Bulletin 340] 



CONTROL OF THE POCKET GOPHER 



349 



(d) Surrounding Small Plots hy a Trench 



Small plots of ground have been protected by being entirely sur- 

 rounded by a trench eighteen inches wide and two feet deep, with 

 open five-gallon cans buried flush with the bottom in the ditch at 

 twenty-five foot intervals, to catch and hold the gophers which tumble 

 into the ditch, and thence into the cans. 



(e) Protection of Ditches hy Cement 



A power company which had much trouble with gophers in a large 

 ditch dug a four-inch trench six feet deep straight down through the 

 middle of the lower bank of the ditch. The dirt was loosened with an 

 iron bar and removed with a narrow shovel of the type used in digging 

 telephone-pole holes. The trench was then filled with a "lean" mix- 

 ture of cement and sand, which was carried on a barge that floated 

 on the water in the ditch. The cement was conveyed to the bottom of 

 the trench by a galvanized iron chute which was built in sections so as 

 to be readily adapted to any depth. This method was said to have 

 been expensive, but satisfactory in the long run. 



A small irrigation ditch having a seven-foot "surface" has been 

 .protected from gophers, weeds and leakage by applying to the sides 

 and bottom, first a yg-ineh coat of 1 to 7 cement and then a surface 

 layer 14-inch thick of 1 to 3 cement. This treatment proved satis- 

 factory. 



All of these preventives are costly and are advisable only in those 

 situations where protection against gophers cannot be obtained by 

 their destruction. 



Transmitted October 31, 1921. 



