In Poland, about sixty fungicides are registered for chemical protection of potato crops against late blight (Phytophthora infestans) and some of them are effective against early blight (Alternaria spp.). Time of appearance of pathogens in potato crops depends on climatic conditions. In Bonin climatic conditions in the years 1998-2002, early blight was observed at the earliest date i.e. 41-56 days after potato planting. Trials carried out at the Plant Breeding and Acclimatization Institute Bonin have shown different usefulness of fungicides in control of some pathogens of potato. The tested fungicides varied in their mobility (contact, translaminar, systemic) and activity against pathogens (protectant, curative, eradicative). All tested fungicides were effective in control of late blight in potato crops. They inhibited the rate of late blight development and in most cases the differences of their effectiveness were not significant. Systemic fungicides with slower mobility have the best efficacy in control of late blight infections occurring on potato stems. In laboratory tests, mancozeb, propineb and mixture of metalaxyl and mancozeb were significantly more effective in inhibiting the development of Alternaria. Fungicides, which are effective in the control of different pathogens, are particularly useful in potato protection programs.

In the years 1999-2001, efficiency of plant protection products in control of early blight (Altemaria so/ani) was evaluated in two series of field experiment. There were examined four contact fungicides: propineb (Antracol 70 WP), chlorothalonil (Bravo 500 SC), mancozeb (Dithane M-45 80 WP) and zoxamide + mancozeb (Unikat 75 WG), and two with local penetrant mobility proparnocarb- hydrochloride + chlorothalonil (Tatoo C 750 SC) and metalaxyl-M + mancozeb (Ridomil Gold MZ 68 WP). In the series I propineb (Antracol 70 WP) showed the greatest efficacy in early blight control while in the series II mancozeb (Di thane M-45 80 WP) did.