Em experimento realizado em casa de vegetação com quatro linhagens e dois híbridos de milho (Zea mays), verificou-se variabilidade para resistência a queima foliar causada por Colletotrichum graminicola avaliada por meio das variáveis área total de lesão por planta (ATL), área média de lesão (AML), comprimento total de lesão por planta (CTL), comprimento médio de lesão (CML) e número de lesões por planta (NL). Quando dois isolados de C. graminicola foram inoculados nessas linhagens e em híbridos de milho não foi verificada interação diferencial entre isolados e genótipos do hospedeiro. Em estudos de herança da resistência, as linhagens genitoras L186 e L64 comportaram-se como suscetível e resistente, respectivamente, ao passo que o híbrido L186 x L64 apresentou resistência. A análise das freqüências observadas de plantas resistentes e suscetíveis na população F2 resultantes da autofecundação do híbrido, indicou ocorrência de herança monogênica com dominância completa para o alelo que confere resistência à doença.

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The soybean stem fly [Melanagromyza sojae (Diptera: Agromyzidae)] is a pest widely distributed in the Asian continent. In Brazil, its occurrence has been reported since the 1980s, but it had not been reported in Brazilian Savannah areas yet. This is the first record of M. sojae in this region of great importance for the soybean world production. Specimens of the soybean stem fly were collected in a volunteer soybean area, in April 2018, in the Goiás state, Brazil, and sent for molecular identification. The similarity index of the collected specimens with M. sojae was higher than 99 %, thus confirming the identification of the species. The infestation level in the collection area was approximately 100 % of plants with damage caused by this insect. In Brazil, the occurrence of M. sojae, up to the present time, had been described as restricted to the southern states. This record raises the hypothesis that M. sojae is widespread in other agricultural areas of the Brazilian Savannah, and that its dissemination is favored by the maintenance of volunteer soybean.

Cassava (Manihot esculenta) plants were observed in the Amazon region showing extensive leaf blight. The identity of the pathogen was confirmed based on morphological characteristics and the sequence of ITS region of the rDNA. Koch's postulates were fulfilled and pathogenicity was demonstrated. Cassava leaf blight, caused by Rhizoctonia solani AG-1 IA, is reported for the first time in Brazil.