Herbicides to Use Around Muscadine Grapes

Pre-Emergent Herbicides

• Pre-emergent herbicides are those that work on weed seeds before they sprout. Woody perennial weeds can easily overwhelm grape vines causing competition for water and nutrients. A pre-emergent herbicide such as oxyfluorfen, oryzalin, pronamide or norflurazon is applied before these weeds become a problem. Direct the herbicide application at the trunk of the vines to avoid damage to new shoots and leaves.

Post-Emergent Herbicides

• Post-emergent herbicides kill weeds that have already begun to germinate and grow.

  Post-emergent herbicides such as paraquat, glyphosate and glufosinate are generally used on muscadine grape vines, according to Integrated Pest Management Centers. Apply these herbicides sequentially to control grass-type weeds that see continued regrowth.

Herbicide Problems

• Those growing muscadine grapes must take care choosing herbicides to avoid damage to plants and fruit. Drifting of herbicides on the wind can produce negative effects on the plants some distance away from the site of application. The herbicide 2, 4-D is no longer used on muscadine grape vines due to curling and strapping on new leaves of muscadine plants, even as much as ½ mile away from the treated area. Clomazone is another herbicide that causes problems on muscadine grapes, with leaf whitening observed on muscadine grapes planted near a tobacco field containing that substance.

Organic Options

• Because of the problems many growers experience with the use of chemical herbicides, more organic methods such as plastic weed barriers and plastic growing tubes continue to gain in popularity. Fertilize the muscadine plants with 10-10-10 fertilizer at a rate of a quarter pound per vine, and repeat application every six weeks until July. Grapes need more magnesium than other plants, so apply an Epsom salts solution of 1 tablespoon per gallon of water onto the vines to prevent deficiency.