Still Wild in the West

With the cooler temperatures here in the West coming in, you'd expect some slow down as far as disease development, NOT! Rapid blight and basal rot anthracnose continue to be issues on Poa greens in California. We're also seeing some junk diseases like Curvularia blight on warm season turf slowing down in the cool weather and algae developing on greens with the reduced day-lengths.

California Disease Summary
Dr. Naveen Hyder did a nice summary of the last four years of disease diagnostic data at the Crop Science Meeting in Pittsburgh a few weeks ago. A copy can be found here:

http://www.turfpathology.ucr.edu/Downloads/CA_Turf_Disease_Trends.ppt

As you can see, Poa annua diseases like rapid blight, anthracnose, brown ring patch and algae are our top trouble makers, with over 50% of our samples being annual bluegrass, Naveen stated to the crowd "either we need to put even more resources towards annual bluegrass disease control, or figure a way to keep it out of greens." Much, much easier said than done....

Pythium in the PNW
As mentioned a few weeks ago, Pythium has been causing issues for superintendents in Oregon and Washington. We finally got an ID on some of the troublemakers involved. Samples from several courses were identified as having either Pythium vanterpoolii or P. torulosum, which can do perfectly well under cool (55 to 65 degree F) conditions, as long as its wet. I haven't had much experience first hand fighting these, but my gut feel is that under cool, wet conditions, many typical fungicides can knock down the Pythium, but it's too cool for the annual bluegrass to recover quickly. If it stays wet, the Pythium can re-emerge when the fungicides have "worn off" and damage turf again. In this situation, the lack of recovery from the turf due to cool conditions just magnifies the sucessive rounds of damage and frustrates the hell outta superintendents.














Annual bluegrass greens damaged by Pythium at Portland Golf Club (left) and several weeks later after multiple fungicide applications, blood, sweat and tears (right). Images from superintendent Forrest Goodling.

Thiophanate-methyl and Pink Snow Mold in Northern California
An interesting question was brought up to me this week about using thiophanate-methyl on annual bluegrass greens in parts of northern California. Some superintendents are using it to manage a problem (hint: rhymes with angina) and were wondering what the impact of that would be on resistance development for pink snow mold, which should pop up as our max. daytime temps start to drop below 65.

If one's using repeated thiophanate-methyl applications at a time when pink snow mold may be active - resistance is certainly an issue. Resistance to the benzimidazole fungicides (benomyl and thiophanate-methyl) was detected for pink snow mold back in the 1980s in Washington State. It's unknown what the current status is in northern California, but certainly, back to back, repeated applications of this fungicide will be putting one at risk for losing it for pink snow mold.

If one is using this approach, make sure to use other materials as front-line fungicides for pink snow mold control. PCNB, iprodione, polyoxin-D, the DMIs, mancozeb, & chlorothalonil and mixtures of some of these are all non-benzimidazole fungicides that can be against pink snow mold.

Signing off from the Left Coast until next week......

The Disease Triangle (part 2): The Host

Everyone that has sat through a pathology or disease lecture has heard of the disease triangle. Consisting of the environment, the pathogen, and a susceptible host, the disease triangle is a critical component of understanding disease pressures on a golf course. In a previous post I talked briefly about the importance of the environmental (weather) component of the triangle. I thought that as we wrapped up the season in the Northeast, I would take this time to speak about the importance of the host.

Unlike cropping systems where the purpose of the host is to grow a plant as large as possible and harvest it for sale or distribution, turfgrass managers must deal with a perennial crop that hopefully remains healthy forever (or at least for a long period of time). So instead of just trying to get to harvest, we must figure out a way to manage the "crop" during the good times and the not-so-good times. In the Northeast, just about all of the typical cool-season turfgrass species are grown and in the transition zone of the region we even grow a few warm-season turfgrasses. Growing grass in this region can be very difficult. Taking the extremes in weather out of the equation, there are still some important things about the host to take into account when identifying and managing turfgrass diseases.

When I first take a look at a turfgrass sample, identification of the genus and species is the first step of the process. Remember to look for key attributes including the vernation, ligule size, leaf tip, growth habit and other key components, Simply identifying the species can eliminate numerous pathogens as potential causes of the problem in question. For example, take-all patch is primarily a disease of creeping bentgrass. If the species affected is primarily annual bluegrass, then this disease can be ruled out (not to mention that take-all is primarily a disease of young putting greens of which little ABG would be present). To the contrary, a patch disease appearing primarily on annual bluegrass could limit the possibilities to summer patch or necrotic ring spot (or possible nematodes). Although summer patch may be present on bentgrass in the extreme heat of the Southeast, it is rarely (never to my knowledge) been identified on bentgrass in the Northeastern United States.

So being able to identify the species at your course can save you a lot of time and increase your chances of making an accurate diagnosis. There are too many diseases to talk about in this post, but below are some common hosts of typical diseases found in the Northeast.

Anthracnose basal rot: primarily annual bluegrass, occasionally creeping bentgrass (does not occur on both species on the same green)

Brown patch: most species, but tall fescue, perennial ryegrass, and bentgrass (particularly colonial bentgrass) are most susceptible

Dollar spot: all species susceptible, particularly important on bentgrasses

Summer patch: Kentucky bluegrass and annual bluegrass, also fine leaf fescues

Take-all patch: creeping bentgrass

Sometime prior to the end of the year, I will wrap up the discussion of the disease triangle with every pathologists most favorite component...the pathogen!

For a disease update, things are just about shut down, but dollar spot did pop up in recent weeks and microdochium patch continues to be active at select regions in the Northeast.

Microdochium patch running amuck!

Thanks to the lovely weather we've been experiencing in the Midwest, Microdochium patch has probably worn out its welcome. We just went through the second coldest October on record and I think one of the wettest! Absolutely perfect weather for Microdochium. Microdochium is a pathogen of many turfgrass species and can be especially severe on cool-season turfgrasses. The symptoms appear as small (<6 to 12 inches) water-soaked patches in absence of snow cover. Affected plants are blighted and may have a greasy appearance or may be a tan color. Stand symptoms can also have a pink or salmon hue evident after snow melt. Also symptoms tend to more severe after extended snow cover.



The conditions that favor disease development are cooler temperatures ( 32 to 60 F), high humidity and high nitrogen content in the leaf tissue. Snow cover is not required for this disease to develop, but is usually more severe when snow cover occurs. Microdochium management is fairly simple because many chemicals are efficacious. The tried and true combination for many people is a tank mixture of chlorothalonil and iprodione. Avoiding late season fertility applications seem to limit Microdochium symptoms. The exact timings to avoid are not know, but we are examining that particular question this winter.

Just returned from Pittsburgh attending the Turf Nerd Conference as John put it. The Agronomy Meetings are my favorite time of year. The graduate students at the meeting give fantastic papers and it is a real joy to find out what all of us are doing. For those that are not familiar with these meetings, our division C-5 is the second largest division in the Crop Science Society. Yet the camaraderie amongst the members of the division is great! I've heard that Pittsburgh was not a nice location years ago, but I really enjoyed my stay in Pittsburgh. Unfortunately I did not make it to Primanti Brothers. I did not have a bottle of Pepto with me and just getting over my recent battle with the flu I did not want to chance an upset stomach. Next time the corned beef and cheese sandwich is mine!!

The Turf Nerds go to...

...Pittsburgh? It figures that in the year that I take a new position at Penn State, the annual Crop Science meeting ends up in Pittsburgh. In the past 4 years, the show has been to Salt Lake City, Indianapolis, New Orleans and Houston. Well, in a year where budgets are slim and we are all trying to scale back it was probably best for me. I just feel sorry for those having to make the trip from the West Coast.

So what is the CSSA-ASA-SSSA annual meeting and why is it a hotspot for all of the turf nerds across the country this week? Well, this scientific tri-society of crops, agronomy and soils is probably the largest scientific conference for those university and industry personnel to catch up on the latest and greatest scientific research from around the country. If you are not familiar how scientific discoveries are made, just know that it is not an overnight occurrence. It generally takes several years to develop a solid project, find a graduate student or technician to assist with the work, analyze and write the results and then submit them for scientific publication. The last part (publishing in a scientific journal) can often take up to one year from the time of submission to the time that the research is actually seen in print. Then it takes another few months for the scientific publication to be rewritten in a format that anyone in the industry would actually be interested in reading before making its way into Golf Course Management, Golf Course Industry, Golfdom or similar trade magazine. So from start to finish, a project may take 3 or more years to go from idea to print.

So why do we go to these meetings each year? These meetings are the pinnacle of the latest discoveries in the field and allow for scientists to share ideas and form possible collaborations to advance the science more quickly or more completely. The information presented is usually the latest and often represents preliminary results to studies that are just getting off the ground. Presentations are given orally or as posters and graduate students even compete against each other for the top presentations in each category (I am actually one of the judges for oral presentations this year). Faculty also present their latest findings and industry representatives provide insights into what is happening on their side as well. The week is culminated in the business meeting where outstanding achievements are recognized and actions are put in place for the next year.

So I am off for Pittsburgh this morning (immediately following my class)...next year I am looking forward to Long Beach, CA!

Check out my list of interesting topics for this week...
Glyphosate-Resistant Annual Bluegrass (Poa annua) in Missouri.

Physiological Changes During Cold Acclimation for Perennial Ryegrass Accessions Differing in Freeze Tolerance.

The Effects of Nitrogen and Trinexapac-Ethyl On the Severity of Brown Ring Patch On Annual Bluegrass Golf Course Putting Greens.

Developing a Predictive Model for Spring Germination of Smooth Crabgrass (Digitaria ischaemum) and Annual Bluegrass (Poa annua) in Michigan.

Sodium Adsorption On Calcined Clays and Zeolites.

Above image used under creative commons license by author

http://www.flickr.com/photos/ztil301/ / CC BY-NC-ND 2.0

The turf is chillin'

I was at Oklahoma State University yesterday to give a couple of presentations at a tree workshop. ("Are you pining for healthy pines?" hah, clever, eh?? maybe not...). My OSU colleagues Damon Smith (plant path), Eric Rebek (entomology), and Mike Schnelle (hort) were great hosts and they also gave some excellent presentations.

But...

Just outside the door.... was the OSU turf research center, and I was excited to find this symptom (in the above photo) in some bermudagrass.

What is going on here?

This is a form of chilling injury. Chilling injury like this usually occurs when temps are between about 32 and 54 degrees. Symptoms tend to appear 24-48 hours after the chilling event. The bleached out areas are due to degradation of chlorophyll. Why the funky pattern? Nobody knows for sure, but it may have to do with small-scale differences in where the coldest air settles.

Ohio State has a collection of podcasts, and there is one that addresses chilling injury.

http://buckeyeturf.osu.edu/component/option,com_wrapper/Itemid,78/

Then, go to the December 2006 section of the archives (blue list on the right).

Or, go to this site:

http://buckeyeturf.osu.edu/profcast1/OSU_Turf_Podcast1.rss

And scroll down about halfway and you’ll see the file for Chilling Injury. You can click and either run it or download it to view later.