412 Report of the Department of Entomology of the 



seedlings that had recently been transplanted in the field, as approxi- 

 mately 50 per ct. died, and the remaining plants were much retarded 

 as a result of the treatment. Plants that were well established 

 and that had made appreciable growth before the application were 

 not harmed. Injuries as a result of the treatment of carbolic acid 

 appeared to be confined to the outer cortex of the root and were 

 much more extensive with some plants than with others. Plants 

 that were only slightly injured by the emulsion recovered from the 

 effects of the treatment but they failed to produce heads. 



Conclusions from tests with carbolic acid.— Carbolic-acid emulsion, 

 when diluted to contain 0.33 per ct. crude acid prevents the eggs 

 of the cabbage maggot from hatching; also the emulsion at this 

 strength is fatal to the larvee of the first and second instars and 

 to some of the recently molted individuals of the third instar. 

 The mature larvae of the third instar are not susceptible to this 

 treatment. As shown in these tests, cabbage seedlings that have 

 been recently transplanted from the cold frame to the field are liable 

 to injury by the carbolic acid, even at the dilute strengths usually 

 recommended, while similar plants, when once the root system 

 has become established, have not been affected by the treatment. 



tests with tar pads. 

 References to use of tar pads for production of early cabbage. — The 

 idea of protecting early cabbage plants by the use of paper collars 

 seems to have originated with W. W. Tracy of Detroit, Mich., who 

 tried manila paper without success. Goff of the Wisconsin Station 

 placed tarred disks on an experimental basis by testing different 

 types of paper for this purpose and devising a tool for cutting the 

 hexagonal disks. He also tried grafting wax to fasten the papers 

 to the stems of the plants. In the preliminary tests the tarred 

 paper disks, without grafting wax, gave efficient protection to the 

 seedlings, so samples of these were sent to gardeners to be tried 

 in commercial plantings. Smith Brothers of Green Bay, Wisconsin, 

 employed the disks for the protection of one or more acres of plants 

 for at least three seasons. The results of this cooperative test, 

 which were very favorable to the paper disk, were reported in detail 

 by Goff. 10 This test was reviewed by Slingerland u who also pub- 



i°Wis. Exp. Sta. 8th Ann. Rept. p. 169-173. 1891. 



10th Ann. Rept. p. 259-261. 1893. 



11 N. Y. Cornell Exp. Sta. Bui. 78, p. 521-527. 1894. 



