Managing Soilborne Disease of Potatoes Using Ecologically Based Approaches

Abstract

Soil fumigation and planting resistant cultivars remain the primary means for control of soilborne plant diseases. Fumigation however, is being constrained by increased costs, urbanization, and its negative environmental impacts. Resistance genes to soilborne pathogens are not available for many crop species. Using verticillium wilt as model disease we examined the potential of non chemical alternatives, specifically the use of organic amendments and green manures, as disease management tools. Application of organic products reduces disease incidence in controlled settings but its application in commercial use was hampered by inconsistent efficacy. Studies now have demonstrated that by-products of animal and plant production, such as meat and bone meal, feather meal, poultry and swine manure, soy meal, etc. can significantly reduce diseases but that the level of control obtained is product and soil specific. Three mechanisms of action for pathogen reduction were identified: 1) generation of toxic compounds such as ammonia and nitrous acid from high nitrogen-containing materials, 2) presence of volatile fatty acids (e.g. vinegar) and 3) alterations in biological agents that may suppress the activity of plant pathogens. For products that work mostly through the generation of active chemical ingredients, knowing the properties that regulate efficacy allows targeting their use to specific locations and thus, increased activity and consistency. Much less is known about how such materials influence rhizosphere residents involved in regulating plant health. New molecular technologies are being implemented to identify key players in maintaining root health. Through an understanding of the microbial soil ecosystem we should be able to develop disease control strategies that are more economical to growers and are more environmentally benign.Resumen La fumigación del suelo y el uso de variedades resistentes permanecen como los primeros medios para controlar las enfermedades vegetales originadas en el suelo. No obstante, la fumigación está siendo limitada por el aumento en los costos, la urbanización, y sus impactos ambientales negativos. Los genes de resistencia a los patógenos del suelo no están disponibles para muchas especies de cultivos. Usando el modelo de enfermedad del marchitamiento por verticillium, examinamos el potencial de alternativas no químicas, específicamente el uso de mejoradores orgánicos y abonos verdes, como herramientas para el manejo de enfermedades. La aplicación de productos orgánicos reduce la incidencia de la enfermedad en condiciones controladas, pero su aplicación en uso comercial se impidió por eficacia inconsistente. Ahora los estudios han demostrado que los sub-productos de la producción vegetal y animal, tales como carne y harina de hueso o de plumas, estiércol de bovinos y cerdos, harina de soya, etc., pueden reducir las enfermedades significativamente, pero el nivel de control obtenido es producto específico del suelo. Se identificaron tres mecanismos de acción para la reducción del patóge...

Effect of Fodder Radish (Raphanus sativus L.) Green Manure on Potato Wilt, Growth and Yield Parameters

“…Defender planted plots [67]. Our results are also in line with those of Lazarovits [73] showing that incorporating millet over 3 years at two potato field sites, lead to 20% increased potato yields at one site and 50% at the other, but little decrease in Verticillium wilt incidence was observed.…”

Rates of Nitrogen Mineralization of Meat and Bone Meals in Mediterranean Soils

“…Several studies Potter 1999, 2005;Lazarovits 2010) found a suppression of the germination of Verticillium dahlie microsclerotia in some soils, with the mechanisms involved being described in Tenuta and Lazarovits (2004) and Lazarovits (2010).…”

Management of Verticillium Wilt of Potato with Disease-Suppressive Green Manures and as Affected by Previous Cropping History

“…Traditionally, control has focused on reducing the populations of microsclerotia in the soil, primarily through the use of chemical fumigants such as methyl bromide and metam sodium. The use of soil amendments and nonchemical approaches to the management of Verticillium wilt have been the subject of recent reviews (17,27,28). Previous research on the use of organic amendments, including animal and green manures, and diseasesuppressive crop rotations, has led to some very interesting and promising results.…”

“…Organic amendments, including chicken manure, liquid swine manure, and ammonium lignosulfonate, have been shown to reduce populations of V. dahUae and reduce Verticillium wilt; however, the specific results and active mechanisms depend on the particular soil and environmental conditions (6)(7)(8)27,41). Green manures of various crop plants, including sudangrass, rapeseed, broccoli, winter pea, com, oat, rye, and buckwheat, have all had significant effects in reducing Verticillium wilt in specific field studies (9,11,33,43,45).…”