Solutions for Take-All Patch
This year, more than any other, we’ve been receiving questions about a lawn disease known as take-all patch, otherwise known as take-all rot. Folks, especially in the South, seem to be losing massive expanses of lawn to the problem and everyone wants to know what can be applied to stop the disease — without using toxic synthetic chemicals.
Caused by the fungus Gaeumannomyces graminis var. graminis, the disease usually attacks St. Augustinegrass most often, but also is known to knock out Bermudagrass and bentgrass. It goes after root systems first and by the time you see symptoms of yellowing grass blades, the problem is probably already serious. Often the affected area will be circular in shape, giving in the appearance of fairy rings — but this is more devastating. Roots can become so damaged that the top of the plant easily pulls from the ground; the roots will appear dark in coloration.
“We sprayed with every chemical we could find, but nothing worked,” said Annibel Suarez of Mississippi. “Do you have any organic solutions up your sleeve?”
Take-all isn’t something I’ve ever needed to personally treat up in the Northeast, but at least two organic solutions do appear to exist. Actinovate and Zerotol are both listed for take-all patch by their manufacturers, both of whom I know to be reputable.
Some good news is that in talking with my organic lawn care colleagues in the South, lawns treated organically rarely seem to be bothered by the fungus. The theory is that the natural soil organisms present in the natural system fight off any pathogens so that symptoms never develop.
The Texas Cooperative Extension service states: “The pathogen survives on infested debris and on infected perennial parts of living grass plants. When conditions are favorable (cool, moist weather), the fungus grows on the surface of roots, stolons, rhizomes, crown and leaf sheaths of the grass and then penetrates and infects the tissues. As the weather becomes warmer and dryer, the infected plants are stressed, and symptoms become more evident. The pathogen can be spread over long distances when infected plants or plant debris are transported mechanically. Infected sod may serve as a source of inoculum even if it shows no immediate symptoms of the disease.”
Excessive watering should be avoided, not just for this disease, but for lawns in general. Far more problems occur with overwatering than in times of drought. Mississippi Extension Service Director David Carter said, “Some scientists say this is a stress-related disease which things like excessive rainfall, excessive nitrogen fertilizer, over liming soils, excessive herbicide use, or poor management practice contribute to.”
Here is a fact sheet from Cornell on the subject: http://plantclinic.cornell.edu/FactSheets/takeall/takeall.htm