Citrus Recovery Alert: Post-Cold Assessment Timeline for Grafted Orange Trees

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Accurate graft union identification serves as the dividing line between saving a commercial variety and cultivating rootstock. The graft union appears as an irregular swelling, slight diagonal scar, or noticeable trunk diameter change typically situated 4 to 12 inches above the soil line. On older trees, bark textures contrast sharply across this boundary.

Executing an accurate freeze injury assessment requires physical testing rather than visual assumptions:

First, run a thumbnail or clean pocket knife along the trunk bark, scratching a 0.25-inch window. Bright emerald green beneath the outer layer signals living, functional cambium. Pale yellow, tan, or mushy brown cambium indicates structural vascular death. Start at the top canopy branches and work systematically downward toward the root collar. Mark the precise boundary where brown cambium transitions back into firm green tissue.

Second, inspect the bark for vertical splitting. Hard freezes expand trunk fluids, popping the outer bark open. Even if the leaves remain green initially, severed bark prevents downward nutrient transport from foliage to roots, causing delayed canopy collapse once summer heat spikes arrive.