Early applications of encapsulated acetamides for reduced injury in crops

An acetamide herbicide composition comprising a combination of a first population of a particulate microencapsulated acetamide herbicide and a second population of the particulate microencapsulated acetamide herbicide, the first and the second populations of the particulate microencapsulated acetamide herbicide comprising a water-immiscible core material comprising the acetamide herbicide and a microcapsule containing the core material and having a shell wall comprising a polyurea, wherein the shell wall is formed in a polymerization medium by a polymerization reaction between a polyisocyanate component comprising an aliphatic polyisocyanate or mixture of aliphatic polyisocyanates and a polyamine component comprising a polyamine or mixture of polyamines to form the polyurea, wherein the first population of the particulate microencapsulated acetamide herbicide has a mean particle size of from 3 μm to 11 μm and the second population of the particulate microencapsulated acetamide herbicide has a mean particle size of between 12 μm and 20 μm, and wherein the weight ratio of the first population of particulate microencapsulated acetamide herbicide to the second population of particulate microencapsulated acetamide herbicide is from 5:1 to 1:5, and wherein the acetamide herbicide comprises acetochlor, the composition further comprising:

• a thickener selected from the group consisting of guar- or xanthan-based gums, cellulose ethers, modified cellulosics and polymers, and microcrystalline cellulose anti-packing agents, and wherein the combination of the first population of a particulate microencapsulated acetamide herbicide and the second population of a particulate microencapsulated acetamide herbicide provides a longer duration of weed control and reduced crop injury as compared to either population of microencapsulated acetamide herbicide applied individually.