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Disease Detection and Losses

Determining the Cause and Extent of Apple, Cherry, and Pear Replant Diseases Under Controlled Conditions. W. F. Mai, Professor, Departments of Plant Pathology, Cornell University, Ithaca, NY 14853 and Geneva, NY 14456; G. S. Abawi, Associate Professor, Departments of Plant Pathology, Cornell University, Ithaca, NY 14853 and Geneva, NY 14456. Phytopathology 68:1540-1544. Accepted for publication 25 May 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1540.

A replant disease of fruit trees was reproduced under growth chamber conditions. Apple, pear, and cherry seedlings, grown in nontreated apple, pear, or cherry orchard soils with histories of replant disease, were stunted and their roots were discolored and reduced in size. Although pre-treatment of the soil with dichloropropene-dichloropropane and related C₃ hydrocarbons (DD) resulted in an improvement in plant growth and development over the nontreated check, it was inferior to the chloropicrin and steam treatments. Growth response of apple, pear, and cherry seedlings to soil treatments was greatest in the apple replant soil. This soil contained high populations of Praty-lenchus penetrans and Paratylenchus projectus. The apple, pear, and cherry orchard soils were respectively sandy loam, loam, and loamy sand with pH values of 7.2, 5.5, and 5.7. We consider the replant disease of fruit trees in New York to be nonspecific and that biological agents in addition to plant parasitic nematodes (principally, P. penetrans) are involved in the replant disease of fruit trees in New York.