What causes replant disease?
■ Replant disease occurs when a plant is replaced by the same type, which then struggles to become established or put on good growth.
■ It mainly affects roses, apples, edible and flowering cherries, peaches, pears, plums and quince.
■ It is a little-understood problem, but one way of solving it is to dig up the ailing plant and move it to somewhere where its variety has not been grown before.
■ Other solutions include lining the sides of the planting hole with cardboard that will decompose by the time the plant is established.
■ Using mycorrhizal fungi (such as Rootgrow), well-rotted manure or high-nitrogen fertiliser when you plant can also strengthen roots.