Abstract
Internationally, farmers planted 134 million hectares of genetically modified (GM) corn, soybeans and cotton in 2009. Crops genetically modified for herbicide tolerance (HT) accounted for 85% of GM crops planted. The majority of HT crops are glyphosate tolerant (RR) soybean, corn or cotton. HT crop cultivation in the USA began in 1996;however, HT crops in Japan are not yet cultivated commercially. This paper discusses the effectiveness of weed control technology on HT crops in Japan. Glyphosate resistant weeds are spreading widely in HT crop fields in the USA. Because of the widespread of glyphosate-resistant weeds, the use rate of glyphosate herbicide and the use of herbicides with other modes of action have vastly increased in RR soybean, RR corn and RR cotton fields. GMHT technology has only succeeded in prolonging the use of glyphosate herbicide, but has not solved the weed problem. Therefore, the necessity for GMHT crops in Japan is low, because the area of conservational tillage is small and farmers use herbicides systematically. It is now abundantly evident that there is a necessity for the development of herbicides with new modes of action.
