THE MONTHLY BULLETIN. 29 



excellent law passed by the recent legislature. It is interesting to know 

 that five potato growers in El Dorado County have expressed their 

 intention to grow certified seed the coming season, as many as entered 

 the list in the whole State this past year. We can only hope tliat at each 

 meeting as much interest Avill be shown, and that in the season of 1916 

 there will be tons of certified potato seed instead of bushels, enough to 

 fill the demand, although we can hardly expect such a result. Certified 

 seed under the law will not only prove a godsend to the potato industry, 

 but it will swell the income of the producer, for sound seed has double 

 or triple the value of that usually sold in the market. No one can 

 afford to plant diseased potato seed, if sound seed is obtainable, I may 

 say, at almost any price. — A. J. C. 



The Woolly Aphis on Pear. — The avooIIv aphis problem has become 

 of so mucli importance that we are publishing the following letter sent 

 to the county horticultural connuissioners for the sake of giving the 

 matter further publicity : 



December 15, 1915. 



Dear Sir: Your attention is called to the fact that the woolly or root aphis of 

 the pear is an extremely destructive pest in many of the better pear growing sections 

 of the State, having been found plentifully in eleven counties. In several of these 

 counties it is rated as the worst insect pest that occurs on this fi'uit. It is now 

 thought to be an entirely different species than the common woolly louse of the 

 apple, and its habits of attack certainly bear out this contention. It is seldom seen 

 above the ground on pear trees, while the habit of the apple species is to attack both 

 root and branches. Inspection to detect its presence on pear must therefore be made 

 of the root system, and the greatest care is necessary. 



As the occurrence of this insect is general, we would urge the most careful inspec- 

 tion of pear nursery stock, both at points of shipment and delivery within j-our 

 county, and wish to lay special emphasis upon the necessity for detecting it at the 

 nttrsery tvhile stock is icing dug, and insisting upon treatment before trees arc 

 shipped. 



Fumigation with hydrocyanic acid gas in a tight box or house, using 1 ounce of 

 potassium cyanide, 1 fluid ounce of sulphuric acid and 3 fluid ounces of water to 

 every 100 cubic feet of space, exposing the trees to the gas for 45 minutes is recom- 

 mended as an effective treatment which will not injure the trees. Sodium cyanide 

 may be substituted for the potassium, using 1 ounce to 1* fluid ounces sulphuric acid 

 and 2 ounces water. Instead of fumigation "Black Leaf 40," 1 part to SOO parts of 

 water, combined with either whale oil soap, 5 pounds or more to 100 gallons of water, 

 or 1 per cent distillate emulsion, may be used. This mixture may be applied either 

 as a spray or dip. If spraj^ed upon the trees a heavy pressure and nozzle giving a 

 driving spray should be used, and the greatest care would be necessary to treat every 

 portion of the root system in particular ; and as an additional safeguard the tops 

 should be sprayed also. If dipping instead of spraying is the method employed, roots 

 should be immersed long enough to allow liquid to penetrate ; fifteen minutes has 

 been recommended by some. As this long immersion entails extra work and loss of 

 time, it is suggested that a heavy sousing be given by violently forcing the roots 

 through the liquid for a number of times. 



The State office has been urged to help with the problem, and fully realizing its 

 importance is asking your careful attention to the matter discussed in this letter. 



Very truly yours, 



A. J. Cook, 

 State Commissioner of Horticulture. 



