THE MONTHLY BULLETIN. 



301 



locality having canker, not yet discovered. The risk of getting other diseases is. 

 however, a factor to be considered. Therefore, when the entomological department 

 of the I'lant Hoard began, about a year ago, to grow the red aschersonia, or red 

 whiteHy fungus, in pure culture, growers at once became interested, and may in the 

 near future refuse to use anything but the pure cultures. While last year, some- 

 what less than 400 cultures were produced and sold, the 1917 crop consists of 

 approximately J.000 cultures. Each culture (Fig. 102) consists of the fungus and 

 spores produced on four or five plugs of sweet potato, about the size of a finger, 

 with some agar (seaweed jelly) all sterilized together in a pint wide-mouth bottle, 

 in a steam sterilizer prior to inoculating (planting) the fungus on it. One of these 

 cultures when mixed with 50 gallons of water is sufficient to treat, or spray, about an 



Fig. 101. — Red Aschersonia, or red wliitedy fun- 

 gus. Natural size. (Courtesy Fla. Exp. Station, 

 Bui. 97.) 



acre of grove. The charge made is 50 cents per culture, plus transportation. The 

 best time to introduce or spread fungus is during the period of summer rains, hot 

 weather and plenty of moisture being necessary for tin' fungus to thrive. 



The red aschersonia. the brown fungus and the while fringe fungus, have been 

 found very effective at times against both the common whitetly and the cloudy-winged 

 whitefly. They appear not to be much of a factor in the control of the woolly while- 

 fly. The red aschersonia has, on the other hand, been several times found effectively 

 controlling at least two other species : the inconspicuous whitefly on sweet potatoes 

 and an unidentified one with black larva 1 and pupa' received on custard apple. 



There is another effective fungus that infects only the cloudy-winged whitefly, 

 namely, the yellow aschersonia. This is similar to the red aschersonia, except that it 

 is yellow. 



