The Midwest is still struggling with heat, humidity and persistent rainfall. As a result, most of the Poa annua in the Midwest is either dead or struggling to say the least. Since I am sitting in the Charlotte airport, I asked Paul Koch for an update on the samples coming into the Turfgrass Diagnostic Lab. It appears that brown patch, Pythium blight and anthracnose are still raging. Our sample numbers are way ahead of last year's entire amount!
It seems that John's post on Monday has caused quite the stir amongst the followers, but he is exactly correct. This is not a "calendar year"! The summer has sucked for most superintendents throughout the US. Grass is dying everywhere and the typical actions like raising the mowing height, alternating mowing and rolling, and other techniques are not helping like we'd like. I think the MOST important thing for golf course superintendents to do is start a line of communication with the owner, membership, golfer, general manager about losing turf. Regardless of the reason or diagnosis this is a banner year for losing turf.
For anyone that knows me I am not a pessimist, but when soil temperatures are above 90 degrees turf is going to have trouble. These temperatures can lead to disease development especially with the amount of rainfall we have had in the Midwest. However, many times grass just dies due to abiotic conditions like poor drainage, anaerobic conditions and heat stress. Remember that annual bluegrass and creeping bentgrass are cool-season grass and prefer to grow when soil temperatures are between 55 and 75 F. Not 90 to 100 F! Lets face it even bermudagrass will struggle when soil temperatures exceed 95 F.
Regarding bacterial wilt, a turfgrass system is a very dynamic biological entity. Many microbes inhabit the rhizosphere of turfgrass plants, which can make turfgrass disease diagnosis extremely difficult. In almost every sample that comes through the TDL, we can find numerous turfgrass pathogens. Furthermore the scientific community is finding that many bacterial species are common epiphytes (live on the surface of leaves) and endophytes (live inside the plant). That being said, it is very common to find bacterial streaming from stressed turfgrass plants. However the signs need to match the symptoms observed in the field and it seems like these two are not jiving.
In my humble opinion, it seems like bacterial wilt has become the perfect fall guy for a brutal summer. It's perfect because it is a mysterious disease with very few effective control measures, but we also have very few control measures for nature.
Summary of a Presentation from APS:
This year's APS meeting was great! Some of the turfgrass pathologist got the opportunity to visit a few golf courses in NC. I was amazed on how quickly I have acclimated to the summers of Wisconsin, damn its hot down there! I really did not have a favorite presentation at this year's meeting. I think the most interesting aspect of the meeting was a special session on Rhizoctonia diseases in turf. There was some fantastic information presented ranging from taxonomic considerations for this genus, biology and management of brown ring patch, management of leaf and sheath spot of ultradwarf bermudagrasses and finally using digital imaging software as a tool to score and identify host resistance in turfgrasses. There was so much information in this session, but the best part was how collegial the speakers were to one another.
Each speaker reference each other and it seemed that they were all working together to help fill in some major gaps with the Rhizoctonia and Rhizoctonia-like diseases in turfgrass. It is cool to be a part of this group, all of my colleagues are extremely helpful and willing to collaborate on projects. As a result, I think we will see many enigmatic problems in turf solved fairly quickly.