Weekly Field Update 8/24/20

Statewide

Dr. Tony Keinath reports, “For the past few years, Orondis Opti on cucumber and cantaloupe and Orondis Ultra on pumpkin and watermelon have been the best fungicides to manage downy mildew. Based on results from a spring 2020 cucumber experiment at Coastal REC, Orondis is no longer the “silver bullet” it was 2 years ago. In my experiment, Orondis Opti rotated with Bravo controlled downy mildew in the early part of the season, but disease increased significantly during the latter part of the season and ended up higher than expected. Part of the shortcoming of the Orondis Opti/Bravo spray program was the Bravo rotation. Bravo sprayed by itself every other week did not control downy mildew at all, so spraying Orondis Opti/Bravo acted like Orondis Opti sprayed every other week, which was not enough. The labels for Orondis Opti and Orondis Ultra say they must be rotated with another fungicide. For the rest of the 2020 season, use Orondis Opti/Ranman + chlorothalonil on cucumber and cantaloupe, and Orondis Ultra rotated with Gavel or Ranman + chlorothalonil on pumpkin and watermelon. Always use the high rate (2.5 pints/acre) of Orondis products. Note that the mancozeb in Gavel or adding chlorothalonil helps to manage other foliar diseases like gummy stem blight and anthracnose. Yield data and input costs from my experiment are being analyzed to see if spraying Orondis leads to a higher net return despite the higher cost of this fungicide. Results will be presented at the virtual Cucurbit meeting in February 2021 to help growers plan downy mildew fungicide programs for the 2021 season.”

Cucurbit downy mildew continues to spread across the state.

Coastal

Rob Last reports, “Fall crops continue to grow well in the area.  Given the current weather patterns pests and disease are active in some crops particularly where there are volunteers remaining from previous crops.  Vigilance will be required in scouting an pesticide management programs.  If In doubt scout.”

Midlands

Justin Ballew reports, “It’s been cool, cloudy, and kind of pleasant outside this past week, though that has the vegetable crops growing a little slower. We’ve gotten some decent rains in most areas around the midlands as well. Bacterial spot is really showing up on fall tomatoes as a result of all the recent rain. It could be a bad fall for bacterial spot if the weather stays like this. Caterpillars are already out there on fall brassicas. It doesn’t take long once they’re planted. Start scouting, scout often, and rotate insecticides. Remember to contact one of us about screening your farm for insecticide resistance in diamondback moths once you start seeing populations build up.”

Bacterial spot and speck start on the bottom of the plant and can be splashed onto higher leaves and fruit by rain drops. Photo from Justin Ballew.
Start scouting for caterpillars as soon as your fall brassicas are planted. Photo from Justin Ballew

Pee Dee

Bruce McLean reports, “Both fruit and vegetable development has slowed a bit due to cloudy conditions. Sunny conditions needed. Sweetpotatoes are sizing well and will be ready for harvest soon. Fall cucumbers and squash should soon be ready to start harvesting. Fall brassicas are being planted now. Muscadine crop is getting close to harvest. Noble is around 90% ripe; Carlos is around 60%; Doreen is still around 25%. Brix (sugar content) is off due to rain and cloudy conditions. Noble and Carlos brix are averaging around 11% with a low of 9.2% and a high of 15.0%. Doreen is averaging less than 10%. Did find a few Doreen that brix was over 19%… candy. Sunny conditions definitely needed.”

Noble muscadines around 90% ripe. Photo from Bruce McLean.

Tony Melton reports, “Beginning to harvest processing sweet potatoes but some have been stunted and delayed by excessive rain.  Spraying processing peas for cowpea curculio.  Starting to plant processing greens by seed.  Even though lots of rain and having to mud through fields cucumbers for pickles are being harvested and still being planted.”

Upstate

Andy Rollins reports, “Blueberry pruning is best served for the dormant time of year late January-late February.  I met with a commercial grower who was anxious about getting started early partly because he has many plants completely unproductive for the second year in a row. I like to call this revenge pruning as that is the primary motivation. Be careful, you could end up hurting yourself more in the long run. In his case, it was all about light and proper pruning to encourage light down through the canopy. The orignial spacing of Rabbiteye type varieties was very close so we also considered killing every other plant to get more light into the bushes but this would not replace the need for properly selectively removing a few of the oldest canes each year, spacing them out so there is better light penetration. For a detailed explanation, please see NCSU Blueberry specialist Bill Cline’s presentation.”