Robert Fritts

Protein and isozyme electrophoresis and isoelectric focusing for the characterization of apple clones

Abstract To identify apple (Malus domestica Borkh.) clones, electrophoretic and isoelectric focusing of protein and isozyme pattern differences were investigated. Existing electrophoretic methods were adapted to obtain satisfactory separation and reproducibility of patterns. Several protein extraction buffers and procedures were evaluated to optimize protein recovery and enzyme activity from shoot bark tissue and other organs and to counteract the interference of other cell components. Sodium dodecyl sulfate—polyacrylamide gel electrophoresis (SDS-PAGE) did not reveal useful differences among cultivars, nor did total native protein patterns (non-denaturing PAGE). Peroxidase, esterase, acid phosphatase and indoleacetic acid oxidase extracted from shoot bark tissue did, however, show isozymic differences useful for identification. These enzymes expressed constant isozyme patterns at different times of the year and from trees growing under different conditions, and patterns were independent of wood age and rootstock influence.

Scion/interstock/rootstock effect on sweet cherry yield, tree size and yield efficiency

Abstract Yield and trunk cross-sectional area of ‘Bing’ and ‘Chinook’ cherries were measured on four tart cherry interstocks, ‘Kansas Sweet’, ‘Northstar’, ‘Montmorency’ and ‘Redrich’, and on four rootstocks, Mahaleb 4, Mahaleb 900, F 12-1 Mazzard and New York Mazzard, over a 20-year period. Additional treatments included both scions on either mahaleb or mazzard rootstocks without interstocks. Fifty-seven percent of total mortality was associated with ‘Redrich’ interstock, with no other single treatment showing disproportionately high mortality. After 20 years, cumulative yield was highest on Mahaleb rootstocks, but there were no significant differences in cumulative yield among interstocks. Trees lacking interstocks had significantly lower cumulative yield than trees with interstocks. Trunk cross-sectional area of ‘Bing’ was smaller than ‘Chinook’, and ‘Northstar’ produced smaller trunks than other interstocks tested. However, trees without interstocks tended to have smaller trunks than those with interstocks, although not significantly smaller than those with ‘Northstar’ interstocks. Trunk cross-sectional area was not affected by rootstock. Yield efficiency of ‘Bing’/‘Northstar’/Mahaleb 4 was the highest of the combinations tested.

Mt. St. Helens volcanic ash: effect of incorporated and unincorporated ash of two particle sizes on runoff and erosion

Abstract The effect of ash from the 1980 Mt. St. Helens eruption on runoff and rill erosion of cultivated land was studied in 1981 and 1982. Ash from the Pullman (fine particles) and Yakima, WA (coarse particles), areas was applied to a silt loam soil, and water was applied. Treatments were: bare soil (fine-silty, mixed, Mesic Pachic Ultic Haploxerolls); ash incorporated with soil; and unincorporated ash on the soil surface. Sediment concentration in runoff first increased with time to a maximum, then decreased to an approximate steady state. Sediment concentrations were higher for unincorporated ash as compared to ash incorporated with the underlying soil, and were even lower for bare soil. Sediment concentration was higher with Yakima ash as compared to Pullman ash or bare soil because of the less cohesive nature of Yakima ash. Rills became wide and shallow with Yakima ash, as compared to deeper and narrower rills for Pullman ash, because of the relatively more cohesive nature and finer particle size of Pullman ash. The finer Pullman ash caused formation of a surface seal, thus restricting the infiltration rate and producing a higher runoff rate than from rills with Yakima ash or bare soil.

Induction of lateral branches in tree fruit nursery stock with propyl 3-t-butylphenoxy acetate (MB 25, 105) and Promalin (GA4+7 + 6-benzyladenine)

Abstract Sprays with 250–2000 mg l−1 propyl 3-t-butylphenoxy acetate (MB 25,105) and 250 and 500 mg l−1 GA4+7 + 6-benzyladenine (Promalin) were applied to scion growth of first nursery trees of ‘Bartlett’ pear (Pyrus communis L.), ‘Bing’ cherry (Prunus avium L.) and ‘Oregon Spur II Delicious’ apple (Malus domestica Borkh.) to stimulate lateral branching in the nursery. Most treatments significantly increased branching compared to untreated controls. Combination sprays of the two chemicals were usually better than either used alone. Chemical treatment usually produced greater branching and wider branch angles than mechanical heading. Both chemical and mechanical treatments reduced tree height and caliper, but the decrease was not always statistically significant.

Hardy framework influence (1969-1983) on yield, tree size and yield efficiency of Wellspur and Goldspur apple

Abstract Cumulative yield, trunk cross-sectional area, and yield efficiency were measured between 1969 and 1983 in an experimental planting (established in 1964 and top-worked in 1965) of ‘Wellspur’ and ‘Goldspur’ apple top-worked on frameworks of 19 cold-hardy cultivars (‘Alnarp 2’, ‘Antonovka’, ‘Beacon’, ‘Canada Baldwin’, ‘Delcon’, ‘Dr. Bill’, ‘Duchess’, ‘Haralson’, ‘Hawkeye Greening’, ‘Heyer 12’, ‘Heyer 20’, ‘J. Luke Seedling’, ‘McIntosh’, ‘Minnesota 447’, ‘Ottawa 271’, ‘Ottawa 292’, ‘Red Astrachan’, ‘Robusta 5’, ‘Yellow Transparent’) that were grafted on domestic seedling roots. There were significant differences in yield, trunk diameter and yield efficiency related to the interstock. ‘Duchess’ and ‘Heyer 12’ ranked highest in yield efficiency and lowest in tree size. ‘Red Astrachan’ ranked lowest in efficiency and largest in tree size. ‘McIntosh’ also tended to be low in efficiency. No severe winter temperatures occurred to test differential cold hardiness.

Rootstock influence on ‘delicious’ and ‘golden delicious’ apple fruit quality at harvest and after storage

Abstract The influence of 9 rootstocks (M2, M7, M25, M26, MM104, MM106, MM109, MM111 and seedling) on fruit quality at harvest and after storage of ‘Wellspur Delicious’ (WS) and ‘Goldspur’ (GS), and of 3 rootstocks (M7, M26 and MM106) on fruit quality of ‘Red King Delicious’ (RK) and ‘Golden Delicious’ (GD) apple ( Malus domestica Borkh.) was evaluated during a 4-year period. Fruits from trees on M26 were larger, developed earlier color and soluble solids (SS), and maintained higher levels of acidity (at harvest and during storage) in comparison with other rootstocks. Fruit from trees on M2 tended to have high SS. Fruit color from trees on MM104, MM106 and MM109 tended to be comparatively poor. There were significant rootstock effects on SS, starch, acidity, color, circumference, weight and box size.

Defoliation of tree fruit nursery stock with CGA-15281

Abstract In 2 test years, the ethylene-releasing agent CGA-15281 [2-chloroethyl-methylbis (phenylmethoxy) silane] had a significant effect on leaf abscission of budded and seedling fruit trees. Several apple cultivars, ‘Bartlett’ pear, and seedlings of apple, pear and cherry were treated with single or double applications (at 4-day intervals) of 1000, 1500 or 2000 mg l −1 . Except for apple and pear seedlings, the 1500 mg l −1 concentration produced nearly 100% abscission, with significantly less effect from 1000 mg l −1 . When trees were replanted after storage (done the second year only), 2–15 cm of shoot dieback was evident on all treatments with ‘Rome’ apple, and delayed bud break was evident on most treatments with ‘Bartlett’ pear. The other plants were much less negatively affected (‘Redspur Delicious’, ‘Goldspur’ and ‘Nured Jonathan’ apples; pear seedlings) or appeared to be unaffected (‘Redchief Delicious’ apple; apple and cherry seedlings).