Walnut: Anthracnose (Blotch) categories: Tree Fruits Walnut Walnut Diseases revision date: 2022-12-05 12:00 Walnut anthracnose infection on leafPhoto by: R.S. Byther Biology Anthracnose or blotch of walnut is caused by a fungus. The disease affects leaves, young twigs, and nuts. Leaves develop irregularly circular reddish-brown to grayish-brown spots up to 3⁄4″ across. Severe infections on […]
Walnut: Blackline categories: Tree Fruits Walnut Walnut Diseases revision date: 2022-12-05 12:00 Walnut with bark cracks and blackline at graft unionPhoto by: J. W. Pscheidt Biology Blackline is a viral disease of English walnut (Juglans regia). It causes death of water-conducting tissues at the graft union. Initially, infected trees show poor growth, yellowing and drooping […]
Walnut: Blight categories: Tree Fruits Walnut Walnut Diseases revision date: 2022-12-05 12:00 Walnut blight symptoms on husksPhoto by: R.S. Byther Biology Walnut blight is a bacterial disease affecting leaves, nuts, and other new growth including flowers. Bacteria are spread to new growth in the spring by rainy weather during the bloom season. Leaves develop reddish-brown […]
Walnut: Thousand cankers disease categories: Tree Fruits Walnut Walnut Diseases revision date: 2022-12-05 12:00 Biology Thousand cankers disease (TCD) of walnut is a fungal disease associated with and spread by walnut twig beetles (WTB). Beetles feed on both healthy and damaged trees, but injured or weakened trees are more susceptible to rapid decline. The beetles […]
Walnut: European fruit lecanium categories: Tree Fruits Walnut Walnut Insects revision date: 2023-04-04 12:00 Lecanium scales on twigPhoto by: R.S. Byther Biology The European fruit lecanium is a shiny brown scale insect found on twigs. Adults are 1⁄8″ to 1⁄4″ in diameter and roughly turtle-shaped. They may have light markings or appear somewhat waxy. Crawlers […]
Walnut: Walnut aphid categories: Tree Fruits Walnut Walnut Insects revision date: 2023-04-04 12:00 Green peach aphid closeupPhoto by: Unknown Biology Walnut aphids are small, pale yellow, pear-shaped insects. They are typically found on the undersides of leaves. A second aphid species common on walnuts is the dusky-veined aphid, a grayish aphid found on upper leaf […]
Walnut: Walnut blister mite categories: Tree Fruits Walnut Walnut Insects revision date: 2022-12-05 12:00 Walnut blister mite damagePhoto by: R.S. Byther Biology The walnut blister mite is an eriophyid mite. These tiny, whitish, sausage-shaped mites cause raised green to yellowish blisters on the upper leaf surfaces. Beneath the blister, on the underside of the leaf, […]
Walnut: Walnut husk fly categories: Tree Fruits Walnut Walnut Insects revision date: 2023-04-04 12:00 Walnut husk fly damagePhoto by: A.L. Antonelli Biology Adult walnut husk flies are slightly smaller than a house fly. They are brown with a yellow mark on the back, and the otherwise clear wings are marked with dark bands. Females lay […]
Walnut: Walnut twig beetle categories: Tree Fruits Walnut Walnut Insects revision date: 2022-12-05 12:00 Walnut twig beetle adultPhoto by: S. Valley, ODA Biology The walnut twig beetle (WTB) is a small bark-boring beetle (Pityophthorus juglandis) believed to be native to the southwestern US. Not a great deal is known about the beetle’s life cycle, but […]