Diseases play a major role in determining the success or failure of quality turf grass in Northern Virginia. Generally, the nicest, thickest, and most uniform lawns are the most susceptible to the spread of unsightly disease problems. Early recognition and proper identification are essential for successful management. Proper seed variety selection, fertilization, site maintenance, and cultural practices reduce disease pressure and increase the effectiveness of pesticide application. Pesticides alone cannot control most diseases. Most turfgrass diseases are caused by simple, microbial organisms called fungi. There are over 100,000 different species of fungi but only about 8,000 of these cause plant diseases and only a very small number are important to turfgrass. These organisms exist in all soils or on plant debris.
Like any infectious agent, fungal organisms require a susceptible host and a favorable environment to produce disease. Susceptible hosts include most varieties of turfgrass. Favorable environments include the proper temperature and moisture levels. The optimum temperature range may be wide or narrow, but a definite minimum and maximum temperature can be established for fungal growth. Most fungi also require plenty of moisture during their germination, growth and infection stages. When all these conditions are present over an extended period of time, fungal disease will develop.
Disease begins with the infection stage when fungal organisms penetrate the turf grass host. They incubate and begin living off the host. As they interact with the host, they begin producing visible disease symptoms, which are expressed in various ways such as lesions, wilting, producing mycelium or a reduction in growth of host plant. Finally, they reproduce, spreading the disease to other turfgrass hosts. The result is a lousy-looking lawn. Many management practices also contribute to the development of fungal disease. Close-mowing, heavy fertilization, and frequent irrigation all contribute to disease in turfgrass. This is where a partnership between the technician and the homeowner can make a difference. Trust Bio Green to help create an environment that’s more favorable to the turf grass than the fungi.
Before you do that, however, you need to first identify your primary disease problem. How can you tell dollar spot from copper spot or anthracnose from red thread? It takes a sharp eye, and very often a 10X lens and an ID book. Here’s what makes diagnosis so confusing: the symptoms among the various diseases are very similar. They also change as the disease progresses. Several symptoms may also combine to form a symptom complex, and if that weren’t enough, symptoms also vary with different turfgrass species, different tissues from the same host, and with environmental conditions. It pays to know the different symptoms. With a hand lens, closely examine the blades, roots, crowns, and stems. In many cases, you can make an accurate match. But for the patch diseases, it takes more than that. It takes a laboratory test. Experts can make educated guesses to identify the patch diseases – Fusarium blight, necrotic ring spot, summer patch, take-all patch or spring dead spot are all possibilities. To be sure though, you need to submit a sample for precise laboratory identification.