What is in this article?:
- Late crop saves North Carolina cucumbers
- Yield loss can be substantial
- Spring cucumbers in North Carolina were heavily impacted by the heat when there were so many 100-degree days.
- The fall crop was a pretty good one.
Yield loss can be substantial
Only the leaves are infected, but yield loss can be substantial.
The strains of downy mildew that American farmers have been experiencing in recent years have been so aggressive and destructive that a farmer can lose all his crop very quickly, says Bost.
For that reason, you have to find out quick if you have it.
Diagnosis can be difficult, Bost says, so if you think you have downy mildew, but it hasn’t been reported yet, call your county agent immediately. The agent will be able to identify it or will know a university specialist who can.
“If downy mildew has already been reported in your area when you see lesions, you can assume you have it,” he says. “You should already be engaged in a routine spray program every seven to 10 days with a broad spectrum material like mancozeb or chlorothalonil.”
Then add a more specific chemical. “There are several, including Tanos, Presidio, Ranman, Previcur, Gavel and Curzate,” he says. “Choose two and alternate them to avoid disease resistance in the pathogen.”
Continue sprays on a five to seven day interval as long as conditions for the disease are favorable, meaning rain or high humidity.
Stay on your spray program until the weather changes. However, even occasional rain may require the use of a downy mildew product once every seven to 10 days.
There aren’t many cultural practices that will help with downy mildew, especially once it is established in the field. Rotation is no help because it doesn’t over-winter in the field. Destroying plant debris won’t help either.
It may help to avoid high plant populations and keep cucurbit fields away from tree borders to maximize air movement.
There are some cucurbit varieties resistant to downy mildew, and it may pay to choose one.
The trend in cucumber harvest in North Carolina to mechanization has continued, and Harden has been part of it. He harvests his cucumbers with a Raven pickle harvester that sorts out oversized cucumbers and puts them back on the field, destroying the crop as it goes over it.
The mechanization procedure is still fairly new in the Southeast but Harden says it works well for him. “The companies are satisfied with the production from mechanical harvest.”
About half the crop was hand harvested and half mechanically harvested in 2010, says Thornton.