Articles
DIAGNOSIS OF APPLE REPLANT PROBLEMS IN NEW YORK ORCHARD SOILS AND EVALUATION OF NEMATODE-SUPPRESSIVE COVER CROPS
Article number
363_16
Pages
121 – 128
Language
Abstract
Nearly half of the New York tree-fruit growers we surveyed reported serious problems in replanting their orchards.
Past research has established that one of the more effective preventive treatments for orchard replant disorders (ORD) has been soil fumigation with broad-spectrum biocides or nematicides.
Increasing restrictions on the use of many soil fumigants necessitate the development of alternative treatment strategies for ORD. The objectives of our studies were to evaluate several cover crops or cultural practices for controlling fruit-tree root pathogens associated with ORD, and to investigate the mechanisms of nematode suppression by certain plants.
We have sampled soils from orchards in the major fruit-growing regions of New York, identifying and quantifying phytonematodes at each site.
We then assessed ORD using a diagnostic bioassay comparing dry weights of apple seedlings grown for 10 weeks in steam-pasteurized (PS) versus untreated field soil (FS). Seedling dry weight ratios (PS:FS) ranged from 1.1 to 7.6. Severe stunting (PS:FS > 2.0) of apple seedlings occurred in half of the non-treated soils, in association with substantial populations of Pratylenchus penetrans and/or Xiphinema spp. nematodes.
We selected five ORD soils for further evaluation of the effects of preplant marigold (Tagetes patula cv.
Sparky), canola (Brassica campestris cv.
Humus), endophyte infested (Acremonium spp.) perennial ryegrass (Lolium perenne cv.
Repel II), sudan grass (Sorghum sudanense), or white clover (Trifolium repens cv.
Sonja) cover crops, and ClandoSan (a chitin-protein plus urea formulation) soil amendment, upon the subsequent growth of apple seedlings in each soil.
We also analyzed leachate from soil/cover crop combinations for toxicity to P. penetrans cultures at crop maturity, and following soil incorporation and breakdown of each cover crop.
Preliminary studies with aqueous leachates showed no significant differences in nematode mortality in cover crop leachates compared with water controls.
Past research has established that one of the more effective preventive treatments for orchard replant disorders (ORD) has been soil fumigation with broad-spectrum biocides or nematicides.
Increasing restrictions on the use of many soil fumigants necessitate the development of alternative treatment strategies for ORD. The objectives of our studies were to evaluate several cover crops or cultural practices for controlling fruit-tree root pathogens associated with ORD, and to investigate the mechanisms of nematode suppression by certain plants.
We have sampled soils from orchards in the major fruit-growing regions of New York, identifying and quantifying phytonematodes at each site.
We then assessed ORD using a diagnostic bioassay comparing dry weights of apple seedlings grown for 10 weeks in steam-pasteurized (PS) versus untreated field soil (FS). Seedling dry weight ratios (PS:FS) ranged from 1.1 to 7.6. Severe stunting (PS:FS > 2.0) of apple seedlings occurred in half of the non-treated soils, in association with substantial populations of Pratylenchus penetrans and/or Xiphinema spp. nematodes.
We selected five ORD soils for further evaluation of the effects of preplant marigold (Tagetes patula cv.
Sparky), canola (Brassica campestris cv.
Humus), endophyte infested (Acremonium spp.) perennial ryegrass (Lolium perenne cv.
Repel II), sudan grass (Sorghum sudanense), or white clover (Trifolium repens cv.
Sonja) cover crops, and ClandoSan (a chitin-protein plus urea formulation) soil amendment, upon the subsequent growth of apple seedlings in each soil.
We also analyzed leachate from soil/cover crop combinations for toxicity to P. penetrans cultures at crop maturity, and following soil incorporation and breakdown of each cover crop.
Preliminary studies with aqueous leachates showed no significant differences in nematode mortality in cover crop leachates compared with water controls.
Publication
Authors
P.T. Pruyne, I.A. Merwin, P.G. Mullin, D.M. Gibson
Keywords
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