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Organic & Integrated Tree Fruit Production

Friday, April 27, 2018


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Search results on 04/27/18

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.

3135. Engelhard, A. W.. 1989. Management of diseases with macro- and microelements.. Amer. Phytopath. Soc. Press, St. Paul, MN.
This book atempts to sort out the extensive amount of research on the influence of fertility status and management on soil borne plant diseases in a number of crops, including cereals. For example, most nutrient elements are reported to have an influence on take-all in wheat. Increased resistance to take-all is most pronounced when plants have a balanced nutrient supply containing NH4-N. Calcium helps maintain cell wall stability and stops leakage of sugars from the roots. It also is a part of compounds in the cell wall that are resistant to enzymes produced by some diseases to break down and invade the cell.

3945. Mahler, R.L.. 1981. Implications of acidification of farmland in northern Idaho.. ID Agr. Expt. Sta. CIS #629.
Loss of Ca and Mg is primarily by crop removal in northern Idaho; wheat crop removes 20-50 lb/ac/yr of each cation; ammonium-based fertilizers have been main acidifying factor; had been a big change in past 25 yrs; large % of soils now below pH 6.0; current wheat varieties in Idaho acid intolerant; soil acidity may favor certain weeds and diseases.

4585. Morrow, L.. 1990. Meaningful relationships.. Growers Guide, May 1990 A6.
Calcium is an important nutrient to consider. It gives strength to plant cell walls, making them more resistant to disease. It also interacts with nitrogen and helps the latter enter the plant through the leaves when foliar fed. It also reduces N volatility. Foliar applications of N have been shown to be twice as effective as soil applications. Calcium by itself is best applied at seeding time.

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.

5799. Reider, G.. 1981. Calcium cyanamide - fertilizer or pesticide?. World Crops, Jan., p.17.
Commercial production of calcium cyanamide was the first opportunity man had to fix nitrogen from the air for the production of nitrogen fertilizer. Calcium cyanamide's market potential is based on its herbicidal, fungicidal and other properties and on the fact that the product itself and its metabolites do not cause any environmental concern. Emphasis is laid on those biological properties which provide some answers to problems associated with crop production systems of today.

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.

8783. Marschner, H.. 1986. Relationship between mineral nutrition and plant diseases and pests. Chpt. 11. p. 369-390.. IN: Mineral Nutrition of Higher Plants. Academci Press, Orlando. 674 pp..
Although plant resistance to diseases is genetically controlled, it is considerably influenced by environmental factors, including level of plant nutrition from the soil. Excees N appears to lower disease resistance while potassium sufficiency increases resistance. Calcium makes cell walls more resitant to fungal parasite attack. Deficiencies of nutrients which lead to an accumulation of low molecular weight organic substances lower plant resistance. Boron-deficient wheat has a higher infection with powdery mildew. The severity of take-all on wheat is greatly inhibited by lower soil pH, beginning at 6.8. Ammonium-based fertilizers which acidify the rhizosphere can inhibit take-all severity, while nitrate N increases pH and disease problems. Ammonia is toxic to certain Fusarium species and nitrite is toxic to Pythium and Phytophthora. There is often a positive correlation between nitrogen application and pest attack, as young or rapidly growing plants are more susceptible. A large potassium supply often decreases pest attack. If a fertilizer increases the content of soluble organic nitrogen in plants, sucking insects tend to become more of a problem. The physical surface of leaves can be made less attractive to insects by some foliar sprays containing sodium silicate. One experiment with wheat found that without chemcial disease control, rust infection reduced grain yield in all fertilizer N treatments, but the zero N plots yielded the greatest. With fungicide, split N application led to highest yields.

10998. Reis, E.M., R.J. Cook, and B.L. McNeal. 1982. Effect of mineral nutrition on take-all of wheat.. Phytopathology 72:224-229.
Take-all developed on significantly fewer roots when P.K. and Mg were made available to the wheat roots at twice, compared with one-half, the concentration in normal Hoagland's solution, and resulted in the greatest increase in root growth. Ca and S had no significant effect on disease or root growth. Nitrate N increased the number of roots but did not influence disease. Zn and Cu treatments each resulted in more roots and less take-all. Mn, and possibly Fe, had suppresive effects on take-all. Field tests showed disease reduction with certain of the nutrient treatments.

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