Gummosis: Phytophthora parasitica, P. palmivora,P. citrophthora

Symptoms

• First symptoms are dark staining of bark which progresses into the wood.
• Bark at the base is destroyed resulting in girdling and finally death of the tree.
• Bark in such parts dries, shrinks and cracks and shreds in lengthwise vertical strips.
• Later profuse exudation of gum from the bark of the trunk.
• Infection extends to crown roots.
• Prolonged contact of trunk with water as in flood irrigation; water logged areas and heavy soils.
• Soil inhabitants.
• Sporangia spread by splashing rain water, irrigation water and wind.
• Irrigation water and wind.

Management

• Injuries to crown roots or base of stem during cultural operations should be  avoided.
• If lesion has girdled less than ½ the girth, remove the diseased bark with a knife along with ½” of uninvaded bark.
• Bark of trunk should be coated with Bordeaux paste.