To control invasive morning glory (Ipomoea) species in multiple soybean fields of an Agricultural Cooperative Corporation, the effects of sequential herbicide applications based on a soybean leaf age development model were studied. Because the error between the estimated and observed number of days for a certain soybean leaf stage was 0.4–1.9 (RMSE of 0.11–0.56), the model was approved as practical for determining the time of applications of herbicides. In the fields where bentazon and glufosinate were applied at the 2- and 5-leaf soybean stages, respectively, the percentages of area infested by Ipomoea coccinea or I. lacunosa tended to decrease in comparison with those where the herbicide applications were delayed or not performed. The effects of sequential herbicide applications in two successive years to reduce the infested area were unclear, because 52–81% of the total area of the soybean fields was not treated at the scheduled time due to bad weather. Ipomoea lacunosa was more difficult to control than I. coccinea because it grew rapidly and were missed easily at the application time of herbicides. In particular, there was a greater percentage of area infested by morning glory species, in comparison to the previous year, with increase in delay of application of bentazon. Therefore, timely control of bentazon at the 2-leaf stage of soybean is important for control of morning glory.

Goosegrass (Eleusine indica (L.) Gaertn.) plants suspected to be resistant to glyphosate were collected at four locations in Saitama prefecture, Japan. Application of 132 g a.i./10 a glyphosate potassium had little effect on viability, suggesting resistant to glyphosate. On the other hand, diquat-paraquat, fluazifop and glufosinate were effective against these goosegrasses. This suggests that mechanism of resistance is likely specific to glyphosate. One of the isolates had glyphosate-resistant mutations (T102I, P106S) in the amino acid sequences of EPSPS, the target protein of glyphosate. This is the first report of target site glyphosate-resistance of goosegrass in Japan. In addition, comparison of EPSPS DNA sequences revealed glyphosate-resistant goosegrass likely occurred independently in multiple regions.