field experiments in destroying weevil. 29 



Cultivation in Connection with Irrigation. 



For an experiment to determine the value of cultivation in connec- 

 tion with irrigation in controlling the alfalfa weevil a field was selected 

 on a farm belonging to Mr. Hansen, 1 mile southeast of Sandy, 

 Utah, containing 16 acres. The soil was a light sandy loam. Some 

 of the weevils had been noticed in this field in 1908 and also in 1909, 

 while the first crop of 1910 was severely damaged and the second also 

 suffered considerable loss. May 11, 1911, the field was irrigated, the 

 infestation being considered heavy. The first crop was cut during 

 the week ending June 10. The plants were about 9 or 10 inches high 

 and the hay yielded less than 1 ton per acre of very poor quality. 

 This field was again irrigated and the more elevated portion of it 

 worked with a spring-tooth harrow while the surface was still soft 

 from the irrigation. This treatment was repeated and when finished 

 the field had very much the appearance of any cultivated field, 

 little resembling a meadow. (See PL VIII, fig. 1.) 



On June 22, while the land was still soft and muddy, a light irriga- 

 tion was given it, so that the water collecting in the lower portion of 

 the held stood to a depth of 2 or 3 inches. Four horses were hitched 

 to a plank leveler and dragged through this mud, as shown in Plate 



VIII, figure 2. This thoroughly "puddled" the weevil in all of its 

 stages beneath the surface. 



By the 30th of June a second crop was starting very nicely while 

 neighboring untreated fields were being retarded by the continued 

 attacks of the weevil. Ten days later the plants were about 12 

 inches high with very few of either larvae or beetles present. How- 

 ever, a patch had been left uncut and unworked in one corner of this 

 field and here the first crop of alfalfa was still standing. (See PL 



IX, fig. 3, at the right.) 



There were a great many larvae and beetles on this patch, which 

 disseminated themselves into the growing alfalfa where the mudding 

 process had been practiced, destroying a strip about 1 rod in width, 

 clearly shown in Plate IX, figure 3. The second crop in this field, 

 July 10, 18 days after the mudding experiment was carried out, was 

 about 14 inches high. (See PL IX, fig. 1.) 



In a near-by untreated field at the same time, four weeks after the 

 first cutting was made, the condition is shown in Plate IX, figure 2. 



Burning Machine. 



Several field experiments were carried out with a machine con- 

 structed with the idea of burning over alfalfa fields after the removal 

 of the first crop for the purpose of destroying the weevils in any stage 

 of development remaining in the field. The machine, as shown in 

 Plate X, figure 1, consisted of an iron frame 9 feet square, 12 inches 



