Effectiveness of Four New Pyrazole-pyrimidines on Phytopathogens: Ultrastructural Evidences on Pythium ultimum

Four newly synthesized molecules derived from pyrazole! pyrimidine were assayed on Botrytis cinerea Micheli\ Fus! arium moniliforme Sheld and Pythium ultimum Trow[ All proved e}ective in inhibiting the growth of the phyto! pathogens at all of the test concentrations "09\ 19\ 49099 mg:ml#[ The most e}ective compound was 0!"2#nitro! phenyl ! 5 ! tri~uoromethylpyrazolo 2\3 ! d pyrimidine ! 3"4H#!thione "CF22#[ Ultrastructural studies on P[ ulti! mum treated with CF22 revealed alterations in the normal hyphal shape and\ at high concentration\ plasmolysis and damage to the wall texture was observed[ At 19 mg:ml di}erent vesicles were seen in the cytoplasm] some appeared quite dense\ and speci_c cytochemical reactions indicated that they were most likely peroxysomes^ other vesicles seem to be vacuoles of varying content[ In some cases there was disintegration of the nuclear envelope[ The e}ects on membrane lipids and interference in pro! tein synthesis are hypothesized as possible mechanism of action of the molecule