THE MONTHLY BULLETIN. Ill 



which in most cases have been insurmountable. Fungi are very 

 dependent upon external conditions and in many cases the apparent 

 absence of a particular fungus in a locality is usually an index of 

 conditions unfavorable for its development, and an artificial introduc- 

 tion will be useless. If a fungus does establish itself in a locality it 

 may not spread far from the centers of artificial infection, showing 

 that conditions are favorable in and near the centei-s of infection, but 

 not beyond them. 



In 1892, Franz Tangl, at one time interested in this subject, and 

 now a well known physiologist at the University of Budapest, per- 

 formed some infection experiments on nun moth caterpillars by using 

 spore emulsions of Botrytis bassiana. In the laboratory the experi- 

 ments succeeded, since all of the infected caterpillars died of "mus- 

 cardine." Infection experiments in nature, however, where infested 

 trees were thoroughly sprayed with spore emulsions, gave negative 

 results. The nun moth caterpillars flourished as before. V. Tubeuf, 

 who has done a great deal of work on caterpillar diseases, tried a series 

 of similar experiments, and likewise obtained negative results when he 

 tried to infect caterpillars in nature with Cordyceps militaris. 



Recently Billings and Glenn (1911) in attempting the artificial use 

 of Sporotrichum globuliferum, the etiological factor of the white fungous 

 disease of chinch bugs in Kansas, have reached very similar conclusions. 

 In a summary of their experiments, they say : 



(1) "In fields where the natural presence of the fungus is plainly 

 evident, its effect on the bugs can not be accelerated to any appreciable 

 degree by the artificial introduction of spores. 



(2) *'/n fields where the fungus is not in evidence spores introduced 

 artificially have no measurable effect. 



(3) ''Apparent absence of the fungus among chinch bugs in a field 

 is evidence of unfavorable conditions rather than lack of fungus spores. 



(4) "Laboratory experiments can be made to prove that artificial 

 infection accomplishes results upon bugs confined in cramped quarters 

 and without food, but in the field, where fresh and usually drier air 

 prevails and food is abundant, an entirely different situation is pre- 

 sented. ■ ' 



Messrs. ]\Iorrill and Back, who have thoroughly investigated the 

 problem of control of the citrus white fly in Florida by means of its 

 fungous diseases, conclude that. "The infections secured by artificial 

 means of introducing fungi, while successful in introducing the fungi, 

 have thus far proved of little or no avail in increasing their efficacy 

 after they have once become generally established in a grove." 



We have in the Citrus Experiment Station at Riverside some of the 

 best mycologists in the country. At least two of these scientists have 

 had much actual experience in the use of entomogenous fungi. That 

 these diseases have practical value in California is very doubtful. If 

 the Experiment Station believes, however, that there is any possibility 

 of even partial success, it will unquestionably make a thorough study 

 of the problem at an early date. Until that time the growers who have 

 infestations of black scale would better invest their money in fumigation 

 rather than in a grave uncertainty. 



It is very gratifying that the County Horticultural Commissioners 

 in the south have issued warnings to the growers to go slow in trying 

 this inexpensive cure. It may be very expensive in the final analysis. 

 Their action is to be commended. 



