UNIVERSITY PARK, Pa. -- Your lawn crunches like potato chips when you walk on it. Even your older trees are showing stress. Although you might be tempted to coddle your plants, you can kill them with too much kindness, say experts in Penn State's College of Agricultural Sciences.

"Pruning, fertilizing and watering can fool plants into thinking it's springtime and trigger new growth," says Robert Nuss, professor of ornamental horticulture. "New growth won't have time to mature before the frost. Not only will you kill it, but you'll use up next year's buds."

"If you have a landscape contractor or arborist do your work, there's only so much they'll want to do during a drought," says Rick Johnson, associate extension agent in Delaware County. "Since normal plant care practices might be harmful under drought conditions, understand that these contractors may advise against them."

Nuss and others offer some specific suggestions.

Lawns and turf

"Grasses go into a semi-dormant state and become vulnerable when it's dry," says Peter Landschoot, associate professor of turfgrass science. "Now that the water's been turned off, you should limit activities and traffic on lawns as much as possible. Come September -- if we get rain and cooler weather -- you can fertilize and overseed to get some recovery. If we don't get enough rain in September, wait until next spring to overseed."

"Focus your watering efforts on plants you can do something about, like ornamentals," he adds. "With lawns, it's just a waiting game until the rain and cool weather return."

Pruning

"Pruning's a gamble," says Nuss. "If you're sure the parts are dead -- if they're brittle and dry -- go ahead and cut back to the live tissue. This will promote some healing and help the plants aesthetically. But remember, if we get some rain, pruning can trigger growth in the buds."

Fertilizing

"Fertilizers are salts -- even organic materials such as manure -- and salts can burn roots," Nuss says. "If you want to give plants nutrients, wait until October when they're fully dormant."

Watering

"Watering is key for woody plants," Nuss says. "When the top 1-1 1/2 inches of soil are dry, water down to 8-10 inches -- to the root zone," he says. "You can accomplish this by direct, slow watering. Trickle water on very slowly so it soaks into the soil, with no runoff. Also, when you water at night, you lose less to evaporation."

But watering has its dangers. "If you overwater in areas with heavy soil or slow drainage, you can saturate the root zone and force out the air," Nuss says. "This can suffocate the roots and kill them."

When roots die, you'll see top wilting in the plant, Nuss says. "Most people interpret this as a lack of water, add even more and aggravate the problem. After watering, most plants should recover overnight. But if the plant remains wilted, you may have root damage from overwatering."

For new plantings, Nuss recommends keeping the initial root ball moist. "Water beyond the planting hole, not just at the base of the plant," he says. "That way, you don't drown the roots, and new roots have moist soil to move into."

Mulching is the next best solution to watering, Nuss says. "But be sure to water under mulch, not on top of it. It takes at least an inch of rain to get through organic mulch."

In extreme conditions like we're having, Nuss says covering the soil surface with black plastic will retain extra moisture. "You can hide the plastic with organic mulch," he says.

To supplement watering, use gray water (from such uses as cooking and the laundry rinse cycle) on ornamentals, Nuss says. "But move from tree to tree so you dilute it. Also, don't use water that contains chlorine bleaches or laundry softeners. For health reasons, don't use gray water on leafy vegetables or root vegetables.

"With a drought this serious, I'd focus watering on high-value plants and shrubs," Nuss says. "Save fresh water for your vegetables, use gray water on the ornamentals, and don't water your flowers. Flowers are going to die with the first frost anyway."

Pesticides

"Droughts have a negative effect on most insect and mite pests that attack landscape plants," says Greg Hoover, extension entomologist. "Because of last year's drought, for instance, we have fewer adult Japanese beetles this year, and probably will see even fewer next year."

But hot, dry weather favors two different groups of insect and mite pests. "Wood-boring insects successfully attack trees and shrubs that are stressed," Hoover says. "If you don't have water restrictions, the best thing you can do for woody plants is water them. Supplement watering with rainfall collected in buckets or barrels, or water from dehumidifiers.

"The twospotted spider mite, a common pest on garden and landscape plants, also thrives in hot, dry weather," Hoover says. "The winged euonymus --what some people call 'burning bush' -- is particularly vulnerable. When indicated, use an appropriate miticide on infested plants."

Hoover recommends using wettable powder insecticide formulations. "They're less likely to damage plant tissues during hot, dry weather when used according to label directions."

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EDITORS: Bob Nuss can be reached at 814-863-2190. Rick Johnson can be reached at (610) 690-2655. Peter Landschoot can be reached at 814-863-1017. Greg Hoover can be reached at 814-865-3256.

Contacts: Kim Dionis KDionis@psu.edu 814-863-2703 814-865-1068 fax