Contact Cornell Cooperative Extension - Suffolk County for cultivars of bluegrass and fine fescues that are resistant to leafspot. Summer patch is a devastating disease that occurs during hot, dry periods. Perennial ryegrass and several bluegrass varieties are resistant to this disease and should be included in a new seed or overseeding mixture. Summer patch is caused by a root pathogen. Therefore, any practice that encourages deeper rooting will make the lawn more tolerant to this disease, including proper pH and fertilization, proper mowing and irrigation.
Red thread is a disease that is common during cool, wet periods in the spring.
The grasses most affected are fine fescues and perennial ryegrass. Select and introduce cultivars that have resistance to red thread. Red thread is usually favored by low nitrogen and potassium fertility. Therefore, maintaining an ample supply of these two nutrients may should make your lawn more resistant to this disease. Rust is a disease that is common on Kentucky bluegrass and perennial ryegrass in the fall.