Pyrimisulfan is a novel sulfonanilide herbicide with high herbicidal activities against major troublesome weeds in paddy elds. To use this chemical compound as a one-shot herbicide for rice, we have developed a controlled-release formulation, pyrimisulfan-1 kg granule (containing 6.7 g a.i.). is granule formulation applied at pre-emergence to the three-leaf stage at 10 kg/ha e ciently controlled troublesome weeds, such as Echinochloa spp., perennial weeds, and sulfonylurea-resistant weeds. Furthermore, pyrimisulfan-1 kg granule exhibited consistent herbicidal e cacy under simulated over ow conditions. erefore, pyrimisulfan-1 kg granule is suitable for use as a one-shot herbicide and is an e ective tool for rice cultivation systems requiring reduced pesticide applications.

The total acreage of rice in Japan in 2009 was 1.62 million ha and most of the paddy fields are mechanically transplanted, using young seedlings grown in nursery boxes.1) It is also noteworthy that most Japanese rice farmers apply so-called one-shot herbicides, which are now essential tools for weed control in paddy fields.2) This has been made possible by the wide variety of one-shot herbicides now available on the Japanese market. While sulfonylurea (SU) herbicides are most commonly used as the active principles in the formulation of one-shot herbicides, because SU herbicides control a wide range of paddy weeds including annual broadleaves and perennial Cyperaceae and about 90% of one-shot herbicides contain 3 to 4 active ingredients. 2)We have so far developed and commercialized our original pyrimidinyl carboxy (PC) herbicides, viz. bispyribac-sodium, pyrithiobac-sodium and pyriminobac-methyl.3-5) These herbicides exhibit their activities by specifically and strongly inhibiting ALS enzyme of plants, which is involved in the biosynthesis of branched-chain amino acids in plants, such as valine, leucine and isoleucine. 6) Because mammals lack ALS enzyme, these herbicides are inherently safe for mammals and, coupled with high activity with low use rates, these PC herbicides are extensively used worldwide as environmentally friendly herbicides.In the course of our researches on PC herbicides, we confirmed that in order for a compound to exhibit high ALS inhibitory activity and high herbicidal activity, the hydrophobic group, pyrimidine ring and acidic group need be placed in a suitable spatial position linked by a suitable spacer group via a suitable linkage group. 7) Based on the findings, we have conducted extensive studies to place various hydrophobic groups and acidic groups in an appropriate position on the pyrimidine ring.PC herbicides have a carboxyl group, but due to their relatively high water solubility as a result of their acidity, PC herSynthesis and herbicidal activity of sulfonanilides having a pyrimidinyl-containing group at the 2-position A novel series of sulfonanilides having a pyrimidinyl-containing group at the 2Ј-position was prepared and their herbicidal activities against paddy weeds and selectivity against rice plants were assessed. The structure-activity relationships were probed by substitution of the sulfonyl group, bridge and benzene ring. Among the sulfonamides, difluoromethyl compound showed comparatively high activity and a broad spectrum to control weeds, including Echinochloa oryzicola. The most preferable substitution position on the benzene ring was in the 6-position and the lower alkyl group showed high herbicidal activity and a broad weed control spectrum, and among the compounds tested, the methoxymethyl group was the best. In respect of the bridge moiety, the hydroxyl group was the best. Among the compounds examined, 2Ј-[(4,6-dimethoxypyrimidin-2-yl)(hydroxy)methyl]-1,1-difluoro-6Ј-(methoxymethyl)methanesulfonanilide, applied at rates between 4 to 16 g a.i./ha, showed excelle...

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Pyrimisulfan is a novel paddy herbicide that was discovered and developed by Kumiai Chemical Industry Co., Ltd.; Ihara Chemical Industry Co., Ltd.; and K-I Chemical Research Institute Co., Ltd. It was registered in Japan in 2010 and launched the first one-shot herbicide containing only one active ingredient (a.i.) developed with our original formulation technology. The compound is sulfonanilide, having a pyrimidinyl-containing group at the 2′-position and an acetolactate synthase (ALS) inhibitor. Pyrimisulfan shows broad-spectrum weed control against annual grass, sedge, broadleaf, and sulfonylurea-resistant weeds without causing phytotoxic injury to rice. At doses of 50-75 g a.i./ha, pyrimisulfan has a wide application window and exhibits long residual activity against these weeds. Pyrimisulfan has favorable toxicological, ecotoxicological, and environmental profiles.

Legume-grass mixed cropping has significant advantages that affect crop yield and soil resources. Generally, grasses grown with legumes take up more nitrogen than those grown under sole cropping. We focused on the effect of cutting hairy vetch during a vigorous growth stage on N uptake in oat under mixed cropping. We evaluated the amounts of N transferred from hairy vetch to oat by using a 15 N dilution method. Cutting hairy vetch increased the number of tillers and dry weight of oat, but total N content was not significantly higher than that under mixed cropping without cutting. In contrast, the amount of N transferred to oat was increased by cutting. Estimated amounts of N transferred to oat were 2.7 g m -2 with cutting of hairy vetch and 0.8 g m -2 without cutting. Cutting half of the oats under sole cropping did not indicate the transfer of rhizodeposited N in oat to the residual plants. In addition, cutting hairy vetch increased the amounts of accumulated solar radiation in the middle canopy of the mixed cropping plots. Therefore, in a hairy vetch and oat mixed cropping system, cutting of the hairy vetch might enhance growth of oat due to the transfer of N from hairy vetch and the reduction of light interception to the oat canopy. N fertility enhancement of the soil by cutting of the legume would be valuable for low-input crop production.

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