Herbicidalactivityevaluationofbenzobicyclonanditssafetytorice

Benzobicyclon, which targets the 4-hydroxyphenylpyruvate dioxygenase (HPPD), is a bicyclooctane herbicide. In order to explore its application in rice fields of China, the weed controlling spectrum, herbicidal activity, and safety of benzobicyclon to rice were investigated under greenhouse conditions. The results showed that the aboveground fresh weight reduction of common weeds in rice field, including Echinochloa crusgalli, Monochoria korsakowii and Cyperus difformis, were all above 90% at active ingredient of 360 g/hm². The GR₅₀ value of benzobicyclon against main autumn weeds were 48-196 g/hm². The biological activity of benzobicyclon was higher than that of mesotrione except in the case of Aeschynomene indica. The safety of 8 rice varieties to benzobicyclon was studied. At the rate of 720 g/hm², the tolerance of Longliangyouhuazhan, Wankennuo 1, Wandao 68 and Lvhanjing 1 to benzobicyclon were good. However, the plant height and fresh weight of Huiliangyou 882, C liangyou 608, Wandao 119 and Y liangyou 1 were inhibited in different degree. Selectivity index of benzobicyclon between Longliangyouhuazhan, Wankennuo 1, Wandao 68, Lvhanjing 1 and three weeds were 3.66-4.37, 4.50-5.37, 3.36-4.01 and 3.29-3.93, respectively, which was much higher than that of mesotrione. In conclusion, benzobicyclon had good herbicidal effect against autumn weeds, and it is safe to 3 japonica varieties mentioned above and Longliangyouhuazhan of 5 indica varieties.