Dans la Merde in the West

Dans la merde is a colorful French term that basically translates into "in the sh*t" and is a good term to describe superintendnets who are currently behind the eight ball fighting active foliar anthracnose outbreaks on annual bluegrass greens in the West.

Right now, anthracnose is coming into our diagnostic lab left and right. It's likely a result of the up and down heat spikes and we've had throughout the summer here in the west.

Although anthracnose should be managed with a combination of solid cultural practices (see www.turf.rutgers.edu/research/GCM-BMP-Anthracnose.pdf) and a solid preventive fungicide program, summer stress and common practices related to tournament prep (low mowing heights, holding back N, drying down greens, etc.) or just high traffic and play can put superintendents in a bad spot. If you find yourself dans le merde, here are three suggestions that may help you get back on top of anthracnose before it's too late

(There are additional things you can do to help pull yourself out of an anthracnose outbreak, these are just three of the most common things to consider - I'd welcome any additional comments from the NE, SE, M and SC as well!)

1. Fungicide applications
If you have active anthracnose on greens, chlorothalonil is your friend. Inexpensive and not at risk for resistance, it can be used aggressively as a "eradicant" application to kill spores in acervuli and prevent new infections. Label rate applications 7 days apart should be made to halt infections in their tracks. You can mix chlorothalonil fungicides with other anthracnose-active fungicides like Medallion and Endorse safely in a rescue type situation. Chipco Signature tank mixed with chlorothalonil can also be a good option. DMI-fungicides like Banner MAXX can also be mixed with chlorothalonil, but be aware of potential PGR-effects when using these at high rates or high temperatures. Beware of using QoIs (Heritage, Insignia, Compass, Disarm) or thiophanate-methyl containing fungicides (Clearys 3336, Fungo, etc.) by themselves as rescue applications. Resistance is a problem for these already and using them as rescue materials is a good way to lose them due to resistance (that's a GCSAA class all to itself). In any case, chlorothalonil can do a lot of work for you as a rescue fungicide, and also beat back any other secondary pathogens coming in to the damaged areas or algae that can fill into thinned areas on greens.

When using contact fungicides like chlorothalonil, it's very important to get good coverage. Apply fungicides in at least 2 gallons of water per 1,000 sq ft for adequate penetration of the fungicide to the lower leaves and crown. Flat fan or air-induction flat fan type nozzles, that produce smaller sized droplets, are much more effective than rain drop or flooding wide angle nozzles for getting the best coverage with contact fungicides.

2. Fertility
Assuming that you can get sufficient knock down of he pathogen, it's important that surviving Poa has enough N to push back and recover from injury. Light applications of N (0.125 to 0.25 lb N/1,000 sq ft) should be made to get your Poa back on its feet. Apply as needed to get regrowth and recovery from damage; but excessive amounts may cause some excess growth and scalping if you're not careful. Although N is the most important component, additional P and K can also help. A 20-20-20 may be a good choice for recovery from anthracnose damage.

3. Irrigation
Once you're hit with anthracnose, don't overwater damaged areas in hopes of increasing damage recovery. Overwatering is just as conducive for anthracnose as is drought stress. Irrigate based on ET-needs, but make sure to mist/syringe greens in during the hottest periods of the afternoon to minimize heat stress on weakened plants.

Hopefully, with some TLC (plus fungicides, nitrogen and irrigation management), you can get outta the merde and back to normal practices on greens. Often, anthracnose is linked to other environmental conditions or agronomic practices (compaction, black layer, drought stress, etc.), so make sure to address those issues as well while you are in "rescue" mode.

Just an observation: If your anthracnose if plowing right through preventive Heritage, Compass or Insignia applications…. Guess what, your anthracnose is probably QoI-resistant. If your anthracnose is plowing through preventive 3336 applications (or any thiophante-methyl containing material), you've probably got benzimidazole resistance. Check out our anthracnose powerpoint here if you haven't already seen it for some chemical control alternatives: http://www.turfpathology.ucr.edu/Downloads/anthracnose_chemical_control.pdf

Other Merde...
Over the last week, we've been absolutely slammed by diagnostic samples in the lab. In addition to anthracnose, the usual suspects are still active, such as brown ring patch, summer patch and rapid blight. Samples coming in with Bipolaris, Curvularia, and Leptosphaerulina (especially on fairway and rough samples) are indicative of summer heat stress on cool season turf.

With temps in the 70s and 80s in coastal locations, I would suspect rapid blight be pretty active in salt affected locations, as well as brown ring patch and even dollar spot. The Central Valley (Fresno) and deserts will have to contend with night time temperatures high enough to flare Pythium on cool season turf. Expect anthracnose and summer patch to be calling on your annual bluegrass greens through out the state.

Signing Off From the Left Coast Until Next Week....