By Chuck
Barber, Regional Sales Manager
Over the past several seasons Dollar Spot has been the
number one problem for turfgrass managers in the Northeast region. I researched my files and ran across
this article printed in Golf Course Management June of 1983 Recognizing
and Neutralizing Another Foe: Dollar Spot.
Richard W. Smiley, Cornell University, wrote the article. The following are highlights from the
article.
Dollar spot is considered among the most persistent of
diseases on golf courses in North America, Japan and Australia. Individual infected leaves develop a
lesion that is first chlorotic, then water-soaked, and finally a bleached
color. Dollar spot lesions are
characteristically bounded by a tan to reddish brown margin, and they generally
enlarge to extend across the entire leaf.
When dew is present on grass blades in the early morning and the
pathogen is active, a white cottony or cob-webby growth of fungal mycelium may
be seen on diseased turf. The mycelium
disappears as it dries.
Disease Cycle
The dollar spot fungi survive unfavorable periods as dormant
mycelia in infected plants and as stromato on foliage surfaces. Dissemination of this fungus is,
therefore, restricted to movements of infected leaf debris by equipment,
people, animals, water or wind.
When the turfgrass environment favors the fungus activity, the dormant
mycelia or stromata resume growing on foliar tissues and out into the humid air. Whenever the aerial mycelium contacts a
moist leaf surface, it may penetrate the leaf and cause an infection. These fungi are not able to infect
roots or rhizomes, but some may produce a toxin in the foliage that adversely
affects root health. The roots
thicken, stop elongating and turn brown.
The new roots quickly become affected themselves, and the root system
becomes incapable of supplying adequate nutrition and water to the foliage.
Prolonged
high humidity in the turfgrass canopy is required for fungal growth. Different variants of the dollar spot
fungi commence activity at different times from late spring through late
autumn. Disease becomes more
severe in dry soils, event though high moisture in the aerial turf canopy is
also required. Turfgrasses that
have low amounts of nitrogen are most susceptible. Favorable environmental conditions for disease, therefore,
include warm, humid weather, cool nights that result in heavy dews; and dry
soils of low fertility.
Maintain adequate to high nitrogen and potassium fertility
during the period of dollar spot activity. Water thoroughly (deeply) but as infrequently as possible
without causing moisture stress between watering. Do not water in the late afternoon or evening, for this
prolongs the period of leaf wetness during cool nights when dew is likely to
form. Many fungicides are also available for dollar spot control.
The following conclusions from our
research at universities validate our claim that the use of Nature Safe when
used as a nutritional program will increase your disease resistance and
increase your effectiveness of your spray program.
·
R-17
Dollar Spot Study Michigan State University, Dr. Joe Vargas, PhD
Conclusion: Nature Safe significantly suppressed Dollar Spot
for the duration of the study versus the control for the synthetic and liquid
test plots. Nature Safe had a
major impact on disease management when used before disease outbreaks and
continued throughout disease pressure .
·
R-4
University of Georgia, Dr. L.L. Burpee
Conclusion:
The use of Nature Safe promotes an environment, which naturally
increases the vigor of turf helping it to better resist diseases.
·
R-7
Rutgers University, Dr. B.B. Clarke and P.Majumdar
Conclusion: The
combination of Nature Safe and Banner demonstrated excellent results a well as
extending the suppressive characteristics of Banner far beyond the normal 28
day period. In fact, the
combination product extended the effectiveness an additional 21 days. By using Nature Safe in a regular
summer program turf managers can increases the effectiveness and longevity of
performance of Banner, thus reducing fungicide use on turf.
·
R-10
Rutgers University, Dr. B.B. Clarke, P. Majumdar and W.Hlubik
Conclusion:
Daconil and Banner performance increased when used in combination with Nature Safe
Fertilizer in a regular fertility program.
·
R-6
Cornell University, Dr. Eric B.
Nelson
Conclusion: Test plots showed a 30% - 50% reduction in
dollar spot and 40% hindrance in the development of grey snow mold.