Anatomy of bark of bud union, trunk, and roots of quick-decline-affected sweet orange trees on sour orange rootstock

This paper concerns the sequence of anatomical changes occurring in sweet orange trees on sour orange rootstock after infection by quick decline. The primary symptom is necrosis of sieve tubes below the bud union. This symptom is followed by degeneration of the older sieve tubes above the union, accelerated cambial activity, and other reactions of a secondary nature.