Insects help control pests


August 01, 1993|By Adriane B. Miller | Adriane B. Miller,Contributing Writer

Ellen Stromdahl is in her element, her head and shoulders among the branches of an apple tree, her magnifying glass poised, looking for bugs.

A black speck the size of a pinhead has caught her attention in Andy Lohr's Churchville apple orchard. When the speck runs around the back of the apple, she knows she's got good news for Mr. Lohr.

"Oh look! Its a stethorus!" she yelled. Before the tiny beetle gets away, she holds it up for him to squint at. They look pleased.

The beetle is a natural predator to another bug, the red mite, one Mr. Lohr does not want in his orchard. Mites could devastate his apple trees.

The presence of the stethorus beetle and the absence of visible mites means that Mr. Lohr can let the orchard go at least another week without using a chemical insecticide.

Ms. Stromdahl, a Jarrettsville resident and graduate student in entomology at the University of Delaware, is a bug scout. She helps Mr. Lohr and other fruit and vegetable farmers in Harford and Cecil counties monitor populations of good and bad bugs in their fields.

By counting how many predators and pests are in sample crops, and by observing how the fields are faring overall, she can help farmers avoid using chemical pesticide sprays unless they must.

Farmers who use scouts are taking part in a program the agriculture industry calls Integrated Pest Management (IPM).

Instead of spraying chemical crop controls as frequently as they've done in the past -- usually once a week -- farmers now spray only when the cost of pest damage exceeds the cost of spraying.

Lee McDaniel, president of the Harford County Farm Bureau, said every fruit and vegetable farmer in the county practices IPM.

They either hire scouts, who charge $12 for vegetables and $25 for fruit per acre annually, or they monitor their crops themselves.

Mr. Lohr still has to spray a chemical fungicide every seven to eight days to control airborne diseases.

"Sometimes we have to put in an insecticide, too," he said. "But we're not spraying on a shotgun basis anymore. We've been as successful with the [stethorus beetles] as we have with pesticides. I won't say I won't use an insecticide again. But we've found the tree can take a lot" before spraying is necessary.

He is as concerned with the financial stability of his farm as he is with the environmental impact of chemical sprays. As little as he uses, he has spent $11,000 this year on chemicals on his 40 acres of fruit and corn. That's about $275 per acre in seven months.

Still, some Harford farmers greet with skepticism the idea of using friendly predators to control pests on their crops.

Wayne Jones, of Jones Produce Farm Market in Edgewood, remembers the failure of a biological pest control tried several years ago.

"They brought starlings over here from England to eat the Japanese beetles," Mr. Jones said. "Now we're

having a problem with the starlings."

Instead of eating the beetles, which the birds fed on in Europe, the starlings were happier to eat farmers' budding ears of sweet corn. They left the beetles alone.

"Mistakes like this are made with all good intentions, even when you're being extremely careful," Ms. Stromdahl says. "It makes people skeptical."

Mr. Lohr is sympathetic to other farmers who don't want to gamble on predators to keep their crops healthy. "You have a lot of money tied up in your crop" in seed and in labor costs, he says. "You can look at that and say, 'I can't take a risk.' "

And he won't attempt to grow and sell "organic" produce.

"I can't believe anyone can grow a peach and get it off the tree" before it has been destroyed by fungus or insects, he says. "We had a hailstorm last year that lasted about 10 minutes. I sat in the kitchen and waited until it was over, then I went out with a fungicide and sprayed. Otherwise, I would have had a total loss."

Mr. Lohr is convinced if he had not used a fungicide, fungus would have destroyed nearly the entire

crop. What remained, he couldn't have sold.

"People want perfect fruit," he said with a shrug.

He said most consumers who want organically grown produce won't accept a peach with brown rot or an apple with red mite damage. Organic produce, with all its blemishes, is tough to sell, he said.

Blemishes on the trees that produce the fruit don't trouble Mr. Lohr, however. His apple trees have been affected by "leaf miners" -- tiny caterpillars that chew holes in the underside of leaves. Unchecked, they would weaken the tree and threaten the crop. But they don't do much damage when controlled periodically with small amounts of insecticide.

Now Ms. Stromdahl is examining several apple leaves and finds mostly dead leaf miners, plus a live one. Mr. Lohr sprayed for the leaf miner last week. Ms. Stromdahl decides the spraying was a success and he shouldn't have to spray again soon.

"I feel we timed that just right," she said.

Scout trainee Jaime Vandarwarka, a Jarrettsville High School senior, has also spent the morning counting bugs in traps and checking weeds on Mr. Lohr's farm.

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.