Antibiotics, plant disease control

Jha, V. "Antibiotics for Plant Disease Control" Mithi-la Univ. Darbhanga, India, 1978 p. 99. 

Reviews on many antibiotics including cycloheximide, griseofulvin and streptomycin tested for the purpose of agricultural use in western countries have been published (1-6). It is the purpose of this paper to discuss the present status of antibiotics as plant disease control agents. The discussion will mainly be limited to antibiotics which are practically used as new pesticides in Japan. For the other literature, the reader may refer the reviews mentioned above. 

One of the most serious problems on plant disease control is the virulence of virus diseases. Trials to develop antiviral antibiotics have been enthusiastically conducted by many workers. Consequently, many antibiotics have been revealed to be effective on inhibiting the multiplication of several plant viruses by in vitro test and pot test. They are blasticidin S, laurusin, bihoromycin, miharamycin, citrinin and aabomycin A etc. However,... 

Goodman (1959) discusses the phytotoxicity of streptomycin, cycloheximide, griseofulvin, polymyxin and tetracyclines. These are antibiotics that have been most used, or considered for use, in plant disease control. Other antibiotics that he mentions which have been observed to be phytotoxic are alternaric acid, glutinosin, mycophenolic acid and gliotoxin. 

The use of antibiotics for the control of plant virus diseases( ) is of interest. Several antibiotics have been tested for inhibition of replication of viral nucleic acid and/or protein synthesis within the host cell. Chloramphenicol, cycloheximide, actinomycin D and others are the most used antibiotics and the disease caused by tobacco mosaic... 

The avermectins, a family of compounds with potent anthelmintic, insecticidal and acaricidal activity, have vividly demonstrated that fermentation products can have entirely unanticipated activities. Besides their utility in animals, they show great promise for the control of insect pests of plants. Although antibiotics have found only a limited role in the control of plant diseases, the desire to find environmentally acceptable alternatives to the chemicals currently used has prompted new research efforts to discover fermentation products for use as pesticides. 

Well over 100 plant pathogens have become resistant to various fungicides under field conditions. Failure of the acyl alanines, benzimidazoles, thiophanates, carboxanilides, dicarboximides, hydroxypyrimidines, some organophosphates, and most of the antibiotics has occurred. In other cases, a moderate decrease in sensitivity without a rapid loss of disease control has been observed as in the case of sterol biosynthesis inhibitors (triazoles, pyrimidines, and imidazoles) and organophosphates. The most effective approach is to use fungicides having different modes of action in combination,... 

The need for effective bactericides is greater today than at any time in history. The recognition that mycoplasma-like organisms and xylem-limited bacteria cause plant disease means that there are additional diseases that are amenable to control with antibiotic-like compounds. X-disease, pear decline, peach yellows, phony peach, and plum leaf scorch are a few examples of diseases on deciduous tree-fruit crops caused by phytopathogenic prokaryotes. 

Resistant of plant pathogens to antibiotics Tolerance or resistance of pathogenic microorganisms to antibiotics has occurred shortly after application of antibiotics for the control of plant diseases as shown in Table VI. In order to reduce or avoid the emergence of tolerant fungi and bacteria in the fields, the alternate or combined application of chemicals with different mechanisms of action is recommended. 

The ability to produce antibiotics is common among the actinomycetes and much of the interest in these filamentous bacteria in recent years may be attributed to this fact. This interest has been manifest chiefly in research connected directly or indirectly with medicine. Soil samples from all over the world have been examined in the search for new species and strains that may produce a new antibiotic suitable for medical use. Hundreds of these antibiotics have been isolated but only a few have been found to be sufficiently non-toxic and specific for use in disease control. Among the best known of these that are in use are streptomycin, terramycin, aureomycin, cycloheximide, chlortetracycline, oxytetracycline, chloramphenicol and neomycin. Some of these have been used to a limited extent in disease control in plants. Their use for this purpose is limited by cost, by difficulty in getting the antibiotic into the plant, and by toxicity when used at concentrations adequate to be effective. The limited time that they are effective is also an important factor (Brian, 1957 Zaumeyer, 1958 Pramer, 1959). The role of antibiotics in soils and their effect on microbial ecology is considered in Chapter 18. 

Blastiddin S, the benzylaminobenzene sulfonate derivative, proved to be least phytotoxic to rice plants and displayed a pronounced antifungal activity against P. oryzae [8] this salt has been produced industrially since 1961 to control rice blast. Other derivatives of this antibiotic, blastiddin A and C proved to be inferior to the S derivative in disease control. The concentration of blasticidin S following spray treatments is 10 to 40 g ha. The chemical caused some phytotoxic effeds on rice plants when higher concentrations were applied. 

Plant phytoalexins [natural plant antibiotics] [1] have the potential of becoming a new class of useful compounds in the control of insect pests. Some phytoalexins have been demonstrated as deterrents to insect feeding. Considerable progress has been made to characterize them chemically and to extend the study of their function in plant disease resistance, but exploration of their role in the control of insect pests is just beginning. 

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