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The Relation of Physiological Stage, Preconditioning, and Rate of Fall of Temperature to Cold Injury and Decline of Peach Trees1


Freezing tests were conducted on 1-year-old ‘Elberta’ peach trees during the dormant season. The degree of injury was recognized by discolored cambial area, bud mortality, vegetative vigor of buds, and retardation of leaf development. Plants preconditioned at 70° until new tissue was evident and then subjected to low temperatures were injured more severely than those not preconditioned. The freezing rate had a greater effect on the degree of injury than the minimum temperature reached within the range tested. Severity of injury at a given temperature was associated with the physiological stage of the trees. Plants exhibited more injury when frozen just prior to a natural “leaf expansion” than at periods earlier in the dormant season, even though the plants were preconditioned to the same apparent growth state. These data along with data on natural temperature conditions in a region where peach-tree decline is severe are discussed in relation to peach-tree decline.