Tuesday, April 15, 2008

Turf - Orchardgrass in Lawns

Orchardgrass can be a problem weed in turf type tall fescue and bluegrass lawns. The following is information on this grass and its control.

Orchardgrass is a bunch-type grass, like tall fescue, with a coarse, upright growth habit. Orchardgrass has very compressed, flat stem bases, is folded in the bud shoot, has no auricles, and has a long, membranous ligule. Infestations are common where hayfields or pastures have been developed but can often is the result of contaminated seed lots. Orchard grass often comes in as a contaminant on grass seed, especially K-31 tall fescue. Buying good grass seed is the first line of defense against this weed. Orchard grass is a pasture grass and therefore is not found in the "Weed seed" portion of the seed label. Rather, orchard grass will be listed as "Other crop seed". Therefore, try to buy grass seed that has 0.0% "Other crop seed".

When there are few weedy patches, orchardgrass can best be cut out with a shovel. Be sure to cut down three to four inches into the soil to get all the stems. The holes should be refilled and seeded or sodded immediately. The seed and soil should be representative of that already in the area. If the area has a large number of plants, chemical control will be more efficient. A nonselective systemic herbicide such as glyphosate (Roundup, many others) or glufosinate (Finale) can be spot-applied. These herbicides will also kill the desired turf species; use care during application. The area should be reseeded 5 to 7 days following application. Stir up the soil by raking or chopping to insure good seed-soil contact.

Often the orchardgrass will grow taller than the surrounding turfgrass. This gives the opportunity to use a wick applicator filled with glyphosate. You pass the wick over the top of the orchardgrass without touching the turfgrass below.

Some information from taken from "Control of Perennial Weedy Grasses in Turf" by Zac Reicher and Clark Throssell, Purdue University Turfgrass Specialists. Addition information from Kansas State University and Gordon Johnson, Extension Horticulture Agent, UD.

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