Tips from the help desk, Fall cool weather lawn fungus, November 2022

Tips from the Help Desk…

Fall cool weather lawn fungus

by David Austin
Residential Horticulture Agent and
Master Gardener Volunteer Coordinator

What up with my grass?

Are you noticing large discolored patches of grass in your St. Augustine or Zoysia lawn?  They start as small thinning areas with a yellow perimeter and they seem to grow larger very quickly. Often they aren’t noticed until they are several feet across. What you may be seeing could be something we call “large patch” (or,  previously, “brown patch”). This is a fungal disease that grows when the nights are cool and the days are warm.

A Large Patch of thinning St. Augustinegrass
The name large patch fits the symptoms of this cool weather lawn fungus. photo by M.L. Elliot

Fungus Among us!

This lawn fungal disease, Rizoctonia solani, often shows up in the fall, winter, and early spring. By May, it usually goes away and the lawn appears to get better during the summer. Once it takes hold in a lawn, it generally returns every fall when the conditions are right.

Getting to the root of it

Like most fungal diseases it is easier to prevent with fungal sprays than it is to cure it once the disease takes a foothold. Preventitive sprays should be started as early as September. If you have a St. Augustine or Zoysiias Lawn you’ll want to click here to read this article from the University of Florida for ways to avoid it damaging your lawn.

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david austin
Posted: December 16, 2022

Category: Home Landscapes, Home Management, Horticulture, Lawn, Pests & Disease, Pests & Disease, Turf, UF/IFAS Extension,
Tags: Highlands County, Highlands Horticulture Digest, Hometown Gardener, Large Patch Lawn Disease, Master Gardener Volunteers, Master Gardeners, Tips From The Help Desk, Turfgrass, UF/IFAS Extension

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