34 



BULLETIN 1243^ U. S. DEPARTMENT OF AGRICULTURE. 



on this point. This is shown in experiments performed under 

 conditions of light infestation, with the possible exception of the 

 zinc arsenite experiments. Injury by this insecticide is not easily 

 estimated by observation. When infestation by the Mexican bean 



Fig. 15. — Dusting beans with a knapsack bellows type of duster. 



beetle is light, variations in yield are attributed to insecticide treat- 

 ment, which often causes a decrease in yield. Each experiment must 

 be compared with check plats and other plats tested at the same 

 time, because of variations in land, season, and climatic factors. 





■w ■ 



A 85, ifc t^di^i 



v. ..- 



1 ' .. *■ •*"*' 



Bnfit'Si 







"*v§2Ss8BP?i--""' -* 







• ■"■■■ '£mf*L ? -- ■ -v - * ■ " r^MwKg 1 





Fig. 16. — Power duster used in experiments in control of the Mexican bean beetle. 



Under typical conditions in the Southeast, summer crops of bush 

 beans do not produce well. 



In experiments where injury from treatment was serious, beetle 

 injury would not be estimated. 



