128 THE APPr.K LEAF HOPPER 



This mixture showed better comparative results than any other treat- 

 ment used in the experimental work this year. 



We had practically established this fact in 1906, but repeated the work 

 in 1907 in order to lie cjuite certain of our results. 



EXPERIMENT NO 17— TARRED PAPER AND TARRED 

 FELT CARDS. 



Cards made from tarred paper and tarred "felt" were used in connec- 

 tion with experimental work on cabbage maggots. These cards were placed 

 around the base of the plants, fitting up tightly against the stalk, in this way 

 preventing the young maggots from crawling down to the roots. The odor 

 from the cards may also act as a repellent to the flies. 



The tarred paper cards were obtained from a New York dealer, and 

 were manufactured especially for the purpose of protecting plants from 

 this kind of injur}'. Thev' are large cards — four inches in diameter, and 

 with four cross cuts, making a star-shaped opening in the center of the 

 card. 



These cards were placed around 50 cauliflower plants set in ground 

 badly infested with cabbage maggot this season. The plants were set May 

 17th, and the cards put on the following day. As a matter of fact, the as- 

 sistant sh(.uld have placed these cards on immediately after planting, and 

 we supposed at the time, that such was the case. Fifty plants in alternate 

 rows were left as checks. The final count on these rows taken Julj^ 26th 

 was as follows : 



H-->« 'Vl^^^f Missing 



Plants with cards 4 26 20 



Checks 22 23 5 



This indicates a decided loss in the plants on which the cards were 

 placed. h'orty per cent of these plants died in the treated row, against 

 only 10?6 in the check row. showing that the loss is probably due to the 

 cards themselves. We obtained similar results in 1906. 



Prof. M. V. Slingerland, in Bulletin 78 of the Cornell Experiment Sta- 

 tion, 1894, advises the use of tarred paper cards, and quotes the experience 

 of Mr. George B. Smith, of Smitli Bros., Green Bay, Wis. Correspondence 

 with Mr. Smith brought forth the following letter, under date of ]\Iay 8th, 

 1907, of which the following is a part: 



"Dear Sir: — Your letter of May 6th on hand, and as you make a mis- 

 take that a great many people do in referring to the tarred pads as paper 

 instead of felt, I wish to call your attention to the fact that tarred paper 

 proved to be a failure when used for this purpose. The action of the ele- 

 ments on the paper makes it curl up and get out of shape, but under 

 ordinary conditions, the tarred felt A\ill do neither. 



"When Prof. Goff first sent out the tarred felt for experimental use, I 

 think he sent some to us the first year, or certainly the second year that 

 he sent them out, sending us about one hundred pads. I cannot say just 

 how long ago that was. but judge it to be around eighteen years. As we were 

 just about to set out our first lot of cabbage plants for the season, the op- 

 portunity was good to make a test. I went out to the bed and put the pads 

 on myself, put them on in a strip through the bed, where there would be 



