Cold Injury of Peach and Nectarine Cultivars after a Fall Freeze

Abstract

Fig. 1. Cold injury ratings of 4year-old nectarine cultivars following an early fall freeze to –11C. Damage rating was from 1 (no visible injury) to 6 (death of the aboveground portion of the tree Cold damage to peach [Prunus persica (L.) Batsch.] trees occurs in many of the peachgrowing regions and can result in tree death or predispose trees to canker caused by Pseudomonas (Yadava and Doud, 1989) or Leucostoma (Chang et al., 1989). Cold damage also can contribute to the peach tree shortlife complex (Nesmith and Dowler, 1976; Savage, 1970). Layne (1992) has recently reviewed available literature concerning peach and nectarine cold hardiness. Information that compares cold injury sustained by peach or nectarine cultivars during a test winter is lacking. The opportunity to collect these data only occurs when uniform plantings of diverse cultivars are exposed to test winters. Such information is valuable for cultivar recommendations and to identify coldhardy cultivars for use in breeding programs. This note reports data collected after a severe freeze on 2 Nov. 1991. Temperatures dropped from 5 to –11C within 12 h at the Fruit Research Station near Perkins in central Oklahoma. There had not been prior freezing temperatures, and trees were fully foliated. Four-year-old peach and nectarine cultivars propagated on Lovell rootstock and trained to an open center were rated on 25 Sept. 1992 for cold injury. Trees were not pruned after exposure to injurious low temperatures. Tree damage was quantified on a rating scale for injury: 1 = none; 2 = crotch areas; 3 = the crotch areas and trunk, 4 = the crotch areas, trunk, and lower portions of the scaffolds; .5 = injury to the crotch areas, trunk, and scaffolds, with trunk splitting, poor shoot growth, and yellow foliage; and 6 = death of the aboveground portion of the tree (rootstock may be suckering). There were four to five trees of each cultivar. Data were tested using analysis of variance with the protected LSD. The soil was a Teller loam (fine-loamy,