The results from the poll posted a couple of weeks ago is in and dollar spot is hands down the winner, with anthracnose and Pythium blight a distant second. A total of 41% of those voting indicated that dollar spot was their biggest challenge. This comes as no surprise to me as that week (August 9-15) marked the real "start" to intense dollar spot outbreaks in our area and apparently many other areas as well.
It seems that dollar spot gets a lot of attention on this blog as many posts have been dedicated to discussing this chronic disease. For this reason, I decided to show some of this year's "early season" dollar spot trials conducted at Penn State. I have been working with early season dollar spot since 2005. In most years, dollar spot can be suppressed with early season fungicide applications. Exceptions occur in atypical years in which the onset of dollar spot is delayed beyond what would be considered typical (late May to early June for most parts of the Northeast). Although dollar spot did not come on with a vengeance until July in 2009, data seemed to follow previous years. In our 2009 trials, Curalan (1.0 oz) again provided the best suppression of dollar spot over the course of the trial. Emerald also provided good control. Prior to a major outbreak of disease in early August, Curalan plots had an average of only 3.5 infection centers per plot (18 sq ft) when compared to the untreated control plots which had an average of 26 infection centers.
From the data (and previous observations at Penn State), it appears that resistant strains of the pathogen at our research plots limit disease suppression with the DMI fungicides. In previous trials at UConn where resistance was not an issue, good control with the DMI's was achieved. My observations from the past 5 years of data indicate that delaying the onset of dollar spot through early season fungicide applications serves two functions: 1) the delayed onset of disease gives superintendents more time to catch the disease once symptoms do start to appear; and 2) dollar spot suppression later in the season appears to be manageable as the disease doesn't appear to get out of hand during the fall.
Other issues in the region...
Perhaps if the poll had been posted one week later anthracnose may have taken the lead. In last week's posts from the West and South Central, Frank and Megan posted about rising anthracnose samples in their regions. Reports around the Northeast (from Rutgers) indicated that anthracnose activity was picking up as well. A walk through some of our plots at Penn State also indicated that anthracnose was increasing. However, this increase in anthracnose was on the creeping bentgrass. Disease activity on our annual bluegrass trials, however, remain very low. Pythium blight was also ranked as a moderate problem and the disease did make an appearance on some fine leaf fescue plots in the last week or so. At this point in time around the region, you can find just about every typical disease including summer patch, fairy ring, anthracnose, Pythium, brown patch, dollar spot, and others. Everyone SHOULD be able to see the light at the end of the tunnel, however, as core cultivation programs are about to begin and temperatures suitable for turfgrass growth resume in the next few weeks.