Controle químico da "ERGOT" (Claviceps africana Frederickson, Mantle & de Milliano) ou doença-açucarada e das principais doenças foliares do sorgo (Sorghum bicolor (L.) Moench) | Chemical control of "ERGOT"(Claviceps africana Frederickson, Mantle & de Milliano) or sugary disease and the main foliar diseases of sorghum (Sorghum bicolor (L.) Moench)

The efficiency of fungicides in the control of sugar disease of sorghum (Sorghum bicolor (L.) Moench.) was evaluated in a seed production field of the sorghum hybrid BR 304. The following fungicides and doses (g a.i./ha) were evaluated : captan (1250.0), fenarimol (80.0), fentin hydroxide (166.7), prochloraz (450.0), chlorothalonil (1500.0), iprodione (750.0), azoxystrobin (150.0), thiabendazole (360.0), procimidone (750.0), ziram (1500.0) and tebuconazole (200.0). A control plot without fungicide application was included in this assay. Applications were performed with a back sprayer, covering the whole panicle, and using 4 days intervals between applications at the anthesis. Seven days after the end of the applications, the percentage of diseased panicles varied of 5.4 for the fungicide tebuconazole and 100 for the most of the other treatments. For the percentage of diseased flowers for panicle, the values varied from 0.3 to 65.0 for the fungicide tebuconazole and check, respectively. No significant difference among the percentages of diseased flowers for panicles in the treatments tebuconazole (0.3), chlorothalonil (2.5) and prochloraz (3.0), being those the most efficient fungicides in the control of the "ergot". However, the fungicide prochloraz was the most efficient in the control of foliar disease casel by Colletotrichum graminicola, while for the fungi Puccinia purpurea, and Cercospora fusimaculans the best control were obtained with the tebuconazole. There was not an increase of the germination in none of the treatments, however the increase in the weight of a thousand seeds was significant for the treatments with prochloraz, chlorothalonil and tebuconazole.

O controle químico da "ergot" (Claviceps africana) foi realizado em campo de produção de sementes do híbrido de sorgo granífero BR 304 (Sorghum bicolor (L.) Moench.), utilizando-se os fungicidas (g i.a./ha): captan (1250,0), fenarimol (80,0), trifenil hidróxido de estanho (166,7), prochloraz (450,0), chlorothalonil (1500,0), iprodione (750,0), azoxystrobin (150,0), thiabendazole (360,0), procimidone (750,0), ziram (1500,0) e tebuconazole (200,0). Parcelas sem aplicação de fungicida constituíram a testemunha. As pulverizações foram realizadas com pulverizador costal manual, com o jato dirigido para as panículas. O intervalo das aplicações dos fungicidas foi de 4 dias, a partir da antese. Aos 7 dias após o término das pulverizações, a porcentagem de panículas doentes variou 5,4 para o fungicida tebuconazole e 100,0% para a maioria dos demais tratamentos. Para a porcentagem de flores doentes por panícula, os valores variaram de 0,3% a 65,0% para o fungicida tebuconazole e testemunha, respectivamente. Não ocorreu diferença significativa entre as porcentagens de flores doentes por panículas nos tratamentos tebuconazole (0,3%), chlorothalonil (2,5%) e prochloraz (3,0%), sendo esses os mais eficientes no controle da ergot. Adicionalmente, o fungicida mais eficiente no controle da antracnose foliar (Colletotrichum graminicola) foi o prochloraz, ao passo que para a ferrugem (Puccinia purpurea) e a cercosporiose (Cercospora fusimaculans), o maior controle foi obtido com o fungicida tebuconazole. Não houve aumento da germinação das sementes em nenhum dos tratamentos; entretanto, o aumento do peso de mil sementes foi significativo para os tratamentos com os fungicidas prochloraz, chlorotalonil e tebuconazole.