Margaret Lauterbach

Margaret Lauterbach: Go natural when battling hosta pests

Hostas spread and fill in nicely in garden beds, but it may seem like you’re growing a lot of slug candy at times. Slugs find food and shelter in hosta beds, taking refuge in the thick growth. It’s hard to reach them with poison bait, too, since you have little control over where the pellets land.

One solution to this problem is to plant hostas that slugs don’t find enticing. Those that have thick, heavily textured leaves are less likely to be devoured by slugs or snails than those with tender tasty leaves. The uninviting hostas tend to have blue-colored, thick and slightly crinkled foliage instead of the pale green or variegated leaves. As with hungry deer, though, hungry slugs will make a mockery of the term “slug resistant.” All hostas are seen as food by deer.

Those with blue-tinged foliage said to be resistant to slugs include Brother Ronald, Hadspen Blue, Halcyon, Blue Mammoth, Great Expectations, Blue Moon, Sum and Substance, Abiqua Drinking Gourd, Big Daddy, Blue Angel, Blue Dimples, Blue Mammoth, Blue Wedgewood, Dorset Blue, Fragrant Bouquet, Sea Lotus Leaf and others.

Hostas also have other enemies in the natural world too. Black vine weevils take quite a toll. Adult black vine weevils only do cosmetic damage, evinced by notches on leaf edges. Weevil offspring, though, are white grubs that feed on roots in the soil. They can be very damaging if their numbers are large. They even can destroy a large rhododendron in one growing season, for instance, so their damage on smaller plants is correspondingly worse.

The best way to control black vine weevil larvae is through introduction of a beneficial nematode in spring. Beneficial nematodes are unsegmented worms, usually tiny, available from insectaries such as Arbico organics or from special garden centers. Arbico advises using specific nematodes to control Black vine weevil: Steinernema carpocapsae and Heterorhabditis bacteriophora. North End Organic Nursery (NEON) also carries beneficial nematodes at their new store on Chinden.

If you were to use a chemical drench to kill the larvae, you’d also be destroying microscopic arthropods, fungi and bacteria that make up a healthy soil capable of sustaining plant life.

Hostas should spread on their own, but that’s a fairly slow spread. Most hosta clusters can be cut apart and replanted in very early spring to fill in a plot more quickly. Hostas do need a fair amount of water, about an inch of water each week. They do withstand some drought, but their appearance suffers from drought.

Corn update

In the vegetable garden, watch out for corn earworms. A few drops of mineral oil on ear tips after the silks have dried to brown (that is, they’ve been pollinated) may protect the ears from invasion. In my garden, Snake River blue corn stalks are up to about 12 feet in height without yet tasseling. There are enough stalks for pollination, but barely enough after the bushy-tailed rodents called squirrels dug and ate the rest of the seeds.

Send garden questions to melauter@earthlink.net or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.

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