We all deal with stress in our lives. It is an unfortunate fact of life that comes with our jobs and overall hyper-busy lifestyles. What do we do about it? We go for walks, exercise, play a round of golf, or spend some quality time with family. Sometimes we take medicine to help alleviate the symptoms associated with stress. Or sometimes we have heart attacks. Now think of all the daily stress without any kind of escape. You just have to stay put and take all the abuse, without the ability to get away from it all.

Welcome to the life of a bentgrass or annual bluegrass plant in the summertime. Cool season grasses are constantly under stress during hot summer periods, but none more so than on golf putting greens. When the root zone is 100°F, the grass is not happy. In fact, the roots are dying. Despite this, the demand for fast, firm, smooth greens is still placed on the superintendents' shoulders. Since these expectations aren't going away anytime soon, we are left with trying to hold on for dear life with the tools we have at hand. We have come a long way, and there seems to be an ever increasing number of products coming to market that claim to help the turf battle summer heat stress and associated disorders. To name a few, there are plant defense activators, plant growth regulators, biostimulants such as seaweed extracts, pigments, sun screens, and synthetic fungicides with additional plant health boosting qualities. As we continue to walk the fine line between high quality and dead greens, any potential aides are strongly encouraged.

At Virginia Tech, we are currently working to put a value on what many of these products actually bring to the table. In collaboration with Dr. Erik Ervin and several within the industry, trials are underway in the Richmond area, where heat stress is a given part of life. The objectives of the studies are to a) quantify plant response to various pigments, plant activators, and other stress reducing products and b) determine secondary impact on suppression of stress-related diseases, such as Pythium root rot, bacterial etiolation, and plant parasitic nematodes. If you notice a sudden change in my writing style, it is because I have copied portions of a proposal we submitted this spring. Please forgive me. Here is a look at what we are doing...

Summer bentgrass decline (SBD) is a term used to refer to a complex of stresses, with no particular causal agent. Carrow (1996) states that SBD may occur as a result of one of four situations; 1) hot and humid conditions, 2) shaded greens with poor air circulation, 3) poor root zone drainage, or 4) salt stress in hot-arid regions. Additionally, when plants are under environmental or abiotic stress, they are more susceptible to pathogens (Couch, 2000; Dernoeden, 2005; Latin, 2011). When a primary stress of high soil temperatures is present, secondary pathogens may become problematic. Some of the most common diseases of creeping bentgrass associated with predisposing heat and/or moisture stress are Pythium root rot, bacterial infections, plant parasitic nematodes, and basal rot and foliar anthracnose (Dernoeden, 2005; Reitman, 2012). Many golf course superintendents look to address issues with secondary pathogens first with fungicides, rather than trying to alter the root zone environment.

This research will be conducted on an established 'Penn A4' creeping bentgrass nursery green planted on USGA specification sand-based rootzone mix in Richmond, Virginia. Most courses in this geography annually battle summer bentgrass decline and associated secondary problems, because of high temperatures and humidity. All cultural practices, pesticide and nutrition applications will be applied in accordance with the rest of the golf course with few exceptions. No fungicides for root-rotting Pythium will be applied during the study, unless sufficient data is collected and greens are in danger of dying. Also, no fungicides that contain known growth regulating (DMI) or plant defense promoting (QoI or phosphites) properties will be applied during the study. Chlorothalonil, iprodione, vinclozolin, polyoxin-D and thiophanate-methyl will be used primarily in rotation or as tank mixtures for primary foliar diseases (dollar spot, anthracnose, brown patch). Initial applications will be made in mid-May and will continue every 14 days through early September.

Measurements to be taken throughout the study include soil and canopy, root zone moisture content, and reflectance data. Reflectance values will be collected from visible red (VIR), red edge (RE), and near infrared (NIR) regions of the electromagnetic spectrum and used to calculate vegetative indices for objective plant health quantification. The most common vegetative index used to quantify plant health is the normalized difference vegetative index (NDVI) and simple ratio vegetative index (RVI). Additional indices may be examined for added statistical separation of treatments. Values will be collected continuously (10 samples per second) and geo-tagged for spatial mapping. Plots will also be rated visually for overall turf quality and the presence of diseases and other abnormalities. In impacted areas, root cores will be collected and analyzed for the presence of Pythium species or excessive populations of plant parasitic nematodes. If symptomatic leaves are exhibiting etiolation commonly associated with bacterial infection, plants will be examined microscopically for the presence of bacterial streaming. At the conclusion of this research, the impact of various plant health promoting products will be quantified for reduced summer bentgrass decline and associated diseases.

So there you have it, folks. This is one of several projects that I am very excited about this season. 2010 and 2011 were excruciating, terrifying, and miserable for golf course superintendents and the defenseless bentgrass. We are going to have either another brutal summer and learn some valuable information, or the research gods will laugh at us for trying to predict the weather and give us some nice cool nights and good grass growing weather. Something positive is going to happen with these trials in 2012, so stay tuned.

David McCall is a plant pathologist, working with Virginia Tech as a research Specialist. David also writes columns for your monthly "LSI Connections"