THE ORANGE THRIPS. 



11 



nnd when both hii\a' and luhihs were present. Tlie second applica- 

 tion was ma(K' eiuht (hiys hiter, and the third three weeks after the 

 second, at which time the thrips be<^an again to be nnnierous. All 

 the spraying was done with a hand outfit, maintaininu- a pressure of 

 140 pounds. 



In recording the results of the spray applications to ascertain their 

 efficiency it was necessary to class the fruit, as regards injury, in four 

 grades, as follows: 



Sound: No thrips iiiiirkiuc:. 



Slijrhtly marked : A slij^lit nmrking at one end or a few streaks on the surface. 



Moderately niarki-d : P.otli ends of fi uit iiiark<'(l and some scal)liinjj; on the rest 

 of llie surface. 



Badly markiHl: Nearly one-half to three-fourths of the surface marked, often 

 with misshapen fruit. 



At picking time 20 loose, or " lug." boxes of oranges from the 

 sprayed trees and 20 from an adjoining block of unspra3'ed trees 

 were counted. The results obtained are oiven in Table II. 



Table II. — Injunj to spraijcd and iiii'^iii-aijcd fruit bij oruiKjc thrips. 



SPRAYED. 



UNSPRAYED. 



20 



2,365 



30 



A commercial grading of the sprayed fruit Avonld have placed 

 nearly 75 per cent as " Fanc}^ *' and the remainder as " Choice," while 

 the unsprayed fruit would have run not more than 15 per cent 

 " Fanc}' " and 50 per cent " Choice,*' the remainder going out as 

 " Standards " and '' Culls." Of the fruit counted from the unsprayed 

 trees, 85.5 per cent w^as marked, while 25.5 per cent only of that from 

 the sprayed trees showed injury, indicating that GO jier cent of the 

 sound fruit was due to the spraying. The thrips-marked fruit was 

 smaller than the sound fruit, as will be seen by comparing the total 

 number of oranges from the 20 boxes of sprayed fruit with that from 

 the 20 boxes of unsprayed fruit. The writers have frequently noticed 

 in the packing houses that the smaller fruit is worse marked than the 

 larger, making it appear that the thrips injury holds back the growth 

 of the oranges. 



