University of Arkansas, Fayetteville, Arkansas, United States


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Publications (2)2.69 Total impact

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    ABSTRACT: Field experiments were conducted near Chickasha, OK, in 1999 and 2000 and near Perkins, OK, in 2000 to evaluate the effects of Palmer amaranth on harvest efficiency of grain sorghum and full-season competition with that crop. Weed densities were 0 (the weed-free check), 1, 2, 4, 6, 9, 12, and 18 plants/15 m of row. In the harvest efficiency experiments, each additional weed per 15 m of row increased grain moisture before cleaning by 0.7 and 0.2% at Chickasha in 1999 and at Perkins, respectively. After cleaning, it increased moisture by 0.2% in both the experiments for each weed. Foreign material increased 67, 2, and 3 kg/ha at Chickasha in 1999, Chickasha in 2000, and Perkins, respectively. At Chickasha in 2000, sorghum seed loss through the combine increased 11 kg/ha for each additional weed per 15 m of row. Grain grades improved at Perkins at higher weed densities. In the. competition experiments, grain yield decreased by 1.8 to 3.5% for each increase of 1 weed/15 m of row. More weeds resulted in higher weed dry weight. Each kilogram of Palmer amaranth dry weight per plot reduced grain yield by 5.3 to 9.1%. In 2000, sorghum seeds per panicle were reduced by 27 to 50 for each weed. Grain grades generally decreased as weed density increased at Chickasha in 2000 but not at Perkins.
    No preview · Article · Sep 2009 · Weed Technology
  • Michael Ditmore · Jerry W. Moore · David O. TeBeest
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    ABSTRACT: The fungal plant pathogen, Colletotrichum gloeosporioides f. sp. aeschynomene (CGA), has been used successfully since 1982 to control northern jointvetch (NJV), Aeschynomene virginica, in rice and soybeans in the USA as COLLEGO®, a bioherbicidal formulation of a single isolate of this pathogen. The interactions and fitness of different field isolates of this fungus and effective bioherbicide have not been fully examined. We examined CGA population structure and inter-isolate competition using molecular markers in field and greenhouse experiments. NJV plants were first inoculated with one isolate or a mixture of two isolates, Cla-5a and 3-1-3, followed by a challenge inoculation containing either one or both isolates, 4 or 5 days later. Plants first inoculated with Cla-5a alone, or in mixture with 3-1-3, had Cla-5a comprising approximately 80% of the population after 21 days regardless of challenge inoculation. In contrast, when the primary treatment was 3-1-3 alone, wounding, or benzodiathiazole, 3-1-3 detection only approached 50% of the population following challenge inoculation. Primary inoculation with Cla-5a significantly reduced the number of lesions caused by 3-1-3 challenge, whereas primary inoculation with 3-1-3 did not significantly affect the number of lesions caused by Cla-5a challenge. Size of lesions caused by the two isolates following challenge inoculations and dispersal of the isolates from lesions to healthy plants were not affected by the primary inoculation. These results suggest a specific interaction by Cla-5a with the host defense response creating a more favorable environment for its own colonization of NJV to the exclusion of 3-1-3.
    No preview · Article · Dec 2008 · Biological Control