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- Author or Editor: Fenton E Larsen x
Abstract
Following publication in 1965 (9) of the identity of Abscisin II isolated from cotton by Addicott's group, it was established that sycamore dormin and Abscisin II have the same structure (3). Abscisin II was later named abscisic acid (1). This and other research (4, 8, 10) shows that this is apparently a widely distributed compound.
Abstract
The growth retarding effect of N-dimethylamino succinamic acid (Alar) on certain deciduous fruit trees in the orchard was first reported in 1964 (1). Its value for size control in the nursery where tree size is sometimes excessive was subsequently reported in 1967 (3). It was reported in 1954 (2) that certain growth regulators applied prior to the application of a nursery stock defoliant reduced the effectiveness of the defoliant.
Abstract
Color slides put more life into all forms of horticultural teaching, in the classroom, for industry and agricultural meetings, as a part of garden club programs, also on television, the largest audience of all. The ASHS Slide Collection is under way. Help develop it! Make use of it! The Education Committee suggests that a good slide set with narrative should be given the same administrative credit as any other form of publication.
Abstract
D-WK (Dupont-WK surfactant with the principal functioning agent being the dodecyl ether of polyethylene glycol) can be used to stimulate leaf abscission of some deciduous tree fruit nursery stock. One to 3 applications of 1 to 2% D-WK were satisfactory for most cultivars tested of apple, pear, cherry, and prune. ‘Early Red Haven’ peach was particularly sensitive to damage, and required lower concentrations.
Abstract
Nurserymen often wish to dig plants prior to natwl leaf abscission. Plants for some areas could be shipped for fall planting if digging could be done early enough. In other areas an extended digging period would lessen harvest pressure or make better use of labor. Early digging would also de crease danger of losses from early fall freezes. Some plants (i.e. Weigela) retain their leaves extremely late in the season
Abstract
A high incidence of longitudinal trunk bark cracking was observed in an apple planting with 4 scion cultivars and 9 rootstocks between Nov., 1969 and Feb., 1972. The injury, occurring mostly in late Nov., was related to scion and rootstock. Almost no cracking occurred on ‘Wellspur’ and ‘Red King’ trunks. More cracking occurred on ‘Golden Delicious’ than ‘Goldspur’ on 3 rootstocks. With these 3 rootstocks, 96% cracking occurred with ‘Golden Delicious’/‘M 7’ and ‘MM 106’ and 52% with trees on ‘M 26’. With ‘Goldspur’ on 9 different rootstocks, the highest incidence of cracking was with trees on ‘M 7’ (85%) and ‘MM 106’ (82%) while 30% cracking occurred with trees on domestic seedling, and 4% with trees on ‘M 25’ No cracking was observed with ‘Goldspur’/‘M 26’. The greatest no. of cracks occurred on the S sector of the trunks with moderate amounts on the SE and E sectors with fewer cracks on all other sectors. The cracking appears to be low temp induced and the effect of rootstocks appears to be an effect on fall maturity of the scion.
Abstract
A 2,4-dichlorophenoxy acetic acid (2,4-D) application in September, 1972, to a grass cover crop and most of a weed free 1.2 m wide strip under the tree row followed by sprinkler irrigation within 24 hours injured 8 year-old pear trees. Fall leaf abscission was inhibited and foliage development was abnormal the following spring. ‘Bartlett’/imported French seedling had no apparent damage while ‘Bartlett/Pyrus calleryana Decne., ‘East Mailing Quince A’ and ‘Provence’ quince was seriously damaged. ‘d’Anjou’/imported French seedling was damaged the least of the 9 combinations and was most seriously damaged on the same 3 rootstocks as ‘Bartlett’. Fruit yields were correlated with damage ratings.
Abstract
Cycloheximide (CHI) [3-(2-[3,5-dimethyl-2-oxocyclohexyl]-2 hydroxyethyl)-glutarimide] and Retzanol TD-8 (RTD-8) [tridecyl alcohol derivative] surfactant alone and in combination stimulated significant leaf abscission on cherry, peach, pear and apple nursery stock. RTD-8 alone was sometimes more effective than CHI alone, and combination treatments were rarely better than either material alone. CHI but not RTD-8 induced bud and shoot tip damage.
Abstract
Combinations of ethephon and D-WK (Dupont-WK) surfactant were effective in stimulating leaf abscission of 20 cultivars in 5 species of tree fruit nursery stock. Species and cultivars varied considerably in sensitivity to mixtures of these chemicals, but 1 to 3 applications at weekly intervals of 200 to 400 ppm ethephon + 1 to 2% D-WK were generally effective. These treatments caused little xylem, phloem or bud damage except to ‘Early Redhaven’ peach and ‘Early Italian’ prune. ‘Rome’ apple was sensitive but was not damaged by concn of 200 ppm ethephon + 1% D-WK. D-WK stimulated leaf abscission when used alone at 1 to 2% but acted more slowly than when combined with ethephon. Ethephon alone at 200 to 400 ppm was usually relatively ineffective.
Abstract
Ethyl 5-(4-chlorophenyl)-2H-tetrazole-2-acetate (PP528) applied in early summer to apple (Malus domestica Borkh.) and pear (Pyrus communis L.) trees stimulated lateral branching the first year in the nursery. Concentrations of 25 to 50 ppm were effective, while 100 ppm or more sometimes killed shoot terminals and stopped or retarded further vertical growth for the season. Branch angles were not measured, but when terminal meristems were not killed, branch angles were wide. If terminal meristems were killed, the uppermost branch angles were narrow. Double applications 2 weeks apart of 25 or 50 ppm were sometimes more effective than single applications. Timing, uniformity of growth, and application during active growth were important to produce maximum branching effect and branching in suitable locations. PP528 caused more branching in 2 nonspurred ‘Delicious’ apple cultivars (up to 9 times control values) than in ‘Oregon Spur Delicious’ (up to 3 times the control). Treatments with up to 200 ppm were largely ineffective on sweet cherry (Prunus avium L.). Use of 100 or 250 ppm GA was of little benefit in overcoming the stunting effect of high concentrations of PP528.