Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu
Glyphosate has been a very useful tool for weed management and is used in commercial fruit plantings. However, it can cause some unwanted injury to perennial crops under certain situations.
Glyphosate should not be allowed to contact leaves, young green bark, fresh trunk wounds, root suckers, open buds, immature fruit tissues, or fresh pruning cuts. All of these can allow for absorption of the herbicide and injury to the plants.
Dormant and spring applications are recommended and there is less chance of injury. Late summer and fall applications have more risk. This is because in the fall, if glyphosate is taken up by the plant, it will be stored in the bark and wood of the stems or canes, as well as the root system. If glyphosate is taken up by the perennial fruit plant, damage symptoms often do not appear until the following spring. When regrowth occurs in the spring the glyphosate in the plant tissue can be translocated and cause injury to new growth. New growth will be yellow and stunted. In fruit trees, lower branches may appear to have strapped leaves and short internodes.
Fruit plants that have absorbed glyphosate will often be weaker and more susceptible to diseases and insect pests.