RESISTANCE OF MAIZE HYBRIDS TO PHYTOPATHOGENIC FUNGUS MACROPHOMINA-PHASEOLINA (TASSI) GOID

The changes in the weather conditions of the last years had an essential effect also on the host-parasite relationships. The spread of warmth-and drought-requiring polyphagous Macrophomina phaseolina pathogenic fungi could be witnessed in Hungary, together with an increase in the damage caused by the fungi. Among our field crops it caused considerable damages on sugar beet, maize, sunflower, soybean, etc. From the authors' phytopathological surveys done in variety and hybrid comparative trials of several years, the results of 1992 on 45 maize hybrids are given. The infection was determined after having cut the stalk. The extent of average infection approached, and exceeded, resp. the 20% in two groups (FAO 200-299, FAO 300-599) and the infection index was between 0,2-0,3. From hybrids with shorter vegetation period, the hybrid SH-05 did not show any damage, followed by SWS-8029, Mutin, Atlet, Diva, Zenit, in case of which an infection not exceeding 10% was determined. All hybrids of the longer vegetation period were attacked, and only in three cases (Pannonia SC, Florencia and Pioneer 9311 SC) the rate of the infection remained under 10%. At a given location there was a considerable difference between the healthy and the most diseased plants, regarding both the frequency of the infected plants (F%=40), and the infection rate of the individual plants (F(i)=1,2). It is recommended to make use of the probable differences in resistance to the pathogen being in the maize hybrids when the reproductive materials are selected for production.