Agriculture Reference
In-Depth Information
ROSETTE
months and are often absent from leaves forming during
summer.
■
Cause
A virus complex of
Prune dwarf virus
and
Prunus necrotic
ringspot virus
.
Source of infection and spread
The major means of spread is by vegetative propagation.
The viruses are transmitted in infected budwood, clonal
rootstocks and seed used for seedling rootstocks. Spread
within an orchard can also occur via infected pollen
carried by pollinating insects.
Symptoms
Peaches and nectarines are affected.
Internodes of affected plants are shortened giving the new
growth a bunched, compact appearance. In severe cases, leaves
may be small and rolled. However, in mild cases, the almost
normal summer growth may obscure the spring symptoms.
Importance
Prunus ringspot is a serious problem if virus-tested
propagating material is not used.
Source of infection and spread
Both viruses may be carried in seed or budwood. Trees may
be infected for some time before showing symptoms, and
budwood taken during this time will produce diseased trees.
Although only one virus causing the disease may be present
in young trees when propagated, the rosette and decline may
The disease affects plant vigor, reduces yield and may
cause skin defects, reduced quality and reduce storage
times for fruit.
Management
•
Avoid planting, propagating or top-working trees with
virus-infected material.
Plant healthy trees some distance from older, infected
trees to reduce the chances of virus infection from
infected pollen.
•
Fig 17.28 Virus induced line pattern symptoms on plum leaves.
Fig 17.29 Peach rosette caused by infection with two viruses.
