Fruit trees usually are hybridized outdoors due to the difficulty and expense of maintaining trees in greenhouses. Hybridizations often are lost due to freeze injury of fruit after pollination. The use of protective cages or screen houses to protect hybridizations from freeze injury has been advocated and utilized by some tree fruit breeders (2), but many of the proposed structures are cumbersome and difficult to construct. This report describes the design and performance of cages which can be built for about $25.00 per tree and can be constructed in about 45 min.
More than 400 genotypes of Prunus were evaluated for “in field” rooting and survival from fall-planted hardwood cuttings treated with 2000 ppm IBA. Cultivars of European and Japanese plums originating from species and interspecific hybrids of the section (sect.) Prunus had the highest survival. Cuttings from cultivars of sand cherry (sect. Microcerasus) and peach (sect. Euamygdalus) averaged 28% to 54% lower survival than European and Japanese plums. Few cultivars of almonds (sect. Euamygdalus), apricots (sect. Armeniaca), and American plums (sect. Prunocerasus) rooted from hardwood cuttings. Chemical name used: 1H-indole-3-butyric acid (IBA).
During the 1984 growing season, 156 peach and 40 nectarine cultivars, 49 plant introductions, and 33 Prunus species or species hybrids were evaluated for susceptibility to bacterial spot [Xanthomonas campestris pv. pruni (Smith 1903) Dye 1978] in North Carolina and South Carolina. Fruit and leaf infection and percentage of defoliation were evaluated in North Carolina, while only leaf infection data were evaluated in South Carolina. No cultivar was immune, but susceptibility varied greatly. Based on leaf infection in the 2 locations, it was concluded that disease pressure was greater in North Carolina. Correlation of fruit infection severity with leaf infection severity and percentage of defoliation in North Carolina was r = 0.30 (P = 0.01) and r = 0.54 (P < 0.01), respectively. Correlation between leaf infection severity and percent defoliation was r = 0.51 (P < 0.01) and r = 0.00 (NS) in North and South Carolina, respectively.