This belongs to the Deuteromycota group of fungi.
Damage. This disease appears as irregular circular patches of yellow then dead brown grass up to 30 cm in diameter on fine turf. These patches eventually merge (see Figure 15.16). Under extreme damp conditions, dead leaves become slimy and then are covered with a light pink bloom, most evident between May and September.
Life cycle and spread. Infection of the leaves by spores and hyphae occurs most seriously between 0°C and 8°C, conditions that are found under a layer of snow (hence its other name, snow mould). However, conditions of high humidity at temperatures up to 18°C may result in typical patch symptoms. Spread is by means of water-borne asexual spores under conditions such as autumn dew with no wind. The fungus can survive in frosty
Figure 15.16 Fusarium patch on turf. Note the area of dying turf. In or dr>' summer conditions as dormant mycelium in the earlier stages of the disease, distinct circular patches about 30 cm dead leaf matter or newly infected leaves. across are seen.
Control. Preventative control measures are important. Avoid high soil nitrogen levels in autumn, as this promotes lush, susceptible growth in autumn and winter. Avoid thatchy growth of the turf, as this encourages high humidity and thus favours the disease organism. The groundsman can drench preventative fungicide such as iprodione in autumn to slow down infection of the fungus. Summerapplied systemic fungicide such as thiophanate methyl is able during the actively growing period of the year to move within the plants and achieve curative control.
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