Critical aspects of grafting as a possible strategy to manage soil-borne pathogens

Abstract

The management of soil-borne pathogens is nowadays complicated by the increasing restrictions in the usage of fumigants. Several factors need to be considered for a sustainable use of this practice such as the susceptibility of rootstocks against soil-borne pathogens which is age-dependent and the incomplete resistance of some of the rootstocks to one or more pathogens. There is an evidence of a pathogenic variation among some isolates of Phytophthora spp. on solanaceous crops and on rootstocks and the development of new diseases or the re-emergence of already known pathogens such as Colletotrichum coccodes after the phase out of methyl bromide. The critical aspects of grafting for soil-borne pathogens management in Italy are discussed.Keywords: solanaceaous crops, Phytophthora nicotianae, Phytophthora capsici, Colletotrichum coccodes 1.IntroductionIn Italy, 59 million vegetable plants, generally grown under greenhouse, are grafted (Morra and Billotto, 2010). In Piedmont (northern Italy) grafted plants are mostly used in tomato cropping system but is becoming more popular also in the case of bell pepper and, in some areas, on melon.Grafted tomatoes are used to reduce susceptibility against pest and root and wilt diseases and to increase yield (Louws et al., 2010;Rouphael et al., 2010). However, resistance may be broken down under high pathogen population pressure and new races of the pathogen may evolve on rootstocks. Recently, some emerging diseases on plants grafted on rootstocks have been recorded in Italy. Verticillium wilt incited by Verticillium dahliae was consistently observed on eggplant grafted on Solanum torvum (Garibaldi et al. 2005), while Colletotrichum coccodes attacks were observed on grafted tomato plants grown in several farms after repeated cropping cycles of tomato (Minuto et al. 2008). This last pathogen can infect several cultivated species, including pepper, potato, eggplant, lettuce, chrysanthemum and some species of Cucurbitaceae and Brassicaceae (Dillard, 1992;Last et al., 1966). Among Phytophthora group, both P. nicotianae and P. capsici can affect tomato (Erwin and Ribeiro, 1996). Rootstocks belonging to interspecific hybrids of Solanum lycopersicum x S. hirsutum (cvs. Beaufort, He Man) and to S. lycopersicum (cv. Energy) were Due to an increased request of grafted plants, experimental activities have been carried out to evaluate the effectiveness of grafting on resistant rootstock against emerging soilborne diseases of tomato. The rootstocks used in this study are considered resistant to many other soil-borne diseases, but their tolerance to P. nicotianae, P. capsici and C. coccodes is not known. 2.Materials and methods Experimental layout.The first set of trials was carried out in 2010 under growth chamber conditions at Agroinnova (Univesity of Torino) to test the susceptibility of several tomato rootstocks to Phytophthora nicotianae and P. capsici under artificial inoculation conditions. The second set of trials was carried out in 2010 in a plastic tunnel at Boves (Cuneo)...

Yield and fruit quality of grafted tomatoes, and their potential for soil fumigant use reduction. A meta-analysis

“…Tomatoes (processing and fresh market) are a major user of soil fumigants in the world's major production areas: the USA, Europe, and Asia (Qiao et al 2010;Deacon et al 2016;Desaeger et al 2017;Grieneisen et al 2017). One of the major benefits of using grafted tomatoes lies in the multi-pathogen resistance of most of the commercially available rootstocks, and the potential for that resistance to reduce the cost and environmental impacts associated with fumigant use in tomatoes (e.g., Rivard and Louws 2008a;Louws et al 2010;Gilardi et al 2013;Kokalis-Burelle et al 2016;Reddy 2016). In some cases, grafting onto pathogen-resistant rootstocks has produced yield increases comparable to fumigation treatments in pathogeninfested experimental systems (e.g., Rivard et al 2010b;Kokalis-Burelle et al 2016).…”

Graft Takes of Tomato on Other Solanaceous Plants

“…To overcome some of these hurdles, farmers rely on grafting technique, which consists in bonding parts of two plants by means of tissue regeneration developing a single plant (PEIL, 2003;CARDOSO et al, 2006;LOOS;CALIMAN;SILVA, 2009;SIRTOLI et al, 2011). Such tool make use of root systems (rootstocks) that are resistant, enabling control of diseases and pests related to the soil (LIN et al, 2008;RIVARD et al, 2012;GILARDI;GULLINO;GARIBALDI, 2013).…”

Survival and compatibility of tomato grafted on solanaceous plants and by different grafting methods

“…The use of appropriate rootstocks may confer resistance to grafted seedlings, allowing control of soilrelated phytosanitary problems (Rivard et al, 2012;Gilardi et al, 2013). Moreover, it may also confer tolerance to salinity (Colla et al, 2010;Flores et al, 2010) and high and low temperatures (Martinez-Rodriguez et al, 2008;Venema et al, 2008;Abdelmageed & Gruda, 2009), and increase the water absorption efficiency and nutrient utilization (Santa-Cruz et al, 2002;He et al, 2009), physiological performance (Abdelmageed & Gruda, 2009), production and fruit quality (Flores et al, 2010).…”