Plant Soil (2014) 374:611–627 DOI 10.1007/s11104-013-1909-4 REGULAR ARTICLE Rapeseed rotation, compost and biocontrol amendments reduce soilborne diseases and increase tuber yield in organic and conventional potato production systems Edward Bernard & Robert P. Larkin & Stellos Tavantzis & M. Susan Erich & Andrei Alyokhin & Serena D. Gross Received: 24 April 2013 /Accepted: 6 September 2013 /Published online: 24 September 2013 # Springer Science+Business Media B.V. (outside the USA) 2013 Abstract Results Rapeseed rotation reduced all observed soil- Aims Integrating multiple soil and disease manage- borne diseases (stem canker, black scurf, common ment practices may improve crop productivity and scab, and silver scurf) by 10 to 52 % in at least one disease control, but potential interactions and limita- year at both sites. Compost amendment had variable tions need to be determined. effects on tuber diseases, but consistently increased Methods Three different potential disease-suppressive yield (by 9 to 15 %) at both sites. Biocontrol effects management practices, including a Brassica napus on disease varied, though Rhs1A1 decreased black (rapeseed) green manure rotation crop, conifer-based scurf at the conventional site and T. virens reduced compost amendment, and three biological control or- multiple diseases at the organic site in at least one year. ganisms (Trichoderma virens, Bacillus subtilis, and Combining rapeseed rotation with compost amend- Rhizoctonia solani hypovirulent isolate Rhs1A1) were ment both reduced disease and increased yield, where- evaluated alone and in combination at sites with both as biocontrol additions produced only marginal addi- organic and conventional management histories for tive effects. their effects on soilborne diseases and tuber yield. Conclusions Use of these treatments alone, and in combination, can be effective at reducing disease and increasing yield under both conventional and organic production practices. Responsible Editor: Hans Lambers. : : E. Bernard S. Tavantzis A. Alyokhin Keywords Biocontrol . Compost amendment . School of Biology and Ecology, University of Maine, Disease-suppressive . Disease management . Potato Orono, ME 04469, USA production . Rhizoctonia solani . Brassica rotation R. P. Larkin (*) USDA-ARS, New England Plant, Soil and Water Laboratory, Orono, ME 04469, USA Introduction e-mail: [email protected] Potato (Solanum tuberosum L.) growers face many M. S. Erich Department of Plant, Soil, and Environmental Sciences, challenges from seed- and soilborne pathogens, includ- University of Maine, ing reduced plant growth and vigor, as well as losses in Orono, ME 04469, USA tuber quality and total and marketable yield. The plant pathogens Rhizoctonia solani Kühn, Helminthosporium S. D. Gross Purdue University, solani Durieu & Mont., and Streptomyces scabiei (ex. West Lafayette, IN 47907, USA Thaxter) Lambert & Loria cause the economically 612 Plant Soil (2014) 374:611–627 important diseases stem canker and black scurf, silver and black scurf in potato. Larkin et al. (2011a)repor- scurf, and common scab, respectively. Short rotation ted a reduction in stem and stolon canker in a man- lengths in many potato production systems exacerbate agement system incorporating compost when com- the problems caused by these diseases (Errampalli et al. pared to the continuous potato control, but black scurf 2001; Specht and Leach 1987; Wharton et al. 2007)but and common scab were comparable between the con- specific crop rotations and organic matter amendments trol and the system incorporating compost. Tuber yield provide control of many plant pathogens (Cohen et al. was, however, increased in the system incorporating 2005; Kirkegaard and Sarwar 1998; Larkin 2008; compost (Larkin et al. 2011a). While this previous Larkin and Honeycutt 2006). study utilized composts derived from dairy manures Brassicaceous species, in particular, have profound (Larkin et al. 2011a), a novel mechanism of suppres- effects on seed- and soilborne diseases of potato sion of rhizoctonia disease in potato is also associated (Cohen et al. 2005; Larkin and Griffin 2007; Larkin with conifer-bark based composts. When conifer bark et al. 2010; Larkin and Honeycutt 2006; Larkin et al. breaks down it releases quinic acid (Boudet 1973), 2011a; Larkin et al. 2011b; Lazarovits 2010). which induces hypovirulence (the attenuation of Brassicaceous plants are known to produce gluco- disease-producing capability) in virulent isolates of sinolates, which break down to produce volatile com- R. solani (Liu et al. 2003). Larkin and Tavantzis pounds that are toxic to many plant pathogens, through (2013) have demonstrated reductions in stem canker a process known as biofumigation (Matthiesen and and increases in tuber yield with the usage of a Kirkegaard 2006;Sarwaretal.1998). The adoption of conifer-based compost. a canola or green manure rotation crop has been associ- Several biological control organisms have shown ated with significant decreases in severity and incidence potential in reducing plant diseases (Asaka and Shoda of black scurf and stem canker (Larkin and Griffin 2007; 1996; Bénítez et al. 2004; Lewis and Papavizas 1987). Larkin et al. 2010; Larkin and Honeycutt 2006), as well Several species belonging to the genus Trichoderma as common scab (Larkin and Griffin 2007;Larkinetal. are capable of parasitizing fungal plant pathogens such 2010). Other brassicaceous species, including oriental as R. solani, producing antibiotics effective against mustard (Brassica juncea) and rapeseed (B. napus soilborne pathogens and competing for infection sites ‘Dwarf Essex’) reduce black scurf and stem canker against pathogens (Bénítez et al. 2004; Vinale et al. (Larkin and Griffin 2007;Larkinetal.2010). Increases 2008). Trichoderma virens and T. harzianum have in tuber yield associated with brassicaceous crops have been shown to be effective at controlling stem can- been inconsistent, despite the beneficial disease suppres- ker and black scurf, as well as increasing tuber yield sive effects (Campiglia et al. 2009; Larkin and Griffin (Brewer and Larkin 2005;Tsroretal.2001;Wilson 2007;Larkinetal.2010), which is comparable to the et al. 2008a; Wilson et al. 2008b). Kurzawińska effects of other rotation crops on tuber yields in potato (2006) also demonstrated an antagonistic effect of production systems (Carter et al. 2003; Davis et al. several Trichoderma species on H. solani, providing 1996). evidence for the potential suppression of silver scurf Organic matter amendments such as composts may by Trichoderma. The bacterium Bacillus subtilis has also provide control of some soilborne diseases disease-suppressive activity against some plant path- (Bonanomi et al. 2010; Hoitink and Boehm 1999; ogens. The production of antibiotics by B. subtilis Larkin et al. 2011b; Liu et al. 2007), though these is effective at controlling tomato damping off, effects may be more variable than results observed with which is caused by R. solani (Asaka and Shoda rotation crops (Bonanomi et al. 2010; Termorshiuzen 1996). Control of black scurf and stem canker by et al. 2007). Suppression of black scurf of potato has B. subtilis have been previously reported (Brewer been reported with composted cow manure (Tsror and Larkin 2005;Larkin2008;Larkinand et al. 2001) and suppression of other R. solani diseases Tavantzis 2013), as well as increases in tuber yield has been reported with green wastes and composted (Larkin and Brewer 2005). Other species of cow manures in other systems (Noble and Coventry Bacillus have exhibited antagonistic activity against 2005;Paneetal.2011). Al-Mughrabi et al. (2008) common scab (Han et al. 2005) and silver scurf reported that various compost tea drenches and foliar (Martinez et al. 2002). Non-pathogenic isolates of of applications reduced the severity of both silver scurf R. solani have demonstrated potential as biological Plant Soil (2014) 374:611–627 613 control agents (Tsror et al. 2001; Bandy and Tavantzis Materials and methods 1990), including a naturally occurring hypovirulent isolate known as Rhs1A1. Rhs1A1 reduced black Field Sites Field trials were conducted during 2007– scurf and stem canker of potato when applied in 2009 at two sites in northern Maine. The sites were field experiments (Bandy and Tavantzis 1990; Wood Prairie Farm (WPF) a commercial, organic farm Larkin and Tavantzis 2013). It was also reported to in Bridgewater, Maine that has been using organic increase dry weight of stem and stolons in a previous production and management practices for 35 years, study (Bandy and Tavantzis 1990), though direct effects and Aroostook Research Farm (AF) a University of on tuber yield have not been observed (Larkin and Maine Agriculture and Forestry Experiment Station Tavantzis, 2013). farm located 35 km north of WPF in Presque Isle, In this study, we evaluated three different disease Maine, that has a history (decades) of conventional management approaches, compost amendment, bio- potato production practices. Soil type at WPF was a control organisms, and a disease-suppressive rota- Mapleton loam (fine-loamy, mixed superactive, frigid, tion, for their individual and combined effects on Dystric Eutrudepts) and soil type at AF was a Caribou soilborne diseases, as well as total and marketable gravelly loam (fine-loamy, isotic, frigid, Typic tuber yield. Although many reports exist on the Haplorthods). Soil physical characteristics (texture) effects of some of the individual treatments incor- were similar at both sites,