UNIVERSITY PARK, Pa. -- It doesn't take a trained meteorologist to know when the weather is hot and dry, but identifying when drought conditions have affected plants is a bit harder, says an expert in Penn State's College of Agricultural Sciences.

"Drought symptoms on plants, particularly woody ornamentals, can be very confusing," says Bob Nuss, professor of ornamental horticulture.

Nuss says herbaceous plants -- that is, varieties that lack woody stems -- almost always droop when deprived of water. An extensive watering usually can help herbaceous plants recover.

Most woody ornamentals will show a variety of symptoms, Nuss says.

--Leaf drop. Leaves on deciduous trees and shrubs often drop after turning yellow or red, a condition called early sensescence. "This doesn't mean the plant is dead," Nuss says. "These plants usually will recover if given sufficient moisture."

--Check the bark. The simplest way to check if a tree or shrub is still living is to peel back the bark on a twig or branch. If there is a green layer beneath the bark, the tree is still alive. If the layer is brown, that twig or branch is dead.

--Check the buds. Pick several buds from a branch. If the bases of the buds are green, the plant is alive.

Signs of Drought on Evergreens

If drought takes place early or in mid-season, Nuss says new growth will droop or curl when the plant is wilting. These symptoms are especially noticeable in spruce and pine trees. "If caught early, evergreens will recover with sufficient watering," Nuss says.

If drought comes late in the season, after growth has stopped and next year's buds have formed, the plant may not show wilting. Nuss says homeowners can test the tree for life by peeling back the bark to check for a green layer.

"The foliage of conifers and evergreens can remain green for up to several weeks after the plant has died," he explains.

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EDITORS: For more information, contact Bob Nuss at 814-863-2196.

Contacts: John Wall jtw3@psu.edu 814-863-2719 814-865-1068 fax