December, '22] 



SEVERIN AND BASINGER: BEET LEAFHOPPER 



405 



West Sacramento Woodland Knights Meridian 



April 27. . 

 May 27 . . 

 June 16. . 

 June 22 . . 

 July 19... 

 August 30 . 



In the Sacramento Valley beets are planted from February to May 

 and records of curly leaf were obtained during 1920 with reference to 

 the time of planting. Five fields were selected in the Meridian beet 

 districts and the percentage of curly leaf in each field was determined 

 twice per month. Spring brood adults were rarely captured in the 

 Meridian beet fields on May 27, and at Davis about 40 miles south on 

 May 26. The dates of planting, number of irrigations, percentage of 

 curly leaf and yield per acre are indicated in table 1. 



Table 1. Percentages of Curly Leaf and Yield per Acre in Meridian Beet Fields 



During 1920. 



= less than 1% curly leaf. * =1 pre-irrigation, 2 summer irrigations. 



It is evident from table 1, that the lowest tonnage was obtained in 

 the April planted beet field. 



During 1921, however, an earlier invasion of the beet leafhopper in the 

 Sacramento Valley occurred. Two spring brood adults were captured 

 on April 15, in half an hour at sunset in a beet field planted early in 

 March at Woodland. No blighted beets were found. The leafhopper 

 was not taken in the Meridian beet fields, about 30 miles north of 

 Woodland on April 16 nor on April 30, when further investigations were 

 discontinued. 



During 1918-1920, the first appearance of curly leaf in the Sacra- 

 mento Valley was about a month later than in the northern portion of 

 the San Joaquin Valley due to a later invasion of the pest. On July 1, 

 1920, 14% of the March and April planted beet fields (Table 1, fields 4, 

 5) were blighted in the Meridian district of the Sacramento Valley com- 

 pared with 94-100% at Union Island and Lathrop in the northern 

 part of the San Joaquin Valley. It is evident that such factors should 

 have a direct bearing on the average tons per acre h( rvested. 



