St. Louis lawns are annually attacked by the fungal disease brown patch. However, brown patch is not the only fungal disease to hit St. Louis lawns. Here is a synopsis of the usual suspects and what you can do to prevent these summer diseases from damaging your lawn.

BROWN PATCH
Symptoms:
Vary depending on turfgrass; rings or circular patches of blighted, brown grass (Fig. 1). Brown Patch is St. Louis' #1 turfgrass foliar disease. It attacks all cool season turfgrasses and can even affect zoysia and bermuda grasses.
Management:
Plant resistant cultivars or a mixture of grasses (Independence Mix); maintain moderate nitrogen fertility; decrease shade and increase air circulation; apply INFUSE Lawn granules as a preventative or curative application.

SUMMER PATCH
Symptoms:
Summer patch is a root disease that will appear in early summer as small circular patches of slow growing, thinning or wilted turf, 1 to 3 inches in diameter. During hot temperatures these patches rapidly fade from grayish green to a light straw color. Often frog-eyes and half rings coalesce. (Fig. 2).
Management:
Tall fescue is less susceptible to SP than Kentucky Bluegrass. Reseed area with tall fescue blend. Avoid quick-release fertilizers, raise mowing height; apply INFUSE fungicide in cool spring weather when fungi are actively growing on roots but not causing visible damage.

NECROTIC RING SPOT
Symptoms:
This is a frog-eyed patch that is seen on Kentucky bluegrass during hot summer months. (Fig 3) It is caused by a root fungus.
Management:
Reduce thatch; plant resistant cultivars; raise mowing height; apply INFUSE fungicide in spring when root fungi are actively growing.

DOG PATCH
Symptoms:
Light straw colored patches that have a dark green ring of taller grass. (Fig. 4) The nitrogen in the urine (urea) causes a burn in the center where the urine concentration is higher. The darker green grass is fertilized with the nitrogen and causes a surge in growth.
Management:
Dog repellents and magic dog pee dilutors won't work. A motion detector will prevent dogs from urinating but it will also hit your mailman. Hose down areas, dig up dead areas and reseed in fall; keep dog in one area of your lawn where it is less visible.