Fight­ing brown patch disease in lawns

The Standard Journal - - LIFESTYLE - By Ricky Ens­ley [email protected]

The beauty of a lawn can be quickly de­stroyed by brown patch (Rhi­zoc­to­nia species), a se­ri­ous fun­gal disease that can af­fect all Polk County lawn grasses. It can de­velop rapidly when tem­per­a­tures are warm (75 to 90 de­grees F) and hu­mid, es­pe­cially on cool-sea­son grasses; (Fes­cue and Rye­grass). It can also oc­cur on these grasses dur­ing warmer pe­ri­ods of the winter months. Warm-sea­son grasses (St. Au­gus­tine, Zoysia, Ber­muda, and Cen­tipede) most com­monly are af­fected by brown patch dur­ing the early spring and late fall.

Symp­toms

Symp­toms of brown patch may vary greatly with the type of grass and soil con­di­tions. The disease usu­ally causes thinned patches of light brown grass that are roughly cir­cu­lar in shape. These ar­eas range in di­am­e­ter from a few inches to sev­eral feet. Of­ten the cen­ter of the patch will re­cover, re­sult­ing in a dough­nut-shaped pat­tern.

When disease con­di­tions are fa­vor­able, large ar­eas of the lawn may be uni­formly thinned and even­tu­ally killed with no cir­cu­lar patch be­ing ev­i­dent. Close in­spec­tion of cool-sea­son grass blades re­veals small, ir­reg­u­lar, tan leaf spots with dark brown bor­ders. In­fected warm-sea­son grasses rarely have leaf spots but in­stead have rot­ted leaf sheaths near the soil sur­face.

Grasses com­monly af­fected

All types of lawn grasses grown in Polk County can be af­fected by brown patch. There are no turf grass species en­tirely re­sis­tant to brown patch cur­rently avail­able. Brown patch is the most com­mon and im­por­tant disease of tall fes­cue in the South­east.

Pre­ven­tion and treat­ment

The best way to pre­vent brown patch in the home lawn is by fol­low­ing good lawn care prac­tices. This is much eas­ier and less expensive than the use of fungi­cides and can be very ef­fec­tive.

Avoid high rates of ni­tro­gen fer­til­izer on cool sea­son grasses in the late spring and sum­mer. Avoid high ni­tro­gen rates on warm sea­son grasses in mid to late fall. The brown patch fun­gus read­ily at­tacks the lush growth of grass which ni­tro­gen pro­motes.

Ir­ri­gate grass only when needed and to a depth of 4 to 6 inches. Wa­ter early in the morn­ing. This disease can spread fast when free mois­ture is present.

Avoid spread­ing the disease to other ar­eas. Re­move clip­pings if the weather is warm and moist to pre­vent spread to other ar­eas dur­ing mow­ing.

Keep lawns mowed on a reg­u­lar ba­sis to the proper height for the grass species you are grow­ing. Pre­vent ex­ces­sive thatch buildup.

Pro­vide good drainage for both sur­face and sub­sur­face ar­eas.

Fungi­cides can be dif­fi­cult to rely upon for con­trol­ling brown patch in the home lawn but reg­u­lar ap­pli­ca­tions can vastly im­prove ap­pear­ance. A good “rule of thumb” to fol­low on ei­ther cool or warm sea­son grasses is to ini­ti­ate fungi­cide sprays when night time low tem­per­a­tures reach 70 de­grees F.

Stop ap­pli­ca­tions when night time lows are fore­cast to be be­low 70 de­grees F for five con­sec­u­tive days. Typ­i­cally, ap­pli­ca­tions are made at seven to 14 day in­ter­vals.

Call Polk County Ex­ten­sion of­fice at 770-749-2142 for rec­om­mended fungi­cides.

Ricky Ens­ley

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