KATYDIDS INJURIOUS TO ORANGES IN CALIFORNIA. 



23 



fruit at this time was principally due to katydids and thrips. No 

 fruits had fallen at this time from sprayed trees, as examination 

 of the ground under 15 trees disclosed. 



At picking time it became evident that a much larger saving of 

 fruit than that just indicated resulted from spraying. During Octo- 

 ber and November all the fruit of all sprayed plats and checks was 

 counted, from which it was found that from 60 to 100 per cent more 

 fruit was produced in each of the sprayed plats than in their unsprayed 

 checks. (See PI. V, fig. 1.) The trees of the different plats varied 

 greatly in size and condition, however, and it was therefore necessary 

 to know how many trees in each plat produced the fruit of that plat. 

 By eliminating the stunted, rebudded, and dead trees, resets, and 

 blank spaces in each plat it was found that the full-bearing, un- 

 sprayed trees matured only 54.2 per cent, or just a little over half 

 as many oranges per tree as the full-bearing trees of the sprayed 

 plats. The saving of crop in all sprayed plats taken together due 

 solely to spraying was, therefore, practically 100 per cent. A greater 

 saving was effected in plats sprayed with lime-sulphur and arsenicals 

 mixed than in those sprayed with arsenicals alone, the former pro- 

 ducing a little over twice as much and the latter only one and one- 

 half times as much fruit per tree as the checks. 



PREVENTION OF INJURY TO MATURED FRUIT. 



The results of the spraying experiments in preventing katydid 

 injury to the final crop of fruit were determined by examination, in 

 the field at picking time, of all oranges in all plats. For convenience 

 of reference these results are shown in Table III. 



Table III. — Remits of spraying experiments with lime-sulphur and arsenicals in pre- 

 venting injury to oranges by katydids, Lindsay, Cal., 1912. 



Iij...-cl i'-i !< . :ui'l 'liJiii ion. 



Plal i: Aroenlte of zinc, 2 pounds; lime-sulphur, 2 gal- 

 lon , per 100 gallon i water 



Plat 2: Arsenito of zinc, 3 pound ; Lime-sulph 



n r L00 gallons water 



Plal •''.: At i nite of /in'-, l pounds; lime-sulphur, 2 gal- 

 lon , per too r 



Plal !: Arsenate of lead, i ■• ■ lime- ulphur, 2 gal- 

 lon , pel ' 



• ol lead, 6 pound ; lime- mlphu 



Ion , per ioo gallons water 



. lime- lulphur, 2 gal- 



per 100 gallon 1 •■■■ aU r 



r 100 

 te of zinc. ■'; pound , per 100 galloi 

 J'l.-u 9: it lenate of lead, 1 pound , per 100 galloi 







Sprayed fruit. 



Percentage 



of sound 



fruit. 



100.00 



>.)•.).'.)<.) 



99. 85 



99. 85 



99 16 



99, 77 



99 02 

 99 i 





IViriT]|;i;v 



of culled 



fruit. 



0.01 

 .11 

 .14 

 .13 



.22 

 .07 

 .07 

 .15 



Unsprayed fruit. 



Percentage 



of sound 



fruit. 



81.45 



Percentage 



of culled 



fruit. 



18.55 



