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Maple Bladder Gall


Galls are irregular plant growths which are stimulated by the reaction between plant hormones and powerful growth regulating chemicals produced by some insects or mites. Galls may occur on leaves, bark, flowers, buds, acorns, or roots. Leaf and twig galls are most noticeable. The inhabitant gains its nutrients from the inner gall tissue. Galls also provide some protection from natural enemies and insecticide sprays. Important details of the life cycles of many gall-makers are not known so specific recommendations to time control measures most effectively are not available.

What is a plant gall?

  • A gall is a plant structure formed by abnormal growth within plant tissues

  • The growth is a reaction to a parasitic attack on/in the plant's cells

  • Galls are numerous, widespread, and come in a variety of shapes and colors

  • By looking at a gall's shape, color, and location on the plant, you can determine what organism caused it

Hershey Kiss Gall

What causes a gall?

  • Excluding viruses, there are 5 major gall-causes: Bacteria, Fungi, Nematode, Acarina and Insecta

  • Each species of gall-cause attacks a specific plant structure, such as the leaves or the roots

  • Because the gall-causers do not destroy the plant, but slowly uses its' nutrients, they can be called parasites

  • The parasites can move inside or remain outside of the plant structures

  • In either case, the parasites act only as a growth stimulus

  • The gall is made up entirely of the plant's (the host's) tissues

  • The plant reacts to the parasite's intrusion by increasing the number of plant cells or enlarge the cell's size

  • Gall tissues form a "bubble" around the gall-causes in order to separate the parasites and any of their harmful by-products from the rest of the plant

  • Therefore, the gall is the plant's way of protecting itself from intruders