ABSTRACT
Because information on the use of fungicides to control of asian soybean rust (ASR) in Paraguay is scarce, the objective of this study was to evaluate the effect of 18 treatments (site-specific fungicides applied alone and in combination with mancozeb) on ASR. Two trials were carried out in La Paloma (Canindeyú, Paraguay) in two planting dates (S1: 10/10/2018 and S2: 01/20/2019) under a randomized complete block factorial design (Factor A: site-specific fungicides, Factor B: site-specific fungicides + mancozebe) with four replications. Analysis of variance was performed for each experiment and the Scott-Knott comparison of means test was performed at 5 % of probability. The Factor A x Factor B interaction was not significant for the variables evaluated in both sowing times. However, Factor A was significant for severity, AUCPE and EC in both planting times, where the mixtures picoxystrobin + benzovindiflupyr, and azoxystrobin + benzovindiflupyr gave rise to the lowest severity of RAS and the highest EC in S1, while in S2 the mixtures of trifloxystrobin + prothioconazole + bixafen, and trifloxystrobin + prothioconazole stood out. The least efficient fungicides were picoxystrobin + cyproconazole, and trifloxystrobin + cyproconazole. The addition of mancozeb to the mixtures of systemic fungicides favored the EC by 7 % in S1 and 3.8 % in S2 and the yield by 174 kg ha-1 in S1 and 128 kg ha-1 in S2.
Keywords
Phakopsora pachyrhizi
; controle químico; fungicidas penetrantes móveis; fungicidas protetores