CHEMICALS have their effects on fungi, viruses and host on the one hand and virus multiplication on the other. Chemotherapy of plant virus diseases does not mean actual curing in most cases. Stoddard (1947) found that disease of peaches able to cure by using ZnSO4 Thomas and Baker (1949) successfully used ZnCl2 and CaCl2 against carnation mosaic disease. Woods (1940) treated TMV infected tobacco leaves with sodium cyanid and found a well pronounced inhibitory effect on virus multiplication by administration of malachite green. Commoner and Mercer (1952) demonstrated that a pyrimidine derivative strongly affected virus multiplication. This effect of thiouracil was reflected both in decreased virus concentration and in a delay of the appearance of TMV induced amorphous inclusions (Hirai, 1958). Porter and Weinstein (1957) found that tobacco plants infected with TMV and treated with thiouracil, the amount of amino acids, amide and ammonia nitrogen increased compared with the untreated controls. Tomlinson et al. (1977) have shown that carbendazim when used as a root drench treatment was effective in the suppression of symptoms of Beet Western Yellow Virus (BWYV) in lettuce and TMV in tobacco plants.
On the other hand, fungus infection may increase the susceptibility of some hosts to some virus infections (Yarwood, 1951, Reyes and Chadna, 1972 and Stevens and Gudauskus, 1982). Furthermore, antagonistic reaction was also reported by many investigators (King et al., 1964, El-Hammady et al. 1983, Omar,1984 and Abd-EI-Mageed,1986)
This study has been designed to illustrate the pathological and physiological interaction between fungal and viral bean infections as well as the role of seed-dressing with fungicides in this respect.
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