Sawflies are now about half-grown. They are feeding on and defoliating pine plantings 

 especially white pines in eastern Illinois. These worms can be controlled with a 

 mixture of 2 pounds of carbaryl (Sevin) per 100 gallons of spray. 



WEEDS 



> 

 ATRAZINE-OIL TREATMENTS 



The wet spring and the rush to plant corn has caused many farmers to put off the appli 

 cation of a preemergence herbicide. The resulting weed problems have created a renewe 

 interest in the atrazine-oil treatment. 



The phytobland (nonphytotoxic) oils used in this treatment should meet certain stand- 

 ards for purity, viscosity, and emulsifier content. Purity is expressed as an unsul- 

 fonated residue (UR) value. A 90 -percent UR value indicates a 10 -percent content of 

 aromatic sulfonated residue. Phytobland oils should have a UR value of more than 

 90 percent. 



Viscosity is expressed as SSU (Seyboldt Seconds Universal) values, indicating the time 

 required for a given quantity of oil to pass through a funnel orifice test. A 100 SSU 

 oil is more viscous than a 70 SSU one. Common viscosities for these oils are 90 to 

 150 SSU. 



The oils are used at the rate of 1 gallon mixed with about 20 to 40 gallons of water 

 per acre. Thus, an emulsifier must be added so the water and oil will mix completely. 

 The usual emulsifier content is 1 to 2 percent. The emulsifier must be kept free 

 from water until final mixing occurs, otherwise the oil may not emulsify with the 

 water. 



Agricultural surfactants are sometimes used rather than oil. Surfactants offer the 

 advantage of a lower quantity of spray additive, because they are used at the rate 

 of 1 to 2 quarts per 100 gallons of spray. The comparative performance of oils and 

 surfactants are often about equal; if there is a difference, it is usually in favor 

 of the oils. Thus there is current interest in a 4-to-l ratio of oil and surfactant, 

 used in combination at the rate of 1 quart per acre- -combining the advantages of both 

 oil and surfactant. 



Some spray applicators use household detergents rather than oils or agricultural sur- 

 factants. These are usually more expensive and less effective than agricultural sur- 

 factants or phytobland oils. Some detergents also cause problems with foaming of 

 sprays and surging of pumps and nozzles. 



The AAtrex (atrazine) rate is 2-1/2 pounds per acre 80W (2 pounds per acre ai). For 

 maximum results, the treatment should be applied before grass weeds are 1-1/2 inches 

 tall. The atrazine-oil postemergence treatment sometimes causes corn injury- - 

 especially on corn that has been under stress from prolonged cold, wet weather prior 

 to spraying and that begins its active, succulent growth after spraying. 



HERBICIDE INJURY 



How do you recognize herbicide injury? Agronomy Fact Sheet W-31, Recognizing and 

 Reducing Herbicide Injury (which was included in the Pesticide Dealer and Applicator 

 Clinic packets), helps answer that question. It is also available from the Agronomy 

 Department. This fact sheet covers the causes and symptoms of herbicide injury and 

 the methods of reducing it. 



