title: Activity of mesotrione on resistant weeds in maize.
abstract: Mesotrione is a new callistemone herbicide that inhibits the HPPD enzyme (p-hydroxyphenylpyruvate dioxygenase) and introduces a new naturally selective tool into weed-management programmes for use in maize. Mesotrione provides control of the major broad-leaved weeds, and it can be used in integrated weed-management programmes depending on the grower's preferred weed-control strategy. At post-emergence rates of 150 g AI ha-1 or less, mesotrione provides naturally selective control of key species that may show triazine resistance (TR), e.g. Chenopodium album L, Amaranthus species, Solanum nigrum L, as well as species of weed that show resistance to acetolactase synthase (ALS) inhibitors e.g. Xanthium strumarium L, Amaranthus spp and Sonchus spp. The data presented show that resistant and susceptible biotypes of these species with resistance to triazine herbicides, such as atrazine, simazine, terbutylazine and metribuzin, or ALS-inhibitor herbicides, such as imazethepyr, remain susceptible to mesotrione. These results confirm that there is no cross-resistance in biotypes with target site resistance to triazine or ALS-inhibiting herbicides. It is important that herbicide choice and rotation becomes an integral part of planning weed management, so as to minimise the risks of crop losses from weed competition, build-up of weed seed in the soil and the further development of weed resistance across a range of herbicide modes of action.
authors.affiliation: Jealott's Hill International Research Centre, Bracknell RG42 6EY, UK. peter.sutton@syngenta.com
authors.forename: Peter
authors.initials: P
authors.lastname: Sutton
authors.forename: Claire
authors.initials: C
authors.lastname: Richards
authors.forename: Larry
authors.initials: L
authors.lastname: Buren
authors.forename: Les
authors.initials: L
authors.lastname: Glasgow
mesh_terms: D000383:Agriculture; D027721:Amaranthus / Q000187:drug effects; D027462:Chenopodium / Q000187:drug effects; D003512:Cyclohexanones / Q000494:pharmacology* / Q000633:toxicity; D004351:Drug Resistance; D006540:Herbicides / Q000494:pharmacology* / Q000633:toxicity; D019684:Magnoliopsida / Q000187:drug effects*; D032322:Solanum / Q000187:drug effects; D003313:Zea mays
chemical_list: D003512:Cyclohexanones; D006540:Herbicides; C432907:mesotrione