Spots Galore

Once again the weather is fantastic in the Midwest! Just a week ago we had very low humidity and temperatures hovering around 75 to 80F. This week is a different story. The forecast is calling for cool, wet conditions for much of the week. Consequently, we are seeing a lot of leaf spot on creeping bentgrass. Most the damage is localized in the older leave tissue, however we have seen samples that resulted in serious damage like in the picture to left.

We have observed a leaf spot on segregates of creeping bentgrass in Illinois and Wisconsin for the last couple years. Symptoms typically develop towards the end of May and continue throughout June. Symptoms tend to dissipate once warmer, drier weather sets in during mid to late summer. Fungicides that are usually very effective against leaf spot diseases do not work well against this particular leaf spot. Headway works very well against this disease, but is very expensive if the disease develops on fairways. We attempted to isolate the pathogen last year to determine the causal agent, but we tried too late in the year. This is a disease that we would like to gain a better understanding of, so if you have seen something similar please let us know.

Nothing new to report in Midwest, except for a few reported cases of dollar spot and yellow patch. The soil temperatures are still perfect for preventative applications targeting fairy ring and take-all patch. Some people prescribe to early-season dollar spot applications and those should already be down or put down this week. The first of June usually kicks off the disease season in the Midwest, so maybe next week will be more interesting.