Interferência do feijão-de-porco na dinâmica de plantas espontâneas no cultivo do milho orgânico em sistemas de plantio direto e convencional.

Objetivou-se avaliar a dinâmica populacional de plantas espontâneas durante quatro anos agrícolas no cultivo de milho exclusivo e consorciado com feijão-de-porco no sistema de plantio direto orgânico, intermediado por um plantio convencional. Os tratamentos foram: plantio direto com composto orgânico e aplicação de herbicidas (PDT); plantio direto com composto orgânico e utilização da roçada como método de controle das plantas espontâneas (PDO1); plantio direto com composto + feijão-de-porco na densidade de três plantas por metro linear e o controle das daninhas com a roçada (PDO2) e plantio direto com composto + feijão-de-porco na densidade de seis plantas por metro linear e o manejo das plantas espontâneas com a roçada (PDO3). Concluiu-se que o consórcio milho com seis plantas de feijãode- porco proporcionou maiores diferenças na composição da comunidade de plantas espontâneas e proporcionou redução na importância relativa das espécies Artemisia verlotorum, Bidens pilosa e Digitaria sp

Glyphosate Excessive Use Affects Citrus Growth and Yield: The Vicious (and Unsustainable) Circle in Brazilian Orchards

The excessive use of glyphosate by Brazilian citrus growers leads to a vicious and unsustainable circle: Increasing the glyphosate use and the selection pressure of resistant/tolerant weeds, as well as the phytointoxication of the crop. In addition, there is speculation on the consequences of using glyphosate and the studies are not conclusive. Therefore, this study aimed to evaluate the glyphosate management in citrus orchards by assessing its effects in a 5-year field experiment using different doses and application frequencies. Here, we determine the weed control levels, the orchard growth and fruit yield, as well as the economic viability of the treatments. Higher weed control was observed more often with the increasing frequency of glyphosate application, and occasionally with increasing doses. However, some species predominated even at high glyphosate usage, such as BIDPI (Bidens pilosa (L.)), RAPRA (Raphanus raphanistrum (L.)), and ERICA (Conyza canadensis (L.) Cronquist). Phytotoxicity symptoms were demonstrated up to the fourth year of the orchard, and onwards the plants no longer expressed them. This was a highlight, since there was a decrease over time in growth (up to 5.3 m3) and fruit yield (up to 36.3 t ha−1), with losses that reached −56% of the total income. This is the first report to demonstrate that the increase in glyphosate usage can occasionally increase weed control, but it can also decrease orchard development and its financial viability