When we talk about stress related diseases Anthracnose is at the top of the list. Collectotrichum cereale is the new name given to Anthracnose. There are more than 20 genera within the class itself. Anthracnose can be found on Poa Annua, bentgrass, and fine fescue. On golf courses Poa Annua is the most affected by Anthracnose. Foliar and Basal Anthracnose have increased in severity over the past few years mainly because of current management practices that do not allow for reduced plant stress.
You can find Anthracnose almost anytime of the year but mainly after Poa Annua seed head production and through the stressful times of summer. After Poa Annua has produced seed heads the plants carbohydrate reserves (CHO) are very low. The plant is at a weaken state and is more susceptible to disease pressure. Stress conditions increase with summer weather and root systems begin to decrease. There is higher photorespiration during these times and this will cause a decline in photosynthesis which causes a decline in root growth. Anthracnose will over winter as a saprophyte in plant debris. When conditions worsen and a growing plant becomes stressed the disease will change from being a saprophyte to a facultative parasite feeding on weak plants. The fungus will attack the plant material through the foliage, stems, or roots.
Research has shown that fertilization practices have played a key role on Anthracnose control. NPK deficiencies can enhance Anthracnose. Nitrogen can have a major impact on disease severity. University studies at Rutgers have shown that by increasing nitrogen during the growing season (April to September in NJ) from 1.5 lbs to 2.5 lbs reduced disease pressure by 20 – 30 %. The extra pound of nitrogen was applied during the growing season at 0.10 – 0.125 lbs/ 1000 sq ft.
Mowing practices have a great effect on disease severity. Low heights of cuts deplete CHO (carbohydrate reserves). Most of the time change the height of cut is not an option for superintendents. Raising the height of cut will reduce disease severity. It is also shown that you should avoid frequent alterations in height of cut.
Chemical control is possible but preventative treatments are a must for acceptable season long disease suppression. The use of tank mixes or rotational spray programs are effective and necessary. Research also showed that there were differences in control among chemical groups. The DMI fungicide group provided mixed results by compound within the group. Strobilurin and Benzimazole classes of chemistries provided good control in the absence of resistance. Phosphonates had positive results when mixed with other chemistry. Phosphonates worked alone early in a preventative program but needed to be tank mixed as disease pressure increased.
Some of the leading products that gave the best control were: Endorse, Daconil, Spectro, Banner Maxx, and 3336 + Daconil. Products giving fair to good results were: 3336, Alude or Signature (Phosphonates), Heritage, Medallion, Chipco 26GT, and Eagle. Using these chemistries in a tank mix or rotational spray program will give suppression of Anthracnose through out the season.
If a curative spray is needed the combination of Endorse + Daconil showed the best results. The only problem with curative sprays is that you will get 92 – 93 % control at best. A turf managers eyes will pick up 6 – 7 % disease in turf. This is above the 92 -93 % control with a curative spray. Even with the best results disease can be seen on the turf. This should be pointed out to the turf manager that with the best combination he will still see some disease present and not to be disappointed with the spray application. Curative sprays also have to be made at shorter intervals then on a preventative program.

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