Leonard from Matthews, Nc writes
The common product which contains Quinclorac in part does not seem effective for crabgrass in the 80-95 degree days in summer.
Quinclorac 75 DFÂ should be applied only in temperatures below 85. Â You should apply in the early morening or late evening on hot temperature days. The product label does state the following regarding crabgrass: Â Complete control may not be achieved under certain conditions to crabgrass at 2 - 4 tiller stage. Â In these cases you will need to make a sequential application for control. Â For best results apply with methylated seed oil either before the second tiller stage or as the weed grass mataures. Â You should treat whenever the crabgrass has just emerged or after it has matured for best results, whenever this is in your area. Â You can also check with your local cooperative extension office for the best advice on timing.
Answer last updated on: 07/21/2017