Cultural Practices Affect Cold Hardiness and Peach Tree Short Life1

Abstract

To determine whether cold hardiness of peach [Prunus persica (L.) Batsch] is affected by cultural practices, 2-year-old ‘Coronet’ trees growing in a peach tree short-life site were treated by soil fumigation with 1,2-dibromo-3-chloropropane (DBCP) late fall application of nitrogen, combination of fumigation and fall applied nitrogen, fall pruning (November), or usual grower practices (control). Cold hardiness was measured by determining the leakage of electrolytes from dormant terminal twig sections exposed to low temperatures, and visually by oxidative browning and ease of phloem-xylem separation. Fall-pruned trees were lower in cold hardiness and survival than controls. Nitrogen applied alone or in combination with fumigation reduced cold hardiness in early winter but increased vigor and survival. Trees grown in fumigated soil and winter-pruned were hardier than control trees and fall-pruned trees in nonfumigated soil. Differences in hardiness were greatest near bloom time. Cultural practices strongly affected cold hardiness of xylem, phloem, and cambium of treated trees, and cold hardiness was associated with tree longevity.

Influence of Peach Seedling Rootstocks on Defoliation and Cold Hardiness of Peach Cultivars1

“…Injury was assessed by the intensity and continuity of tissue browning. Oxidative browning of tissues is a reliable index of injury for peach stems (12,13). Injury ratings were as follows: 1 = absence of browning; 2 = light to moderate brown ing in the apical region with discontinuous browning in the median and basal portions; 3 = moderate but continuous brown ing in the apical and median portion with discontinuous brown ing in the basal portion; 4 = moderate to severe and continuous browning of tissues from the apex to the base.…”

“…Cold injury is an important limitation to peach production especially in the Northern United States and Canada (8). It may also be more important than formerly thought in the Southern U. S., because of its association with the peach tree short life problem (12). Recently, differences in hardiness of peach seed ling rootstocks were reported in which Siberian C seedlings were the hardiest of those studied, followed in descending order by seedlings of Harrow Blood, Rutgers Red Leaf, 'Halford', 'El berta', and Nemaguard (8,9).…”

Evaluation of Different Methods to Assess Cold Hardiness of Peach Trees1

“…Cold injury to the trunk is initially associated with cambial browning and appears to occur during late winter dehardening of the trees (4,5,14). Trees on a site with a previous history of peach cultivation (short-life site) are generally much more susceptible to PTSL than those on a new site (non-short-life site) with no previous peach production (2,12).…”

“…In climates where severe root zone freezing may occur, absolute rootstock hardiness is critical, since once the root system is dead or severely injured, the scion will also surely die shortly after the trees leaf out in spring (8). Late-winter cold hardiness has been associated with peach tree longevity in the Southeast (2,12). This study was designed to examine the effects of 7 peach seedling rootstocks and 2 orchard sites on the cold hardiness of 'Redhaven' peach trees.…”

“…The generally accepted procedure to estimate cold hardiness under controlled conditions is to freeze plant tissue to desired temp, then thaw and determine degree of survival or injury. The various tests to assess cold hardiness, following artificial or natural freezes, that have been employed from time to time could be classified as: electrical methods (1,5,7,9,12,21,23,24,25); color or spectrophotometric determinations (11,13,14,16,17,18,22); visual discoloration or physical integrity of tissue (1,3,6,12,17,18); growth and recovery tests (3,5,7,9,18,21); and xylem pressure potential and chlorophyll fluorescence methods (2). A recently developed test (20) has also been used to evalute the effect of artificial freezing on the susceptibility of peach twigs to bacterial canker development (BCD) after inoculation with Pseudomonas syringae van Hall.…”