Galls are abnormal swellings, lumps or growths which can occur on virtually any type of plant tissue.
Galls can be caused by certain fungi, bacteria, insects or nematodes.
Crown Gall: Bacterial gall (Agrobacterium spp)
Large bumpy growths occur at the bottom of stems or trunks, sometimes on roots of plants, such as peaches, roses, grapes, apples, and dahlias.
Control: Destroy affected plants. Dipping plant material during propagation with fungicides, or in a weak bleach solution.
Bacterial Gall on Oleander (Pseudomonas syringae pv. savastanoi)
Entry of this bacteria is through damaged plant material caused by pruning, wind damage, vandalism, etc. Stems, leaves, flowers and fruiting bodies are all infected. Younger leaves may split open resulting in rough lesions and may be distorted. Rough woody galls may appear on fruiting bodies (seed capsules).
Control: Prune off infected material and burn. Disinfect secateurs between cuts. maintain the plant in active healthy growth by supplying suitable fertilizers and watering.
Azalea Leaf Gall (Exobasidium vaccinii)
Affects blueberries, azaleas & rhododendrons.
Symptoms: Leaves & flowers commonly develop bladder-like swellings. Sometimes other parts will also be affected. Remove & destroy infected parts, spray the remainder with copper-based sprays.
Stem Gall on Wattles (Botryosphaeria acaciae)
Small cushion-like galls, up to 10mm across, appear on the stems either singly or in groupings, producing a knobbly appearance.
Control: Prune off infected material and dispose of it.
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