FOR RELEASE THE WEEK OF AUG. 6, 2000:
What are the small, slug-like creatures that appear on pear trees during the summer? They are slimy and about 1/4- to 3/8-inch long and are larger at one end than the other. Do they come up from the ground and what can we do to rid the tree of this messy thing? Frank and Gwen Baldan, Fruitvale
Those slug-like creatures are called pearslugs. They’re the larvae of the sawfly and they do indeed emerge from the ground, says Bob Stoltz, University of Idaho extension entomologist. They like cherries, plums and mountain ash in addition to pears. Actually yellow underneath, they’re covered with slimy, olive-green fecal matter.
All that nastiness aside, pearslugs won’t really bother your tree’s fruit, although they will nibble leaf surfaces down to pink or brown patches or even to veins. "If you get enough of them, they can defoliate the tree," says Stoltz. "If you just have a few, pick off the infested leaves. If you have more than a few, try spraying them with Sevin or neem."
How do I know when my eggplant is ready to harvest?
Harvest your eggplant when it’s reached the right size for its variety and when its color—whether white, purple or another shade—is uniform, says Michael Colt, University of Idaho extension horticulturist. "If you press the side of a fruit slightly and an indentation remains, the fruit is mature," he says. "Harvest before the flesh becomes tough."
If you planted long, slender Japanese eggplant, pick them when the fruit is finger- to hotdog-size, Colt says.
Because heavy-bearing taxes small plants, try to keep your mature eggplants picked. Repeatedly remove all but three or four fruits and the plants will produce over a long period.
My evergreen trees and shrubs are infested with spider webs, and some needles are turning yellow. What’s causing this?
Check the webbing for dark, yellow-green mites large enough to see with the naked eye. If you find them, the cause of your problem is spruce spider mites, which attack spruce, arborvitae, juniper, hemlock, pine, Douglas fir and Siberian larch, among others.
According to Bob Stoltz, University of Idaho extension entomologist, spruce spider mites feed on needles—especially in old growth—turning them first yellow, then brown. "You need to kind of watch what’s going on with it," he says. "You can have a fair amount of damage before you see the webbing."
Webbing alone isn’t indicative of spruce spider mites. Innocuous spiders will also make webs in your evergreen trees and shrubs—but they don’t kill needles.
Try blasting the webs with water in the cool of the morning, Stoltz says. If that doesn’t work, you have several miticidal options, including insecticidal soap, diazinon, hexakis or Kelthane. If you have serious infestations of spruce spider mites in August, treating now can protect the tree against further damage in the fall.
Stoltz notes that mites can flare up after trees and shrubs are treated for other insect problems. If you’ve recently applied Sevin or a synthetic pyrethroid, you may have destroyed beneficial insects that would otherwise have kept the mites in check. To avoid contributing to these ecological imbalances, you might want to switch to one of the newer, soil-applied systemic insecticides when treating your trees for scales, aphids or leafhoppers.
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