Table of Contents

Preemergence Crabgrass Control

Clark Throssell and Dan Weisenberger

Objective

Our objective was to determine the effectiveness of commercially available and experimental preemergence herbicides to control crabgrass.

Rationale

Crabgrass is one of the most common weeds invading turfgrass stands in Indiana. Turfgrass managers frequently use preemergence herbicides to control crabgrass. New preemergence herbicides for crabgrass control are being developed and refinements are continually being made to currently used preemergence herbicides. It is important that new herbicides and improved herbicides are evaluated under Indiana growing conditions so we can determine how effectively they control crabgrass.

How It Was Done

A stand of Kentucky bluegrass turf at the Agronomy Research Center, that has a known history of crabgrass invasion, was selected as the site for this experiment. The turf was mowed twice each week at 2 inches with clippings returned. No fertilizer was applied during the course of the experiment unless fertilizer was the carrier for a granular preemergence herbicide. Turf was irrigated to prevent any sign of drought stress. The initial date of herbicide application was 24 Apr 1997 for all treatments and for those treatments with a split (sequential) application, the split application was made on 26 June 1997. Sprayable formulations were applied using a three nozzle hand held boom in 4 gals. of water per 1,000 sq. ft. Granular products were applied using a hand shaker jar. Data collected were phytotoxicity to the Kentucky bluegrass turf and a visual rating of percent of the plot covered by crabgrass on 1 July, 25 July and 25 Aug 1997.

Results

• None of the herbicide treatments caused any phytotoxicity damage to the Kentucky bluegrass turf.
• The untreated check had 47% crabgrass cover on 25 Aug 1997. This indicated that a substantial crabgrass population was present on the site.
• On this test site, any treatment providing 10% or less crabgrass cover was deemed acceptable. Many preemergence herbicides at various rates provided 10% or less crabgrass cover (Table 9).

The addition of the surfactant Primer to several preemergence herbicide treatments appeared to have little benefit in controlling crabgrass at the rates used and under the conditions of this experiment.

Table of Contents

Send corrections, suggestions, and comments to biehlj@purdue.edu