Effect of Cultivation and Timing of Nitrogen Fertilization on Large Patch Disease of Zoysiagrass

Abstract

Obasa, K., Fry, J., St. John, R., and Kennelly, M. 2013. Effect of cultivation and timing of nitrogen fertilization on large patch disease of zoysiagrass. Plant Dis. 97:1075-1081.Large patch of zoysiagrass (Zoysia spp.) is caused by Rhizoctonia solani anastomosis group 2-2 LP. The effects of summer cultivation (core-aerification, verticutting, and sand topdressing) and spring and fall versus summer nitrogen (N) fertilization on large patch in fairway height 'Meyer' zoysiagrass were investigated from 2008 to 2011 in Manhattan, Haysville, and Olathe, KS. Disease was assessed by measuring patch diameters or analyzing digital images of affected plot areas to determine the percentage of non-green turfgrass within patches. Cultivation did not affect thatch temperature, soil temperature, soil water content, or turf recovery from large patch in early summer. Furthermore, cultivation did not result in overall significant reductions in patch diameters or average weekly rate of patch diameter increase among plots at the three experimental locations. In some site-year combinations, spring and fall N fertility was associated with lower percentages of non-green turf within affected plot areas in Manhattan and Haysville. In some cases, applications of N during spring and fall may alleviate large patch symptoms.Zoysiagrass (Zoysia japonica Steud. and Z. matrella (L.) Merr.) is a warm-season (C4), perennial turfgrass that is widely used on golf courses in the "transition-zone" of the United States, a region that includes Kansas and states eastward to Virginia and North Carolina. Compared with certain cool-season (C3) turfgrass species used on fairways, such as creeping bentgrass (Agrostis stolonifera L.), zoysiagrass has lower water, fertilizer, and pesticide requirements while maintaining a high-quality surface (16). Large patch, caused by Rhizoctonia solani Kühn anastomosis group (AG) 2-2 LP, is the most common and most severe disease of zoysiagrass.In Kansas, symptoms of large patch appear during spring (April to May) and autumn (September to October) as roughly circular, slightly matted tan patches with bright orange margins (17,40,45). Patches can range from 1 to 6 m or more in diameter (17,45), with healthy turf sometimes scattered within the patches. Symptoms on individual plants occur as reddish-brown to black lesions on the basal leaf sheaths. During summer conditions, regrowth within patches often results in full turf recovery, though weeds can encroach while the zoysiagrass is thinned.In laboratory tests, a temperature range of 15 to 25°C was optimum for infection of zoysiagrass by the fungus (17). It has been suggested that the lack of symptoms during summer months is because thatch and soil temperatures often exceed 30°C, potentially hindering growth of the fungus while, at the same time, favoring zoysiagrass root and shoot growth (17). Additionally, soil moisture and leaf wetness are important factors in large patch development and severity. Severe large patch symptoms on zoysiagrass have been associated wi...

Impact of Nitrogen Application Timing, Nitrogen Source, and a Single Fungicide Application on Large Patch of Zoysiagrass

“…This result supports previous research indicating N applications during the large patch infection period do not increase large patch severity and may in fact reduce it (Obasa et al, 2013;Miller et al, 2016). This result supports previous research indicating N applications during the large patch infection period do not increase large patch severity and may in fact reduce it (Obasa et al, 2013;Miller et al, 2016).…”

“…Green et al (1994) found that summer urea rates did not affect large patch severity, and there was no significant difference in disease severity between summer-applied synthetic and natural N sources. Spring and fall urea applications were associated with decreased large patch severity compared with summer standard urea applications (Obasa et al, 2013). In another study, separate fall and spring N applications did not increase large patch severity compared with summer-only N applications (Miller et al, 2016).…”

“…fairways, tees, and lawns in the US transition zone. However, no research exists linking spring and fall timings of N to increased large patch incidence, and only a few trials have focused on the response of large patch severity to fertilization during the infection period (Obasa et al, 2013;Miller et al, 2016). This experiment examined the effects of N application timing, N source, and a single fungicide application on disease severity.…”

“…This experiment examined the effects of N application timing, N source, and a single fungicide application on disease severity. Spring and fall urea applications were associated with decreased large patch severity compared with summer standard urea applications (Obasa et al, 2013). In the field, these N sources were applied on a standard summer schedule, or augmented with fall, spring, or fall + spring applications when 5-d average 5-cm soil temperatures reached 18°C.…”

“…Consequently, N applications on warm-season grasses have been discouraged during spring and fall to decrease the chance of large patch outbreaks (Smiley et al, 2005). However, no research exists linking spring and fall timings of N to increased large patch incidence, and only a few trials have focused on the response of large patch severity to fertilization during the infection period (Obasa et al, 2013;Miller et al, 2016). Green et al (1994) found that summer urea rates did not affect large patch severity, and there was no significant difference in disease severity between summer-applied synthetic and natural N sources.…”