Chemical structure and fungicide selectivity
The influence of stereo- and other isomers, homologues and structural variations on the activity of various types of systemic fungicides is reviewed.
Fungitoxicants and fungal taxonomy
SummaryCertain chemicals are selectively toxic to specific groups of fungi. For example, benzimidazoles and thiophanates are selectively toxic to Ascomycotina and Deuteromycotina, oxathiins are selectively toxic to Basidiomycotina, and pyrimidines, polyenes, and polyoxins are toxic to many fungi but not Mastigomycotina. Chemicals selectively toxic to Mastigomycotina include fenaminosulf and prothiocarb. Such chemicals contribute to fungal taxonomy in several ways. Incorporated into isolation media they facilitate the recovery of specific groups of fungi from natural habitats. In some cases the distinctive response of a fungus to a specific chemical facilitates identification of the fungus. Arrangements based on sensitivity to selective fungitoxicants often match classifications based on morphological characters. Selectivity data then provide opportunities to assess the naturalness of established or experimental classifications, to demonstrate the predictive power of classifications or to show the ability of alternative classifications to accommodate apparent exceptions. Selective fungitoxicants also contribute to chemotaxonomy of fungi in two major ways. Fungi can be partitioned into groups on the basis of their responses to an external chemical and research on the mechanisms of action of selective fungitoxicants provides information on the comparative biochemistry of fungi.
Suppressed Light Emission of the Reaction Zone in Detonation
THE detonation of high explosives in water can be photographed with an open camera and a flash light as the explosive gases do not emit light. The method has been used1 to investigate the spread of shock waves and explosive gases, and to investigate the initiation by shock waves2. We have found that it can be used also in certain gases such as butane and propane. The method is not suitable, on the other hand, for explosives with two levels of detonation velocity in the case of low velocity. A great part of the reaction then occurs after the reaction zone has passed and the expanding explosive gases are very luminous even in water.