A Maine apple grower is exploring alternatives to using glyphosate
(e.g. Roundup etc.) for vegetation control in tree rows. The reason is
concern about immediate and long term effect of glyphosate drift onto
trunks. Despite efforts to reduce drift and accurately target herbicide
application, grower feels there is still too much risk of trunk contact.
There are some lower trunk cankers, but whether these are due in part to
previous glyphosate exposure not determined.
Orchard is ca. 10 acre pick your own. Ground cover system is
permanent sod alleys/row middles with vegetation suppression in the tree
row during growing season, with moderate regrowth allowed in late summer -
early fall for protection against winter low temperatures. The trees are
ca. 15 year old Mac and Cortland on M26. New plantings will be tall
spindle.
Previous tree row vegetation management has been annual glyphosate
application in May-June. The objective is to find program that will
provide similar results with less risk of trunk injury than associated with
glyphosate.
New approach being considered is tree row application of 2,4-D (for
annual and perennial broadleaves) + Poast (for annual and perennial
grasses) in post petal fall period.
Gramoxone (paraquat) as alternative burn down herbicide not acceptable
because of acute toxicity risk.
Rely provides similar postemergent efficacy as glyphosate (though only
Fair vs. Good for perennial grass and perennial broadleaf), but may also
share the same trunk hazard as glyphosate.
Alley sod management will continue to be regular close mowing.
Your thoughts on this approach, and the reasons for making this change
(i.e. concern about glyphosate) will be appreciated.
--
Glen Koehler
University of Maine Cooperative Extension
Pest Management Office
Voice: 207-581-3882
491 College Avenue, Orono, ME 04473
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