prevent pest species from having a desirable habitat.
Peppers are nearing harvest in the Midlands.
Rob Last, ©Clemson Extension
Pee Dee Region
Brittney King
- The Pee Dee got some much-needed rain last week, with most areas getting between 2-3 inches. Please remember to scout your fields for signs of disease, as the recent weather is perfect for disease development.
- Tomatoes are being harvested in good volumes. Fruit set seems to be heavier than last year, which is good.
- Watermelons are starting to be harvested this week. Fruit set so far looks great. Gummy stem blight is the main issue I am seeing so far.
- Blackberries and blueberries are still being harvested with no issues to report.
Upstate Region
Andy Rollins
- Just beginning to pick some of our early blueberry varieties in the Upstate. We’re seeing some cracking in larger fruiting varieties like Titan. Growers need to keep protectant fungicides like Captan on these fruit to keep them disease-free. Liquid Captan leaves less residue, but good agitation in the tank is also important.
- Semi-freestone peaches like Harvester, Caroking, Redhaven, and Juneprince are coming in, some of the better-eating varieties than many of the clingstone varieties.
- We’re harvesting a strawberry experiment where we are evaluating the benefits of dipping or drenching strawberry plants with Switch and Zivion for Neopest management. There is some concern that dipping with Switch is stunting plants.
A new blueberry farm in the Upstate.
Andy Rollins, ©Clemson Extension
