Melon Weed Control (March 4, 2015)

The list of herbicides available for use in melons is very limited. Fortunately, most of the types of melons produced here grow rapidly and nonchemical weed control practices like cultivation and plastic mulch can be effective. Shallow cultivation and nonselective herbicides with no soil activity can be effective if used after bed formation and before planting. Both contact (Gramoxone, Aim) and systemic (glyphosate) herbicides can be used. Prefar can be applied either before or after planting, but before weeds emerge. Prefar sticks very strongly to the soil and must be incorporated with as much overhead water as possible. It does not work well when drip or furrow irrigation are used. There are more herbicide options after the crop has emerged and developed three or four leaves. Dacthal and Trifluralin can be used as layby applications before weeds have emerged. Both can cause unacceptable stunting of the crop if applied too early. Prowl is not safe to melons at normal use rates and is not registered. Sandea is registered and can be effective on nutsedge and several broadleaf weeds. It is safe to most melon types after they have four leaves and before blooming. Carryover in the soil is a consideration if sensitive crops are to follow. The grass herbicides, Select, Select Max, Poast, and generics of these, are registered and effective on most grasses. Poast will not control sprangletop or annual bluegrass, but the highest rates of Select, Select Max, and generics of Clethodim are. Temporary crop injury from Select Max can occur where the sprayer overlaps or slows down at the end of rows. This normally only occurs where a 2x or greater rate is applied.

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To contact Barry Tickes go to: btickes@ag.arizona.edu.