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Monday, April 23, 2018

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1819. Elliott, L.F. (ed.). 1987. STEEP - Conservation concepts and accomplishments.. Washington State Univ. Publ., 662pp..
A compilation of 48 papers covering: tillage and plant maagement; erosion and runoff predictions; plant design; pest management; socio-economic; integrated systems; technology transfer for cropping systems; 22 technical notes. T: many

1424. Cook, R.J.. 1988. Management of the environment for the control of pathogens.. Phil. Trans. R. Soc. London B 318:171-182.
Pathogens can be controlled by management of the environment of 1) the host plant, to maximize resistance, 2) non-pathogens associated with the pathogen to enhance antagonisms, and 3) the pathogen itself, to limit its activity or longevity directly. Often only the slightest change in the environment will bring about a major change in disease activity, such as drying of the soil. The quality and quantity of non-pathogens are both important, and contribute to more complexity, and usually more biological stability. Fusarium foot rot of wheat first was a serious problem in the low- to intermediate-rainfall areas, particularly with the more progressive farmers. This was traced to the occurrence of severe plant water stress triggered by excessive nitrogen fertilization. By managing plant water potentials, the parasitic activities of Fusarium culmorum are virtually prevented. By leaving standing stubble, the saprophytic activities of this fungus are virtually prevented. Pythium root rot generally requires control only in the intermediate- to high-rainfall areas. The most effective controls are combinations that 1) minimize wheat straw on the surface or in the top 10-15 cm soil, 2) keep the soil surface exposed to drying winds and sun, especially in early growth, and 3) keep soil matric potentials in the top soil drier than -0.4 to -0.5 bar. Straw can be eliminated by burning, burial, or rotation (peas, lentils). Fumigation of the soil, not the straw, is necessary to eliminate the pathogens. Pythium is also limited by early seeding, and is less prevalent in soils without a tillage pan. To maximize take-all antagonism, tillage and delayed seeding can be used. Also the use of ammonium rather than nitrate fertilizer suppresses take-all, and any fertilizer will suppress it on an N-starved soil.

10814. Heim, M., R.J. Cook, and D.J. Kirpes. 1986. Economic benefits and costs of biological control of take-all to the Pacific Northwest wheat industry.. Research Bulletin 0988, Agr. Res. Center, Washington State Univ., Pullman, WA.
Take-all can severely lower wheat yields. One possible control is through the use of antagonistic Pseudomonad bacteria applied to wheat seed. Disease surveys in the region verified increased disease problems with grain intensive rotations and with reduced till or no-till farming. Overall, an estimate 600,000 acres are affected by take-all in the region. Estimates of the cost of a commercial bacterial seed treatment were $14.30/ac applied. Wheat yields were assumed to increase an average of 5-10% from this. At a wheat price of $3.00/bu, a minimum 5 bu/ac increase is needed to break even on the treatment.

10903. Weller, D.M., R.J. Cook, E.N. Bassett, R.L. Powelson, and R.R. Peterson. 1986. Rhizoctonia root rot of small grains favored by reduced tillage in the Pacific Northwest.. Plant Disease 70:70-73.
The first field identification of Rhizoctonia root rot of wheat and barley was made in eastern Oregon and Washington at six different locations. At all sites where the disease occurred, the wheat or barley was either direct drilled into stubble, sown with minimum tillage, or sown the same day the soil was tilled. In experimental plots with winter wheat, there were 9.9, 2.8, and 1.4 patches per treatment in which no-till, reduced till, and conventional till, respectively, were practiced.

11017. Cook, R.J.. 1986. Wheat management systems in the Pacific Northwest.. Plant Disease 70(9):894-898.
Strategies for reducing disease problems and increasing yields closer to potentials of the site are described for four agroecosystems: rainfed wheat-fallow, rainfed annual crop; irrigated; western OR and WA.

11057. Cook, R.J.. 1980. Fusarium foot rot of wheat and its control in the Pacific Northwest.. Plant Disease 64:1061-1066.
Fusarium foot rot occurs mainly in low to intermediate rainfall areas of the PNW (20-40 cm) where wheat is grown after fallow. The disease appears related to water stress. Sometimes nitrogen use can induce water stress and was blamed for the disease. Wheat varieties vary in their susceptibility to the disease. The disease can be controlled by minimizing pathogen population increases and by reducing or delaying water stress. Oats should be avoided since they are an excellent host for the disease. Actions to improve water infiltration and storage reduce the chance of water stress. By maintaining residue on the surface, airborne saprophytic fungi will colonize it and prevent Fusarium from doing so. N applications should be based on realistic yields so water stress will not be induced. September seeding, rather than August, avoids excessive foliar growth which can induce water stress.

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