Apricot: Bacterial canker Categories: Apricot Apricot Diseases Tree Fruits Last review date: 2026-01-29 02:57 Bacterial canker on apricot Photo by: R.S. Byther Biology Bacterial canker is favored by cool, wet weather and is common in western Washington. The bacteria overwinter in cankers, buds and other host tissues. Dark, cankered areas on trunks and branches may […]
Walnut: Anthracnose (Blotch) Categories: Tree Fruits Walnut Walnut Diseases Last review date: 2025-08-23 12:19 Walnut anthracnose infection on leaf Photo 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 […]
Walnut: Blackline Categories: Tree Fruits Walnut Walnut Diseases Last review date: 2025-08-23 12:21 Walnut with bark cracks and blackline at graft union Photo 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 […]
Walnut: Blight Categories: Tree Fruits Walnut Walnut Diseases Last review date: 2025-08-23 12:24 Walnut blight symptoms on husks Photo 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 […]
Walnut: Thousand cankers disease Categories: Tree Fruits Walnut Walnut Diseases Last review date: 2025-08-23 12:29 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 […]
Walnut: European fruit lecanium Categories: Tree Fruits Walnut Walnut Insects Last review date: 2025-08-23 12:31 Lecanium scales on twig Photo 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 […]
Walnut: Walnut aphid Categories: Tree Fruits Walnut Walnut Insects Last review date: 2025-08-23 12:33 Green peach aphid closeup Photo 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 […]
Walnut: Walnut blister mite Categories: Tree Fruits Walnut Walnut Insects Last review date: 2025-08-23 12:34 Walnut blister mite damage Photo 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 […]
Walnut: Walnut husk fly Categories: Tree Fruits Walnut Walnut Insects Last review date: 2025-08-23 12:36 Walnut husk fly damage Photo 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. […]
Walnut: Walnut twig beetle Categories: Tree Fruits Walnut Walnut Insects Last review date: 2025-08-23 05:01 Walnut twig beetle adult Photo 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 […]
Plum, Prune (Fresh): Armillaria root rot Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:22 White fungal mat of Armillaria root rot infecting trunk Photo by: C.R. Foss Biology Armillaria root rot is a fungal disease often found in newly cleared soils or soils which have been flooded. Aboveground […]
Plum, Prune (Fresh): Bacterial canker Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:29 Sunken area on trunk from bacterial canker infection Photo by: R.S. Byther Biology Bacterial canker can infect twigs, branches, fruit, or the trunk. Elongated, dark, purplish cankers develop during early spring, often producing bacterial ooze […]
Plum, Prune (Fresh): Black knot Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:30 Mature black knot on twig Photo by: R. Byther Biology Black knot is a fungal disease that infects cherry and plum. Early infections of twigs are elongated olive-green, corky knots. They turn black and hard […]
Plum, Prune (Fresh): Brown rot Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:33 Brown rot mummified plum Photo by: R.S. Byther Biology Brown rot is a blossom-infecting fungal disease. Infected flowers first appear water-soaked, then wilt and die. The light brown blossoms remain attached to the twigs, becoming […]
Plum, Prune (Fresh): Crown gall Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:34 Large gall on crown Photo by: R.S. Byther Biology Crown gall is caused by a soilborne bacterium. The bacteria infect through wounds on the crown and roots. Young galls are fleshy, white, enlarged masses on […]
Plum, Prune (Fresh): Cytospora canker Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:36 Cytospora-infected peach twigs Photo by: R.S. Byther Biology The fungi which cause Cytospora canker attack through wounds on twigs and branches. Initial cankers are small but enlarge quickly and may streak up and down the […]
Plum, Prune (Fresh): Plum pockets Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:38 Plum pocket infected fruit Photo by: R.S. Byther Biology Plum pockets is a fungal disease affecting fruit, twigs, and leaves. Infected fruit initially develop small, white spots which rapidly enlarge. The spots later turn reddish […]
Plum, Prune (Fresh): Russeting Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:39 Fruit russeting on plum Photo by: R.S. Byther Biology Russeting of plum can be caused by several factors. Rain during the period of full bloom, mechanical rubbing against other fruit or branches caused by wind, or […]
Plum, Prune (Fresh): Shothole (Coryneum blight) Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:41 Coryneum blight symptoms on leaves and fruit Photo by: R.S. Byther Biology Coryneum blight is a fungal disease. Lesions on leaves are initially small, purplish, round to oval areas which expand into brown spots […]
Plum, Prune (Fresh): Silver leaf Categories: Plum, Prune (fresh) Plum, Prune (Fresh) Diseases Tree Fruits Last review date: 2025-08-23 07:43 Silver leaf symptoms on leaves Photo by: R.S. Byther Biology Silver leaf is a fungal disease affecting cherry, apricot, plum, and other stone fruits. The fungus typically grows on dead wood, but it can infect […]