356 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



beets against 13 per cent for the unti'eated. Steeping twent}^ houi-s 

 has been found too long, because it causes a delay of fifteen days in 

 the germination of the seed. By limiting the steep to fifteen hours, 

 even whilst using a 0"5 per cent solution, the result is the same, but 

 seeds withdrawn after ten hours only gave 50 per cent of sound plants. 

 To facilitate disinfection, Carlson advises to soften the seed for three 

 days in pure water of 17"5''-19°C., and only put them in the carbolic 

 acid afterwards when it acts quicker. Tarschebinski has made 

 numerous experiments which have confirmed those of Carlson. He 

 found that corrosive sublimate disinfected beet seeds without previous 

 steeping in water. Carbolic acid does not completely disinfect until 

 after steeping of the grain ; without that precaution disinfection is only 

 relative. He also found that carbolic acid destroyed the spores of 

 fungi much easier than bacteria. Wilfarth and Wimmer believe that 

 carbolic acid must be completely soluble in water to give favourable 

 results, and for that reason they prefer the crystallized acid of com- 

 merce. 



Method of Disinfection. — After having perfectly dissolved the 

 carbolic acid in water the seeds are added ; they are stirred energetically 

 to moisten them uniformly ; the seeds are then pressed by boards and 

 weights so that they are entirely covered with liquid disinfectant. 

 After twenty hours' steeping the seeds are withdrawn and spread out 

 in thin layers in an airy place, where they are frequently turned. 

 The seeds so dried may be preserved as long as desired without that 

 being injurious to them. Mark advises for the disinfection a mixture 

 of carbolic acid and blue vitriol. 



Potato Scab. — Frank and Kruger tried to disinfect the soil with 

 carbolic acid to overcome this bacterian disease of the potato. They 

 used an emulsion containing 250 grammes (0"55 lb.) of carbolic acid and 

 500 grammes of soap for a plot of 4 square metres. The result was 

 not so good as in disinfection by petroleum. 



Bacillus solanacearum (bacterial disease of Irish potato, and egg 

 plant, Solatium melongena). — Sackett recommends the disinfection of 

 potatoes and tomato seed by a 5 per cent solution of carbolic acid. 



Bhizoctinia violacecs betce. — Eriksson found that disinfection of the 

 soil by carboUzed Hme appreciably diminished the number of these 

 fungi. 



Uncinula Americana, How. (oidium of the vine). — Vesque, after 

 experiments to overcome oidium, found that carbolic acid of less 

 strength than 1 per cent does not destroy oidium, whilst O'l per cent 

 solutions are injurious to grapes. 



Use against Insects. — Mclolontha vulgaris, L. (cockchafer). — 

 To preserve strawberry plants from the larvae of the cockchafer, it is 

 advised to till along the borders and to sprinkle the hollows with a 

 0-1 per cent solution of carbolic acid. 



Magdalis cenescens, Lee. — Against this insect which lives in the 

 bark of the apple-tree on the Pacific coasts, Chittenden advises to 

 coat the trunk in the springtime, up to end of May, with an emulsion 

 of carbolic acid, lime, and soap. 



Anthonomus 2Mviorum (apple blossom weevil). — Whitehead recom- 



