Landscape and Turf - June Weed Notes

The following are some notes that I made for weed control in landscapes and turf areas in June.

• If you have not done so already, apply the second application of preemergence crabgrass herbicide (such as pendamethalin) to turf with a crabgrass problem. There may already be crabgrass breaks with all the wet weather and a postemergence material will be necessary in that case (such as fenoxaprop or quinclorac).
• Wet weather will promote yellow nutsedge growth. Postemergence herbicides with activity on nutsedge include halsulfuron , sulfentrazone , and bentazon. All 3 can be used in turf; halsulfuron and bentazon can be used around some landscape plants (check the label). Glyphosate and glufosinate can be used as a directed, wiper, or spot spray application in landscapes. Two applications are often needed with bentazon, glyphosate, or glufosinate for effective nutsedge control.
• Summer annual weed escapes in landscape beds will be evident. Hand weeding is often the only option. Directed applications of glyphosate, glufosinate, or pelargonic acid herbicides can be used where there is space between desirable plants. Post emergence grass herbicides (fenoxaprop, clethodim, fluazifop-P-butyl, and sethoxydim) can be used over the top of many landscape plants where annual grass weeds are dominant.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County