Efecto in vitro del fungicida iprodione sobre alternaria spp. y prospección para su inclusión en estrategias de manejo en papa, tomate, ajo y cebolla

the sensibility to iprodione of alternaria solani (ell and mart) j. and gr. on two wild isolates obtained from potato and tomato leaves with the diseases symptoms, and two of a. porri (ell) nierg from onion and garlic, by radial growth of colony test with tomato juice-agar culture medium, with the addition of the fungicide in concentrations from 0.1 to 100 mg a.i./l. the ld50 and ld95 for a. solani of potato were 0.61 and 3.64 mg a.i./l, and from tomatoes were 0.61 and 3.68 mg a.i./l, respectively. the values for a. porri in garlic were 0.61 and 3.68 mg a.i./l, and for onion were 0.48 and 3.12 mg a.i./l. the behaviour of diseases was evaluated in field conditions, with three chemical strategies of control that included iprodione alone, iprodione alternated with mancozeb, ditiocarbamates and a control without treatment, in a completely randomized design. sensibility to iprodione was tested on 258 isolates took up from lesions appeared after each treatment. higher control level was observed in variant of iprodione and when it was combined with mancozeb, which showed significant differences in relation with ditiocarbamates treatments and with the control, with average of 20 and 25% of attack index respect to 55 and 70%, respectively, at the end of cultivation cycle. all isolates were sensible to iprodione, thought it is recommended iprodione/mancozeb combination in order to avoid resistance development.