| Summary: | 碩士 === 國立中興大學 === 農藝學系所 === 103 === In order to select herbicides effective for weed management in grass turfs of the Golf course, with reduced rates, five herbicides were tested and the possibility of herbicide application at reduced rate was also estimated. In 2012, five herbicides including flazasulfuron, halosulfuron, pyrazosulfuron, quinclorac and bentazon, at the rates of 100%, 67% and 50% of their recommended rate were applied on two grassturf, i.e., Bermuda grass (Cynodon dactylon (L.) Pers.), and Manila grass (Zoysia matrella (L.) Merr.), and these experimental results showed that no toxic effect of tested herbicides on Manila grass and only a slight injury appeared on Bermuda grass. At the recommended rates of 5 herbicides, weeds in two grassturfs were effectively controlled 3 weeks after treatment. In general, the application rate of herbicide reduced to 67% of the recommended rate still kept the effect similar to that of the full rate. Flazasulfuron residue analysis after application showed that most of the flazasulfuron was absorbed by shoot of Bermuda grass and existed in two soil layers. Due to the frequent mowing in Glof course, flazasulfuron in Bermuda grass was rapidly left away from this turf grass. In addition, the frequent rainfall after herbicide application lead to the fast dissipation of flazasulfuron, only 0.23 ppm flazasulfuron was found in 10-20 cm soil layer 3 days after treatment. Detection of flazasulfuron in 0-10 cm and 10-20 cm soil layer in September in golf court showed that flazasulfuron leached from 0-10 cm soil layer to 10-20 cm soil layer. On the other hand, soil column experiment in greenhouse confirmed that a part of flazasulfuron move downward with water. Field assessment found that there was no flazasulfuron in pond and water drainage holes beside the experimental plots in golf court, which probably resulted from the low-dosage of flazasulfuron applied and water dilution. Exploration of the fate of flazasulfuron revealed that chemical hydrolysis, microbial degradation and photolysis are able to degrade flazasulfuron, especially the chemical hydrolysis.
|
|---|
