What an excellent time of year. Spring green-up and all of the new growth that
comes with it puts almost everyone in a better mood with a sense of fresh
excitement. The smell of fresh-cut grass in the spring—one can’t help being
giddy about what it means, even those who suffer from Satan’s nasal dust
(pollen) like me. Down south, there are the magnolias that suggest spring has
arrived. Up north, the dogwood, apple, and cherry blossoms draw in crowds to
also soak up the sunshine after a long winter of snow-cover that mostly keeps
people from using recreational fields. Spring is magical here in the middle
too, but it also comes with a couple of four-letter words for many bermudagrass
athletic field managers: “Dead” and “Spot.”
spot is typically a mild nuisance for turf managers in the Deep South when
bermudagrass is never fully dormant but it is of great concern for those in the
transition zone where bermudagrass completely shuts down each winter. Field
managers in these regions typically begin thinking about the disease as their
bermudagrass breaks dormancy everywhere except those ugly, bare, sunken
circular patches sporadically placed across the playing surfaces. Their
thoughts may include: How bad will it be this year? Will this make my field
unsafe for athletes? How long will it take to recover? How many other
four-letter words should I associate with this disease?
Sooner or later
bermudagrass-growing transition-zone turf managers into three categories: 1)
those that have it each year, 2) those that have it bad each year, and 3) those that don’t have it yet, but will soon move to one of the former categories.
disease is just as the name implies; dead spots in the spring, specifically on
bermudagrass recreational surfaces. However, the problem develops in the fall
and winter so management strategies are a bit tricky. One important
consideration in managing this disease is that patches reappear in the exact
same location for several years, gaining a little momentum each spring.
been battling spring dead spot for decades with mixed results at best. We’ve
known about it. We’ve dealt with it. We’ve hated it. It always seems that with
every step forward, there is a step or two backwards. There are some new and
exciting fungicides out there that can be applied in the fall but it always
comes with a caveat. “The product is too expensive to spray everything.” “The
product doesn’t work consistently in my area.” “The product is only available
for use on golf courses.” There is always something that prevents sports field
managers from successfully and consistently suppressing the disease.
at Virginia Tech is trying to tackle spring dead spot from several different
angles to provide better management recommendations. We continue to investigate
traditional methods for both suppression and recovery. But we’re also trying to
think outside the box by blending technologies that are currently on the
periphery of our industry.
we are using drones to build disease incidence maps and GPS sprayers for
targeted fungicide applications. Advancements in equipment availability,
reduced costs, accessibility for rapid data processing, and improved
understanding of how to integrate these technologies into our current
management are paving the way for a brighter future. The process sounds
complicated and developing the initial template was time consuming, but the
concept is quite simple. Simply put, we are using these technologies to put the
right product in the right place, at the right time.
research was conducted on five fairway sites within a golf course in Richmond,
VA beginning in the spring of 2016 and continuing through 2018. The
much-abbreviated version follows. We flew drones over a series of fairways each
spring to collect thousands of images. These images were stitched together like
a complex puzzle using post-flight imaging software and then the fun began. We
developed a series of algorithms for our mosaicked images to digitally
differentiate healthy bermudagrass from symptomatic spring dead spot and
quantify the damage, with each pixel of our image having a precise GPS
coordinate (within 3 inches of the actual location). This compilation of work
resulted in a spatially accurate, georeferenced spring dead spot incidence map.
We refined this procedure throughout the study so that we were could digitally
analyze data within our research sites.
research site consisted of eighty 18 x 20-foot plots that received one of the
following four treatments over 20 replications: 1) untreated control; 2) 3.6F
Tebuconazole at 0.9 fluid ounce/1,000 square feet across the entire plot
(blanket); 3) Velista at 0.7 wt ounce/1,000 square feet across the entire plot
(blanket); and 4) site-specific Velista at 0.7 wt ounce/1,000 square feet based
on historical disease incidence maps. We used the precise coordinates of each
spring dead spot center with a 3-foot buffer around each patch for our targeted
site-specific applications. Treatments were made in the fall when soil
temperatures were consistently at or below 70F for 3 consecutive days using a
GPS-guided Toro 5800 MultiPro sprayer with GeoLink, individual nozzle control,
and RTK correction for enhanced GPS precision. We used the same georeferencing
software to create a GIS layer of these plots that were used in conjunction
with our incidence map. The spatial accuracy allowed us to know exactly where
disease occurred the previous spring and our plot boundaries.
technology sounds cool if you’re a nerd like me but is meaningless if it
doesn’t work. Fortunately for my career, it worked and it worked well. The most
important take-home message of this research is that we were able successfully
reduce our fungicide inputs by 65% without sacrificing control. We were able to
use the right product (Velista, in
this study) to control spring dead spot where needed (right place) in the fall after recording previous spring outbreaks
(right time) at approximately
one-third of the cost and still reduce disease compared to a cheaper
alternative that can only be applied on golf courses. There are other effective
new chemistries for spring dead spot suppression and these same principles
new innovations can be a hard pill to swallow, especially with so many
unknowns. Things change over time and we all must adapt or be left behind. My
primary focus used to be on effectively keeping grass alive and healthy. I
still do this frequently but it has taken a back seat to effectively keeping my
kids alive and healthy. I now spend a lot of time as a spectator on
bermudagrass soccer fields watching my daughter, sometimes cringing when she
runs across a sunken spring dead spot. I’m very fortunate; I’m able to merge
these two interests by making the fields safer through addressing spring dead
spot using some pretty cool technologies.
We’ve made a lot of progress in our ivory research tower but the technology will only make a difference when people start to adopt these uses. We will continue to refine our methods and apply them to other pest outbreaks while also working with turfgrass professionals to make these practices a reality. Since completing this project, we have flown 16 locations including some larger multipurpose sports complexes. More details of this project can be found at https://www.gcmonline.com/research/news/spring-dead-spot-management.
anything we do in research, there were a lot of people that made this happen.
First and foremost are my partners in crime, Jordan Booth, CGCS, and Dr. Dana
Sullivan, owner of TurfScout, LLC. They completed the hard tasks while I take
the credit. We would like to thank the Environmental Institute for Golf and the
Virginia Golf Course Superintendents Association for their financial support of
this project. We would also like to thank The Toro Company and Syngenta Crop
Protection for the use of products and services during this project. Many
thanks to Christian Sain and David Rathke of the Country Club of Virginia for
hosting this project. We would also like to acknowledge Wendell Hutchens,
Travis Roberson, and numerous other individuals for continued contributions to
the success of this project.
McCall, PhD, is an assistant professor in Virginia Tech’s Department of Plant
Pathology, Physiology, and Weed Science.