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RUST DISEASE SHOWING UP IN NORTH CENTRAL IOWA

September 24, 2012

Here are some pictures of rust disease on Kentucky bluegrass submitted by Damian Richardson, Landscape and Conservation Specialist from Alden, IA.  Rust is caused by fungi in the genus Puccinea.  It is common on Kentucky bluegrass and other grass species in Iowa, but there has not been a lot of it so far this year.  It usually begins to show up about the first of August.  This is the first report of it that I have received this year.  This one was on September 20.  These are some good closeups of the rust pustules on the individual blades of grass.  Thanks for submitting them Damian.

While there are several fungicides that will control rust, I usually do not recommend chemical treatment unless it is on a critical area.  It is usually a sign of relatively low nitrogen.  Just add a little nitrogen and mow regularly and the problem should run its course and disappear.  Some cultivars of Kentucky bluegrass are more susceptible that others.  If it is a continuous problem each year, you may want to kill the existing cultivars with Roundup and replace them with more tolerant varieties.  For information on which varieties show tolerance of rust, see the National Turfgrass Evaluation (NTEP) web site at  (http://www.ntep.org/).  They have data over several years on rust infestation of many cultivars of Kentucky bluegrass.

If anyone else is seeing a lot of rust, let me know.

Category: 
iaTURF Blog
Tags: 
disease, rust, Kentucky Bluegrass, fungi, fungicides, nitrogen

ANOTHER GRAY LEAF SPOT WARNING

September 4, 2012

A year ago, on August 31, 2011, I put up a post warning about Gray Leaf Spot on perennial ryegrass.  This disease shows up rather infrequently in Iowa, but it does occur around Labor Day on years when temperatures are unusually high.  Last year's Labor Day temperatures were in the 90's and if you check the post from September 19, 2011, you will see that it did occur on several golf courses with perennial ryegrass fairways.

This disease is caused by the fungi Pyricularia grisea. It seems to selectively hit perennial ryegrass on intensely managed areas such as golf course fairways and sports fields. Under the right conditions, it can be more devastating than Pythium blight. When it hits, it can wipe out large areas of turf overnight.  Fungicides, such as Banner/Daconil will control it, but they must be applied before the outbreak.  Once the disease begins, it is too late to apply.

The reason I bring this up is that we are in the same weather pattern again this year.  The disease does not always occur when its hot around Labor Day, but it did last year and I would watch for it this year.

The pictures below were taken in 1998 on Willow Creek Golf Course in Des Moines and last year on Cedar Poine golf course in Boone. The dead grass is perennial rye and living grass is Kentucky bluegrass.

If anyone has an outbreak of Gray Leaf Sport this year, let me know and send some pictures. 

Category: 
iaTURF Blog
Tags: 
Gray Leaf Spot, disease, perennial ryegrass, fungi, fungicides