Below: image from the earliest snow storm in State College, PA history (October 15, 2009).
annual bluegrass weevils are moving, annual bluegrass seedhead treatments are going out, and early season dollar spot applications are just around the corner. This week I posted a poll (top right of the blog) and it seems that the verdict is still out with regards to when seedhead controls should be applied. So far there is a tie between those of you checking the boot stage and those of you using the degree day 50 model to time your applications. In State College, we are at 89.5 GDD this year, but I have yet to see the boot stage of annual bluegrass much less any actual seedheads. I am sure some of you have already started to see them, but I haven't yet. Although seedhead control doesn't seem to be very related to disease activity, the work coming out of Rutgers showed that controlling seedheads and then following up with Primo applications did not increase anthracnose activity and in some years even resulted in a slight reduction in disease severity. This is a question that I get a lot at this time of year because anthracnose is active throughout the region on some courses.
As I mentioned, early season dollar spot is an area gaining considerable interest among golf course superintendents and there is no shortage of controversy among pathologists either. My lab has been conducting studies on the early season control of dollar spot since 2005 and it does appear to be effective at suppressing the pathogen early in the season (See the old blog post for more info). Differences, however, have been observed in effective fungicides among geographic regions (Jim pointed this out in this post). So, although there is not an exact science with regards to these applications, here are my thoughts (for what its worth):
- Early season applications can be applied around the second true mowing.
- Early season fungicide applications reduce inoculum and/or delay the onset of the disease.
- I don't care which fungicide you use as long as you pick one that you know works for dollar spot at your course.
- There may not be a huge difference in the level of control you see from these applications when compared to a more traditionally timed (~late May), but "anecdotal" evidence suggests that these applications may reduce the severity of the disease later in the year (more work to come).
- There is no need for these applications unless you experience chronic, difficult to control dollar spot symptoms during the year.
- Don't delay/reduce/stretch fungicide applications if conditions favorable for dollar spot exist in the fall. We have seen many cases of "disease resurgence" where dollar spot within treated areas becomes more severe than in areas that had never received an application. This is often where we see the fall pitting type of dollar spot.
Signing off from the right coast (and with only 9 fingers)...
...to hear the inspiration for the blog title click here.