A note from Dianne Olsen, horticulture educator at Cornell Cooperative Extension in Putnam, about a lawn disease they’ve been seeing in recent days:
“We’ve been seeing a disease called red thread in lawns over the past 10 days. 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. This is distressing because fine fescues are such a valuable grass for the semi-shady lawn.
“The picture shows a fine, bright red substance that looks like string — this disease is very easy to spot because the red is so bright – not natural-looking at all.
“Red thread grows happily in soils that are low nitrogen and potassium. A little extra fertilizer — (the label might read 10-0-10 or even 15-5-20) — can help your lawn resist the disease.
“Red thread typically does not do too much damage to lawns. However, if control is deemed necessary, a relatively new product called Heritage is available for red thread. Heritage 50WGis active on leaf surfaces but also has systemic activity.
“The active ingredient, azoxystrobin, was derived from, and is chemically very similar to, a class of naturally occurring fungicides called strobilurins. These are chemicals produced by various wood decay fungi. These fungi produce these to eliminate other fungi from competing with them for nutrients.
“Synthetic products labeled for red thread include mancozeb, thiophanate-methyl, propiconazole and Bonide Fung-onil Concentrate.”
Dianne K. Olsen
Environmental Horticulture and Natural Resources Educator
Cornell Cooperative Extension of Putnam County
1 Geneva Rd., Brewster, NY 10509