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Search results on 03/21/18
1466. Coventry, D.R. and J.F. Kollmorgen. 1987. An association between lime application and the incidence of take-all disease in wheat.. Aust. J. Exp. Agric., 27:695-699.
The effects of lime, deep ripping and fertilizer treatments on the occurrence of take-all symptoms in wheat. Although liming the soil increased damage by Gaeumanomyces graminis var. tritici, and perhaps other pathogens, the overall grain yields were not reduced because of the countering effect of lime promoting yield. Lime also altered the composition of grasses in pasture plots, resulting in more brome grass and barley grass. The control of take-all by crop rotations and controlling grassy weeds in pasture could be a necessary adjunct to liming if maximum yield benifits are to be obtained. Liming severely acid soils benifits the host more than the pathogen, whereas in moderately acid soils the reverse was true. The traditional rotation is a long-term clover ley pasture (5-8 yrs) with a significant component of annual grasses that host G. graminis var. tritici, followed by 2-4 years of consecutive cereal crops. This system therefore favours a build-up of inoculum of the take-all fungus and liming may therefore increase grain yield losses.
5981. Rovira, A.D.. 1986. Influence of crop rotation and tillage on Rhizoctonia bare patch of wheat.. Phytopathology, 76(7):669-673.
Rhizoctonia bare patch was more severe in direct drilled wheat than in wheat sown into cultivated soil. The area of affected crop was consistently larger when wheat followed a mixed annual pasture of grasses and Medicago spp. than when wheat followed wheat, peas, or grass-free pasture of Medicago spp. All isolates of R. solani were pathogenic on wheat, barley, peas, Medicago spp., annual ryegrass, and barley grass.
10098. Reeves, T.G., A. Ellington and H.D. Brooke. 1984. Effects of lupin-wheat rotations on soil fertility, crop disease and crop yields.. Austral. J. Expt. Animal Husb. 24:595-600..
Three experiments were conducted between 1974 and 1979 in northeastern Victoria to investigate the effects of rotating wheat and sweet lupins on crop yields, soil fertility and crop diseases. The grain yield of continuous wheat was 2.58 t/ha and of continuous lupins 0.66 t/ha. Wheat, grown after a lupin crop, yielded 750 kg/ha more than wheat after wheat, and a second wheat crop, after lupins, yielded 420 kg/ha more than a third successive wheat crop. Lupins, grown after wheat, yielded 50-165% more than lupins after lupins. Grain N of wheat was significantly increased after lupins. Differences in soil mineral N were apparent ten weeks after sowing, with mean N levels of 37 and 55 kg/ha under wheat and lupins, respectively. Soil mineral N was consistently greater after lupins than after wheat. Overall, mean accretion of mineral N under lupins was 41 kg/ha/year. Lupins after lupins suffered severly from brown leaf spot, up to 63% of plants being infected compared with only 18% after wheat. Disease incidence in wheat (mainly G. graminis) increased from less than 1% in the first year of cropping, to 36% infection in year 3 of continuous wheat. When wheat was grown after lupins, disease incidence was negligible.
11085. Cook, R.J. and A.D. Rovira. 1976. The role of bacteria in the biological control of Gaeumannomyces graminis by suppresive soils.. Soil Biol. Biochem. 8:269-273.
The suppresion of take-all by certain soils or following certain soil treatments is considered to be an expression of either specific or general antagonism. Specific antagonism is effective in dilutions as high a 1 in 1000, can be transferred from soil to soil, operates near or on wheat roots, is destroyed by 60 C moist heat, is fostered by wheat monoculture, but may be lost by fallow or rotation with certain crops, especially legume hay or pasture. Strains of Pseudomonas fluorescens may be involved. General antagonism is a soil property which cannot be transferred and is resistant to 80 C heat, to chemical fumigation, but not to autoclaving. Take-all control by organic amendments, minimum tillage, or a soil temperature of 28 C may be expressions of increased general antagonism. In southern Australia, take-all losses can be very heavy. Some general antagonism occurs, but seldom any specific antagonism. Both types occur in dryland wheat areas of the Pacific Northwest, where take-all is virtually non-existent.