SC Fruit and Vegetable Field Report – September 12, 2022

Zack Snipes

Zack Snipes

Rob Last reports, “Fall cucurbit crops, including cantaloupes and watermelons, are ripening and approaching harvest. Disease pressure from powdery mildew and gummy stem blight has really increased significantly over the last week. Maintaining a tight spray program will be key to managing diseases. As we look forward to strawberry planting, the land is being prepared. If you plan to fumigate, ensure 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, “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.”

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. However, 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.”

Rob Last reports, “In our area, crops are developing well with few pest or disease issues currently. Some brassicas are displaying a reddening to the older leaves associated with reduced phosphorous uptake. Phosphorous uptake can be reduced in cold temperatures but will recover when we see some warmer temperatures. There is no response to an additional application. Where strawberries are flowering or have fruit, it is advisable to remove those to minimize sources of Botrytis gray mold for later in the year.”

Rob Last reports, “Pest and disease issues in the area remain very low; however, as temperatures rise, we expect activity to increase.  Although it is quiet, it is still essential to continue to scout. Assessment of crops indicates that we have escaped the worst of any chill injury or loss of plants. Pruning of fruit crops continues while dormancy holds and labor begins to return to the area.”

Dr. Matt Cutulle reports, “I saw my first nutsedge plants this year pop up in the plastic mulch of a fellow researcher’s trial last week in Charleston. Soil temperatures in plastic mulch systems are going to be higher, which may lead to earlier sprouting of yellow nutsedge tubers. New tubers begin forming four to six weeks after a new shoot emerges. Individual nutsedge plants may eventually form patches 10 feet or more in diameter, thus it is important to practice field sanitation once an infestation is recognized.”

Zack Snipes reports, “It has been a very windy spring. The winds are drying out our soils and beating up plants.  I have looked at some tomatoes, and the ones that aren’t tied are wind-whipped, and the ones that are tied have callus tissue forming where the string is touching them. We have some beautiful lettuce and greens coming in right now, along with spring onions.  I have also seen some squash coming in on farms that grew squash in high tunnels.  Strawberry plants are still small and have very few blooms for this time of year.  We are harvesting highbush blueberries in high volumes right now.  I think we escaped more cold damage than previously expected.”

Zack Snipes reports, “It seems like everything is coming in from the fields right now. We got some rain but could really use some more. I am seeing lots of aphids on a variety of crops (melons, cukes, eggplant). I am also seeing ladybird beetles and parasitized aphids in these fields, which means our predators are out there working for us. Bacterial wilt and Southern blight are starting to appear on tomatoes as well. Knowing the difference and preparing for next season’s crop is critical. It is getting hot and is still windy, so growers might consider adding one or more irrigation cycles to their fields. Remember that in our sandy soils, any irrigation event over an hour is just wasting water. More frequent 30-45 minute cycles are more efficient.”

Rob Last reports, “Insect and disease activity is increasing in the area, across a broad range of crops. In cucurbits, we are seeing powdery mildew and gummy stem blight in watermelon. Remember to keep spray intervals tight. Loopers are also being found in the area, and applications to manage rind worms will be beneficial as we rapidly approach harvest. Fusarium wilt of watermelons is showing up in many fields. At this stage, there is no effective treatment; however, soil temperatures are likely to reduce the incidence of new infections. Tomatoes and peppers are developing well with Southern blight and bacterial wilt in evidence. Spider mites are very active right now. Blackberries are just coming to harvest with good flavor and quality. Remember to scout your crops regularly to ensure timely applications can be made.”

Rob Last reports, “The first of this season’s strawberries are coming to market with good quality. Growers still need to be very mindful of spider mites. Populations are around in the area but are variable. As we get into harvest season, gray mold management will be critical, so sanitation and appropriate fungicide applications will be needed. Otherwise, preparations for watermelon planting and some early cantaloupes have been sown. Damage assessments on later variety peaches will continue.”