Dollar spot can infect
most turfgrasses, including Kentucky bluegrass and creeping bentgrass putting greens.
Although the disease can develop under any growing conditions, it primarily
turf when daytime air
temperatures reach 59 to 86 F, followed by cool evenings and heavy dew.
Infected turf produces
bleached white spots about the size of a dime, which can increase to the size
of a silver dollar and eventually coalesce to produce large patches. Cottony
myceliu m often are visible on infected turf in the morning,
especially if dew is present. Leaf constriction approximately half way up the
blade and a bleached hourglass-like spot with a black or red margin are
noticeable with the naked eye. The fungus lies dormant in thatch and soil until
environmental conditions are right, then it infects the turfgrass if adequate
leaf moisture is present.
COMMENTS on disease
Primarily a foliar disease, the
fungus produces a toxin that can kill the crown of the plant and even the roots
during a severe infection.
Many fungicides are available that are
effective in preventing or curing
dollar spot. However, infections on
residential lawns are rarely severe enough to warrant chemical control.
Daconil Ultrex (chlorothalonil),
nitrogen fertility, water deeply and infrequently,
avoid prolonged leaf wetness by
watering in the morning, prevent thatch buildup and use resistant turfgrass