THE MONTHLY BULLETIN. 109 



THE USE OF FUNGOUS DISEASES AGAINST THE 



BLACK SCALE. 



By Harry S. Smith. 



Considerable activity is in evidence at the present time on the part 

 of persons interested in a commercial way in the use of a fungous 

 disease as a practical means of control of the black scale. Any attempt 

 to lesson the cost of fighting this and other insect pests is highly com- 

 mendable, but methods of this kind should not be commercialized until 

 they have been proven to be of value by persons fully competent to 

 carry on research and who are financially disinterested. Until their 

 usefulness is thus demonstrated it is not only the privilege but the 

 duty of the agricultural and horticultural officials of the state to warn 

 the growers to go slowly in paying out money for such questionable 

 remedies. It should be made plain that the writer is not challenging 

 the hon^^sty of anyone putting these remedies on the market, but it is 

 a fact that the determination of the practical value of entomogenous 

 fungi, as in the case of other natural enemies, is a problem of such 

 complexity that only men of special training or great experience are 

 capable of solving it. There is an excellent field for experimentation 

 but the method is not yet ready for commercialization. It is not only 

 a question of a dollar or five dollars per acre thro^vn away for the 

 introduction of the fungus, but where the treatment is ineffectual we 

 must add to this cost the serious injury by the scale, whieli cost conld 

 have been avoided by fumigation or spraying. One has only to think 

 of the million dollars which reliance upon the chinch bug fungus cost 

 the farmers of Kansas and Nebraska, to understand the importance 

 of thorough investigation before a remedy of this kind is placed upon 

 a commercial basis. 



Professors Rolfs and Fawcett. in a bulletin on the use of fungous 

 diseases in combating the white fly in Florida.* state that the,y secured 

 satisfactory results by the artificial introduction of the spores of fungi 

 attacking the white fly. The use of entomogenous fungi in Florida is 

 a very different matter, however, from the attempted use of this method 

 in a country with a dry climate like that of our own state. It is 

 axiomatic that fungous diseases require humidity, hence their practical 

 use in California is confronted with an almost insurmountable handicap 

 at the outset. This handicap should not stand in the way of experi- 

 mentation. l)ut it should make us doubly cautious in accepting the 

 "Fungus cure" for our insect ills in this state and in spending money 

 for their introduction into our orchards. 



Unfair advantage is sometimes taken of the growers' lack of reliable 

 information on such subjects. The commercial concern which advertises 

 to dissipate your insect pests via the fungus route works about as 

 follows: A small amount per acre, usually from a dollar to three 

 dollars, is charged in advance to cover the cost of introducing the 

 fungus. If the insect against which the measures are directed does not 

 become seriously abundant a further amount is collected from the 

 grower. Should the insect increase in the usual way, no further charge 



*Bulletin No. 119, Florida Experiment Station. 



