550 BULI^ETIN 78. 



(pyrethrum ?) and Paris Green was added. The plants soon dwindled and 



died from the treatment. 



Sulphur. 



A Washington State correspondent, Mr. H. A. March ("Rural New 

 Yorker," p. 678) in 1889 records an experiment in which he saved many 

 plants by dipping them in a puddle of %. pound of sulphur and water. How- 

 ever, no definite conclusions can be drawn from the puddling, for matters 

 were complicated by the further application of ^ teaspoonful of dry sulphur 

 on the soil around each plant after setting. The evidence warrants a further 

 trial of sulphur either as a puddle, or applied on the surface. 



Soap and Quassia, or Carbolic Acid and Soap. 



Mr. Whitehead, of England, in his report for 1892 advises that plants be 

 dipped in "solutions of soft soap and quassia,composed of 7 lbs soap, 12 lbs. 

 of quassia, to 100 gals, of water ; or of 7 lbs. of soft soap and 6 or 7 qts. of 

 carbolic acid." No evidence is given in support of either recommendation 

 and the effectiveness of the first is very doubtful, while the second would be 

 liable to inj ure the plants. 



3. Application on or about the Plants. 

 {a) Coal Dust, or Sulphur. 



Coal Dust. — All the recommendations of this substance as a preventive are 

 based on an experiment made in Russia in 1855 (Bull. d. 1. soc. imp. des 

 natural, de Moscou., XXVIII). Through Taschenberg's account of this ex- 

 periment, it has clung to the literature to the present time. The experiment 

 indicated that the flies avoided those plants about which coal dust has been 

 scattered. But, as Taschenberg observes, it is necessary to the success of the 

 experiment, that some plants be left untreated as baits to entice the flies to 

 oviposit on them ; these baits are afterwards to be destroyed with their ac- 

 companying maggots. When no plants are left for baits, Taschenberg says 

 the flies then accommodate themselves to the beds entirely covered with the 

 coal dust. It is curious that so simple a preventive seems not to have been 

 tried since this first experiment. We have but little faith in its effectiveness, 

 but it should receive a trial wherever practicable. 



Sulphur. — All the evidence in regard to the use of this substance as a pre- 

 ventive seems to come from Mr. H. A. March, of Washington State. His 

 method of using the substance has been stated above in discussing the pud- 

 dling of the roots in sulphur. Mr. Crozier ("The Cauliflower," p.98) 

 quotes Mr. March as follows : "The best thing I have found for the maggot 

 is a />o<?r grade of sulphur, sulphur before being purified, that smells very 

 strong. Sprinkled over the plants it seems to drive the fly away." The 

 substance is evidently worthy of a further trial. 



(b) Insecticides. 

 Powdered Tobacco, and Tobacco Decoction. 

 In 1857 {''Country Gentleman,''-^. 319) E. Saunders reported that an Albany 



