With fall rapidly approaching and 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 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 out-grow 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 square feet usually you might have a few infected areas which might total approximately 500 feet. Instead of buying control products to treat 5,000 square feet, you can concentrate your efforts into the 500 feet (i.e. 10 percent 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 Disarm or Dual Action Disease Killer and Cleary's 3336 (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 Cleary's with one of the other two 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.
Does the West Nile Virus out-break in Dallas scare you? Kill mosquitoes now with Cyonara. Also look around your yard for any areas that collect water that mosquitoes could breed in. Usually I recommend organic repellents that do not kill mosquitoes just keep them away from you; however, with 10 dead in Dallas it is time to say, 'Cyonara!'
Always read, understand and follow product label. The product label is a Federal Law.
(Bill Lamson-Scribner can be reached during the week at Possum's Landscape and Pest Control Supply. Possum's has three locations 481 Long Point Rd in Mount Pleasant (971-9601), 3325 Business Circle in North Charleston (760-2600), or 606 Dupont Rd, in Charleston (766-1511). Bring your questions to a Possum's location, or visit us at possumsupply.com. You can also call in your questions to ' The Garden Clinic', Saturdays from noon to 1 p.m., on 1250 WTMA (The Big Talker). The Horticulture Hotline is available 24 / 7 at possumsupply.com.)