Crown Gall (bacterium – Agrobacterium tumefaciens): This soil-borne bacterium will sometimes infect wisteria, causing galls or swellings on the main roots or stems. Inspect plants before buying and discard any plants with knots, galls, or swellings on the roots. (See the section on Crown Gall)
Leaf Spots (fungi – Phyllosticta wisteriae, Septoria wisteriae): Different fungi may cause leaf spots on wisteria. Pick off and destroy spotted leaves. Fungicide applications are normally not necessary.
Powdery Mildew (fungus –Erysiphe cichoracearum): A white-grayish mold develops on the surface of the leaves. Spray with a protective fungicide if the disease occurs frequently.
Root Knot Nematode (nematode – Meloidogyne spp.): (See the section on Root Knot Nematodes)
Cotton Root Rot (fungus – Phymatotrichum omnivorum): Wisteria is moderately susceptible to cotton root rot.
Consult the Chemical Control Supplement (B-1140A) for specific chemical control suggestions.