Please note that none of these diseases we will discuss today are severely damaging to the overall health of the golf course. I am not writing today to raise alarm; my purpose is to raise your awareness of these issues, and to further your turfgrass education!!
DOLLAR SPOT
On fairways, turf disease Dollar Spot is caused by the pathogen Sclerotinia homeocarpa. (See picture below) Annually, this is the most common disease we see on fairways during the growing season in our climate. Dollar Spot shows itself as silver dollar sized spots of damaged turf. If left untreated, Dollar Spot will coalesce into larger areas and kill turf plants, leaving an ugly playing surface that will need to be re-established. This disease is the focus of our preventative fungicide program on fairways all season long.
Our fairways have been treated twice for Dollar Spot, yet the damage we see this spring has "leaked" through preventative fungicides. Eventually, damaged plants will recover. Damage we see is aesthetic and not a huge concern, but rather a reminder that Mother Nature is always in charge!!
To help fairways heal faster, we will suspend the next scheduled growth regulator treatment planned for later this week. Allowing fairway turf to grow at its normal (faster) rate will hasten the healing process. Also, last week's fairway fertilizer application will help turf recovery, as dollar spot is a rare disease that is slowed by higher nitrogen soil fertility. Most turf diseases spread aggressively with nitrogen fertilizer applications.
LEAF SPOT
Another disease present (in roughs) is called Leaf Spot. It is caused by many different fungi from the Helminthosporium species. Leaf spot is present as partly circular patches one to two feet in diameter. (see picture below) Leaves of infected turfgrass have small brownish areas of damage evident. Again, we are seeing leaf spot this year because of the weather conditions we have seen. Warmer weather will stop the damage on plants, and turf should recover nicely during later June and July. Damage has not spread to greens, tees or fairways because all these areas have been treated with fungicides this year. Leaf spot present in roughs is not a serious situation that warrants expensive fungicide treatments.
FAIRY RING
Fairy rings are present annually and show up on greens and fairways around June 1st. Named from European fokelore because "inside the circles is where the fairys danced." Fairy rings can be both small (6 inch to 12 inch) or larger areas (up to 60 feet in diameter) of circular darker green areas of turf. The fungi use, then release excess nitrogen to the turf. The turf roots find the nitrogen giving the infected areas darker green turfgrass. Sometimes, toxic mushrooms also grow within the darker green circles.
We treat to control fairy rings on greens only, due to potential uneven putting conditions if left untreated. This year, fungicides were applied on May 28th. Fairy rings on fairways are not treated, due to expensive $ 1,500.00 per acre cost for fungicide treatments that would be necessary for successful control.
RED THREAD
Finally, we have seen a few patches of disease Red Thread this spring. Red thread is fascinating in that turfgrass infected has vibrant pink or red strands growing from mowed leaves. It tends to be injure turf in 4 to 18 inch sized circular patches of damaged turf. If left untreated, Red Thread can damage fairways severely, but we are safe because of the two fungicide treatments during 2009.
