Gymnosporangium Rusts

Gymnosporangium rusts, such as Cedar Apple Rust, need both junipers and woody plants in the rose family to complete their life cycle. Learn more in this factsheet.

Gray Mold (Botrytis Blight)

Gray mold (or Botrytis blight) is a common and often serious fungal disease that can affect plants of all kinds. Learn more in this factsheet.

Tar Spot of Trees and Shrubs

Tar spot is a common, visually distinctive and primarily cosmetic fungal leaf spot disease that can affect many species of maple, including silver maple, sugar maple and Norway maple. Learn more in this factsheet.

Herbicide Damage

Herbicide damage is any adverse, undesired effect on a plant that is caused by exposure of that plant to a pesticide designed for weed control. Learn symptoms and more in this factsheet.

Armillaria Root Disease

Armillaria root disease, a/k/a shoestring root rot, can affect most conifer and hardwood species, and is an often lethal disease of tree and shrub roots and lower stems. Learn more in this factsheet.

Deciduous Tree Galls

Galls are abnormal growths on plants that can result from the feeding of living organisms such as bacteria, fungi, nematodes, insects and mites. Learn about common galls in this factsheet.

Maple Gall Mites (Eriophyidae)

Inside little green or red bumps or other weird growths on maple leaves are tiny eriophyid mites, feeding on the developing gall tissue. Learn more about these mites and what to do about them in this article on maple gall mites.

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