The Big
Pendulum
AUGUST 21, 2015
By David Oatis, Regional Director, Northeast Region
Recently, I’ve visited
several golf courses where the accumulation of organic matter in putting green
soils was a problem. You’re probably thinking I’m referring to excessive
organic matter, because excessive organic matter in putting greens is a common problem
– not this time. In excess, organic matter – or thatch – is a problem. A thick
layer of thatch at the surface of a putting green functions much like a kitchen
sponge – i.e., it retains moisture at the surface, keeping putting greens soft.
Thatchy greens play poorly and have problems with localized dry spots, disease,
scalping, algae, moss, etc. However, some thatch is essential because it
stabilizes the soil and provides resiliency. Immature greens often do not have
enough thatch and, as a consequence, frequently experience more injury from
maintenance and golfer traffic.
The problem I’ve recently
noticed on some greens – even older greens – is that they don’t have enough
thatch. Insufficient organic matter can result from several factors like
excessive aeration, verticutting, or topdressing and inadequate fertilization.
Several courses have
reported above-normal turf growth and reduced efficacy of plant growth
regulators this summer, which I attribute to peculiar weather patterns –
especially rainfall. Regardless of the cause, a typical response has been to
reduce nitrogen fertility until turf growth subsides. Reducing nitrogen
fertility is becoming a common trend and, as has been observed many times in
the past, low nitrogen fertility can work really well…for a while. Maintaining
greens at lower nitrogen levels often results in faster green speeds and finer
leaf texture, but greens receiving too little nitrogen rely on soil reserves
that eventually will be depleted. The depletion of soil nitrogen reserves may
happen slowly – making it difficult to detect – but the health, wear tolerance
and wear recovery of turf gradually decreases under deficit nitrogen fertility.
At first, you may notice that ball marks are slow to heal, the greens may be
slow to heal from aeration or a gradual decrease in turf density. Over a longer
period of time soil organic matter levels may decline. In extreme cases when
organic matter levels become too low, putting greens can become unstable and
more prone to disease outbreaks.
It wasn’t long ago that
anthracnose was the scourge of annual bluegrass greens. Fortunately, research
and field observation eventually revealed that increasing nitrogen fertility is
one of the easiest ways to prevent anthracnose. Memories of anthracnose-ravaged
greens have faded, but low nitrogen fertility programs threaten a return of
anthracnose.
My advice? Don’t fall into
the trap of repeating past mistakes. Low nitrogen fertility programs can work
well for a while, but problems arise once nitrogen reserves are depleted. Don’t
be fooled; malnourished turf is susceptible to numerous maladies – e.g., moss,
algae, anthracnose, or an inability to handle stress and wear – which can be
easy for the “next” superintendent to fix. Now is a good time to closely examine
your fertility program. There are good trends and bad ones; an ultra-low
nitrogen program is one trend to avoid.
August can be a great time
to aerate greens, so aerators are beginning to fire up at courses across the
region. With optimal growing conditions, aerated turf often will heal in a
couple weeks, leaving the fall golf calendar free of disruption. However,
August also can be a bad time to aerate if turf is weak or the weather is
stressful. Be sure to carefully evaluate turf health before determining how
aggressive to aerate. Also recognize that summer patch outbreaks can be kicked
off with aeration. Make sure your turf is protected.
