By Natural Choice Editor
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.
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.