172 



SCIENTIFIC AGRICULTURE 



April, 1921. 



17tli— Misty and warm. 

 18th — Clear and very warm. 

 19th — Very warm rain at night. 

 20th — Cloudy, warm and muggy. 



It is very probable that the scab developed very 

 rapidly during these few days and was largely respon- 

 sible for the heavy infestation of the dusted apples. 



The sprays used were chiefly lime sulphur and ar- 

 senate of lead and dusts arsenate of lead and dust 

 sulphur. However, in Nova Scotia Bordeaux mixture 

 was used sometimes and in Quebec arsenate of lime was 

 used on several occasions both in sprays and dusts. 



Another very important thing to consider is the in- 

 jury to foliage and fruit due to burning. This has ap- 

 peared more or less severely for the past four years in 

 the sprayed areas but as yet there has been no burning 

 from the application of dusts, whii'li have crntaiiicd as 

 high as 15 per cent arsenate of lead or 10 per cent ar- 

 senate of calcium. 



So far as biting insects are concerned all the results 

 the writer has seen show dusted arsenicals as good, and, 

 in most cases, better than sprayed ar.senicals. In this 

 connection the following figures on wormy apples are 

 taken from Sanders' & Kelsalls' tables: 



Place. Years. Unsprayed. Sprayed. Dusted. 



New York 4 



Michigan 2 



Illinois 4 



Nova Scotia 4 



The above figures are all in favor of dusting. The 

 codling worm upon which apparently the above figures 

 are based is only of minor importance in Quebec but 

 the following figures are for insects of great economic 

 importance here : 



Variety. 

 Alexander 

 Duchess- ■ 



Year. 

 1917 

 1918 



Unspraved. 

 99"- 

 100-00 



Sprayed. Dusted. 



10-7 110 



30 20 



Further it is very interesting to note that this year 

 (1920) dusting for the control of the apple maggot gave 

 better results than any spraying results ever obtained 

 here. A mixture containing 4.5 per cent sulphur, 47V2 

 per cent hydrated lime and 71/2 per cent calcium ar- 

 senate, was applied on July 19 and on August 5th. The 

 dusted trees Iiad less than 1 per cent of the fruit at- 

 tacked but the check trees had from. 50 per cent to 90 

 per cent of the fruit injured. 



Another very important consideration in comparing 

 these methods is their relative value in controlling suck- 

 ing insects. In many fruit growing sections this would 

 probably be the most important phase of the subject 

 but in Quebec it is by far the least important and hard- 

 ly needs consideration. It is only rarely that aphids 

 are present in suffieien"t numbers to be of economic 

 importance and the oyster shell bark louse could prob- 

 ably be held in cheek by dusting. 



One of the most difficult comparisons to make is that 

 of cost, because present day dusts are only experimen- 

 tal formulae and as this part of the work is in sucli a 

 rudimentary condition it is difficult to arrive at con- 

 clusions that are satisfactory. However, the following 

 figures are based on experimental work done at Hem- 

 mingsford : 



1917, spraying, $16-09; dusting, $30-50 



1918, spraying, $23-70; dusting, $40-40. 



1919, spraying, $27-58; dusting, $27-26. 



The above figures for 1917 and 1918 show dusting 

 almost twice as costly as spraying, whereas in 1919 the 

 cost is practically the same. The cause of the great 

 reduction in the cost of dusting was in using a mixture 

 in which the sulphur and poison were greatly reduced 

 and replaced by a cheap filler. If it were: not for se- 

 vere russetting, in some seasons, of our best varieties, 

 Faineuse and Mcintosh, Saiulers" copper lime arsenic 

 dust would be the cheapest to use, but owing to this de- 

 fect it is not advisable to use it for the calj'x and later 

 applications. 



The question of mixtures to suit the numerous con- 

 ditions existing in various parts of the country is a 

 broad one. So far very little information is at hand 

 but if the work of the past few years is continued with 

 as much interest for the next ten years, there will ju'ob- 

 ably be dusts equal to liquids for any condition which 

 might arise. 



Conclusions. 



1. Dusting has develoiicd vi-ry i-apidly in tlie jiast 

 8 years. 



2. The results of ex|)eriiiiental work in New York, 

 Michigan, Illinois, Nova Scotia and Quebec show dust- 

 ing to be as efficient as sjjraying in the control of ajiiile 

 scab and biting insects. 



3. The cost of dusting in the past 2 years has been 

 practically the same as spraying under Quebec con- 

 ditions. 



4. Tlie two most impm-tant iiLsecticides, calcium 

 arsenate and lead arsenate may be safely used with 

 either system. 



5. Without any reliable data to haiul it must be 

 stated that dusting is inferior to spraying for the con- 

 trol of sucking insects. However, tliere is sufficient 

 evidence at hand to cause us to believe the solution of 

 this problem will be discovered in the next few years. 



CROP PEST COMMITTEE FORMED. 



Regina, Sask., April 14. — ]\leeting of entomologists 

 of the Federal and Provincial Governments, and some 

 of the Western States, held during the past two days, 

 to discuss the grasshopper menace, resulted in the for- 

 mation of a permanent committee to be known as the 

 North-West International Committee on Crop Pests. 

 Xorman C. Riddle. Federal entomologist, was appointed 

 chairman. It was decided to hold the next meeting in 

 one of the Western States. 



In discussing waj's of controlling crop pests, it was 

 stated that gras.shoppers could be destroyed by deep 

 ploughing before they hatch, scattering straw among 

 the insects on the roadsides, and burning it at night, 

 and employing poisoned bait. 



THE WINNIPEG CONVENTION. 



Members of the Canadian Society of Technical 

 Agricxdturists (and prospective members) who are go- 

 ing to attend the First Annual Convention at Winnii)eg 

 on June 15, 16 and 17, .should advise the General Sec- 

 retary as soon as possible, and not later than I\Iav 31st. 

 Accomodation will be reserved if desired, but )iotice 

 should be given in any ca.se to facilitate preliminary 

 arrangements and in order that an estimate, may be 

 formed of the probable attendance. — Address all com- 

 munications to Fred. H. Grindley, Gardenvale, P. Q. 



