Turfgrass Diseases: patch (Causal : Microdochium nivale)

Microdochium patch, sometimes referred to as Symptoms and Signs patch or Gerlachia patch, is caused In Pennsylvania, Microdochium patch symptoms occur on by the fungus Microdochium nivale, and results occasion during early to late . Symptoms on putting in patches of blighted turf on golf course greens and tees include pink or red patches of blighted putting greens and tees blades in circular or roughly circular patches, often with some healthy-appearing grass in the center. Patches typically range from 1 to 8 inches in diameter, sometimes coalescing to damage larger areas of turf. White fungal can sometimes be observed on the periphery of patches during periods of wet weather and overcast conditions.

Figure 2. Microdochium patch symptoms on annual bluegrass Photo: Peter Landschoot, Penn State putting green (left), and an individual patch showing copper-colored in the diseased area, and some Microdochium nivale also causes pink mold, which has healthy-appearing turf in the inner portion of the patch (right). similar symptoms except that it occurs under snow cover, Photos: Peter Landschoot, Penn State whereas Microdochium patch develops in the absence of snow cover. Disease Cycle Microdochium patch begins with of turfgrass leaf tissues by mycelium of M. nivale which reside on plant debris in , or by germinating (conidia). Mycelium and conidia spread from plant to plant during wet, cool, and overcast conditions causing that result in patches of blighted leaves, stems, and crowns. Conidia are formed in -bearing structures called sporodochia on diseased tissues and can give rise to new infections and form patches if favorable conditions persist. Microdochium nivale survives as dormant mycelium in leaf litter, thatch, and soil during spring, , and fall.

Figure 1. Microdochium patch symptoms on annual bluegrass/bentgrass putting green. Photo: Peter Landschoot, Penn State Disease Development DMI, 3, acropetal Microdochium patch typically occurs in early to mid-spring triticonazole penetrant Trinity during extended periods of cool and rainy periods that result in Dicarboximides long periods of moisture on leaf surfaces. Microdochium patch is found on close-cut turf, such as golf course putting greens 26GT, Andersons and tees, but is not as common as some other spring foliar X, diseases, such as anthracnose and leaf spot. Annual bluegrass Chipco 26019 is the most common host of M. nivale and can be severely FLO, Iprodione injured if conditions are ideal for disease development. Pro 2SE, Ipro 2, Dicarboximide, 2, Ipro 2SE, Lesco 18 Cultural Control iprodione local penetrant Plus Cultural practices that may lessen the severity of Phenylpyrroles Microdochium patch include using only moderate amounts of (PP) nitrogen fertilizer in spring, removing moisture from leaf Signal surfaces, and avoiding prolonged tarping of putting greens in transduction, 12, spring. fludioxonil local penetrant Medallion Chemical Control Quinone outside inhibitors (QoI) Fungicide applications can be used to control Microdochium patch on golf course putting greens and tees. To obtain Heritage, Heritage successful control, should be applied as soon as TL, Strobe 50WG, symptoms become apparent. QoI, 11, acropetal Strobe 2L, Strobe azoxystrobin penetrant Pro Some penetrant fungicides labeled for control of Microdochium patch (sometimes referred to as Fusarium patch Disarm G, Disarm on fungicide labels). QoI, 11, acropetal 480 SC, Fame fluoxastrobin penetrant Granular, Fame SC Fungicide class, QoI, 11, local Insignia SC FRAC code*, and pyraclostrobin penetrant Intrinsic Active ingredient plant mobility Product according to class classification** name(s)*** QoI, 11, local trifloxystrobin penetrant Compass Demethylation inhibitors (DMI) Succinate dehydrogenase Andersons Golden inhibitors (SDHI) Eagle DG, Eagle 20EW, SDHI, 7, acropetal DMI, 3, acropetal Myclobutanil pydiflumetofen penetrant Posterity myclobutanil penetrant 20EW Some combination product fungicides labeled for control of Andersons Microdochium patch (sometimes referred to as Fusarium patch Prophesy DG, on fungicide labels). Banner Maxx II, Dorado, Lesco Fungicide class, Spectator, FRAC code*, DMI, 3, acropetal Propiconazole and plant propiconazole penetrant 14.3, Savvi mobility Product ArmorTech TEB Active ingredient classification** name(s)*** 360 XL, Mirage QoI, 11, acropetal Stressgard, Sipcam penetrant + Host Clearscape ETQ, defense induction, DMI, 3, acropetal Tebuconazole 3.6, azoxystrobin + P1, systemic tebuconazole penetrant Torque acibenzolar-S-methyl penetrant Heritage Action Andersons DMI, 3, acropetal Fungicide VII, triadimefon penetrant Bayleton FLO

Page 2 Turfgrass Diseases: Microdochium patch (Causal Fungus: Microdochium nivale) QoI, 11, acropetal Goliath XP, SDHI, 7, penetrant + DMI, Headway, acropetal azoxystrobin + 3, acropetal Headway G, penetrant + QoI, propiconazole penetrant Contend B fluopyram + 11, acropetal trifloxystrobin penetrant Exteris Stressgard QoI, 11, acropetal penetrant + DMI, QoI, 11, acropetal 3, acropetal penetrant + DMI, azoxystrobin + penetrant + SDHI, fluoxastrobin + 3, acropetal propiconazole + 7, acropetal myclobutanil penetrant Disarm M pydiflumetofen penetrant Posterity XT QoI, 11, acropetal QoI, 11, acropetal penetrant + DMI, penetrant + DMI, fluoxastrobin + 3, acropetal azoxystrobin + 3, acropetal ArmorTech tebuconazole penetrant Fame+T tebuconazole penetrant Zoxy-T, Oximus Dicarboximide, 2, SDHI, 7, local penetrant + 26/36, acropetal iprodione + MBC, 1, acropetal ArmorTech TMI, penetrant + DMI, thiophanate-methyl penetrant Lesco Twosome benzovindiflupyr + 3, acropetal Ascernity, Dicarboximide, 2, difenoconazole penetrant Contend A local penetrant + SDHI, 7, iprodione + QoI, 11, acropetal Interface acropetal trifloxystrobin penetrant Stressgard penetrant + QoI, SDHI, 7, boscalid + 11, local acropetal pyraclostrobin penetrant Honor Intrinsic penetrant + DMI, Chloronitrile, M5, isofetamid + 3, acropetal contact + tebuconazole penetrant Tekken chlorothalonil + Dicarboximide, 2, DMI, 3, acropetal iprodione local penetrant E-Pro ETQ, penetrant + QoI, Chloronitrile, M5, mefentrifluconazole 11, local contact + + pyraclostrobin penetrant Navicon Dicarboximide, 2, Aromatic local penetrant + hydrocarbon, 14, chlorothalonil + MBC, 1, acropetal contact + DMI, 3, iprodione + penetrant + DMI, PCNB + acropetal thiophanate-methyl + 3, acropetal tebuconazole penetrant Premion tebuconazole penetrant Enclave QoI, 11, local Chloronitrile, M5, penetrant + SDHI, contact + DMI, 3, pyraclostrobin + 7, acropetal chlorothalonil + acropetal fluxapyroxad penetrant Lexicon Intrinsic propiconazole penetrant Concert II QoI, 11, local Chloronitrile, M5, penetrant + DMI, contact + DMI, 3, pyraclostrobin + 3, acropetal acropetal triticonazole penetrant Pillar G chlorothalonil + penetrant + Signal Instrata, propiconazole + transduction, 12, Versagard MBC, 1, acropetal fludioxonil local penetrant Fungicide G penetrant + SDHI, thiophanate-methyl + 7, acropetal Oxidative flutolanil penetrant SysStar WDG phosphorylation uncoupler, 29, *FRAC is an abbreviation for Fungicide Resistance Action contact + DMI, 3, Committee. The FRAC code/resistance group system consists fluazinam + acropetal of numbers indicating classes or groups of fungicides based on tebuconazole penetrant Traction mode of action, and letters that refer to broad classifications of fungicides (P = host plant defense inducers; M = multi-site

Page 3 Turfgrass Diseases: Microdochium patch (Causal Fungus: Microdochium nivale) fungicides; and U = unknown mode of action and unknown Code: ART-7096 resistance risk). Due to the risk of fungicide resistance, turf managers should avoid excessive use of fungicides within the same FRAC code/resistance group and alternate products among different FRAC codes/resistance groups.

**Plant mobility classification refers to a fungicide’s ability to penetrate plant surfaces or remain on plant leaf or stem surfaces without penetration. Fungicides that penetrate plant surfaces and are translocated mostly upwards through plant xylem tissues are called acropetal penetrants (acropetal = toward the apex). Fungicides that enter plant cuticles or move limited distances in internal plant spaces, but do not translocate through vascular tissues (xylem and/or phloem) are called local penetrants. Contact fungicides do not penetrate plant surfaces and only inhibit fungal pathogens residing on leaf and stem surfaces.

***Follow label precautionary statements, restrictions, and directions regarding tolerant turfgrass , rates, and timing of applications.

References Buhler, W. Fungicide spraying by the numbers. Clarke, B.B., P. Koch, and G. Munshaw. Chemical control of turfgrass diseases 2020. University of Kentucky, Rutgers University, and University of Wisconsin. Latin, R. 2011. A practical guide to turfgrass fungicides. American Phytopathological Society Press, St. Paul, MN. Smiley, R.W., P.H. Dernoeden, and B.B. Clarke. 2005. Compendium of turfgrass diseases, 3rd Edition. American Phytopathological Society Press, St. Paul, MN.

Authors Peter Landschoot, Ph.D. Professor of Turfgrass Science [email protected] 814-863-1017

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