SPRAYING TO CONTROL ENEMIES OF CITRUS TREES. 



oranges that have been damaged by mites and those that have not, 

 since in commercial houses all large, coarse fruits, as well as more 

 or less fruit that is inferior, are always placed in the second or third 

 grades with the " russets." This reduction in size is so great, how- 

 ever, that even in commercial grading the difference in size in the 

 respective grades is considerable. Thus, in 941 boxes of oranges 

 of the first grade, 7,111 boxes of the second, and 3,376 boxes of the 

 third there were, on an average, 184.2, 197.9, and 200.4 oranges per 

 box ; a difference of 7 per cent in the number of fruits per box in the 

 first and second grades, and of 8.8 per cent of those in the first and 

 third grades. 



The difference in size of the fruit of the various grades ranges 

 from 4 to 14 per cent. In one community the general run of " bright " 

 fruit (unaffected by mites) averaged 203.8 oranges per box, and the 

 russeted fruit 222.2, or a difference of 9.28 per cent in favor of un- 

 affected fruit. In another near-by grove that was sprayed the 

 " bright " fruit averaged 214 and the " russets " 228 fruits per box, 

 which is a difference of 6.6 per cent. 



The number of grapefruit in 360 first, 970 second, and 279 third- 

 grade boxes of fruit averaged 53.2, 57.5, and 51.9, respectively. In 

 this instance the difference in number of fruits per box in the first 

 and second grades is 8.2 per cent. Undoubtedly so many large, 

 coarse fruits were placed in the third grade that these made the 

 average number of fruits per box less than even in the first grade. 



It is much better, however, to make comparison of fruit of the 

 same variety from the same grove, and data are given here for this 

 purpose. Table 4 shows the numbers of grapefruit per box for the 

 various grades in a car of sprayed and of unsprayed fruit and of 

 fruit which was not sprayed after June. These are the same car- 

 loads of fruit referred to on page 7, grove 3. 



Table 4. — Number of grapefruit per box from trees sprayed and unsprayed and 

 from trees unsprayed after June. 





Number of grapefruit per box. 



Grade. 



Sprayed. 



Not 



sprayed 



after 



June. 



Not 



sprayed. 



1. Fancy 



42.2 

 43.6 

 45.2 

 38.8 



46.6 

 49.7 

 52.3 

 43.2 



0.0 



2. Bright 



48.4 



3. Russet 



49.3 



4. Plain 



46.1 









42. 8 49. 



49.1 











It will be seen that the sprayed fruit averaged 42.8 and the un- 

 sprayed fruit 49.1 fruits per box. This difference may not appear to 

 be very great at first sight, but if the unsprayed fruit had been as 

 21698°— 18— Bull. 645—2. 



