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10338. Morrow, L.. 1992. Chloride fertilizers.. Growers Guide, Feb. 1992, p.A6.
Chloride is provided when KCl fertilizers are used. It affects photosynthesis, enzyme activation, cation transport, stomatal activities and other processes. In soil, Cl inhibits the conversion of ammonium to nitrate. This maintains a lower pH near the root. Cl increases the number of non-pathogenic organisms in the rhizosphere. Cl competes with nitrate for plant uptake, and reduces plant nitrate levels, which can also reduce certain plant diseases. Take-all, tanspot, stripe rust, septoria, leaf rust, and common root rot have all bee suppressed by chloride.
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.
1521. Davies, D.B.. 1977. Soil management. 3rd edition.. Farming Press Ltd., Suffolk..
Soil compaction increased chances of root disease (take-all, foot rot); problems of loss of soil structure; leads to reduced fertilizer use efficiency, especially N & P; winter cereals less sensitive to poor structure than spring cereals; 2-3 yr grass/alfalfa stand helps restore structure; benifits of subsoiling on silt soils; best time is when soil is dry.
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
3550. Kauraw, L.P. and R.S. Singh. 1982. Effect of organic amendment of soil on the incidence of root rots. Indian J. Mycol. Pl. Pathol., 12(3):271-277.
Amendment of soil with oil cakes of margosa, castor of groundnut increased incidence of root rot caused by Pythium graminicolum. This increase was proportional to the amount of oil cake used. Margosa and groundnut cakes reduced root rot caused by Fusarium spp., while castor cake increased it. All the oil cake amendments reduced the incidence of Sclerotinium root rot. Amendment of soil with saw dust increased root rot caused by Fusarium spp. and H. sativum, but significantly decreased that caused by P. graminicolum or S. rolfsii even at the lowest dose used.
5735. Rasmussen, P.E. and C.R. Rohde. 1988. Stubble burning effects on winter wheat yield and N utilization under semiarid conditions.. Agronomy J. 80:940-942.
Burning vs. not burning was examined at 3 nitrogen levels over 6 years (3 crops). Burning had no effect on grain yield or grain N uptake. Burning increased straw yield when wheat was fertilized by N, but had no effect on straw N uptake. Burning did not decrease foot rot incidence or severity, but did reduce downy brome density. T: Effects of stubble burning and N fertilization on grain and straw of winter wheat 1980-85. Effect of stubble burning on foot rot infection. Effect of stubble burning on downybrome infestation.
6359. Smiley, R., D. Wilkins, W. Uddin, S. Ott, K. Rhinhart, and S. Case. 1989. Rhizoctonia root rot of wheat and barley.. OR Agr. Expt. Sta. Special Report 840, p. 68-79..
Rhizoctonia root rot is now considered the most severe root disease of barley in the PNW. It is more important than take-all and Pythium on wheat produced in drier areas (<16" precip.). Based on long-term plots at Pendleton, different management systems are unlikely to greatly influence the biological resistance of soils to Rhizoctonia. Rotational crops susceptible to Rhizoctonia include wheat, barley, peas, chickpeas, lentils, and rapeseed. The disease is less apparent on small grains after legumes than after cereals. Rhizoctonia damage is always highest on no-till systems, but yields may not suffer due to improved water relations under conservation tillage. Australian research indicates that applications of N and P fertilizers can reduce the disease. There appear to be detrimental herbicide interactions with Rhizoctonia, particularly Glean on high pH soils. Also, the use of glyphosate increased disease incidence, perhaps by signalling the pathogens to move from the dying plants to newly seeded ones. A delay of at least 2 weeks is suggested between chem kill and planting of a new crop.
6370. Smiley, R.W.. 1990. Seed treatment fungicides for wheat and barley.. Sherman Station Field Day handout, OSU, Moro, OR.
Seed applied fungicides failed to improve yields of winter wheat or were inconsistent from site to site and/or year to year. The most consistent treatment for winter wheat was a combination of Apron and Vitavax 200. This mixture increased wheat yields by 3%. Fall barley yields were either unchanged or reduced, while spring barley showed the best economic response. Thus, an economic response to seed treatment is unlikely in the absence of damaging amounts of smut disease. Since control of smut depends on the combination of fungicide seed treatments and genetic resistance, which has been stable for decades, the use of untreated seed is discouraged to avoid the loss of genetic resistance by cereal cultivars.
9846. Stewart, R. and J. Stephens. 1910. The effect of formalin on the vitality of seed grain.. Utah Agr. Expt. Sta. Bulletin 108, Utah State Univ., Logan, UT.
The use of formalin for the prevention of smut in wheat, oats and barley was found to be effective. However, it was also found that for greatest effectiveness and vitality of seed, some general guidelines must be followed. The best strength of solution to use is one pound of 40% strength formalin to fifty gallons of water. The seeds may be effectively and safely treated in this solution from 10 to 60 minutes. If the treated seed is thoroughly dried, it may be safely stored for at least six weeks after treatment.
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.