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  • Author or Editor: Herb S. Aldwinckle x
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Abstract

Apple seedlings of two progenies whose parentage was predominantly cultivated apple (Malus spp.) were forced under optimum growing conditions in the greenhouse. Without chilling, flowering started on occasional plants 16 months after germination. Manual defoliation induced synchronous bud break very efficiently. By 20 months after germination 86% and 68% of surviving seedlings in the two progenies had flowered. The phase change from juvenile to adult occurred 10-14 months after germination or possibly earlier.

Open Access

Regeneration from apple (Malus × domestica Borkh.) M.26 leaf tissue was completely inhibited by (μg·ml-1) 1 geneticin, 5 kanamycin, 10 to 25 paromomycin, and 100 neomycin. nptII-transgenic M.26 had an increased tolerance to all four of the antibiotics tested, with inhibition of regeneration occurring at (μg·ml-l) 2.5 geneticin, 100 kanamycin, 375 paromomycin, and 375 neomycin. Paromomycin (100 to 250 μg·ml-l) and neomycin (250 μg·ml-1) significantly increased the amount of regeneration from nptII-transgenic M.26 apple leaf tissue. p35SGUS-INT, a plasmid with a chimeric b -glucuronidase gene containing a plant intron, was useful for studying the early events of apple transformation by eliminating GUS expression from Agrobacterium tumefaciens. It was used to determine that the optimal aminoglycoside concentrations for the selection of nptII-transgenic M.26 cells were (μg·ml-1) 2.5 to 16 kanamycin, 63 to 100 neomycin, and 25 to 63 paromomycin. Geneticin was unsuitable as a selective agent.

Free access

Abstract

Orchard production systems have experienced rapid and dramatic changes over the past 3 decades in both the techniques and geno-types used. We expect this rate of change to accelerate in the future. As production costs escalate, the demand will become ever stronger for systems providing early, heavy, reliable yield fo high-quality, easy-to-harvest fruit. These systems must, however, be reasonably priced and durable. The grower will be less able to afford tree losses, whether due to biotic, climatic, or edaphic hazard, and will need to economize on use of machinery and chemical pesticides. Growth regulators will be employed only where there are effective, economically justified, and environmentally acceptable.

Open Access

Abstract

Reactions of 122 apple clones, representing 26 pure and hybrid species of Malus, to Erwinia amylovora (Burrill) Winslow et al. were evaluated in the greenhouse, orchard, and field nursery. Vigorously growing shoots, 7 to 9 weeks old, were tip inoculated by injecting a 24-hour broth culture of a highly pathogenic isolate of E. amylovora. Lesion development, measured 5 to 7 weeks after inoculation, was expressed as a percentage of the current season’s shoot length killed by fire blight. Inter- and intraspecific variation in resistance, similar to that reported for Pyrus, was observed. The highest level of resistance, typified by a small necrotic lesion 2-3 mm in diameter around the inoculation point, occurred in small-fruited selections derived from Asiatic species. Few selections of the cultivated apple, Malus pumila Mill., were resistant. Fire blight ratings were assigned the clones based on their potentials as parents for breeding apple rootstocks.

Open Access

Abstract

Seedling progenies from controlled crosses involving Malus sp. clones were tested for resistance to Erwinia amylovora (Burrill) Winslow et al. by shoot tip inoculation. In progenies from crosses between fire blight-susceptible M. pumila selections, over 90% of the seedlings were killed. In most progenies from crosses between resistant and susceptible selections, regardless of species source, few resistant seedlings occurred. Progenies from crosses between resistant parents generally had the most resistant seedlings, but segregated some highly susceptible offspring. Distribution patterns suggested quantitative control of resistance, with resistant parents heterozygous for resistance genes. In progenies from crosses of the highly resistant M. × robusta No. 5 (R5) and M. × sublobata PI 286613 (613) with susceptible parents, about 1/8 of the seedlings exhibited the fire blight reaction of the highly resistant parent. All progenies of 613 and R5, including those obtained by selfing and by crossing the two with each other, segregated some susceptible offspring. In a replicated nursery test involving seedlings of a 613 progeny, various fire blight resistance classes in the population were distinguished statistically. Resistance in 613 and R5 was interpreted as oligogenic (conditioned by few genes), with dominant, additive genes carried in the heterozygous condition.

Open Access

Abstract

‘Freedom’ is a productive, large, red apple, Malus domestica Borkh. that is very resistant to apple scab [Venturia inaequalis (Cke) Wint.], moderately resistant to apple powdery mildew [Podosphaera leucotricha (E. & E.) Salm], resistant to cedar apple rust (Gymnosporangium juniperi-virginianae Schw.), and to fire blight [Erwinia amylovora (Burrill) Winslow et al.]. It has been grown for 23 years without any disease-controlling sprays, and no losses have occurred in New York State. This apple was tested under the number NY 58553-1.

Open Access

Abstract

‘Novole’ is being introduced for its value as a parent in resistance breeding programs and for trial use as a vole-resistant root- and trunk-stock for the commercial apple orchard. ‘Novole’ transmits to progeny resistance to a number of environmental hazards, including pine vole and meadow vole.

Open Access

Abstract

In 1973, Ross Byers at VPI's Winchester laboratory and rootstock breeder Jim Cummins and plant pathologist Herb Aldwinckle at Cornell's Geneva station initiated a cooperative project to explore Malus for resistance to the pine vole, Microtus pinetorum Leeone. The Geneva breeders furnished more than 300 clones during the next 5 years, representing 12 Malus species and including many interspecific hybrids. Byers and his associates tested the voles' responses to the many choices offered. Throughout the several years of testing, the voles consistently exhibited a strong nonpreference for a Japanese crabapple, now introduced as ‘Novole’, and later for many of its hybrids (1, 6).

Open Access

The Geneva® Apple Rootstock Breeding program initiated in 1968 by Cummins and Aldwinckle of Cornell University and continued as a joint breeding program with the USDA-ARS since 1998, has released a new dwarf apple rootstock named Geneva® 41 or G.41. G.41 (a progeny from a 1975 cross of `Malling 27' × `Robusta 5') is a selection that has been tested at the N.Y. State Agricultural Experiment Station, in commercial orchards in the United States, and at research stations across the United States, Canada, and France. G.41 is a fully dwarfing rootstock with vigor similar to M.9 T337, but with less vigor than M.9 Pajam2. It is highly resistant to fire blight and Phytophthora with no tree death from these diseases in field trials or inoculated experiments. G.41 has also shown tolerance to replant disease. Its precocity and productivity have been exceptional, equaling M.9 in all trials and surpassing M.9 in some trials. It also confers excellent fruit size and induces wide crotch angles in the scion. It appears to be very winter hardy and showed no damage following the test winter of 1994 in New York. Propagation by layering in the stool bed G.41 is not consistent and may require higher layering planting densities or tissue culture mother plants to improve its rooting. G.41 also produces some side shoots in the stool bed. The nursery liners of G.41 produce a smaller tree than G.16 liners, but similar to M.9, which is very acceptable. Unlike G.16, G.41 is not sensitive to latent viruses. G.41 has similar graft union strength to M.9 and requires a trellis or individual tree stake when planted in the orchard. Suggested orchards planting densities with this rootstock are 2,000-4,000 trees/ha. This rootstock has been released for propagation and commercial sale by licensed nurseries.

Free access

The Geneva® Apple Rootstock Breeding program, which was initiated in 1968 by Dr. James Cummins and Dr. Herb Aldwinckle of Cornell University and which has been continued as a joint breeding program with the U.S. Dept. of Agriculture Agricultural Research Service (USDA-ARS) since 1998, has released a new semi-dwarfing apple rootstock which is named Geneva® 935 or G.935. G.935 (a progeny from a 1976 cross of `Ottawa 3' × `Robusta 5') is a selection that has been widely tested at the New York State Agricultural Experiment Station in Geneva, N.Y., in commercial orchards in the United States and at research stations across the United States and Canada. G.935 is a semi-dwarfing rootstock that produces a tree slightly larger than M.26. G.935 is the most precocious and productive semi-dwarf rootstock we have released. It has had similar yield efficiency to M.9 along with excellent fruit size and wide crotch angles. It showed no symptoms of winter damage during the 1994 test winter in N.Y. G.935 is resistant to fire blight and Phytophthora; however. it is susceptible to infestations by woolly apple aphids. G.935 has shown tolerance to replant disease complex in several trials. It has good propagation characteristics in the stool bed and produces a large tree in the nursery. G.935 has better graft union strength than M.9, but will require a trellis or individual tree stake in the orchard to support the large crops when the tree is young. G.935 will be a possible replacement for M.26. Suggested orchards planting densities with this rootstock are 1,500-2,500 trees/ha. It has been released for propagation and sale by licensed nurseries. Liners will be available in the near future.

Free access