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Red Thread is a common lawn diseaseResistant varieties of grass disrupt this lawn disease
By: Sandy Feather
©2009 |
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Q.
My creeping red fescue lawn gets red thread every year. I use
fungicides and fertilize to help it grow out, but it comes back
every year. Is there anything I can do to get rid of it once and for
all? |
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A.
The only way for you to get rid of it once and for all is to
completely renovate your lawn to get rid of the susceptible creeping
red fescue and replace it with a variety of grass that is resistant
to red thread. Plant pathologists use a device known as the plant disease triangle to describe the conditions required for a given disease to develop. |
Conditions for Development
These conditions include the susceptible host
(creeping red fescue), the disease-causing agent (causal fungi, Laetisaria fuciformis), and the correct environmental conditions
(67-75 degrees F, rain) over a period of time. All three legs of
the triangle must be present for red thread to develop.
Red thread is most severe on perennial ryegrass and fine fescues. It often appears with another disease called pink patch, Limonomyces roseipellis. Both diseases have similar symptoms. The causal fungi overwinter on dead blades of grass or clipping debris from last season. Air temperatures of 65 to 75°F and rainy or humid weather favor the development of red thread and pink patch. Red thread and pink patch are spread on turf equipment and by foot traffic. From a distance, affected patches of grass have a reddish or pink cast. Affected leaf blades dry out and take on a bleached out straw color. Distinct symptoms appear as the diseases progress. For red thread, reddish, thread-like fungal mycelium extends from the tip of infected blades of grass. Pink patch appears like pink cotton candy coating infected blades of grass. Cultural Controls
Cultural controls include
maintaining adequate fertility levels;
red thread and pink patch can be indicative of low fertility. Be
careful to use a moderate amount of nitrogen, one-half to one
pound of nitrogen per thousand square feet. Too much nitrogen
can create favorable conditions for other, more serious diseases
such as leaf spot to develop. Fungicides
While home lawns rarely warrant fungicide applications to
control red thread, it may be necessary when lawns are composed
of pure stands of perennials ryegrass or fine fescues.
Fungicides labeled to control red thread and pink patch on home
lawns include Cleary's 3336 (thiophanate methyl), Bayleton (triadimefon),
and those containing mancozeb as the active ingredient. More |
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Landscaping
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