If the wild radish density and size is large, waiting this late may result in yield loss, and quite possibly a reduction in control. Applying nitrogen too early to gain a weed control advantage may result in nitrogen deficiency in late season during grain fill. The best rule of thumb is to apply each at its proper time and if these times coincide, a tank mix may be employed. If not, the factors above need to be weighed before such a practice is performed. This class of chemistry affects the ability of a susceptible plant to manufacture certain amino acids.
Amino acids are the building blocks of proteins which are used for plant growth and development.
Affected wild radish plants appear stunted and die slowly. These materials are very effective on wild radish and are less injurious to most cereal grains as compared to the phenoxy materials. Sulfonylureas can be applied at the two to three leaf stage of wheat through the second node stage of jointing. However, late applications made during the flower stage of wild radish may result in poor control. These types of materials are also metabolized by the grain, but the factors which cause phenoxy injury do not affect sulfonylurea break down.