April, '15] 



HERR]CK: FRUIT-TREE LEAF-ROLLER 



181 



There was so little difference between the sprayed and unsprayed por- 

 tions that it did not seem worth while to make a count of the fruit. 

 The orchard produced only about two hundred and fifty barrels of 

 apples out of a normal eight hundred barrels and these were mostly 

 in the tops of the trees and in portions of the orchard not so badly 

 infested. In this connection, the w^ork of one of the better and more 

 intelligent fruit-growers in New York is of interest. 



The large orchards in question were sprayed five times and sprayed 

 thoroughly and intelligently. The orchards were sprayed first, in the 

 dormant condition, just before the buds burst, with lime-sulphur, 1 

 gallon to 6^^ gallons of water with 1 pint of black-leaf-40 to every 100 

 gallons for the aphis. The second spraying was made just before the 

 blossoms opened with lime-sulphur 1 to 50 and 3 pounds of arsenate 

 of lead. The third application was made just as the petals had fallen 

 and consisted of lime-sulphur 1 to 50, arsenate of lead 3 pounds and 

 black-leaf-40, | pint to 100 gallons. A fourth spraying was made 

 about 10 days to two weeks after the third with lime-sulphur 1 to 50 

 and 3 pounds of arsenate of lead. At about this time the owners 

 became much worried about the roller and sprayed a fifth time with 

 arsenate of lead alone, 4 pounds to 50 gallons. In spite of this extraor- 

 dinary amount of careful and thorough spraying, the trees and cover 

 crop under the trees were alive with larvae and 40 per cent of the crop 

 was ruined. 



Gillette and Weldon performed a series of experiments in Colorado 

 in 1912 in an attempt to control the leaf-roller by the use of poison 

 sprays.^ The first spray was applied May 5. The cluster buds had 

 separated but the buds had not begun to open up. At this time 

 ''practically every blossom bud picked had from three to five larvae 

 feeding in it." They estimated that 75 per cent of the larvae were 

 killed by this and succeeding applications. Unfortunately 25 per cent, 

 where the larvae are multitudinous, is quite sufficient to cause disas- 

 trous results. The question, of course, arises as to whether the remain- 

 ing 25 per cent can be caught before they enter the buds or get out of 

 the way of the poison. Mr. J. B. Gill, in his thorough work in New 

 Mexico and Canon City, Colo., found that ''applications of arsenicals 

 alone and in combination with 40 per cent nicotine solution have 

 greatly reduced the amount of injury to the fruit and foliage, but these 

 sprays have not been so effective as desirable." On account of the 

 long period of egg-hatching it is almost impossible to poison the larvae 

 before they become safely hidden. Especially is this true in case of 

 late varieties of apples. 



1 1912, Circular 5, Colorado Experiment Station. 



