for combining herbicides is to control more kinds of weeds. Combination rates are 

 usually half to two- thirds of the rate for each component used alone. Too low a 

 rate may let some weeds escape that would normally be controlled at full rates. Too 

 high a rate will increase the cost and may cause crop injury. 



Combinations often involve a grass herbicide and a broadleaf herbicide. Different 

 kinds of applications may also be used to control more weeds. Contact herbicides 

 may be combined with a preemergence herbicide, such as in the zero- tillage combina- 

 tions . 



Herbicide combinations are sometimes used to reduce herbicide carryover problems, 

 especially in small grains, forage crops, and vegetable crops. Most of the herbi- 

 cide carryover injury to soybeans in Illinois is caused by misapplication or im- 

 proper rate selection. 



Herbicides with marginal crop tolerance are sometimes used in combinations at re- 

 duced rates to increase crop safety. Herbicide combinations may be used to provide 

 greater flexibility concerning soil, climatic, and cropping conditions. Herbicides 

 are not always compatible in terms of application and the need for incorporation, 

 so sequential applications are sometimes used--as with the "piggyback" and "stale 

 seedbed" concepts. 



Some of the disadvantages of herbicide combinations are caused by incompatibility 

 problems with formulations and various brands. Emulsifiable- concentrate and wettable- 

 powder formulations sometimes do not mix in the concentrate form, although they may 

 combine if each formulation is mixed separately with water before being added to- 

 gether. Mixing with fluid fertilizers may decrease problems with wettable powders 

 because of a better suspending ability, but the salt effect of the fertilizer may 

 also break the emulsion when emulsifiable concentrates are used. Always check com- 

 patability in small containers before mixing large volumes of herbicide combinations, 

 whether these are mixed with water or with fluid fertilizers. 



Industrial incompatibility is caused by the failure of different manufacturers to 

 cooperate on a combination clearance by exchanging information and using the same 

 rates . 



Herbicide combinations are not a panacea. Selection must be based on crop tolerance, 

 the cropping program, weed problems, and soils. Trial use on a limited acreage is 

 one of the best ways to determine whether a particular combination will be profit- 

 able for you. 



DO NOT mix any two herbicides together unless they are labeled for such use. If they 

 are not labeled for combination, you are responsible for possible crop injury or 

 crop residue. The new federal pesticide law states that unlabeled uses are illegal 

 and are subject to fine. 



The current herbicide combinations for corn and soybeans are listed below. In tank- 

 mixes, the herbicide with label or supplemental instructions on rates and restric- 

 tions is listed first. The Lasso and Lorox labels both carry instructions, but the 

 rates and ratios do not agree. 



