Plan the perfect garden with our interactive tool →

Brown Rye Grass Questions

grass image by palms from

Rye grass is a turf grass used on golf courses and sports fields, but can be used in some home landscaping applications. One of the more common concerns about rye grass is when brown patches appear. This infection is called "brown spot," "dollar spot" or simply "brown rye grass." Understanding what causes the problem can help you to treat and prevent brown rye grass in your turf.

What is Brown Rye Grass?

Find brown rye grass where a fungal infection is evident. The brown color is the effect of a pathogen that attacks turf grass, with perennial rye grass being one of the more damaged types of turf. Brown patch is also known as Rhizoctonia blight, states the University of Maryland. Brown patch usually occurs in perennial rye grass with warm humid conditions. It does not cause permanent loss of the turf except turf planted less than a year earlier, according to the University of Kentucky.

What Causes Brown Rye Grass?

Look for Rhizoctonia solani or Rhizoctonia zeae fungi. Brown patch requires a minimum daily temperature of 63 degrees with rain or 95 percent humidity for the fungus to activate, according to the extension services of both universities. Daytime temperatures above 85 degrees with high humidity create ripe conditions; if those conditions should occur for over eight hours, the possibility of the R. solani fungus activating is high. According to the University of Maryland, evening thunderstorms between June and September, combined with evening temperatures above 68 degrees, can lead to severe disease causing injury to grass.

Can I Accidently Cause Brown Rye Grass?

Over fertlizing during spring and summer can increase the occurance of brown rye grass. According to published information from the University of Kentucky, lush, succulent growth produced by heavy nitrogen fertilizer can favor the development of this turf problem. Other factors, such as overwatering, late-day watering, poor drainage, poor air movement and lack of adequate drying of the turf can bring on brown rye grass. Mowing too high, excessive thatch, mowing when the grass is wet and chopping grass with dull mower blades can also increase the severity of the disease.

How Do I Know My Grass is Infected?

Look for rough circular patterns varying in size between one to five feet. Both universities state that, while not always evident, fine gray cobwebs of fungus can be found along the edge of brown areas indicating active fungal growth; this is most promenant during early morning hours. As early morning dew dries, the "smoke ring" effect of the newly growing fungus vanishes. Diseased patches will merge and areas become irregular in shape, according to the extension services. The extension of the University of Kentucky says to look for lesions on blades of tall fescue from recent infections. These lesions will appear olive-green at first; as the grass dries, the lesions turn tan and add a thin brown border. Look for leaf blades to wither and die. The University of Maryland says that lesions may start out oval and small, but then elongate and extend down the surface of the leaf blade.

When Should I Look for Brown Rye Grass?

Watch for brown rye grass during the months of July and August. Careful observance is suggested for young stands of perennial ryegrass especially during the first year after planting by the University of Maryland Extension. Notice that the brown patch problem kills leaves and sheaths but avoids roots and crowns; because of this, affected turf can recover during September if kept properly fertilized, irrigated and mowed properly

How Do I Treat Brown Rye Grass?

Treat brown patches by using fall fertilization between September and October. Irrigate in the morning so the turf has a chance to dry in the afternoon sun. Mow turf to a height of three inches to avoid a high canopy. Apply fungicide during extended high nighttime temperatures and humidity as recommended by the University of Maryland Extension.

How Do I Prevent Brown Rye Grass?

Use a slow release nitrogen fertilizer, sulfer coated urea and natural organics during autumn as suggested by the University of Maryland Extension. Collect clippings so that any infected clippings do not re-infect the turf; if the turf is not infected, allow clippings to remain so nutrients are returned to the soil. Early-morning mowing will allow cut grass to dry during the day, thereby slowing the fungus. Remember that very dry soil and cool temperatures during the night will reduce the onset of the disease; this is also the optimum time to apply fungicide. Apply fungicide when the signs of disease first arise. Water the turf to a depth of four inches so deep roots develop.

Garden Guides