Each year, ornamental and shelterbelt trees are damaged through improper use of herbicides. Damage ranges from minor symptoms to death.
Injury to shelterbelts can occur during nearby crop spraying, roadside spraying, lawn spraying or soil sterilant applications around buildings, driveways and sidewalks.
Many herbicides are involved in shelterbelt damage, including phenoxys such as 2,4-D and MCPA, dicamba, bromoxynil, glyphosate and picloram.
One product of particular concern is dichlorprop plus 2,4-D (estaprop). This combination is a potent brush killer that is deadly to shelterbelt trees, though it is often used in cereals.
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Caution is advised when applying glyphosate near desirable plants. This chemical kills anything green, including trees and shrubs.
Shelterbelt injury can result from root or leaf uptake of the chemical. Uptake might not occur until certain conditions develop, often some time after application.
Injury symptoms can develop slowly. Tree roots can extend over a great distance and can quickly pick up the chemical, causing injury or death.
Any herbicide that is water soluble and persists under dry conditions, like dicamba, can cause problems.
It is often included in lawn weed control mixes. Damage can occur when dicamba from successive applications in dry years suddenly becomes available after heavy rainfall.
Chemical injury to shelterbelts can be avoided with proper planning and control. Read labels and apply herbicides at the proper rate and time. Allow at least a seven metre buffer zone between the shelterbelt and ground chemical application.
For aerial application, a larger buffer zone is required. Only apply herbicides during low wind that is directed away from the trees.
For more information contact the PFRA Shelterbelt Centre at Indian Head, Sask., at 306-695-2284.
