Trees show no definite symptoms other than poor growth. They produce lower yields than trees grown on virgin soil or on sites where other crops have been grown. Effects can range from slight to severe, and can endure for the life of the planting. Soil fumigation before planting is often recommended to control replant disease, although it's never been known exactly what in the soil causes the problem and fumigation is not always a successful solution.
Fumigation sterilizes the soil and eliminates many different organisms.
Potential causes of replant disease include nematodes, fungi, bacteria, and plant nutrition. It is likely that different problems or combinations of problems are involved in different sites.