Systems and rates of aerial application of fungicides in irrigated rice/Sistemas e taxas de aplicacao aerea de fungicidas em arroz irrigado

The present research studied the performance of flat-fan and hollow-cone nozzles, with application rates of 20 and 30 L [ha.sup.-1], and rotary disc atomizer with application rates of 10 and 15 L [ha.sup.-1]. The test was conducted with a fungicide spray tank composed of Azoxystrobin + Difenoconazole, in which the density and penetration of droplets into the canopy were evaluated using a water-sensitive paper and the distribution of the active ingredients in the plant was evaluated through the chromatographic analysis. Higher application rates resulted in higher droplet density in the upper stratum of plants. In all treatments, the penetration of the droplets was 26% into the middle stratum and 23% into the lower stratum, in relation to the top of the crop, resulting in an average 25% penetration of droplets into the leaf canopy. The active ingredients were distributed in greater quantity in the upper stratum of the plant. For the same weight, the upper part of the 'Puita Inta CL' rice cultivar has a leaf area 6.4 times larger than the lower part. It was concluded that higher application rate leads to higher droplet density in the upper stratum of the leaf canopy and that all systems and application rates promoted similar penetration of droplets into the canopy. Key words: Stol[R] nozzle Travicar[R] nozzle aerial application Estudou-se o desempenho dos bicos defletor e conico, com taxas de aplicacao de 20 e 30 L [ha.sup.-1], e atomizador rotativo de discos com volumes de 10 e 15 L [ha.sup.-1]. O ensaio foi realizado com uma calda de fungicida composta da Azoxistrobina + Difenoconazol (Priori + Score[R]), onde se avaliou a densidade e penetracao de gotas no dossel das plantas com auxilio de papel hidrossensivel e a distribuicao dos principios ativos na planta atraves da analise cromatografica. Em todos os tratamentos a penetracao das gotas no estrato medio foi 26% e no inferior 23% em relacao ao topo da cultura, resultando numa media de 25% de penetracao de gotas no dossel foliar. Os principios ativos distribuiram-se em maior quantidade no estrato superior da planta, em estadio R3. Para o mesmo peso, a parte superior da cultivar de arroz Puita Inta CL possui area foliar 6,4 vezes maior em relacao a parte inferior. Conclui-se que o maior volume de aplicacao proporciona maior densidade de gotas no estrato superior foliar e que todos os sistemas e volumes de aplicacao promoveram similar penetracao de gotas no dossel. Palavras-chave: bico Stol[R] bico Travicar[