ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00829.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract.Nutrient manipulation through fertilization or modification of the soil environment to influence nutrient availability is an important cultural control for plant disease and an integral component of production agriculture. Fertilization decreases soil‐borne diseases by maximizing the inherent disease resistance of plants, by facilitating disease escape through increased nutrient availability or stimulated plant growth, and by altering the external environment to influence the survival, germination and penetration of pathogens. The flexibility in most disease‐nutrient interactions permits a much broader utilization of this cultural control in decreasing disease severity than is presently practised. It is clear that the severity of most diseases can be decreased and the chemical, biological or genetic control of many plant pathogens enhanced by proper fertilization. Breeding nutrient‐efficient or disease‐tolerant crops and establishing cultivar requirements should further improve production eff

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00830.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract.Biological control by manipulating agricultural practices has been used for thousands of years. In the more restricted sense, of adding antagonistic micro‐organisms, biological control is still a very small part of the chemical pesticide market, but reliable products are becoming available. Achieving consistent results in realistic agricultural conditions is a problem, but there is a good possibility of controlling root diseases, especially where the soil characteristics or the environmental conditions can be controlled. The use of biological control in integrated control is successful, and in the long‐term genetic engineering techniques will be important in the development of biological control. Environmental safety and effective patent protection are still being developed, but there seem to be no insuperable probl

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00831.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract.Root diseases are often hard to identify or quantify visually, particularly by the inexperienced, so several modern methods of diagnosis from other branches of biology have been modified for soil‐borne plant pathogens. Though very sensitive, most of these techniques are slower and more laborious than the routine inspection of plants for disease symptoms, yet they need less expertise and are consistently accurate. Apart from immunology, most laboratory diagnostic procedures have so far proved ill‐suited for field use, as they are neither sufficiently flexible nor portable. Despite the rapid detection and identification of numerous viruses by routine enzyme‐linked immunosorbent assays (ELISA), there have been until recently few suitable protocols adapted for fungi. DNA hybridization forms the basis of another group of fairly rapid diagnostic techniques which will probably be restricted to the laboratory for some while yet. Nevertheless, DNA techniques have proved valuable in various investigations, such as unravelling the phylogeny of some species of soil‐borne pathogens. For the foreseeable future methods based on antibodies and DNA probes are likely to extend their domination of detection and diagnosis techniques. By making recognition easier, these techniques play complementary roles in expanding our understanding of the biology, taxonomy and ecology of soil‐borne

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00832.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract.The recent spread of sugar‐beet rhizomania and barley yellow mosaic virus in Europe has stimulated fresh interest in plant viruses with soil‐borne fungal vectors. Although there are at least 20 such viruses, most of which cause diseases of important field crops, there are many gaps in our knowledge of their epidemiology because much research has concentrated exclusively on the viruses. The vectors are lower fungi that are obligate parasites of plant roots and are therefore difficult to study experimentally. Resting spores containing virus can survive indefinitely in soils but effects of rotation have not been greatly studied. There is no quantitative information relating inoculum levels of fungus and virus to disease development. Only limited information is available about inoculum distribution in soil and factors affecting its potency. The diseases are mostly dispersed by soil movement during agricultural operations but some features of disease distribution in infested fields await adequate explanation. Little is known about interactions with other micro‐orga

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00833.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract. There are many records of mycorrhizae, particularly ectomycorrhizae, protecting roots against soil‐borne plant pathogens, though fungal or viral diseases of the green parts are usually more severe in mycorrhizal plants. There are various mechanisms by which mycorrhizae protect themselves against soil‐borne diseases. The occurrence and ecological significance of these mechanisms are discussed in relation to environmental factors. Mycorrhizae will probably become a very effective means of biological control once we have learned how to manage t

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00834.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract.The most important root diseases of wheat in southern Australia are take‐all, rhizoctonia bare patch and cereal cyst nematode. Control of grasses in annual pastures in the year preceding wheat crops decreased take‐all on wheat and the amount of the take‐all fungus in soil, decreased the damage caused byRhizoctonia, and gave yield increases. Fumigation of cereal‐growing soils gave yield increases in wheat of 0.75 to 2.8 tonnes per hectare, indicating that in southern Australia soil‐borne root diseases impose a major constraint on productivity. Residues of the herbicide chlorsulfuron one year after application to an alkaline soil increased root damage byRhizoctoniain barley and decreased grain yields by 1.5 tonnes per hectare. Root damage by cereal cyst nematode was decreased by direct drilling wheat and also by having a barley cultivar resistant to the pathogen as a preceding crop. The number of cysts of cereal cyst nematode on wheat roots was increased by the application of superphosphate in bands with the seed. These results show that in southern Australia soil management strategies which decrease the levels of root disease greatly increase gra

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00835.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract.White rot (Sclerotium cepivorum) causes serious losses inAlliumcrops throughout the world. The pathogen produces sclerotia which survive for long periods and are the main source of inoculum. Sclerotial germination is stimulated by the host and new sclerotia are produced on the host near the soil surface.Alliumcrops are cultivated in various systems and environments and no one method of control is effective. There is increasing interest in control strategies based on combinations of treatments which decrease the populations of sclerotia in the soil, thereby improving the effectiveness of present methods of control. Materials and methods being tested for inclusion in programmes of integrated control include germination stimulants, soil fumigants, solar heating, roguing, aerobic composting, microbial control and combined chemical/microbial control with fungicide‐resistant micro‐organi

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00836.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract.The relationship between take‐all and grain yield was investigated in a first spring wheat crop grown in a field experiment on artificially infested soil. Different incidences and severities of disease were obtained by using different cultivations to incorporate equal amounts of inoculum (killed oat grains colonized by the fungal pathogen) at different depths. The intention of incorporating inoculum at different stages in the same sequence of cultivations to achieve identical soil conditions with inoculum at different depths was not entirely successful because of weather conditions.For most sampling dates and different assessments of disease, there was a strong relationship between yield and disease: regression coefficients were negative and significant (P= 0.01). The linear regression model using logit transformations of disease data from infestations achieved using similar sequences of cultivations accounted for>70% of the variance at all sampling dates, but with untransformed data (percentage plants and percentage roots infected) percentages of variance accounted for were much less at sampling times before anthesis. The plot area affected by premature ripening (whiteheads) also correlated well with yield where similar sequences of cultivations were used, but less well where rotovating to different depths created different soil conditions.The results are discussed in relation to published results from (1) farm surveys, (2) field experiments with natural infection and (3) experiments using different amounts of artificially‐produced inoculum. The wider application of artificially‐produced inoculum in field experiments on take‐all is also con

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00837.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0266-0032    

DOI:10.1111/j.1475-2743.1990.tb00838.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY