Rust Disease – 2013
The 2013 rust disease outbreak seems to have arrived a
little earlier than usual. My thoughts
about the current rust epidemic are intended for lawn care professionals, who
must address reasonable questions from their clients. Most professionals are very familiar with the
basics of rust disease. To briefly
review from the 2013 perspective--the ample precipitation favors dispersal of
rust spores and subsequent infection of susceptible turf. The disease is largely cosmetic, but the
orange spores that are easily dislodged from leaf surfaces can be more than a
nuisance, covering shoes, pets, and lawn mowers with a rusty residue. New spring-seeded lawns that lose vigor
during heat and drought conditions of summer may be severely damaged by rust.
One question about rust is asked more than any other—Will it
harm my dog? The answer is no…and no
further explanation is necessary.
Another question frequently asked is – If I collect my
clippings after mowing, will the disease disappear? The answer here is “no” also. There are tens of millions of rust spores in
the air--inoculating your lawn every day.
Also, because the rust pathogen must complete every stage of its life
cycle on a LIVING host, spores on your clipped grass blades will soon die, and
no longer be a threat to the yard.
A final question regards control—both long and short
term.
If the lawn is in need of any kind of renovation, now is the
time to consider Kentucky bluegrass cultivars with rust resistance. Many of the newest cultivars are only
slightly affected by the rust pathogen. Local
lawn care professionals or garden stores will have access to information about
rust-resistant grass.
Keeping the grass healthy with water, fertilizer, and
regular mowing normally will keep rust at bay.
This year seems to be a little different, maybe because of all the rain,
and the fact that nutrition is a little low at this time of year. Suggest trying the fertilizer route
first. Applying the equivalent of 0.2 lb
N per acre may do the trick. Be prepared
to resume mowing if the rain continues, and do not apply if the 3-4 day
forecast includes daily high temperatures in the 90’s.
The final approach is chemical. There are excellent fungicides available that
will shut down a rust outbreak in less than a week. The DMI and QoI (strobilurin) fungicides are very effective
against rust but, on well-established turf, should be considered only as a
remedial treatment. On newly seeded
stands, fungicides should be applied at the first sign of disease. In most cases, outbreaks will be quelled with
a single application of an effective fungicide combined with efforts to
encourage turf growth.
Dr. Rick Latin, Professor of Plant Pathology
