Citrus gumming
Gum formation in the pockets on the trunk or branches of citrus trees is typically due to a Phytophthora spp.
The wood beneath the blister shows a pink-orange color and it can be exacerbated by freeze damage, high water tables and salt accumulation. Gumming can also be caused by lack of copper.
Gumming that occurs under new bark or on fruits could be as a result of copper deficiency.
Growers should check using tissue analysis and apply the appropriate micronutrient fertilizers to the leaf to ensure supplies of copper are not limiting growth.
