Rhizoctonia Large Patch

Rhizoctonia Large Patch Disease Understanding and Management Strategies

Large Patch • Formally zoysia patch, zoysia large patch • Affects all warm season grasses • Zoysia • Centipede • St. Augustine • Seashore paspalum • Bermuda • Buffalograss

Zoysia

Centipede

St. Augustine

Seashore paspalum

Large Patch – Symptoms • Large patch occurs in the fall and spring as circular, discolored patches that expand over time. • In the fall, large patch appears as generally circular areas with orange borders, varying from six inches to more than 20 feet in diameter. • Large patch is a leaf shealth and crown disease which can make it harder to control with some fungicides • The leaves and stems are not usually infected, but will die as the infected sheaths and crowns deprive them of nutrients and water.

Large Patch – Pathogen information • Normally infects turf in fall and spring when the turf in going into or out of dormancy. Large patch infection starts in mid to late September and may continue into December if thatch temperatures are above 50° F and moisture is adequate. • Spring infection can be present through May but declines as temperatures increase into the 80’s. • In warmer climates, disease can be active all the time • The stresses of cold temperatures, excessive thatch, insects and traffic can increase the potential for disease • In the spring, symptoms appear as light brown sunken patches that are slow to come out of dormancy. The same areas may be infected in both the spring and fall, or may occur only intermittently in either season.

Agronomic practices for preventing major outbreaks • Keep mowing heights above 1 inch and mow only after turf has dried to reduce spreading of wet, infected leaves. • Avoid overwatering and facilitate drainage with tiling or slit trenches if possible. Water in the morning to reduce periods of leaf wetness. • Core aerate or verticut in June or July to reduce thatch. But remember that such disturbance while symptoms are present can weaken the turf and spread the disease. • Increase air circulation by removing or trimming trees and shrubs. • For zoysia, avoid using more than 2 lb./1000 sq. ft. of nitrogen during the growing season or using fast release nitrogen in late summer.

Use of fungicides to control Large Patch • In areas with a history of large patch infection, turf managers should make one or two preventive fungicide applications in September to early October. A preventive fungicide will not only prevent fall infection, but will also delay or reduce the spring recurrence of the disease. • When to start fungicide applications depends on location, check with local university for more specific timing. • Waiting till the disease symptoms show up is not the way to go. Symptoms can persist for some time even if the pathogen has been controlled. • Two fall applications work best and sometimes a spring application may be required if weather conditions are favorable for disease development • Fall fungicide applications normally minimize the spring epidemic, but not always

Dunes Club – Myrtle Beach – St. AugustineBayer fungicide applied once in Oct 2008 at .45 oz/1000Picture on the right taken on May 16th 2009 Before picture – Oct 2008 After Picture – May 2009

Myrtle BeachTriton WDG applied once at .45 oz/1000 on Oct 6 2008Picture on right taken on May 14 2009 Large Patch Oct 2008 Picture Taken May 2009

Myrtle BeachTriton WDG applied once at .45 oz/1000 on Oct 6 2008Picture on right taken on May 14 2009 Before Picture Oct 2008 After Picture May 2009

2009/2010 Bayer Large Patch Prevention Program

For Residential and Commercial TurfFor 100% Control ProgramApply two fall and one spring application as follows:

For Residential and Commercial TurfFor 90+ % Control ProgramApply two applications as follows:

2009 BACKED BY BAYERLARGE PATCH PREVENTION PROGRAMFor Residential and Commercial Turf • Begin Fall applications when the turf thatch temperature is running 70 to 75 degrees in the afternoon. • Get superior control with the confidence and backing that you expect from a Bayer product. • If you do not get the performance expectations from your Bayer Large Patch Program, just contact your Bayer distributor, or Bayer Field Sales Rep. • Bayer will supply Prostar for a curative treatment to areas expressing infection symptoms. We want your turf looking great for Spring.

Rhizoctonia Large Patch