Specific Replant Diseases of Apple and Cherry and Their Control by Soil Fumigation

The characteristics of the disorders here termed "specific replant diseases”' are briefly described and an account is given of a three-year series of field studies. The test plants used were of apple (Malus pumila Mill.) and cherry (Prunus avium L.), each planted in cherry and apple land; the fumigants chloropicrin, chlorobromopropene, dazomet, dichloropropane-dichloro- propene, methyl bromide and methyl isothiocyanate, were applied at various rates prior to planting. All effected some improvement in plant growth, but chloropicrin proved outstanding, the growth of cherries being increased up to threefold by rates as low as 10 gallons per acre. Results obtained with apple were less clear-cut, probably because apple replant disease proved to be of little importance on the experimental fields used. Although these were primarily fumigant-screening trials, it can be deduced that tylenchid plant-parasitic nematodes do not cause either apple or cherry specific replant diseases.