47 



caiLse to the presence of alkali salts in the irrigating water, while a 

 third was confident that in his case it was the result of commercial 

 fertilizer. In the opinion of the writer, based upon the observation 

 of thousands of plants, the prime cause of death to the young plants 

 was careless setting. 



The principal varieties grown in this district are the Brand}' wine, 

 the Lady Thompson, and the Arizona. The Brandj-wine is the only 

 variety found to be attacked by the grub up to the time of writing. 



The method of attack upon the plants, as observed this season, is as 

 follows: In the latter part of April or earh' in May the grubs enter 

 the plants l)y boring into the stem 1 or 2 inches below the surface 

 of the ground and tunnel upward to the crown. Here the work con- 

 tinues till the plant is killed. No evidence was found of any boring 

 into the stems of the plant above the crown, nor any destructive work 

 upon the foliage. Upon the death and eventual drying up of the plant 

 the grub apparentl}' returns to the soil, being found in great numbers 

 in the soil immediately surrounding the roots of the dead plants. In 

 very few instances were grul)s found in plants that had l)ecome dried 

 up, and ill no single instance was a pupa ever found in the plants. The 

 depths to which the gru])s penetrated the soil appeared to be governed 

 to a great extent by the moisture. In parts of the held where the 

 plants had all been killed and the soil allowed to l)ecome dry, the 

 majority were found at a depth of about 5 inches. Where irrigation 

 had been continued and the soil was moist the}' were found within 2 

 inches of the surface. 



The first pupa was found June 3, and the first Ijeetle June IT. July 

 28 beetles were numerous upon and under the litter on the ground, 

 and the soil surrounding the roots of the plants contained numerous 

 specimens of larva^, pupa?, and beetles. 



Experiments were made, at the request and with the assistance of 

 the owner of the infested patches, with carbon bisulphid. The object 

 sought was to learn whether the soil could be practically cleared of the 

 grubs, and the question of injury to plant life was not taken into con- 

 sideration. The ground was irrigated, and then allowed to dr}^ oif 

 until the moisture conditions were judged such as would conduce to 

 the most effective diflusion of the vapor. One-third of an ounce was 

 used as a dose, and injections were made as follows: One injection 

 every lineal 3 feet in the row, one every 18 inches, and one every 2 

 feet. In this instanc-e the majority of the grubs and pupje were found 

 at a depth of 5 inches, and an eflort was made to place the dose 

 approximately near this depth. 



Twenty-four hours afterwards an inspection of the treated rows was 

 made, and the following methods were emplo3^ed to determine the 

 results obtained. Four feet was measured and staked off in each row 

 treated, the soil was removed from a width of 24 inches ajad to a depth. 



