Cytological changes observed in the successive phases of the wheat rust caused by Puccinia recondita f. sp. tritici after the treatment with Tilt 250EC

The disease process of wheat (Triticum aestivum) cv. Parada caused by rust (Puccinia recondita Rob. ex Desm. f. sp. tritici) and the effect of applying the fungicide Tilt 250EC are described. The application of spraying at the time of inoculation, during incubation and at the beginning of the actual disease is most effective, thus attests to the highest pathogen susceptibility to that chemical agent at these phases of the disease. Tilt 250EC (propikonazole) inhibits the ergosterol biosynthesis in the fungus cells. Application of the preparation caused the inhibition of the development and necrosis of the intra- and extracellular mycelium. Observed were: irregular growth of intercellular hyphae, perforation of septas, homogenization of protoplasts and collapsing of cells. In the haustoria observed were: the thickening of the cell wall, modification of the perihaustorial space, protoplast degeneration and finally the haustorium obliteration