REPORT OF THE ENTOMOLOGIST AND BOTANIST 247 



SESSIONAL PAPER No. 16 



also very much more liable to injure the trees treated. Crude petroleum may with 

 care be applied to healthy peach trees in a mechanical mixture with water containing 

 20 to 25 per cent of the oil ; but, when using this mixture, it is rather difficult even 

 with the best pumps made for the purpose to keep the percentage of oil constant, and, if 

 applied carelessly by reckless, inexperienced or inattentive men, there is great risk of 

 the trees being killed. When recently examining the results of the experiments made 

 with crude oil on Catawba Island, Ohio, and also in Ontario, the benefit of special 

 training of op2rators in this kind of work was very apparent. "Where orchards had 

 been carefully and skilfully sprayed, excellent results had followed. This was par- 

 ticularly the case where the work had been done by the trained Government officials, 

 but, besides this, where good practical fruit-growers had carried out instructions care- 

 fully, the trees had been protected and paying crops had been gathered. The advan- 

 tage of experience was also conspicuous in some of these orchards, the owners acknowl- 

 edging that, although they thought they had done good work the first year, they could 

 easily see that the second year's work was far better, and they believed that they would 

 be able to do more thorough work next year and secure better results. Where trees, 

 as was the case in some places, had been treated in an indifferent or perfunctory man- 

 ner, very little good had been done, even although considerable expense had been in- 

 curred. Spraying for the San Jose Scale, to be effective, must be done with the 

 greatest care as to every detail, and with great thoroughness, so that every part of 

 the tree is reached with the material spraj'ed. I found that one of the most fertile 

 causes of imperfect work was the difficulty of reaching the whole of a tree with the 

 mist-like spray in which it is necessary to distribute the liquids. This work is facili- 

 tated very much by a wind which will help to carry the spray through the branches. 

 Unfortunately, a change of the wind favourable for spraying both sides of the trees 

 seldom occurs in the same day, or within a short spice of time. Several fruit-growers 

 had sprayed one side cf their trees, but as there had been no favourable wind for the 

 other side, only half of each tree had been treated. The good effect of the crude oil 

 was remarkably apparent on some of these trees which had been only lightly infested 

 in the spring. The side which showed on the bark the residue of vaseline left after the 

 volatile parts had evaporated, was free of living scales, while on the other side of the 

 same branch there was a thick coating of healthy scales reaching right up to the oily 

 surface. Crude petroleum is a very effective and cheap remedy, but great care must 

 be exercised in using it. 



During the summer of 1901 the experiments with this substance have been ear- 

 nestly watched by fruit-growers, and several have themselves experimented with it. 

 Much good work has been done on peach trees with a 15 per cent mixture, and no cases 

 of injury are recorded. As an outcome of this work, there will doubtless be a much 

 more extensive use of crude petroleum oil next year. It is to be feared that the good 

 results obtained in destroying a large proportion of the scales without injury to the 

 trees with 15 per cent and 20 per cent mixtures may, next season, possibly give rise 

 to a reckless or careless spirit when spraying orchards so as to get quicker and more 

 decided results. This is a real danger and it seems most desirable to advise caution, 

 or there may be considerable loss from trees being sprayed with too much oil. Fruit- 

 growers must bear in mind that the application of remedies for such a persistent 

 enemy as the San Jose Scale is no easy matter which can be attended to by an un- 

 trained man, unless the greatest care is exercised. From what I have seen of the work, 

 I judge that the heavy oils are the safest and the most effective. Prof. J. B. Smith, 

 of New Jersey, says : — ' It is a fair requirement that a straight crude petroleum should 

 have a specific gravity of 43° or over by the Beaume oil test, at a temperature of 60° 

 Fahr. ; anything less might be harmful ; anything more than 45° is unnecessary.' 

 When the heavy oils have been used, the deposit of vaseline on the bark remains for 

 a long time and without injuring the trees renders the bark unsuitable for the scales to 

 fix themselves. The oils which have been used for the most part in Ontario are Cana- 

 dian oils which Mr. Fisher tells me test 39-10° to 39°, Beaume. Upon peach trees 



