Aperfeiçoamento de anthracocystis panici-leucophaei como bioherbicida para o capim amargoso (digitaria insularis)

Abstract

The control of weeds is one of the main challenges in agriculture, especially concerning sourgrass (Digitaria insularis), a species resistant to herbicides such as Glyphosate. This resistance arises from the repetitive use of herbicides with the same mode of action, favoring the selection of resistant biotypes. In crops like soybean, corn, and cotton, productivity losses can reach up to 80%. To address this resistance, integrated management, which combines different control methods, is essential. Among the available alternatives, biological control stands out through the use of phytopathogens, such as the fungus Anthracocystis panici-leucophaei. This fungus can inhibit sourgrass growth by more than 60% and significantly reduce its seed production. In Brazil, weeds like ryegrass, horseweed, and sourgrass infest approximately 20.1 million hectares, generating annual costs exceeding R$ 3.8 billion. Sourgrass, being perennial and capable of producing up to 40,000 seeds per plant, poses one of the greatest challenges. This study evaluated the use of A. panici-leucophaei spores applied in different spray volumes. The lowest volume (50 L/ha) was the most effective in controlling the plants, while the highest volume (400 L/ha) showed no whip symptoms. The optimal incubation period for spore production in liquid fermentation was found to be between 2 and 3 days, at temperatures ranging from 20 to 30 °C. Additionally, the adjuvant Break Thru proved to be the most compatible, resulting in higher spore germination rates. The study also highlighted the importance of pesticide application technologies to maximize efficiency, considering factors such as droplet size and interactions with adjuvants. These findings reinforce the potential of using A. panici-leucophaei in the biological control of sourgrass, contributing to sustainable weed management.