(July 16, 10:39 a.m.) No substantial damage from downy mildew has been found yet in Michigan’s cucumber crop, but it could be too early to tell what effect, if any, the disease might have, grower-shippers said.

Michigan cucumber growers have been advised to spray their fields to prevent the spread of downy mildew, which can cause extensive damage to the vegetable.

Mary Hausbeck, professor of plant pathology at Michigan State University, on July 2 confirmed a downy mildew finding in a cucumber field in Monroe County, which is in the state’s southeastern corner.

On July 9, Hausbeck found the disease on the western side of the state.

The findings so close together on opposite sides of the state indicates the disease is spreading quickly and that all fields must be sprayed, Hausbeck said.

“Clearly we have a widespread event,” she said. “This year is similar to 2004, when there was quite a bit of damage.”

Growers understand better

What’s different about this year, and cause for hope, Hausbeck said, is growers understand downy mildew better now and are much more likely to spray.

Some wet fields that were picked in June had some downy mildew damage, but by July the problem seemed to have cleared up, said Jeff Mattner, president of Benton Harbor, Mich.-based Jeff Mattner Produce. Mattner grows cucumbers and sources from other growers in the Eau Claire, Mich., area.

“That’s pretty much behind us — I haven’t seen any in the area,” Mattner said.

Those who plant cucumbers on raised ground and with tunnels shouldn’t have any trouble with downy mildew, Mattner said. It’s bare-ground fields that suffer heavy rainfall that are at risk, he said.

Mattner hadn’t heard of any significant reductions in volume as a result of downy mildew this summer.

Cost of spraying

Talbert Nething, general manager of Byron Center-based Hearty Fresh, said July 15 his company’s packinghouse hadn’t received any cukes with downy mildew.

Even if growers prevent the spread of downy mildew, which causes yellow spots on the top of leaves and gray fungus on the bottom of them, the cost alone of spraying throughout the season, “really puts the industry in jeopardy,” Hausbeck said.

Hudsonville, Mich.-based Miedema Produce Inc. began marketing cucumbers the week of June 30 and expects to ship through September, said Todd Miedema, principal at the company.

As long as it stays relatively dry, downy mildew can be controlled, said Miedema, who had not heard of any findings this year in fields farmed by his suppliers.

If, however, rains continually wash chemicals off plants, downy mildew is very hard to contain, he said.