The Effects of Formalin and Other Soil Treatments on the Replant Disease of Apple

Various biocidal and fungicidal treatments were applied to the soil of a 39-year-old apple orchard and their effects studied on the growth of replanted apples. With pot-grown apple seedlings as test plants, pre-planting soil treatments with chloropicrin, propylene oxide, steam or formalin increased growth on average by 123% and did not differ significantly from one another; the effect of furalaxyl* was small. With M.9 rootstocks as test plants and in situ soil treatments, formalin increased growth on average by 188%; furalaxyl and metalaxyl* did not cause significant growth increases.