Monday, November 26, 2018

Strange Brown Areas In Your Yard?


Horticulture Hotline 11/26/18
By Bill Lamson-Scribner

While walking and driving around it seems that brown patch/ large patch/ Zoysia patch has invaded the Lowcountry. From the questions I’m getting and the sales of fungicides at Possum’s, I would feel safe to say many of your lawns are being attacked by this disease. With the sunlight hours getting less, the grass will begin to transition into a dormant state. As the cooler weather comes and the grass growth rate slows down, large patch / brown patch / zoysia patch fungus will begin to show up in our lawns. This disease is always present in the lawn, it just manifests itself when the environmental conditions are right and your grass cannot outgrow the damage.

Since this disease is a big problem in the Lowcountry, knowing that it is a soil borne disease can help you with control strategies.  Being a soil borne disease, you know that it will reoccur in the same areas year after year.  If a leaf blade with large patch is moved from one part of the yard to another (lawn mower), this can begin a new infection area (although not very common); however, these are not spores flying through the air.

As a soil borne fungus, if you map the areas that you have the disease, you can concentrate your control efforts (dollars) into a smaller area, putting less control products into the environment.  If your yard is 5,000 sq ft usually you might have a few infected areas which might total approx. 500 ft.  Instead of buying control products to treat 5,000 sq ft, you can concentrate your efforts into the 500 ft (i.e. 10% of your total yard).  If Large Patch was an air borne fungus with spores, you would have to treat the entire yard because air borne fungus spreads a lot quicker than soil borne fungus.

As your grass is going into dormancy and the temperatures begin to cool at night, large patch will be ready to attack your grass.  A good granular one-two punch control strategy is T-Methyl and Fame (all systemic fungicides that get into the plant).  Use these products in areas where you have had Large Patch previously at the preventive rates and intervals recommended on the labels. Be sure to use T-Methyl with Fame so you are switching chemistry classes and mode of action. Good control early on can help avoid flare ups in the spring also.

Large patch usually likes wet, heavy thatch, improper nutrition, and/or compacted soils.  Culturally you need to manage your irrigation system, raise any low areas, and correct drainage problems.  Reducing thatch (we have a great organic granular product for controlling thatch), maintaining proper fertility levels, and aerating to alleviate compaction, will also help control large patch. A healthy turf (following soil test derived feeding schedule) with a soil with a lot of bio-diversity (use of cotton burr compost, SeaHume and other organics) has shown to help manage this disease.  

Always read, understand and follow product label. The product label is a Federal Law.