|PAN, XIAOWEI - University Of Missouri|
|RICHARDSON, MICHAEL - University Of Arkansas|
|DENG, SHIPING - Oklahoma State University|
|KREMER, ROBERT - University Of Missouri|
|ENGLISH, JAMES - University Of Missouri|
|MIHAIL, JAMES - University Of Missouri|
|SAMS, CARL - University Of Missouri|
|SCHARF, PETER - University Of Missouri|
|XIONG, XI - University Of Missouri|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2017
Publication Date: 5/25/2017
Citation: Pan, X., Richardson, M.D., Deng, S., Kremer, R.J., English, J.T., Mihail, J.T., Sams, C.E., Scharf, P.C., Veum, K.S., Xiong, X. 2017. Effect of organic amendment and cultural practice on large patch occurrence and soil microbial community. Crop Science. 57(4):2263-2272. https//doi.org/10.2135/cropsci2016.09.0809.
Interpretive Summary: Zoysiagrass (Zoysia japonica Steud.) is a popular turfgrass used in golf course fairways and other landscaped areas, yet it is susceptible to a number of fungal diseases. In particular, large patch disease is a common problem in zoysiagrass that is caused by a fungus (Rhizoctonia solani Kuhn) that leads to large patches of blighted turf. Very little is known about the role of cultivation practices and amendments in supporting healthy zoysiagrass and how these practices interact with soil microorganisms to promote or suppress fungal pathogens. This study evaluated the progression of large patch in zoysiagrass and shifts in soil microbial community structure in response to two cultural practices (aerification and topdressing) and multiple amendments: chicken manure, a sewage-based organic N fertilizer, a plant byproduct, a synthetic N fertilizer, and a synthetic fungicide. The study was conducted over two years in Columbia, MO. Topdressing involved incorporating a mixture of the amendment with sand into the turf canopy to a depth of 0.6 cm. Aerification involved making two passes using hollow tines measuring 1.3 cm diameter and 7.6 cm apart to a depth of 5.1 cm. Relative to the untreated control, chicken manure and synthetic fungicide reduced large patch severity by 49% and 86%, respectively. Shifts in microbial community structure were also observed, indicating that aerification reduced the ratio of fungi to bacteria relative to topdressing, potentially stressing the fungal population. The results of this study will benefit managers of zoysiagrass, including sod producers, business landscapers, lawn care professionals, and managers of golf fairways.
Technical Abstract: Organic amendments may suppress soilborne pathogens by stimulating soil microbes. However, little information is available about the effects of organic amendments and cultural practices on suppressing large patch caused by Rhizoctonia solani Kühn on zoysiagrass (Zoysia japonica Steud.) associated with a composition shift in microbial community. The objective of this study was to evaluate the effect of organic amendments and cultural practices of aerification or topdressing on large patch of zoysiagrass and on changes in soil microbial community composition. A two-year field study was established on a zoysiagrass fairway at a golf course in Columbia, MO. Organic amendments applied included an animal waste-based product (AW; chicken manure), a sewage-based organic N fertilizer (ON; Milorganite), and a plant byproduct (PB; mustard seed meal), in addition to a synthetic N fertilizer (SN; UMAXX), a synthetic fungicide (SF; azoxystrobin), and a nontreated control (NC). The materials were applied by aerification or topdressing twice per year for two years. Over the two-year period, AW and SF reduced disease severity by 49% and 86% of those in NC, respectively, as measured by area under disease progress curve (AUDPC). Amendments applied resulted in a shift of soil gram positive to gram negative bacteria (G+/G–) ratio, with a similar trend as AUDPC. Additionally, aerification reduced the fungi to bacteria (F/B) ratio and stress indicators, compared to topdressing. These results suggested that aerification stressed fungi but stimulated bacteria. The AW amendment led to a significant large patch suppression, which may be associated with the reduced G+/G– ratio.