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  • Author or Editor: M. N. Westwood x
  • Journal of the American Society for Horticultural Science x
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Abstract

The nutritional status of ‘Bartlett’ pear growing on P. communis seedling, Old Home × Farmingdale (OH×F), and several Pyrus species seedling rootstocks was compared to those growing on Bartlett seedling rootstock at 3 locations over a 2-3 year period. Few significant differences were found in leaf element content of scions growing on Bartlett seedling rootstock and those on the rootstock clones or other Pyrus seedlings. Nitrogen was higher in the scions on 5 of the OH×F rootstocks but did not seem related to yield efficiency. Generally the leaf element content of Mg and Mn was lower and Fe higher in leaves of trees growing on the OH×F clonal rootstocks when compared to trees on Bartlett seedling. Nutrient uptake and passage through graft unions appeared unrelated to the degree of graft compatability, based on the similarity of nutrient levels of ‘Bartlett’ scions grafted directly on quince rootstock and those with an Old Home interstem. Root system genetics seems to be the controlling factor of nutrient uptake rather than the interstock.

Open Access

Abstract

Effects of cultivars, rootstock, and long-term growth regulator and herbicide treatments on above-ground tree damage from a December 1972 freeze were recorded soon after the freeze and again 7 years later. Ultimate injury was greatest with ‘Jonared’ and least with ‘Golden Delicious’ apple (Malus domestica Borkh.) in the growth regulator plot, while in the herbicide plot it was opposite for the 2 cultivars. There was not a good relationship between injury to specific plant parts (flower buds, spurs, leaders, and lower trunks) observed soon after the freeze, and ultimate tree mortality. Growth regulator treatments significantly increased freeze damage to flowers and spurs, but ultimate tree mortality was reduced by daminozide sprays. Clean cultivation increased flower and spur mortality but did not reduce yield or increase tree mortality compared to the sod treatment. Trees on Mailing (M) 5, M 7 and M 9 rootstocks showed greater initial trunk injury than those on seedling roots, but only those on M 9 showed significantly greater ultimate mortality.

Open Access

Abstract

The pear cultivars ‘Anjou,’ ‘Bartlett’. ‘Bose,’ ‘Cornice,’ ‘Seckel’ and ‘Packham's Triumph’ grown on 9 rootstocks were observed for tolerance to pear decline, tree size, bloom density, yield, fruit weight and leaf nutrient content. Cultivars on Old Home clonal rootstock or Old Home on nurse roots of Mailing Quince A, Winter Nelis seedling or Bartlett seedling were smaller, had lower yield efficiency and greater uptake of Ca, Mg and Mn than when worked directly on Winter Nelis or Bartlett seedling rootstocks or Pyrus calleryana Decne. Winter Nelis and Bartlett seedling rootstocks were similar in performance but Winter Nelis seedlings had a lower yield efficiency than did Bartlett seedlings. Both had better uptake of Fe and Zn but were less precocious than P. calleryana. Fruit size was increased on P. calleryana and P. betulaefolia Bunge seedling rootstocks, particularly when topworked with ‘Seckel’. Cultivars with Call rootstock had greater uptake of K than other rootstocks. A hybrid of P. nivalis Jacq. as a rootstock was inferior to other seedling rootstocks.

Open Access

Abstract

A 10-year study of 4 vegetation management regimes in an apple (Malus domestica Borkh.) orchard showed that a mowed sod ground cover resulted in less efficient trees than those with cultivation, residual or nonresidual herbicides. Considerable differences were found among treatments in the kind and population density of orchard weeds. Of the 6 rootstocks tested, seedlings produced the largest but least efficient trees. Trees on Mailing (M) 4, M 1 and M 7 rootstocks gave the greatest yield efficiency during the 10-year period. No interactions were found between rootstock and orchard floor management practices.

Open Access

Abstract

Repeated winter rain or water soaking in the laboratory reduced the time required for breaking winter rest of ‘Bartlett’ pear (Pyrus communis L.) and ‘Starkrimson’ apple (Malus domestica Borkh.). Possibly a water soluble inhibitor is leached from the buds.

Open Access

Abstract

Trunk cross-sectional area was found to bear a linear relationship to total above-ground weight of apple trees. From these data, it is suggested that trunk measurements can be used to estimate the potential bearing surface of any orchard tree as long as it has not been pruned heavily to prevent crowding. This relationship permits the calculation of yield efficiency as fruit weight per cm2 trunk cross-section. Estimates were made of maximum bearing surface potential (tree weight) per acre (as cm2 trunk area) for several kinds of tree fruits and nuts.

Open Access

Abstract

Tests in 11 plots of ‘Italian’, ‘Early Italian’, and ‘Brooks’ prunes showed several influences of rootstock on tree growth, flowering, yield, fruit size, maturity, and quality. Of the 6 Prunus species represented by the 19 rootstocks tested, myrobalan roots usually resulted in larger trees, heavier bloom, but lower yield efficiency than did peach roots. Trees on Marianna and several P. domestica L. roots varied in size and yield, but most of them had greater bloom density than trees on peach root. ‘Italian’ fruit firmness varied inconsistently with rootstock. ‘Early Italian’ fruits were firmer on peach than on other roots, but ‘Brooks’ fruits were less firm on peach than on other roots. The tendency for internal fruit browning of ‘Italian’ was greater on plums than on peach roots. Other fruit maturity and quality factors varied by cultivar and by individual rootstock. Fewer trees on peach root died from trunk canker (Pseudomonas syringae van Hall) than did those on several clonal plum roots, but some plum-rooted trees outgrew the canker and survived as well as trees on peach stock.

Open Access

Abstract

Plantings of the ‘Italian’ prune (P. domestica L.) were established on seedling peach (P. persica L. Batsch) and clonal Myrobalan 29-C, B, 2-7 (P. cerasifera, Ehrh.); Marianna 4001, 2623, 2624 (P. cerasifera × Munsoniana?, Wight and Hedr.); and St. Julien A (P. insititia L. Bullace) rootstocks in 7 orchard sites in Oregon. Leaf samples were collected in the years 1968 to 1970 and analyzed for element content. Trees with plum rootstocks had greater leaf N, K, Mn, and Zn and slightly less B and Mg than those on peach. Plum clones, Myrobalan 29-C, Myrobalan B, and St. Julien A, were more efficient in the uptake of Ca. There were positive correlations between N and Ca, N and Mg, N and B, N and Zn, Ca and Mg, Ca and B, and Mg and B for most of the stocks. There was a negative correlation between K and Mg for Myrobalan 2-7 and the 3 Marianna clones. Myrobalan B and Marianna 2623 and 2624 had a negative corrleation for K and Ca whereas St. Julien A had a positive correlation.

Open Access

Abstract

Roots of most of the primitive Pynus species were infested with pear root aphid Eriosoma pyricola Bak. and David., and increase or decrease in number noted 30 days later. Although seedling populations varied somewhat, P. amygdaliformis, P. elaeagrifolia, P. syriaca, P. betulaefolia, P. calleryana, P. koehnei, P. ussuriensis, and P. nivalis can be considered resistant. P. communis, P. cordata, P. gharbiana, P. pashia, P. Fauriei, and P. pyrifolia were either susceptible or very variable in resistance. Only P. bucharica, P. dimorphophylla, and P. mamorensis had no resistant seedlings in the lots tested. Interspecific hybrid populations were predictable though variable in resistance.

Open Access

Abstract

A survey of 18 pear species using the scanning electron microscope showed considerable variability in the size, shape and surface topography of both anthers and pollen grains. The size, shape and surface topography of anthers or anther cells did not vary directly with the size, shape and topography of pollen from the same species. The degree of similarity of individual features among species did not seem to coincide with their geographic distribution. However, the combination of pollen and anther features was unique for each species, indicating their value for taxonomic identification.

Open Access