Pear rust: how to recognise and treat it

Disease

Pear rust — Photo: Maurice Flesier, CC BY-SA 4.0, Wikimedia Commons

Symptoms

Bright orange spots on the upper side of pear leaves in summer and early autumn.
Brown acorn-shaped growths up to 6 mm tall under the leaf spots.
On juniper, swellings on stems and branches that push out orange jelly-like masses in wet spring weather.
The fungus needs both pear and juniper to complete its life cycle.

Organic treatment

Cut out infected juniper branches or remove infected junipers near pears.
Prune out cankers on pear branches.
Do not strip heavily infected pear leaves; losing them harms the tree more than the rust.

Chemical treatment

Fungicide with myclobutanil on pears from the pink bud stage in spring; follow the label dose and pre-harvest interval.

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Prevention

Do not plant susceptible junipers such as Juniperus sabina, J. chinensis or J. scopulorum near pears.
Choose J. communis, J. horizontalis or J. squamata, which are immune or highly resistant.
Buy rust-free juniper plants.

Plants it affects

Sources

Figures checked against these sources.