Pears are the most resistant tree fruit crop and are most likely to remain healthy in a relatively wet site. Among apple rootstocks, seedlings are relatively resistant. Among stone fruits, plums are relatively resistant, whereas the remainder are susceptible to very susceptible. Mahaleb is the most susceptible cherry rootstock, whereas Mazzard, Morello, and Colt are somewhat more resistant and would be recommended on heavier soils Soil fumigation is generally considered ineffective because it never completely eradicates the fungus from orchard soils, and the Phytophthora fungi are easily reintroduced into fumigated soil. New fungicides have recently been developed, which are effective in controlling these diseases when used preventively, but they are seldom effective in reviving trees once the crown has become infected and moderate symptoms of decline have appeared.
Fungicides are most effective when used in combination with the cultural practices described above.
New York State Agricultural Experiment Station, Cornell University Extension. Soil removal is important, because the disease can remain in the soil for over a year. Making sure that all organic matter is plowed under will give the fungus less places to develop.