Rotational grazing systems have developed on temperate pastures consisting of perennial ryegrass and white clover. Kentucky bluegrass and Fescue are less susceptible to "Pythium" blight than Perennial ryegrass and Bentgrass. White clover is commonly grown in mixtures with forage grasses, e.g. perennial ryegrass ("Lolium perenne"). The grass was of the Perennial Ryegrass type and cut to 8mm. Several resistant varieties of perennial ryegrass, fescues, and Kentucky bluegrass are available. It is sometimes considered a subspecies of perennial ryegrass ("Lolium perenne"). These grasses include bentgrass, annual bluegrass, perennial ryegrass, fine fescue, and kentucky bluegrass. Since 2002, the courts used for Wimbledon have been sown with 100% perennial ryegrass. The field is made up of Perennial Ryegrass, which is grown directly at the site. The fungus grows on dead plants, especially on perennial ryegrass near the ground (25mm height). Creeping Bentgrass, Fine & Tall Fescue, Perennial Ryegrass, Kentucky & Rough Bluegrass. Perennial ryegrass has a fibrous root system, with thick main roots and thinner lateral branches.