SUMMER PATCH AT HORTICULTURE RESEARCH STATION

Nick Christians
nchris@iastate.edu
July 10, 2013

These are pictures of Summer Patch on Kentucky bluegrass at the Horticulture Research Station.  It is caused by the fungi Magnaporthe poae.  It typically shows up in early summer, particularly in years like this that are very wet early followed by a quick drying period and hot temperatures.  This showed up over the 4^th of July (right on time).

The blighted areas with a green center that are surrounded by a circle of dead grass are known as “frog-eyes” and are typical of a number of patch diseases.  It is believed that the organism begins as a saprophyte (organism that feeds on dead plant material) in the middle and moves outward in a circle without damaging living grass.  It only attacks living grass if conditions are right and it reaches a certain level of virulence. The patches here are 10 to 12 inches in diameter, which is common for this disease.

There are several systemic fungicides labeled for this disease, but the trick is to get them down before the symptoms develop.  Contact fungicides will not work.  To treat now would do no good and the symptoms will like last through the summer.  This is a disease for which good records are a must.  On this area, I would need to apply a systemic fungicide in late June next year before symptoms develop.  Core aeration in the fall and irrigation during the stress period of early summer can also help prevent its development.

MYSTERY ORGANISM GROWING ON UREA PELLETS

Nick Christians
June 26, 2013
nchris@iastate.edu

A couple of weeks ago, I posted a picture of coral fungus from a lawn in Iowa.  That prompted the following pictures from a reader of the blog.  This is a strange organism growing on urea pellets.  I had not anything like this before, so I sent it on to Melissa Irizarry at the Plant Disease lab.  Melissa decided that it is not a coral fungi, but was not sure what it was.  She sent to Leonor Leandro in plant pathology.  Leonor doesn't think that it is a fungi at all, but that it may be a bryophyte or maybe an unusual moss.  She sent it on to Jim Colbert, an expert in these types of organisms.  Jim says the following:

1.  They aren't coral fungi

2.  They could be lichens in the genus Leptogium, some of which look a bit like this (http://www.nature-diary.co.uk/nn-images/1101/110123-leptogium-hibernicum.jpg)  when they're wet. Were these specimens wet?

3.  The specimen in the center of "fungi 2.jpg" looks very much like an acrocarpous moss.

4.  Fertilizer pellets would be a pretty unusual habitat for either of these types of organisms…

We are getting a sample to study in more detail.

Has anyone else out there seen this type of organism growing on urea (or any type of fertilizer) pellets?

CORAL FUNGI IN LAWNS

Nick Christians
June 20, 2013

Here is a new one for me.  These pictures are from Melissa Irizarry in the Plant and Insect Diagnostic laboratory at Iowa State University.  It was found in an Iowa Lawn.  She identified it as Coral Fungi.  Here is what Wikipedia has to say about it:

The clavarioid fungi are a group of fungi in the Basidiomycota typically having erect, simple or branched basidiocarps (fruit bodies) that are formed on the ground, on decaying vegetation, or on dead wood. They are colloquially called club fungi and coral fungi. Originally such fungi were referred to the genus Clavaria ("clavarioid" means Clavaria-like), but it is now known that clavarioid species are not all closely related. Since they are often studied as a group, it is convenient to retain the informal (non-taxonomic) name of "clavarioid fungi" and this term is frequently used in research papers.

I have never seen it before.  I am wondering if anyone else out there is running into it.  Let me know by e-mail  nchris@iastate.edu.

LEAF SPOT SHOWING UP ON CREEPING BENTGRASS FAIRWAYS

Nick Christians
June 10, 2013

Conditions have been very wet in the Midwest this spring, which has resulted in a very fast growth rate of turf.  Most of us are having a hard time keeping up with mowing.  These wet conditions in spring are often followed by a leaf spot breakout in turf.  The picture below is from the Chicago area.  It shows the typical leaf spot symptoms on fairway bent.

Symptoms generally include blighting from the tip down on bent, rather than the standard leaf spot lesions seen on other species.  The turf on the area may also look like it is dry, even if the soil is wet.  The grass also takes on a brown "haze" when you look at it from a distance.

The fungi that causes this is usually attributed to Bipolaris or Dreschslera (formerly Helminthosporium), depending on the author.  I will let the pathologist sort that one out.

Chlorthalonil (Daconil and other commercial names) is the standard answer for this problem, although there are several fungicides labeled for this disease.

This disease can also hit greens, but most golf courses are treating greens and it is not as common as it once was.  Because of the cost, fewer superintendents are treating fairways and that is where we are seeing most of the problem this spring.