July 21, 2013

Maine Gardener: Oh, the weather outside is blightful

By TOM ATWELL

The weather for most of the 2013 growing season has been damp. As of July 11, there has been measurable precipitation more days than not since Memorial Day. Even on those days that it has not rained it has been humid.

While this pattern has been uncomfortable for humans, it has also been hard on plants, many of which are being hit by fungal diseases, which thrive in the damp weather.

When the Maine Landscape and Nursery Association held its summer twilight meeting in early July at Maine Coast Vineyards in Falmouth, owner Steve Melchiskey said he was already seeing signs of powdery mildew on his grapes -- a problem he normally doesn't get until August, he said.

"Usually by the time a homeowner sees a fungal issue," said Barbara Murphy, a consumer horticulture specialist with the University of Maine Cooperative Extension in Oxford County, "it is actually too late unless they want to use a pretty intensive chemical."

But, she said, if it helps to improve air flow around plants so they dry out more quickly and are less susceptible to fungal diseases.

"If you are trellising tomatoes, for example," Murphy said, "it helps to remove the lower leaves."

And, she said, you should remove all of the leaves that are infected with disease and take them away from your garden.

Murphy and Lois Berg Stack, an ornamental horticulture specialist with UMaine Extension in Orono, both said that for future years, or if you are doing later plantings this year, you should seek out disease-resistant varieties.

"As in all gardening," Stack said, "you should choose the right plant for the right place. You should choose a tomato that is resistant to early blight and other fungal diseases. A lot of people have a problem with powdery mildew on zinnias, but there are zinnias that are resistant to powdery mildew."

Stack does warn, however, that "resistant does not mean immune." The resistant plants are less likely to get the specific disease, but it still could get it if there is a lot of disease pressure.

Healthy plants are less likely to get disease.

"You should do everything possible to learn about the plant you are going to grow and provide the conditions that promote healthy growth," Stack said. "Just like people who are really healthy do not get sick as often, healthy plants fend off a lot of disease organisms."

This one will have to wait until your crops next year, but Stack believes in keeping your plants under wraps as long as possible.

"At this time so many small growers, and even home gardeners, are putting up high tunnels and cold frames, and using row covers," she said. "That really helps protect the plants."

She said many gardeners think they are designed to extend the season, but a large part of it is keeping pests like cucumber beetles away and allowing the plants to dry off occasionally between rainstorms.

On plants that require pollination, you do have to remove the covering when they start flowering so that bees and other pollinators can do their work, Stack said.

For those who are willing to use chemicals, garden centers have some available that do the job.

Melchiskey said he will use a copper-based fungicide called Milstop to stop the mildew on his grapes. That fungicide -- as are many copper-based products -- is approved for organic gardens.

Ginny Moody of Moody's Garden Center sells a lot of Safer products, also organically approved, including Safer Garden Fungicide, that do the job quite well. She said it is good on vegetables as well as ornamentals.

Another Safer product that is selling well kills moss and algae on all kinds of surfaces, and the moss and algae is thriving this summer.

She also said she has a Neem Oil product that is approved for organic gardens that will work as a fungicide. And Serenade is another organic product that comes highly recommended.

"For those who are not organic, we have Bayer rose and garden products," Moody said. "They are systemics, and they work quite well -- especially on roses."

What I think would be the best cure would be a couple of weeks of dry weather. And it would give me a chance to use the water in our three rain barrels.

As part of her job, Murphy is chairwoman of the Maine Harvest for Hunger program, in which home gardeners and commercial farmers donate food to help feed the poor.

With produce beginning to come out of gardens statewide, she urges people to make arrangements to donate their surplus food. For information go to umaine.edu/harvest-for-hunger.

Tom Atwell can be contacted at 767-2297 or at: 

tomatwell@me.com

 

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