Study on usage reduction of glyphosate mixed with a novel protoporphyrinogen oxidase inhibitor-X18002

In order to reduce the usage of glyphosate, delay the growth of glyphosate-resistant weeds, and expand the weed control spectrum of glyphosate, the effect of temperature, light and simulated rainfall on herbicidal activity, and the absorption and conductivity of glyphosate and X18002compound name was ethyl 3-(2-chloro-5-(3,5-dimethyl-2,6-dioxo-4-thioxo-1,3,5-triazinan-1-yl)-4-fluorophenyl)-5-methyl-4,5-dihydroisoxazole-5-carboxylate were studied by indoor bioassays. Mixture proportion screening tests and tank-mix field trials were carried out after investigating the difference between glyphosate and X18002 and the necessity of a mixture. The result showed that the fresh-weight inhibition rate of X18002 (37.50 g a.i/hm²) and glyphosate (600.0 g a.i/hm²) against Portulaca oleracea L. and Eleusine indica (L.) Gaertn. under high (30-35 ℃) and medium (20-25 ℃) temperatures were 83.48%-100.0%, significantly higher than those under the low temperature (10-15 ℃). The herbicidal activity was significantly reduced under low temperature. The fresh-weight inhibition rates of X18002 (37.50 g a.i/hm²) were 16.03%-95.46% and 2.24%-85.04%, significantly increased with the increase of illuminance within the range of 0-22000 lx. X18002 was proved to be light-demanding herbicide, while glyphosate was proved to be a light-independent herbicide. X18002 had stable herbicide activity with no significant decrease of fresh-weight inhibition rate between simulated rainfall after 0.5 h of application, which was 100.0% and 81.76%-87.62% to P. oleracea and E. indica, and unsimulated rainfall with a dose of 37.50 g a.i/hm². Glyphosate had a weak rainfastness with a significant decrease in inhibition rate when simulated rainfall within 0.5-8 h of application compared to unsimulated rainfall with a dose of 600.0 g a.i/hm². The absorption and conductivity tests showed that both two compounds could be absorbed by the root, stem, and leaf of Abutilon theophrasti Medic.. Compared to X18002, which only had acropetal translocation capability, glyphosate had the ability of acropetal and basipetal translocation. The proportions of mixture which showed the synergistic effect on Erigeron canadensis L., E. indica and Cyperus iria L. were 1 : 10 and 1 : 20. The result of the field trials showed that total control effect of X18002 + glyphosate tank-mix at 45.0 + 450.0 g a.i./hm² dosage on Alternanthera philoxeroides (Mart.) Griseb., E. canadensis, Digitaria sanguinalis (L.) Scop. and C. iria were better than or equivalent to glyphosate at 1200.0 g a.i./hm² treatment. The usage of glyphosate could reduce to 750.0 g a.i./hm². Meanwhile, X18002 + glyphosate tank-mix at 45.0 + 450.0 g a.i./hm² treatment had a faster action than glyphosate and a longer lasting effective period than X18002.