Biologically based alternatives to methyl bromide for controlling a common soil-borne disease of tree fruits CALS Impact Statement

We are testing disease-resistant apple rootstocks, soil amendments with compost, and integrated fruit-growing practices in an effort to provide sustainable alternatives that eliminate the need for soil fumigation with broad-specturm biocides such as methyl bromide for control of a common disease problem in replanted orchards.

For 50 years, soil fumigants such as methyl bromide have been used to control soil-borne diseases of fruit and vegetable crops. These soil fumigants have been implicated in global ozone depletion, groundwater contamination, and human health problems. Our recent research has demonstrated that several new apple rootstocks from Cornell`s rootstock breeding program are genetically resistant to a disease complex that severely damages young apple trees in replanted orchards. These rootstocks could ensure successful renovation of orchards without the need for chemical soil fumigants, helping to protect the environment and improve the profitability of orchards in New York and other fruit-growing regions.

We planted an orchard on three new and three conventional rootstocks, in a site with severe apple replant disease. For four years we have monitored the growth and productivity of trees on each rootstock, and used DNA fingerprinting to study changes in soil microbial communities on each rootstock genotype. We are finding that apple rootstocks can influence strongly the microbial communities in soil around roots, and that yields are greater on disease resistant rootstocks in unfumigated soil than on susceptible rootstocks in fumigated soil.

Apple growers in New York, Washington, New Zealand, and other fruit growing regions are interested in these and other new rootstocks from Cornell`s rootstock breeding and development program. Propagation and commercialization of these rootstocks has been accelerated. We are also developing a more comprehensive understanding of the microbial ecology of apple replant disease, and the role of rootstock genetics in resistance or tolerance to soil-borne plant diseases. This knowledge will enable development of more biologically based controls for soil-borne diseases, reducing the need for chemical soil fumigants and pesticides.

- Federal Formula Funds - Research (e.g., Hatch, McIntire-Stennis, Animal Health)
- Private/Other (e.g., unrestricted funds, commodity groups, foundations, companies)

Overview