Neste trabalho, avaliou-se o efeito de fungicidas no desenvolvimento da ferrugem asiática, causada pelo fungo Phakopsora pachyrhizi, e na produtividade da soja. Os fungicidas foram pulverizados quando as plantas estavam no estádio de desenvolvimento R4. Utilizou-se a cultivar Fepagro-RS 10 e delineamento blocos ao acaso com quatro repetições e dez tratamentos. A avaliação da severidade da doença foi feita 30 dias após a pulverização, utilizando-se uma escala de notas de 0 a 5, considerando-se a porcentagem da área foliar infectada. Os tratamentos com os fungicidas azoxystrobin, difenoconazole + propiconazole, fluquinconazole, myclobutanil, pyraclostrobin + epoxiconazole, tebuconazole e trifloxistrobina + propiconazole, controlaram o patógeno em relação à testemunha, mostrando notas médias de severidade igual ou inferior a 2 e não diferiram entre si. O tratamento com difenoconazole (nota 3,05) controlou o patógeno, mas com nota inferior ao tratamento com carbendazin (nota 3,85) e à testemunha (nota 4,5). Todos os tratamentos mostraram produtividades superiores à testemunha, variando entre 14,5% e 27,3%. O peso de cem sementes foi superior ao da testemunha para todos os tratamentos (11,8% a 14,4%), com exceção do carbendazin (5,2%).
This work was done in order to evaluated the fungicides effect on the control of soybean rust caused by Phakopsora pachyrhizi, as well as their effect on yield. The fungicides were sprayed when the plants were at the growth stage R4. The cultivar used was Fepagro-RS 10. The experimental design used was a randomized blocks replicated four times and with ten treatments. The disease severity evaluation was done 30 days after spraying using a scale of notes (0 to 5), measuring the infected leaf area. The treatments with the fungicides azoxystrobin, difenoconazole + propiconazole, fluquinconazole, myclobutanil, pyraclostrobin + epoxiconazole, tebuconazole and trifloxystrobina + propiconazole controlled the pathogen when compared with the control, showing severity average notes equal or lower then 2, without difference among them. The treatment with difenoconazole (note 3.05) controlled the pathogen, with lower note than the carbendazin treatment (note 3.85) and non-treated plants (note 4.5). All fungicides treatments showed higher yield than non-treated plants varying from 14.5% to 27.3%. The weight of 100 seeds was higher than the control (11.8% to 14.4%), except for carbendazin (5.2%).