Browsing by Author "Mathre, Don"

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Bio-Priming Seed Treatment for Biological Control of Pythium Ultimum Preemergence Damping-Off in SH-2 Sweet Corn
(American Phytopathological Society, 1990) Callan, Nancy W.; Mathre, Don; Miller, James B.
Sweet corn (Zea mays) with the shZ gene for enhanced sugar content is highly susceptible to preemergence damping-off, caused primarily by Pythium ultimum in Montana’s Bìtterroot Valley. Rhizosphere bacteria that adhered to hyphae of P. ultimum and were antagonistic to the growth of this pathogen were isolated from Bitterroot Valley soils. An isolate of Pseudomonas fluorescens, AB254, provided superior seed protection from Pythium damping-off in naturally infested soils. At least 1 X 100,000,000 cfu per seed of AB254 was needed to achieve maximum protection. In a process we have termed “bio-priming,” dry seed was coated with P. fluorescens AB254 and allowed to imbibe water under warm temperatures until a 35-40% moisture content was achieved. During bio-priming, bacterial populations increased from 10 to over l0,000-fold, depending on initial inoculum level. Bio-priming provided protection against damping-off as good as or better than seed treatment with metalaxyl when the seeds were planted in cold soil. This process may be of interest and value to growers who wish to plant sweet corn or other temperature-sensitive crops into cold soils where damping-off is a problem and the use of chemical seed treatments is not desired.
Combined Biological and Chemical Seed Treatments for Control of Two Seedling Diseases of SH2 Sweet Corn
(American Phytopathological Society, 1995) Mathre, Don; Johnston, Robert H.; Callan, Nancy W.; Mohan, S.K.; Martin, John M.
Experiments were conducted in both the glasshouse and in the to determine if biological and chemical control agents could be used together on sweet com (Zea mays L.) seed to control Pythium ultimum damping-off or Penicillium oxalicum seedling disease. Pseudomonas aureofaciens AB254 and Pseudomonas sp. AB842 were used for control of P. ultimum and P. oxalicum, respectively. Metalaxyl seed treatment for control of P. ultimum was used at rates from 100 to 0.01% of the recommended rate either alone or in combination with P. aureofaciens AB254. Imazalil seed treatment for control of P. oxalicum was used at rates from 100 to 1% of the recommended rate either alone or in combination with Pseudomonas sp. AB842. In field tests, combining a chemical treatment with the biological agent did not affect the efficacy of disease control. Nor did combining low rates of chemical with the biocontrol agent increase the efficacy or reliability of disease control.
From Discovery to Use: Traversing the World of Commercializing Biocontrol Agents for Plant Disease Control
(American Phytopathological Society, 1999) Mathre, Don; Cook, R. J.; Callan, Nancy W.
Microorganisms play an enormously important role in plant disease control. As naturally occurring resident antagonists, they can be managed or exploited to achieve the desired results. They are responsible for the “crop rotation effect,” which is possibly still the single most important disease management tool used worldwide. On the other hand, the addition of organic materials such as compost, barnyard manure, and green manure is known to intensify the soil-sanitizing benefits of resident antagonists so much that it is sometimes possible to eliminate the need for crop rotation. Entomology is commonly used as the standard for success with biological control agents introduced into the environment. Compared case-for-case, plant pathology is a barely-visible distant second to entomology. In fact, we would have to say it is a distant third, since there are more successful cases with introduced biological control agents of weeds—herbivorous insects and pathogens—than of plant diseases. On the other hand, if we narrow the comparison to biological control with introduced micro-organisms, plant pathology begins to look quite respectable. Examples of biological control sparked the current and much more successful effort with plant-associated microorganisms as agents introduced for biological control of plant pathogens.