Farm Progress

Calendar helps growers gauge when pests might strike

April 5, 2017

3 Min Read
BUG WOES: A tiny caterpillar called the larch casebearer can destroy needles on pine trees, turning them brown. An online phenology calendar can help gardeners and nursery owners schedule a pest management program.Roger Ryan, USFS PNW Station,

Spring arrived early in Ohio this year, and then it came to a screeching halt, says a scientist in the College of Food, Agricultural and Environmental Sciences at Ohio State University.

Despite unseasonably warm days in January and February, March’s cool temperatures put Ohio’s weather back on par with last year’s, says entomologist Dan Herms.

“It was like climate whiplash,” Herms says. “Now things are back to — I hate to call it — normal, a ‘new normal,’ as plants are blooming and insects are now emerging at the same time they did last year.”

However, compared to a couple decades ago, spring is early due to climate warming, Herms says.

Along with the early buds and blooms that came this year sooner than usual, in southern Ohio a few early-season pests emerged a couple of weeks earlier than they did last year.

In southern Ohio, a tiny caterpillar called the larch casebearer and the exotic ambrosia beetle have already found their way to trees, and soon to follow is the European pine sawfly, a grayish-green insect that can quickly strip needles from pine trees. With the return of cooler weather, insects that emerge during mid-spring are back on schedule.

Gardeners and nursery owners might be left uncertain when to spray for certain pests if it weren’t for a phenology calendar Herms developed that predicts when to expect various insects.

Using the calendar, a gardener can type in his or her ZIP code and see when to brace for, say, the emerald ash borer or the ambrosia beetle or more than 50 other pests that typically zero in on Ohio’s greenery every year.

“The power is in prediction. We can predict what plants are blooming and what insects are active anywhere in Ohio on any day,’’ Herms says.

A nursery grower may plant 50 to 100 different crops, and each attracts different pests, so it is critical for the grower to know when to spray to fend off each of them.

“The challenge of scheduling a pest management program can be fairly daunting,” Herms says.

The ambrosia beetle kills redbud, dogwood and maple trees among others, eating away at nursery growers’ profits. Larch casebearers and European pine sawflies home in on pine trees, turning their needles brown.

Spraying these and other bugs at the wrong time could mean missing them entirely. And if a grower sprays multiple times to be sure to attack the insect, that’s an added, unnecessary expense and additional pesticide in the environment.

The online phenology calendar uses the amount of heat generated each day to gauge when certain insects will appear. The sequence in which the insects appear does not vary from year to year, but the week — or month — in which they appear could, depending on how warm the weather has been.

Tom Demaline, owner of Willoway Nurseries in Avon, began using Ohio State’s phenology calendar in 2004 to help determine not only when to spray for pests, but also when to propagate various trees as well as cover and uncover plants.

“We seem to be in really erratic weather cycles,” Demaline says. “It’s a great tool to have to be able to figure out where you’re at in the growth cycle. At least you can see the light of the oncoming train so you can move over.”

Source: OSU Extension

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