The extended summer drought has stressed yard and garden plants. Insect pests and root rots can take hold of weakened trees and shrubs, but homeowners can take steps to limit or prevent damage.

Learn how to fight insects that may snack on drought-stricken trees and shrubs

The extended summer drought has stressed yard and garden plants. Insect pests and root rots can take hold of weakened trees and shrubs, but homeowners can take steps to limit or prevent damage.


Michigan State University Extension forestry educator Russell Kidd says the most obvious  early symptoms of drought injury to deciduous plants are brown or curled leaves or scorched leaf edges and, in some cases, premature leaf drop. Secondary pest problems may not arise until the following growing season. Recognizing the early signs now may help you avoid dead plants next season.


Kidd says these secondary pest problems are slow to develop and may take more than one year to kill a plant.


Treat both primary stress factors (such as drought) and secondary stress factors to maintain healthy plants. Trees and shrubs near the home may be watered to keep the soil moisture stress to a minimum. Watering an extremely large tree or trees growing in a forest or greenbelt is usually difficult.


The best way to water a tree is very slowly. Let a hose or sprinkler run very slowly or gently underneath the drip line of the tree. Placing a thin layer of composted mulch around the base of a tree will conserve soil moisture once it’s been restored to near normal levels.


Monitor plants and make note of any unusual signs or symptoms, especially at the beginning of the 2013 growing season.


“A conifer tree’s first line of defense is to try to ‘sap out’ the invader, so you will see sap dripping and trailing out of borer entry or exit holes.  With other borers, you may see signs of sawdust around the holes or below the holes on the ground or on the bark of major branches. For most borers, however, the first sign that many homeowners notice is that part of the tree is dead,” Kidd said.


Borers are the immature stages of a variety of beetles, wasps and moths. Adults lay eggs on the bark or in bark crevices. Once the eggs hatch, the larvae bore underneath the bark, making tunnels as they feed. Eventually they girdle a tree and cause dieback — when the top portion of the tree dies first – or kill the whole tree. Kidd advises treating plants promptly when signs of borers become visible with some type of systemic pesticide applied to the soil or injected directly into the tree before a plant becomes too weak to respond to treatment. However, there is no pesticide control for most root rots, so homeowners cannot do much to save badly infected trees.


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