Document Type

Thesis - Open Access

Award Date

1972

Degree Name

Master of Science (MS)

Department

Horticulture

Abstract

Because of the devastation caused by Dutch Elm Disease to American elm an expanding avenue of. research is the quest for a replacement for the elm. Since green ash is native throughout Eastern United States and Great Plains, is easy to transplant, and grows rapidly while young, increased emphasis has been placed on this tree as a possible replacement. Green ash is the most widely ranging of American ashes. It develops into a small to medium-sized tree with a broad, irregular crown. It is exceptionally cold and drought hardy and once established will persist. It is necessary to use vegetative propagation to produce selected, improved trees of green ash. Vegetative propagation of green ash has several advantages over reproduction by seeds. Asexually propagated trees often attain a usable size more rapidly and produce a higher percentage of salable stock than do trees started from seed. Asexual propagation is also essential if superior growth rate, form, and disease and insect resistance are to be insured. Moreover, it enables selection for staminate flowering or male trees, which is desirable in order to prevent promiscuous seeding that results with pistillate flowering, female trees. Nevertheless, it should be pointed out that vegetatively propagated plants do have the disadvantage of perpetuating disease; thus, clean stock is of the utmost importance. Seedling rootstocks used in budding and grafting are variable and may modify the plant to such an extent that it is difficult to determine the selection's value. Furthermore, cuttings are preferred in order to circumvent problems that may arise with stock-scion incompatibility or with poor graft unions. Grafted or budded plants show additional difficulties. Rootstocks often sprout, and some plants tend to sucker heavily from basal regions after the trees have reached salable size. Cuttings are often less expensive and may be more rapidly and simply produced. This study assesses the ability of softwood cuttings from several selected trees of green ash to produce roots, to initiate new growth, and to survive the winter in containers. Further, it tests the relative rooting capacity of softwood cuttings taken from several species of ash. Factors which affect the rooting response of plants were investigated in respect to their importance in rooting green ash. Factors explored were length of cutting, type of cutting (node, internode, or heel from terminal shoots), stump sprouts, blanching, clonal variations, girdling, length of rooting period, hormones, hormonal concentrations, and juvenility.

Library of Congress Subject Headings

Plant propagation
Ash (Plants)

Format

application/pdf

Number of Pages

71

Publisher

South Dakota State University

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