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Protective, curative and eradicative effects of fungicides to control soybean rust caused by Phakopsora pachyrhizi, in greenhouse

Protective, curative and eradicative effects of systemic fungicides (azoxystrobin 50 g a.i./ha + nimbus 0,5%, carbendazin 250 g a.i./ha, tebuconazole 100 g a.i./ha, difenoconazole 50 g a.i./ha e epoxiconazole 25 g a.i./ha + pyraclostrobin 66,5 g a.i./ha) were evaluated in soybean (Glycine max) plants inoculated with a urediniosporal suspension of Phakopsora pachyrhizi, in greenhouse. To evaluate the protective effect plants were treated with fungicides and inoculated four, eight and 14 days after the treatment. To evaluate the curative and eradicative effects, the plants were inoculated with a urediniosporal suspension of P. pachyrhizi and treated with fungicides after two, four and eight days. Disease severity was assessed 16 days after each inoculation. With the exception of the fungicide carbendazin, all of the fungicides inhibited over 90% of urediniosporal germination until eight days after the treatment. Plants inoculated 16 days after the treatment with carbendazin presented severity statistically similar to unsprayed plants, while plants treated with fungicides of ergosterol biosynthesis inhibitors and strobilurin groups showed over 60% germination control. None of the tested fungicides provided an eradicative effect when applied before symptoms developed. However, all treatments reduced disease severity and urediniosporal viability. With the exception of carbendazin, all fungicides inhibited over 60% of urediniosporal germination until eight days after inoculation, in the incubation period of the disease.


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