You Are Here: Management Updates 2004 Archive August 9, 2004

Date: August 9, 2004
Category: Diseases
Subject: Rust, Summer Patch, Anthracnose

Rust is widespread in lawns at this time.  This disease is caused by a fungus that needs water on leaf blades and prefers soft, succulent leaf tissue that is produced after heavy fertilization. However, good water and N also help the grass to grow faster, so the leaf blades are usually mowed off before rust can develop. That means that rust is more common where the infected leaf blades don't get mowed off such as compacted areas, low N turf, and droughty turf.  Rub a white tissue or piece of fabric across a rusty lawn, and you will see the powdery orange spores. Luckily, this disease rarely kills plants, and the fungus is not toxic.  At this time of year, the easiest solution is to get the grass growing, so the rusty leaves will be mowed away.

The disease is also common when leaf blades are green, but the top growth has stopped in the fall. Again, we are lucky in New England because most of the spores will die over the winter, and the turf will grow back healthy and rust-free in the spring. There are resistant cultivars of perennial ryegrass and Kentucky bluegrass. See the National Turfgrass Evaluation Program website for information: http://www.ntep.org

Summer patch is unusually active this summer, especially in fairways. At this point, fungicides are probably not cost-effective because cooler weather is approaching.   Anthracnose is also common, mostly on greens, but fungicide is necesary for this disease because it can stay active into the fall.  Fungicides are most effective when coupled with cultural practices that help the turf recover from the various summer stresses.

- Submitted by: Dr. Gail Schumann

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