Summer Stress of Turfgrass
Written By: email@example.com
2012 has been a record setting year with respect to temperatures and drought. The year started earlier than normal with record high temperatures in March and April that required maintenance practices such as fertilization and pesticide applications to begin almost a month earlier than normal. Starting around the 1st week of June many parts of Michigan entered a drought of 6 weeks or longer. The drought and accompanying high temperatures resulted in turf loss on greens, tees, and fairways. The drought has exposed inefficiencies in irrigation systems on many courses. Turfgrass areas that reveal poor irrigation coverage first are typically edges of fairways, banks of greens, tees, and bunkers, and the rough. Many of these areas are also high traffic areas that are subject to compaction. Some of these trafficked, compacted, heat stressed areas may need to be reestablished this fall. In an effort to compensate for poor irrigation coverage and improve water management, hand watering has become commonplace on golf course putting greens. In Michigan, we are accustomed to syringing greens during periods of drought but usually not fairways. In Mediterranean climates like southern Europe where it does not rain from the middle of May until the middle of September and the temperatures are in the 90’s every day, the superintendent will usually have 3 or more people assigned every day to syringe fairways. When we have similar conditions it becomes necessary to syringe fairways. It is commonly perceived that noon is the warmest part of the day, when in reality it is often later in the day around 4 to 6 p.m. Syringing late in the afternoon might have made the difference this year between turf living or dying. In a time when most budgets have been shrinking, superintendents may be challenged to add hand watering to an already depleted labor budget. Wetting agents have been critical this summer to alleviate localized dry spot but even with wetting agents hand watering will have to be done when prolonged periods of drought occur. The good news is most of the turf that “died’ from lack of water actually went into dormancy to protect itself and with cooler temperatures, especially night temperatures, the turf will break dormancy and begin growing.
Following the high temperatures and drought of June and July, isolated rain events finally arrived and along with it came the humidity and accompanying diseases like dollar spot, brown patch and Pythium blight developing overnight. Most people treat for dollar spot and brown patch on a regular basis. Pythium blight is not normally treated for on a regular basis in Michigan but when day time high temperatures are in the 90’s and night temperatures above 70°F following a rain, chances are optimal for a Pythium blight outbreak. Following an inch or more of rain in a short period of time you can usually rely on crown rot anthracnose developing so preventive fungicide applications should be made to prevent the disease from developing. We have confirmed reports of crown rot anthracnose being resistant to the thiophanate methyl fungicides and the Qo I fungicides. If you are not getting satisfactory control out of either of the fungicides you should switch to a DMI fungicide or Polyoxin D. If caught in time, the turf should recover from the dollar spot, brown patch and Pythium blight, which are primarily foliar diseases. Unfortunately, since crown rot anthracnose attacks the crown where new roots and shoots arise, when this disease occurs the plant will die.
Summer patch is becoming an ever-increasing problem. The early 65 and 75¬ degree models for scheduling fungicide applications that worked so well for so many years have not worked that well the last two years in our research trials. We are now suggesting fungicide applications the first of June, July, and August. The products of choice should be the DMI fungicides and they should be watered into the top inch of the turf where the elongated crown of the turfgrass plant is. If you can keep the crown of the plant healthy the plant will survive no matter how many roots become infected.
The early spring and extremely warm summer have both extended the turf disease season as well as caused most diseases to be more severe. Most golf courses we visit are now facing a dilemma as their pesticide budgets are about all used up because of the early start to the season. I know budgets are tight especially with the way the Michigan economy has been the past few years. However, given the option of going over the pesticide budget or not treating for disease the choice should be to treat. If treatments are not made and the turf dies, there will be a reduction in play and green fee revenue making financial conditions even worse. Maybe the only consolation is the early golf season this year resulted in additional revenue for March and April that can hopefully make up for some of the extra money that will have to be spent on pesticides to keep the turf healthy.
Dr. Joseph M. Vargas Jr. and Dr. Kevin Frank
MSU Turf Team