This study was conducted on two rangeland sites in south Texas with large populations of huisache (Acacia farnesiana (L.) Willd.); the Bush Ranch in Goliad County, and the Hitchcock Ranch in Bee County. The purpose of the study was to evaluate the effect of three herbicide treatments and three seasons of application on 1) apparent mortality of huisache, 2) huisache canopy cover, 3) huisache stem density, and 4) herbaceous ground cover. Herbicide treatments included aminocyclopyrachlor alone at a rate of 0.315 kg a.i. ha-1, aminocyclopyrachlor + triclopyr at a rate of 0.210 kg a.i. ha-1 + 0.420 kg a.e. ha-1, and triclopyr + picloram at a rate of 0.560 kg a.e. ha-1 + 0.560 kg a.e. ha-1. Herbicide treatments were applied over 3 x 30 m plots containing previously mowed huisache in May, July, and October of 2010 with ground-broadcast equipment at a rate of 140 L ha-1. Randomly selected huisache individuals and herbaceous ground cover at randomly selected points were monitored for the duration of the study. Statistical analyses of huisache mortality, canopy area, and stem densities revealed that at both sites one year after treatment, huisache mortality across the three seasons of application was consistently higher in plots treated with aminocyclopyrachlor + triclopyr (50 to 99%) versus those treated with aminocyclopyrachlor alone (16 to 78%) or triclopyr + picloram (4 to 70%). This mixture also provided the greatest reductions in huisache canopy area (60 to 99% reduction) and stem density (61 to 99% reduction). Also at both sites, spring applications consistently provided the greatest huisache control and canopy and stem reductions. Herbicide treatment and season of application had little effect on post-treatment herbaceous ground cover, likely due to extreme drought conditions in 2011. Of the possible combinations of seasons of application and herbicide treatments, the application in the spring of aminocyclopyrachlor plus triclopyr provided the most desirable results in terms of huisache mortality, canopy reduction, and stem density reduction. However, for sites invaded by huisache that are located near to potentially susceptible crops, the application of aminocyclopyrachlor plus triclopyr or aminocyclopyrachlor alone in the fall after the harvest of those crops may be more appropriate in order to avoid non-target injury while still providing acceptable huisache control.

Fundação de Apoio a Tecnologia e Ciência / This study had the objective of to describe the biology and management of the Tilletia barclayana, determine the effects of different rates of nitrogen topdressing application on the incidence and severity of kernel smut on irrigated rice, to assess the level of crop damage, and to determine the effectiveness of fungicide applied in different rice stages. To achieve these objectives, it was conducted two field experiments at Dona Francisca City, Rio Grande do Sul state, in the 2007/08 growing season, using the IRGA 422 CL cultivar. The Experiment 1, using rates of 108 kg ha-1 and Experiment 2, 135 kg ha-1 N, being applied in both experiments four rates of Miclobutanil (75,150, 225 e 300 g ha-¹ de a.i.) and one rate of Trifloxistrobina e Propiconazole (93,75+93,75 g ha-¹ de a.i.). The results showed that there was no significant difference between the two N rates for grain yield, milling yield, whole grains and mass of thousand grains. The kernel smut incidence, number of infected grains and sterility of spikelets had the higher average under application of 135 kg ha-1 N. On the other hand, the amount of healthy grain and yield of broken grain had higher values with the application of 108 kg ha-1 N. The fungicide application in R3 proved to be more efficient when compared to the R4 application in both experiments. In regards to the active ingredients, it was observed in Experiment 1, higher efficiency of Trifloxystrobin and Propiconazole 93, 75 + 93, 75 g ha-¹ a.i. for the variable incidence and grain yield. In Experiment 2 was a higher average of variable healthy grain, lower average of sterility of spikelets under application of Myclobutanil 75 g ha-¹ a.i. For the average yield whole grain yield and mass of thousand grains had better result with application of Myclobutanil 300 g ha-¹ a.i. / Este trabalho teve por objetivo descrever a biologia e o manejo de Tilletia barclayana, determinar os efeitos de diferentes doses de adubação nitrogenada sobre a incidência e severidade da cárie-do-arroz na cultura do arroz irrigado, avaliar os danos provocados à cultura, determinar a eficiência de ingredientes ativos em relação ao controle do patógeno e a melhor época de aplicação dos mesmos. Para isto foram conduzidos dois experimentos no município de Dona Francisca RS na safra agrícola 2007/08, utilizando a cultivar IRGA 422 CL. O experimento 1, com a dose de 108 kg de N ha-1 e o experimento 2, 135 kg de N ha-1, sendo aplicadas em ambos experimentos quatro doses de Miclobutanil (75,150, 225 e 300 g ha-¹ de i.a) e uma dose de Trifloxistrobina e Propiconazol (93,75+93,75 g ha-¹ de i.a). Os resultados obtidos mostraram que não houve diferença significativa entre as duas doses de N para as variáveis produtividade, renda do benefício, rendimento de grãos inteiros e massa de mil grãos. As variáveis incidência de T. barclayana, grãos cariados e esterilidade de espiguetas apresentaram maior média sob aplicação de 135 kg de N ha-1. Já as variáveis grãos sadios e rendimento de grãos quebrados apresentaram médias superiores com a aplicação de 108 kg de N ha-1. O controle em R3 mostrou-se mais eficiente em relação ao controle em R4 em ambos os experimentos. Com relação aos ingredientes ativos, observouse no experimento 1, melhor eficiência da mistura formulada de Trifloxistrobina e Propiconazol na dose de 93,75 + 93,75 g ha-¹ de i.a para a variável incidência e rendimento de grãos inteiros. No experimento 2 observou-se maior média de grãos sadios, menor média de esterilidade de espiguetas sob aplicação da solução fungicida Miclobutanil 75 g ha-¹ de i.a. Para as médias rendimento de grãos inteiros e massa de mil grãos foi observada melhor resultado com aplicação de Miclobutanil 300 g ha-¹ de i.a.