Late Fall and Early Spring Application of Granular Preemergence Herbicide on a Fertilizer Carrier for Season-Long Crabgrass Control

Abstract

Abstract Though sprayable preemergence herbicides will provide season-long control of crabgrass when applied in fall or early spring in the northern states, little work has been done with the now popular granular formulations of preemergence herbicide on a fertilizer carrier. Dimension (dithiopyr) or Barricade (prodiamine) on a fertilizer carrier were applied in October, November, March, April, May, or June in three trials and crabgrass control was monitored the summer following application. A single granular application of 0.56 kg ai·ha−1 (0.5 lb ai·A−1) of Dimension in November or March can provide control equivalent to that expected from typical mid-April applications. Barricade at 0.72 kg ai·ha−1 (0.65 lb ai·A−1) applied in November or March provided season-long crabgrass control equivalent to traditional mid-April application timing, though season-long crabgrass control from a November application of Barricade at 0.72 kg ai·ha−1 (0.65 lb ai·A−1) can be improved by a sequential May application of 0.28 kg ai·ha−1 (0.25 lb ai·A−1). Adding a sequential May application of Dimension at 0.28 kg ai·ha−1 (0.25 lb ai·A−1) only minimally improved crabgrass control over a November Dimension application at 0.56 kg ai·ha−1 (0.5 lb ai·A−1). Granular formulations of preemergence herbicide on a fertilizer carrier applied in November or March can provide season-long control similar to when applied at the traditional timing in mid-April in the Midwest and Mid-Atlantic regions of the United States. However, it is important for season-long crabgrass control to use the high label rate or follow with a sequential application in early summer if lower rates are used in the fall.