Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1997. / Errata and addenda attached. Bibliography: leaves 195-211.

MENv.Sc / Department of Ecology and Resource Management

A comparative study of phytoseiid populations was made of two well- cultivated and regularly sprayed apple orchards with two unsprayed orchards in Cache Valley, northern Utah. Two phytoseiid species, Typhlodromus mcgregori Chant and T. occidentalis Nesbitt were observed on the apple leaves, under the bark, and occasionally in the litter and soil. Amblyseius cucumeris (Oudemans) occurred in the soil and litter and occasionally under bark. T. mcgregori was dominant in the unsprayed orchards, and T. occidentalis in the sprayed. Of the phytophagous mites, which served as food for the phytoseiids, the two-spotted mite, Tetranychus urticae Koch was dominant. Other phytophagous mites were the brown mite, Bryobia rubrioculus (Scheuten), the European red mite, Panonychus ulmi (Koch), and the McDaniel mite, Tetranychus mcdanieli McGregor. The study suggests T. mcgregori to be a non-specific, facultative predator of phytophagous mites. T. mcgregori was adversely affected by standard pesticide practices, but T. occiden talis survived in larger numbers. The phytoseiids seem well adjusted to the environment of the unsprayed orchards and to contribute to the low phytophagous mite populations in those orchards. In the sprayed orchards, the phytoseiids failed to control the high populations of phytophagous mites which developed. No statistical differences were found in the efficiencies of the mite brushing machine and Berlese funnels in removing either phytoseiid or phytophagous mites from apple leaves.

The sweet cherry crop has always been the number one fruit crop in Utah until the last three or four years when it shifted to second place due to severe spring frosts. However, the outlook for its continued success is still very good. Even though there are drawbacks such as virus infestations, spring frosts, nutritional disorders, cracking, doubling, and bird injury, new plantings are being made each year in each of the important fruit producing counties. Utah is also important in the national production of sweet cherries and is presently sixth in the nation.

Master of Science

4 pp. / Managing salts in Southwestern pecan orchards can be a major challenge for growers, due to limited soil permeability and/or low-quality irrigation water.

Revised; Originally Published: 2006 / 4 pp.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 192-209). Also available on the World Wide Web.

4 pp. / Leaf analysis is an excellent tool for determining the nutritional status of pecan trees.

Revised; Originally Published: 2006 / 3 pp.