Recent heavy rain in Maine was good news in terms of mitigating ongoing drought conditions. Unfortunately, it was also good news for a specific type of mold that attacks growing vegetables. And that’s bad news for gardeners.
It was already shaping up to be an optimum year in the Northeast for cucurbit downy mildew, which first showed up earlier this summer in New Jersey. Last week it was spotted in eastern Kennebec County, according to information posted by the Maine Organic Farmers and Gardeners Association.
The mildew can heavily damage cucurbit plants, one of the most commonly grown vegetable families in home gardens. It’s the species with the most varieties of items people eat. It includes cucumbers, melons and squash.
According to Caleb Goossen, crop and conservation specialist with MOFGA, it can be especially hard on cucumbers and cantaloupes if it makes its way into Maine.
“Many years it is not an issue here in Maine because it does not overwinter here,” Goossen said. “When it showed up in New Jersey a lot earlier than we often see it there, it seemed like it could be a potential for a bad year.”
The summer’s early dry conditions kept the humidity-loving, airborne mildew from getting to Maine, but recent rainfalls and warm temperatures gave it the boost it needed.
According to Goossen, the specific cucurbit mildew currently in Maine only infects cucumbers and cantaloupes. He said he’s gotten two reports this week of it appearing on cucumbers.
Another variety of the mildew that attacks winter squash and pumpkins has been reported in Massachusetts this week, he said.
The first visible sign of the mildew on plants is yellow spots on the leaves. As it progresses, it can create dark lesions on the bottoms of the leaves. The worse it gets, the more the leaves will dry up and weaken the entire plant, inhibiting vegetable growth.
In really bad cases, it can wipe out an entire crop.
The problem, according to Goossen, is once you can see the mildew and associated symptoms, it’s too late. Early infection is asymptotic.
“For the home gardener, once you notice it, it’s pretty much game over,” Goossen said. “The best protection for your plants is advance warning.”
Goossen recommends planting mildew-resistant crops that can fend off the attack. If you suspect mildew could be spreading to your area he urges application of a fungicide on the plants to prevent it from taking hold.
“That is why I recommend folks sign up for our pest report,” he said. “I send it out every two weeks during the growing season.”
For organic growers, there are copper and bio-fungicides that are effective when used as preventatives.
