An occurrence and importance of apple replant disease in Polish orchards

The occurrence of apple replant disease in Polish orchards was investigated in 1986-1994. Soil samples were collected from 244 apple orchards in the most important fruit growing regions. The biological tests, using apple seedlings of cv. Antonovka as test plants, have been applied for determining its occurrence, type and intensity as related to different factors. The replant disease has been determined in 60.7% of the investigated orchards. Its occurrence was more frequent in light than heavy and in neutral or slightly acidic than in acidic soils. Disease was specific in 27.9%, unspecific in 16.4% and mixed in 16.4% of the orchards. It was confirmed that root parasitic nematodes are responsible for unspecific type of replant disease.