Program '11 Update: Dry and Cool

It's been dry in Raleigh during most of June, and cool (compared to last year, at least) for the last couple weeks. Disease pressure on our 'A-1' bentgrass green has been relatively light as a result. Nevertheless, we still made several changes to Program '11:

Dollar spot pressure was still pretty high in early June, so instead of applying Disarm C on June 6 we applied Honor for its better activity against dollar spot. We skipped the application of Subdue Maxx that was planned for June 13 because of the dry conditions. Then on June 20 we applied the Disarm C that was originally planned for June 6.


All of the programs are providing good brown patch control. Dollar spot is still reducing turf quality in the Syngenta Program, but all other programs are providing very good turf quality this week.


For more information about our Program '11 Project, or to follow along on Facebook or Twitter, please visit our website turfpathology.org.

If it's yellow, just be mellow

Rumors have been swirling around the golf industry over the last week about 'bacterial wilt'. For the record, I want to make it clear that we have diagnosed NO cases of bacterial wilt in North Carolina or any other state.

I repeat, we have diagnosed NO cases of bacterial wilt in North Carolina or any other state.

Yellow spot of creeping bentgrass.

We have seen suspicious amounts of bacteria in bentgrass expressing symptoms of yellowing, etiolation, and gradual thinning. We don't know if these bacteria are the cause of the problem or if they are a secondary invader. As a result, we don't know if this is an actual disease or not. For more information, see our recent blog post.

A severe case of yellow spot on creeping bentgrass.

'Bacterial wilt' is caused by Xanthomonas translucens and is primarily a problem on Poa annua but also occurred on 'Toronto' creeping bentgrass back in the 1980s. Bacterial wilt causes rapid wilting and dieback of infected plants. Chlorosis, etiolation, and slow thinning of the turf doesn't fit the description of this disease. Therefore, what we are seeing now is NOT bacterial wilt.

We've had countless calls and samples over the last week from superintendents who fear they have bacterial wilt because they are seeing chlorotic or yellow turf. It's important to realize that many things can cause turf to turn yellow, and that if you aren't seeing the etiolation and gradual thinning then you probably don't have this suspected bacterial problem. For more information about some of the most common reasons for yellowing turf, please refer to this post on turfdiseases.org.

Several of the samples that came into our clinic this week turned out to be yellow spot. This disease causes chlorotic spots and patches on creeping bentgrass putting greens, but does not cause an abnormal growth habit and we've never seen it lead to thinning of the turf.

Yellow spot symptoms are especially prevalent during dry and hot weather. That certainly fits the conditions we're experiencing in North Carolina right now. For more information about yellow spot, please refer to this Golf Course Management article from the November 2006 issue.

Avid Receives 24(c) Label for Nematode Control in NC

Golf course superintendents in North Carolina have a new option for nematode control on putting greens.

Avid (abamectin) has been granted a 24(c) Special Local Need label for control of sting and ring nematodes on golf course putting greens. The supplemental label can be downloaded here. It is important to emphasize that this 24(c) label applies only to the Avid brand, is only valid in North Carolina, and only allows for application to golf course putting greens.

The application rate is 57 ounces per acre, with a recommended 3 to 4 applications on a 14 to 21 day interval. Tank-mixing with a non-ionic surfactant is recommended to improve penetration into the root zone, and applications should be watered-in immediately with 0.1" of irrigation.

Suspected Bacterial Disease of Creeping Bentgrass

Over the last two weeks, the Turf Diagnostics Lab at NC State received several samples of a suspected bacterial disease on bentgrass putting greens. All of the affected golf courses have been in the Piedmont region, from Raleigh to Greensboro to Charlotte.



Most locations are reporting yellowing and etiolation of the bentgrass followed by a slow thinning. The symptoms are relatively mild in these locations. Two courses experienced a more rapid and widespread decline. In all cases, the symptoms are limited to areas that were severely damaged last year by heat stress or other diseases.

We are working to isolate and identify the bacteria associated with these samples. Since there are bacteria in almost every turf sample we receive, we need to determine if the bacteria are pathogenic before we can be sure that they are the cause of the problem.

In the meantime, golf course superintendents who are seeing these symptoms are advised to avoid abrasive practices like aerification, verticutting, and topdressing. If the symptoms are localized to cleanup passes or certain greens, then dedicate a mower to those areas or wash the mower thoroughly and spray it with a 10% bleach solution before moving to other greens. Mowing affected areas last after the dew has dried or spraying with a hydrogen peroxide solution before mowing may also help to minimize the spread of bacteria.

In addition, anything that can be done to minimize stress on the turf is advised; for example raising mowing heights, switching to solid rollers, or skipping mowings on affected areas.

We are investing all of our effort and resources into determining the cause of this problem and developing a practical solution. We have initiated trials at 4 golf courses to evaluate practices that may help to control it. Be sure to follow our blog or sign up for email alerts to receive regular updates:

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Program '11 Update: More Dollar Spot and Brown Patch

Dollar spot pressure has continued to be very high, and brown patch exploded over the last week as well. For our Program '11 treatment, we proceeded as planned on May 23 with an application of 26GT (4 fl oz) + Fore (6 oz). We also made the scheduled application of Terrazole (4 oz, watered-in) to clean up any Pythium root rot activity that may have been triggered by recent wet weather.

The changes that we made to Program '11 have done a good job of getting the dollar spot under control. In fact, Program '11 is the only treatment that is clean of dollar spot this week. All of the other programs contain noticeable amounts of the disease.

All of the programs are providing excellent brown patch control.

Turf quality is still mostly being impacted by dollar spot. Only Program '11 and the Bayer Program are providing acceptable (>5) turf quality, with Program '11 providing significantly greater quality than all other treatments.

For more information about our Program '11 Project, or to follow along on Facebook or Twitter, please visit our website turfpathology.org.

Type I fairy rings in warm-season grasses

Type I fairy ring symptoms on a bermudagrass fairway

This spring we've seen a tremendous amount of Type I fairy ring on bermudagrass fairways and landscapes established with zoysiagrass and centipedegrass.  Type I fairy ring symptoms are the most severe, causing decline or death of the affected turf. In most cases these symptoms appeared as soon as the turf began to green-up in the spring. The affected turf never greened-up, indicating that it had been killed over the winter.

Note how the symptoms stop near the drainage basin

How and why did this happen? I suspect that these rings began to develop last year during periods of wet weather in the spring. In fact, some people noted that these same areas had green (Type II) fairy ring symptoms last year. All of this fungal growth may have turned the soil hydrophobic, or water-repellent, and caused the turf to be killed by winter desiccation. Or maybe the extra nitrogen released into the soil profile by the fairy ring fungi caused the turf to be more prone to winter injury.

Either way, the important thing now is to take steps to encourage a rapid recovery. Wetting agents or soil surfactants should be used to re-wet the soil in affected areas, and spiking or aerification should be done to break up the mat of dead turf. Avoid application of DNA herbicides, like prodiamine, as these inhibit root growth and will slow recovery. Fungicides probably won't help to speed up the recovery, but they may help to prevent the problem from recurring next year. For a list of fungicides labeled for fairy ring control, please visit the Disease Management Utility on TurfFiles.

For more information on fairy ring, check out our fairy ring disease profile.

Brown Patch Alert

Brown patch has exploded on tall fescue landscapes and creeping bentgrass putting greens over the last week in the Piedmont of North Carolina. Warm night temperatures, high humidity, and rain have created ideal conditions for this disease to develop.

Looking at the weather forecast, conditions will remain favorable for brown patch for the foreseeable future. Creeping bentgrass putting greens and high-value tall fescue landscapes should be treated with preventive fungicides as soon as possible. If the disease is allowed to progress much longer, recovery will be very slow now that the summer heat has set in.

The QoI fungicides azoxystrobin (Heritage), fluoxastrobin (Disarm), pyraclostrobin (Insignia), and trifloxystrobin (Compass) are best for brown patch control and provide 21 to 28 days of protection against the disease. None of these products are readily available to homeowners, and the products you'll find on the shelves at home improvement stores are not very effective against brown patch. If you have a brown patch problem in your lawn or landscape, it's best to call a professional.

For more information about brown patch, please visit turfpathology.org.