Study On The Chemical Control Of The Dominate Weeds In The Maize Field

In this paper, the main weeds in maize field in the Yangtze Delta Region was chosen as the main research object. The chemical control technology was studied. First we use the bioassy method to choose several complex pesticide, then we did the field efficacy trials to verify the control effect to the weeds and also observed the safety of the maize. The results obtained are listed as following:To expand the weed-controlling spectrum, improve the control effect and save the cost, we did the combination and ratio selection of some herbicides in maize field. First We did the bioassay with seven single hebicide. The susceptibility of weeds to seven herbicides belonging to different classes was determined by pot experiments. Based on the ED50(g a.i./667m2), the susceptibility of weeds to three soil-treatment herbicides was in the following sequence:pendimethalin(1.8501g)> prometryn(6.1278g)> acetochlor(21.1743g); four leaves-treatment herbicides was in the following sequence:nicosulfuron(0.0519g)> bromoxynil(1.1135g)> mesotrione(3.1967g)> atrazine(29.2587g). According to the controlling effect and costs, the equivalent line method was used to select the optimization mixing proportions of herbicides mentioned above. The results were as follows:A to B was5to1, C to D was4to1, E to F was5to1. The herbicides mixture can not only extend the weed-controlling spectrum, but also have good herbicidal activity.To verify the reasonable of the complex herbicide and observe the control effect on the weeds in maize field and also the safety to the maize, we did the soil and leaves-treatment field trail of the complex herbicide choosen above. The results showed that:using the soil-treatment herbicide of60%acetochlor and prometryne125-166.67mL/667m2, the stem control effect could reach89.92%-94.26%, the fresh weigh control effect could reach92.34%-95.19%; using25-30g/667m2of the leaves-treatment herbicide of75%nicosulfuron and bromoxynil, the stem control effect could reach89.9%-94.26%, the fresh weigh control effect could reach92.39%-96.66%. Two of the complex herbicides had a good integrated control effect and were safe to the maize. As a result, two of the complex herbicides as a soil-treatment and leaves-treatment herbicides respectively could be used Extension in agriculture production.