Walnut Pest Management Guidelines
UC agricultural management guidelines for control of walnut pests. Relative Toxicities of Pesticides Used in Walnuts to Natural Enemies and Honey Bees (12/07) Walnut Weed Photo Gallery, with Common and Scientific Names (12/07) Integrated Pest ... [... more]
University of California IPM |
Lesion nematode: Pratylenchus vulnus
The severity of nematode damage depends on the age of the tree and density of the nematode population. If young trees are replanted in a heavily infested site, the roots will be severely damaged and the trees stunted and weak. Mature trees can ... [... more]
University of California IPM |
Scientific Name: Hyphantria cunea
From July to September, fall webworm caterpillars can be found forming silken tents and skeletonizing leaves, leaving behind only leaf veins. On small trees, infested twigs may be cut out and destroyed. Insecticide sprays applied for other pests ... [... more]
University of California IPM |
Walnut Blight
In walnut blight, one to several black lesions may appear on catkins. Infected nuts develop black, slightly sunken lesions at the flower end (end blight) when young; more lesions will develop on the sides of the nut as it matures (side blight). ... [... more]
University of California IPM |
Establish Female Biofix
Monitoring and treatment decisions in a mating disruption orchard Monitoring and treatment decisions in a conventional orchard Codling moths overwinter as full-grown larvae in thick, silken cocoons under loose scales of bark or in trash on the ... [... more]
University of California IPM |
Scientific Name: Diaspidiotus (=Quadraspidiotus) perniciosus
Female San Jose scale give birth to living young that emerge from under the edge of the scale covering. These tiny yellow crawlers wander in a random fashion until they find a suitable place to settle. Immediately upon settling, the crawlers ... [... more]
University of California IPM |
Scientific Name: Panonychus ulmi
The European red mite overwinters in the egg stage on twigs and branches. The red orange eggs have a long spike that is visible with a hand lens. Eggs hatch in early spring when the walnuts leaf out. Immature mites are bright red; adult females ... [... more]
University of California IPM |
Tolerant rootstocks.
Trees with Armillaria root rot have thin canopies with yellow leaves and twig, shoot, or limb dieback. Infected roots have white rot wood decay with white to yellowish fan-shaped mycelial mats (plaques) between the bark and the wood. Dark brown ... [... more]
University of California IPM |
Walnut Husk Fly
The adult walnut husk fly is about the size of a housefly and very colorful. A yellow spot just below the area where the wings are attached and a dark triangular band at the tip of the wings distinguishes the husk fly from other flies likely to ... [... more]
University of California IPM |
Frosted Scale and European Fruit Lecanium
UC Management Guidelines for Frosted Scale and European Fruit Lecanium on Walnut. The frosted scale is the most important soft scale pest of walnuts. Its frostlike cover and copius honeydew secretion in spring make it easy to recognize. This ... [... more]
University of California IPM |
After weeds emerge (postemergent)
COMMENTS: Broadcast preplant incorporated. Plant tree roots below treated soil. Do not place treated soil near roots during planting. Controls many annuals, and is helpful on perennial weeds. Residual period: 2-12 months. COMMENTS: For use on ... [... more]
University of California IPM |
Pathogen: Agrobacterium tumefaciens
Crown gall appears as rough, abnormal galls at or below the soil surface on roots or trunk. Live galls are not hard but soft and spongy. The centers of older galls decay. Young trees become stunted. Older trees often develop secondary wood ... [... more]
University of California IPM |
