Root and Crown Rots

This factsheet covers root/crown rot, which is a general term that describes disease of woody ornamentals where the causal organism attacks a plant’s root system and/or lower trunk or branches near the soil.

Purple Bordered Leaf Spot

Purple-bordered leaf spot (also called eye spot or Phyllosticta leaf spot) is a common, but mostly cosmetic, disease on maples. This factsheet describes symptoms and management.

Guignardia Leaf Spot

Guignardia leaf spot is a fungal leaf spot that affects vining plants such as Boston ivy and Virginia-creeper, and is associated with a leaf spot and fruit rot of grape called black rot. Learn more here.

Golden Canker (Cryptodiaporthe Canker)

Golden canker is a visually distinct and common disease of alternate-leafed dogwoods such as pagoda dogwood, which can be lethal if on the main trunk of a tree. Learn more in this factsheet.

Dutch Elm Disease

Dutch elm disease is a lethal fungal disease of native elms. This factsheet describes symptoms, spread and management of this serious disease.

Black Walnut Toxicity

Black walnut trees produce a toxic substance (called juglone) that prevents many plants from growing under or near them. Learn more about this compound and how to work around it in this factsheet.

Bacterial Blight

Bacterial blight is a disease of Chinese, Japanese, Persian and common lilac, as well as apple, pear, plum and cherry. This factsheet describes symptoms and management of this common disease.

Ash Yellows

Ash yellows is a chronic disease of ash trees, especially white ash, causing unusual leaf growth and witches brooms. It can also affect lilacs. Learn about this unusual disease in this factsheet.

Black Knot

Black knot is a disfiguring and potentially lethal disease of trees and shrubs in the genus Prunus, such as plums and cherries. This factsheet describes symptoms and management.

Sudden Oak Death

Sudden oak death (aka Ramorum) is mostly in California, but can be spread on a variety of nursery plants. This disease should be reported immediately. Learn what to look for in this factsheet.

Mistletoe

Hanging high in trees in warmer climates, mistletoe is a plant that has a long history of myth and tradition dating back to ancient times. To find out more about this interesting group of parasitic plants, read this article…

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