Method for controlling herbicide resistant or tolerant weeds

A method for controlling undesirable vegetation which comprises applying to the vegetation or the locus thereof a herbicidally effective amount of (±)-2-exo-(2-methylbenzyloxy)-1-methyl-4-isopropyl-7-oxabicyclo [2.2.1]heptane, any of its individual enantiomers or any non-racemic mixture thereof (herbicide A) wherein:

• the undesirable vegetation comprises at least one herbicide resistant or tolerant weed species which is selected from (A) Poa annua and (B) Digitaria insularis;
• the herbicide resistant or tolerant weed species is a biotype with resistance or tolerance to at least one herbicide selected from the group consisting of acetyl COA carboxylase (ACCase) inhibitors, acetolactate synthase (ALS) inhibitors, and photosystem II (PS II) inhibitors;
• the herbicide A is the only herbicidally active ingredient;
• the herbicide A is applied in an amount of (A) 50 to 500 g/ha when the herbicide resistant or tolerant weed species is Poa annua or (B) 10 to 250 g/ha when the herbicide resistant or tolerant weed species is Digitaria insularis,
• the herbicide A is applied before emergence of the undesirable vegetation,
• the herbicide A has a herbicidal activity of at least 85 against the at least one herbicide resistant or tolerant weed species,
• the herbicide A has a herbicidal activity of at least 85 against a sensitive standard of the at least one weed species when applied in the same amount as against the at least one herbicide resistant of tolerant weed species, and
• the herbicidal activity is expressed as a percentage of weed aerial moieties destroyed by application of the herbicide A.