Watch the weather

Watch the weather

Humidity and nighttime air temperatures are top dollar spot warning signs.

April 2, 2014

Golf Course Industry visited with Dr. Jim Kerns, turfgrass pathologist at North Carolina State University, to get his thoughts on the outlook for dollar spot pressures after this past harsh winter and what superintendents should be doing to prepare.

What are your thoughts on dollar spot pressures on the fairways after the harsh winter weather that hit much of the country?

So far we haven’t seen anything. Some may question the viability of the pathogen or how it survived the winter. I really don’t think the winter is going to be a factor. We actually store the pathogen at minus 112 Fahrenheit. What the weather does this spring is going to determine dollar spot pressures.

So what should the superintendent be looking for?

If possible, monitor relative humidity and nighttime air temperatures. If the relative humidity stays at 70 percent or more with nighttime temperatures at 50 to 52 degrees, dollar spot can really take off. If you haven’t been tracking weather conditions, look for dew formation. It corresponds with these two factors.

Then what?

If those conditions exist, get your preventive spray program started. If you miss a few days you should be able to keep ahead of the fungus. If you miss it by weeks or a month you are going to really have a problem keeping dollar spot at bay. There are a whole suite of fungicides that are very successful when used preventatively. Most superintendents are well aware of the fact that resistance is plentiful in the dollar spot population. Be sure that you rotate the different chemistries available. You should also consider different tank mixes and switch them around throughout the season. There are new products coming out, so we are broadening our tool box when it comes to dollar spot control. It is one of those things that we deal with on a regular basis but, thanks to continual research and new tools, we can effectively keep it suppressed, for the most part.

Are there any other thoughts you’d like to share with superintendents?

We hear from time to time, especially over the last four or five years, that this product or that product didn’t seem to do the job. There has been a breakthrough of the fungus between applications. Maybe 21 days of protection was expected and disease shows up after 14 days but before the 21 days. When that happens, the first thing I suggest is that the superintendent go back and review the fertility program. If the fertility program is not dialed in correctly, the product is not going to perform as expected. Make sure the fertility is adequate to allow the plant to outgrow the fungus.

On the other hand, I ask superintendents to keep in mind that when we test products, our job is to do so under the most trying conditions. When they see research that indicates a product gave 10 to 12 day control, they might obtain 14 to 21 days depending on their cultural practices. With the testing we do, I feel very confident that the suggestions we provide are going to provide the results shown, or even better.