No description available.

No description available.

Amaranthus retroflexus L. (redroot pigweed) is a major weed of many crops in North America including corn, soybean, and potato. It can be readily controlled by chemical and cultural methods. However, some populations of A. retroflexus have developed resistance against the application of triazine herbicides. Biololical control could be an alternative method to control this weed species. In 1990, a Macrophoma sp. causing foliar lesions was isolated from redroot pigweed and the potential of this plant pathogenic fungus as a mycoherbicide was evaluated. Large numbers of infective propagules were produced in solid substrate fermentation with chickpeas. When inoculated with 10$ sp8$ or 10$ sp9$ conidia m$ sp{-2}$, plants at the cotyledon to 2-leaf stage showed the most severe damage. Disease developed over a wide range of dew period durations (6 hr to 24 hr) and temperature regimes (14 C to 26 C), and the most rapid and destructive disease development occurred following a 24-hr dew period at 18 C. In controlled environment studies, this Macrophoma sp. was pathogenic to the genus Amaranthus and the closely related genus Celosia.

Phomopsis convolvulus Ormeno, a foliar pathogen of field bindweed, is a good candidate to be developed as a bioherbicide. Large numbers of infective propagules were produced in shake-flask liquid fermentation with modified Richard's (V-8) medium and in solid-substrate fermentation with pearl barley grains. In complex liquid media, pycnidium-like structures were observed. Most conidia stored at $-$70$ sp circ$C remained viable and virulent for at least six months. / In controlled environment studies, a minimum of 18 hr of dew was required for severe disease development on inoculated plants. The addition of gelatin, Sorbo $ sp{ rm TM}$, or BOND$ sp{ rm TM}$ to the inoculum did not enhance the disease under various leaf wetness periods. A continuous dew period of 18 hr was superior to the cumulative effect of three interrupted 6 hr dew periods. Secondary inoculum was produced on diseased plants placed under moist conditions for 48 hr or more. / In greenhouse experiments, seedlings at the cotyledon and 3- to 5- leaf stage were severely diseased and killed when inoculated with 10$ sp9$ conidia/m$ sp2$. This inoculum density adversely affected the regenerative ability of 4 wk old seedlings and established plants, but few plants were killed. Inoculation of the healthy regrowth from plants previously inoculated with the fungus resulted in much less disease symptoms than expected.

Thesis (PhD)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: David K. Weaver. Includes bibliographical references.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2000. / Includes bibliographical references.

Dissertation (PhD)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

M.Sc. / A phytotoxic protein-lipopolysaccharide complex (PLPC) was isolated from 7 day old culture filtrates of Verticillium dahliae. The complex was purified to electrophoretic homogeneily by means of acetone precipitation, gel, chromatography and preparative agarose electrophoresis with a yield of 4.5 mg PLPC per litre culture filtrate ...

Pumkin seedlings (Cucurbita maxima) were inoculated with the fungus Sclerotinia sclerotiorum (Lib.) de Bary. Center regions of non-infected and infected cotyledons of various lengths were cut into 1 x 2 mm strips and processed for ultrastructural investigations. Complementary portions of opposing non-infected cotyledons were also processed as control tissue, and contained fewer storage products in cells than cotyledons of comparable size from non-infected plants. Young non-infected cells contained distinct lipid bodies, protein bodies and electron dense inlusions which were translocated out of older cells by abundant plasmodesmata. Initally, infected cells became plasmolyzed, followed by breakdown of the cytoplasm. Host cells were generally affected only 4-6 cells from the infection front. Many infected cells had abundant rough endoplasmic reticulum and all organells were eventually completely disrupted. Action of enzymes from fungal cells did not appear to be limited to the area immediatedly adjacent to hyphal cells.

No description available.