Brown Ring Patch Management for 2009

Highlights

MAY, 2009

Brown ring patch management In This Issue: Brown ring patch management for 2009 1 New tool for disease prediction 1 for 2009 Preventing damage from recycled water 2 Rolling right along with anthracnose 2 Cultural practices for disease control 3 Fungicides and the diseases they control 4

Member benefits c o r n e New tool for disease prediction Brown ring patch caused by Waitea circinata var. Relationship between BRP and low soil moisture on a circinata on Poa annua green. Poa annua green. Note the high incidence of BRP (yel- Which diseases are ready to attack your low dots) in the driest areas (red) of the green. turf in the coming week? To answer this Brown ring patch (BRP), which is triggered by threat temperatures greater than 60F question, you can now turn to your PACE (16C), has begun to strike in many locations. Caused by the fungus Waitea circinata Turf Weather Alert’s “Forecasted Disease var. circinata, it is a relatively new disease that has been causing significant damage Threats.” This listing uses temperature on poa greens. Its management is similar to that for Rhizoctonia diseases, but recent data for each turf disease, in combina- research shows that it differs in several important ways as well. tion with weather forecasting information from your location, to identify the Table 1. Top performing products for curative control of brown ring patch. Products shown in green are desig- disease threats that you are likely to en- nated as reduced risk or as biopesticides by the US Environmental Protection Agency. With the notable exception of counter in the near future. thiophanate-methyl (Cleary’s 3336), most products that are effective against Rhizoctonia diseases are moderately to highly effective against BRP. The products, below, however, have shown the best curative activity of all of those tested to date. What should you do if a disease threat appears on your Weather Alert? De- Active Rate/ 1000 Product Comments pending on your history with the dis- ingredient sq ft ease, the action taken can range from Prostar 70 WG flutolanil 2.2 oz best results across all tri- monitoring, to implementing cultural als; slow-acting, but long practices, to fungicide applications. residual (>5 wk) activity PACE Turf’s searchable online archive Endorse 2.5 WP polyoxin-D + 4 oz + 1 oz fast acting and long re- of disease management information, in + Banner Maxx 1.3 propiconazole; sidual activity combination with your knowledge of the MEC disease’s impact and management, can Endorse 2.5 WP polyoxin-D 4 oz fast-acting, but shorter (2-3 help you to select the most appropriate wk) residual activity practices. Headway 1.39 EC azoxystrobin + 2 oz fast acting, but shorter (2-3 propiconazole wk) residual activity premix

The most important difference in the brown ring patch (BRP) vs. brown patch control strategy is BRP’s ability to survive applications of thiophanate-methyl (Cleary’s 3336). A list of the top-performing products for BRP is shown above. The following cultural and chemical practices have been shown to be the most effective against brown ring patch. This information is based on GCSAA-funded field stud- ies conducted during 2008, and implemented by Drs. Frank Wong, Larry Stowell and Chi-Min Chen. continued on page 3

For the first time, golf courses that had previously been ing with courses that have a plumbing option to switch allowed to use low–salinity and low-sodium domestic water from the recycled water source to the domestic water to irrigate salt–sensitive poa greens are being required to source for a short period of time for leaching to drop soil switch from domestic to recycled water. At some of these salts and sodium. golf course, rapid blight is already a serious problem due to To help you in your communication with water districts on sodium accumulation when irrigating with domestic water, this topic, we have prepared the document, “Recycled wa- and the switch to recycled water can make a bad situation ter impact mitigation”, which is available on the PACE Turf even worse. Thus, the switch to recycled water will require member web site. It can be used to show water districts the diligent monitoring and careful management. guidelines that are necessary to prevent serious damage When possible, water districts are working with golf course due to sodium and salt accumulation, and also lays out the superintendents to develop methods that are science- conditions that should trigger a switch to domestic water based and allow the golf course to leach poa greens using in order to prevent turf damage. domestic water if salt and sodium accumulation is exces- sive following irrigation with recycled water. We are work-

Rolling right along with anthracnose control

There is some good news for those locations (look at your emailed of anthracnose, they can, along with the of you who struggle every summer PACE Turf Weather Alert to see if cultural and chemical practices summa- with anthracnose. While it has been anthracnose is listed under “Dis- rized in the PACE Turf Update “Anthra- known for some time that increas- ease Threats” your location) this cnose management: a comprehensive ing mowing heights can reduce an- information comes at a good time. approach”, result in higher quality turf thracnose, the resulting decrease in Although improved mowing and roll- with fewer inputs. green speeds made this practice a ing practices probably can’t elimi- hard sell at many courses. But now nate the need for fungicide control it turns out that you can have the best of all worlds, with higher mowing heights, less anthracnose damage and faster greens, according to research conducted by Dr. John In- guagiato and colleagues at Rutgers University, and reported in the May, 2009 Golf Course Management ar- ticle, “Mowing and rolling strategies to manage anthracnose on annual bluegrass greens”.

The two year Rutgers study convinc- ingly shows that even small increas- es in mowing height can reduce anthracnose severity by as much as 17%, and that more frequent mowing (twice a day) and rolling (every other day) can keep greens speeds up, even when mowing heights are higher. Mowing 2X/day and rolling every other day resulted in high green speeds, even with higher mowing Since anthracnose season is on its heights. Data from Inguagiato et. al., May 2009, Golf Course Management. Treatments in green had sig- way, or has already landed in many nificantly faster green speeds than the standard greens, which were mowed at 0.110”, with 1X daily mowing and no rolling. The treatment in red had significantly slower speeds than the standard treatment.

2 Cultural practices for summer Brown ring patch disease on cool-season greens management

Cultural practices are the foundation of continued from page 1 any successful disease IPM program. These will help to prevent disease by decreasing When threat temperatures reach 60F stress and keeping turf healthy. (16C), begin to monitor greens for early signs of BRP symptoms. • Monitor your threat temperatures using the PACE Turf Weather Alert, and begin • When symptoms are first found, your summer disease management pro- treat immediately with one of the gram when threat temperatures of 65F products or product combina- (18C) are stably reached. Summer patch on Poa annua roots. Note how the tions shown in the Table on page roots have disintegrated and become discolored as 1. For best performance products • Apply low rates of nitrogen (0.1 lb a result of the disease. should be applied in 2 gallons N/1000 sq ft/week, or 0.2 lb N/1000 sq water/1000 sq ft. A follow up ap- ft/2 weeks). plication will almost certainly be • Apply Primo Maxx at 0.125 oz/1000 sq necessary. ft every 14 days. DO NOT use in conjunc- • Make weekly applications of 0.2 tion with Trimmit. If poa seedheads are nitrogen/1000 sq ft. Effective of concern, add Proxy (5 oz/1000 sq nitrogen sources include ammo- ft) to the tank. This combination also nium sulfate (21-0-0), calcium ni- contributes to reduced anthracnose trate (15-0-0) and urea (46-0-0). damage. For more information on the pow- • Schedule a monthly “venting” using Take-all patch on bentgrass green erful effect of nitrogen on BRP small diameter (1/4”) hollow cores or control, see this PACE Update. solid tines. Always check soil salt levels • The addition of Primo Maxx (0.125 and leach to remove excess salts prior oz/1000 ft every two weeks) to to venting. the nitrogen will improve turf • Raise mowing heights as much as pos- quality further, due to improved sible. Even an increase of 1/100 inch can color and density. Always include make a noticeable difference. Maintain nitrogen in the tank when Primo greens speeds by rolling as frequently as is applied, though, as Primo alone every other day. The use of growth Proxy plus Primo not only re- has a growth regulator effect • Keep manganese levels above 30 ppm duces Poa seedhead production, but also reduces that causes an apparent increase anthracnose damage. for suppression of take-all patch on in disease symptoms. While the bentgrass. Primo does not cause increased disease, the symptoms of the dis- • Maintain adequate soil moisture using a soil moisture probe, and do not dry out ease are more obvious after ap- turf. plication. • Maintain good soil moisture. Re- Mowing height vs. disease. search trials have shown that Increasing mowing height low-moisture soils are hit much even slightly can significantly reduce anthracnose severity. harder by BRP. We have seen On a given date, treatments that the surfactant Revolution L followed by different letters (6 oz/1000 sq ft) can contribute are significantly different from one another. Data from to BRP control, probably due a summer, 2004, as reported soil moisture-related effect. We in Inguagiato et. al., May highly recommend the use of a 2009, Golf Course Manage- ment. soil moisture meter to maintain adequate moisture levels.

3 Fungicides and the diseases they control best

Some systemicity

Contact R Resistance threat azoxystrobin boscalid chlorothalonil cyazofamid etridiazole fenarimol fluoxastrobin fludioxonil flutolanil fosetyl-Al iprodione mancozeb mefenoxam metconazole myclobutanil PCNB phosphites polyoxin D zinc propamocarb propiconazole pyraclostrobin thiophanate- methyl triadimefon triticonazole trifloxystrobin vinclozolin Algae Oscillatoria, cyanobacteria Anthracnose Colletotrichum cereale R R R R R Bentgrass/bermuda dead spot Ophiosphaerella agrostis Blight, melting out, leaf spot Curvularia, Bipolaris, Dreschlera Brown ring patch Waitea circinata Brown/yellow patch Rhizoctonia spp. Dollar spot Sclerotinia homeocarpa Fairy ring basidiomycete fungi Gray leaf spot Pyricularia grisea R R R Gray snow mold Typhula Necrotic ring spot Ophiosphaerella korrae Pink snow mold/Microdochium patch Microdochium nivale Pythium foliar blight Pythium spp. Pythium root dysfunction Pythium volutum Rapid blight Labyrinthula terrestris Red thread Laetisaria fuciformis Root rot Pythium spp. Rusts Puccinia spp. Southern blight Sclerotium rolfsii Spring dead spot Ophiosphaerella spp. Summer patch Magnaporthe poae Take-all patch and decline Gaeumannomyces graminis IMPORTANT: Products listed above have consistently shown good efficacy in multiple research trials against the diseases shown. Products not listed here may perform well, but data was not made publicly available for analysis. Chemical control is only one component of disease management. Consult the PACE Turf website for cultural practices that should be implemented for each disease. Fungicide tank mixtures are sometimes the most effective strategy and are dealt with in a separate table. Always refer to the product label to confirm all use, handling and application requirements.

ACTIVE INGREDIENT TRADE NAMES ACTIVE INGREDIENT TRADE NAMES azoxystrobin Heritage metconazole Tourney boscalid Emerald myclobutanil Eagle, Golden Eagle chlorothalonil Concorde, Daconil, Echo, Manicure PCNB (quintozene) Defend, Penstar, Terraclor, Turfcide cyazofamid Segway phosphites Alude, Magellan, ReSyst, Vital etridiazole (ethazole) Koban, Terrazole polyoxin D zinc Endorse fenarimol Patchwork, Rubigan propamocarb Banol fludioxonil Medallion propiconazole Banner Maxx, Propiconazole Pro fluoxastrobin Disarm pyraclostrobin Insignia flutolanil Prostar thiophanate-methyl Cavalier, Cleary’s 3336, Fungo fosetyl-Al Aliette triadimefon Accost, Bayleton, Fungicide VIInul F iprodione Chipco 26019, Chipco 26GT, Iprodi- trifloxystrobin Compass one Pro triticonazole Trinity, Triton mancozeb Dithane, Fore, Mancozeb, Protect vinclozolin Curalan, Touche, Vorlan mefonoxam Subdue Maxx, Quell Fungicides shown in blue are considered reduced risk, and those shown in green are considered biopesticides by the US EPA