Here is a sneak peek at my June Newsletter (Piper) article regarding nematodes:
Grass Clippings
Brian J. Stiehler, CGCS, MG
June 2019
Nematodes are
microscopic roundworms that
are found in sandy soils that, at a large enough populations, can create a lot
damage to turfgrass by feeding on the roots.
The health of a putting green is directly correlated to the health of
the root system below the ground. There
are about 10 different species of nematodes that affect turf, and some species
can be more problematic than others. For
example, in Florida, the sting nematode is the most destructive of all species
and can create damage at very low numbers.
Spiral nematodes on the other hand, can create damage to turf, but only
if the population gets too large. In order
to determine if nematodes are an issue, I send a 100 cubic centimeter volume of
soil to a lab (in my case, Clemson University or the University of Florida)
which manually counts the number of nematodes present under a microscope. In terms of population numbers, 5 sting
nematodes per 100cc of soil is enough to damage a putting surface whereas with
Spiral nematodes, it would require 2,500 nematodes per 100cc of soil. Each species of nematode has a threshold to
determine if treatment is required.
At
Highlands CC, nematodes have been an issue for a long time, going as far back as
1980. I found several old USGA
consulting reports that mention the issue going back that far. My first experience with nematodes at HCC was
in 2005 on #16 green. During the spring
of 2005, that green wasn’t healing from aerification like the others. After exhausting all my options, I decided to
send a nematode analysis to a Nematologist at the University of Florida. I overnighted the sample and two days later,
Dr. Crow called me and said our spiral nematode count was 3,200 per 100cc of
soil. This was off the charts and
treatment was required. The next day I
applied a nematicide and immediately began to see that green turn the
corner. Since then, I knew we had a
potential problem. Unfortunately, today,
there are very few nematicides on the market that are effective. There are several available but not near as
effective as they were in the past.
Historically, nematicides were very toxic and the reason the EPA pulled
them from the market.
Nematode
populations are continually shifting.
There are times the numbers get high and we simply must back off the
aggressive maintenance of our putting greens and ride it out until the
population declines. Our main issue
becomes greens #1, 2, 3, 4, 6, 7, 8, 11, 12, 15, and 16 which don’t receive
near enough sunlight. The root system
under these 11 greens is compromised and already under an incredible amount of
stress. Adding high nematode counts to
these greens creates an impossible situation to overcome. On the other hand, greens like #9, 17 or 18,
receive ample sunlight and can tolerate more stress. In short, our greens require and incredible
amount of pesticides simply because the shaded environment we grow them
in. We have no wiggle room and no margin
for error. Any damage that occurs during
the season whether it’s a fungus or a ball mark, will not recover.
Given
my experience, several years ago, I elected to work with Clemson University by
doing monthly nematode assays. The 1st
day of each month, I send a plug from #1 green to their lab. Our April sample revealed 4 species of
nematodes with 1 species (Stubby Root
Nematode) being above the threshold for damage. When we got the results, we immediately
treated the greens at Highlands CC. I’ll
be anxious to see what the population numbers look like when I send them a
sample on May 1. Hopefully, they will be
considerably less than the April soil sample.
The
attached pictures show you what a nematode looks like under a microscope as
well as how it feeds on turf roots, eliminating all the necessary feeder
roots. If gone unchecked and untreated,
the damage can be substantial. Often
Superintendents misdiagnose the damage for something else, like a fungal
disease or excess traffic. By the time
they realize what is happening, it’s too late.
At Highlands CC, we will continue to monitor monthly and treat with the
products available to us, as needed. In
the coming years however, we must determine ways to get more sunlight to our
greens. Lack of adequate sunlight is
holding us back tremendously. Every
year, trees are growing larger. If a
tree grows 12” taller, that means its shadow is at least 12” longer resulting
in us losing more and more control over greens quality every year. There is no substitute for sunlight, the
primary driver of photosynthesis and how a plant makes its food. Just like we cannot survive without food or
on a very poor diet, neither can a plant.
Hopefully
this serves as a small lesson in Agronomy and gives you some insight into what
we do everyday. As always, please never
hesitate to call me if I can make your experience at the club any better! We are here for YOU! Happy Golf!