93 



They were evidently more slowly but more seriously alieeted by 

 the spniy th.in the youn<j;-er .ind more vif^orous trees. 



liy Auijust 20, when a linal insi)ection of these trees was made, 

 all except the peach were still in j^ood condition, and many were 

 bearing excellent cro[)s. l^'our of the peach-trees slij^htly injured 

 in the bej^inninfc had rallied com[)letely and showed no trace of 

 the treatment, and thirteen wer(; now <iead or nearly so. 



So far as this experiment j^oes it may l>e held to show that ap- 

 ple-, pear-, and cherry-trees may be safely treated with either pure 

 kerosene or crude petroleum — the latter of rather lif^ht specific 

 f^ravity provided the a[)p]ication is made after si)rin{^ conditions 

 are v/ell established and the fruit-buds have be<^un to swell, and 

 provided also that care is taken not to apply the si)ray more freely 

 than is necessary fairly to coat the surface of the bark, lioth in- 

 secticides were very effective, killing' very nearly every scale on 

 the infested trees. The peach, on the other hand, was endangered 

 by both applications even under the favorable conditions indicated, 

 very young- trees suffering- somewhat but recovering promptly, 

 while older ones were either injured slightly or seriously, or, in a 

 few cases, killed outright. 



The McNeill orchard was badly infested with canker-worms, but 

 it was noticed April 29 that the bark of all trees which had been 

 sprayed with crude petroleum was coated with a gummy ])lack 

 residue, — the non-volatile jjortion of the oil, and that all trees in 

 this condition were entirely free from canker-worms. The bark 

 of a tree sprayed with kerosene, on the other hand, was i)erfectly 

 clean, and on this the canker-worms were abundant, i^'rom this it 

 would seem that the gummy coating left by the crude petroleum is 

 an elfective j)rotection against these insects. 



At ('atavvi'-a Island, Ohio. 



The above conclusion with reference to the danger of the 

 use of crude oil for the peach, even under favorable spring con- 

 ditions, is notably confirmed by a report made to me by Inspector 

 K. C. Green, of my office, of a visit made late in May, r>()2, to 

 the Catawba Island district, in northern Ohio, where about 

 three car-loads of crude oil had Ijcen used in March and April 

 of this year. Of 40,398 trees examined by him 3,237 had been 

 killed, 2,87s were dead in the top, 6,232 others had been seri- 

 ously injured, and 21,603 slightly so, only 6,448 remaining- with- 

 out injury. Or, stated in ratios, 16 per cent, were unhurt, f>i per 

 cent, were slightly injured and '[^ percent, seriously so, 7 per cent. 



