210 EXPERIMENTAL FARMS 



7-8 EDWARD VII., A. 1908 



remedy, Paris green invariablj^ gave good results. The Colorado Potato Beetle and 

 the Potato Rot, a fungous disease, are now of such regular occurrence throughout 

 all the eastern parts of Canada that spraying the vines regularly with the poisoned 

 Bordeaux mixture by means of the best spraying implements obtainable, should be 

 recognized as a regular part of the practice of growing potatoes commercially, as 

 well as in gardens, even of only limited extent. The cost and labour are comparatively 

 small, but the profits are certain. The formula which is recommended for potatoes, 

 is: — 



Copper sulphate (bluestonc) 6 lbs. 



Lime (unslaked) 4 " 



Water 40 gals. 



Paris green 8 ozs. 



If preferred, 3 lbs. of arsenate of lead may be used instead of the 8 ozs. of Paris 

 green. This material is supplied in the market in the form of a thick paste. It is 

 necessary that it should be thoroughly thinned with some water before putting into 

 the spraying mixture. This is easily done; but, if the paste is put into the mixture 

 without first dissolving it, it will not mix thoroughly. One of the advantages of 

 arsenate of lead is that it remains on the foliage much longer than Paris green, and 

 it is well known that it is not so destructive to the foliage. 



In addition to the Colorado Potato Beetle, extensive injury is sometimes done by 

 a small flea-beetle known as the Cucumber Flea-beetle, Epitrix cucumeris, Harr. 

 This beetle, strange to say, is difficult to control v/ith the ordinary applications of 

 Paris green ; but, if the poison is mixed with Bordeaux mixture, it is very effective, 

 and it, like all other foliage eating insects, can be prevented from injuring the crop. 



Enemies. — A subject which is always of much interest is the detection of the 

 parasitic and predaceous enemies of any common injurious insect. During the past 

 year specimens of the useful and beautiful little Carab, Lehia grandAs, Hentz, were 

 observed with interest and in some numbers, by Mr. Richard Gibson, of Delaware, Out. 

 He noticed them on several occasions attacking the larvae of the Potato Beetle and 

 destroying them. The Rev. Robert Hamilton, of Grenville. Q\ie., also sent me 

 specimens of the predaceous bug, Podisus spinomis, DalL, which he had found prey- 

 ing on the larvffi of the Colorado Potato Beetle. He had seen a great many of these 

 larvse lying dead among his potatoes and was induced to look for the cause, when he 

 found an unusual number of the predaceous bugs. There are a great many parasites 

 of this regular enemy of the potato grower; but, unfortunately, they are never abun- 

 dant enough to affect appreciably its numbers, and spraying potatoes will probably 

 always be every year a necessary part of the successful cultivation of that important 

 crop. 



The Potato-leaf Aphis, Nectaropliora solanifolii, Ashm. — An occasional but 

 destructive enemy of the potato is the above named plant-louse, which in the spring 

 of 190G was very abundant at Ottawa. The potato fields in the month of June were 

 much infested, and the plants were stunted by the attacks of the insects, thus aggra- 

 vating to a marked degree the effects of the protracted drought which prevailed in 

 the Ottawa valley. About the beginning of July the insects suddenly disappeared, and 

 in favourable localities the plants to some extent outgrew the injury. The life habits 

 of this species of aphis are as yet unknown; but it is probable that at that time the 

 species migrates to some other food-plant, as is known to be the case with other 

 species. Although some kinds of ladybird beetles were observed on the plants, it was 

 considered that they were not in sufficient numbers to account for the sudden diminu- 

 tion in the numbers of the plant-louse. On a small scale, experiments in spraying 

 with the ordinary insecticides for this class of insects were quite effective. Whale-oil 

 soap, 1 lb. in 5 gallons of water, and kerosene emulsion made with Tak-a-Nap soap 

 gave the best results. 



