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.
