METHODS OF STUDY. 15 



Gloeosporium lagenarium (Pass.) Sacc. and Roum. 



Conidia only produced: 



Citrullus vulgaris Schrad. (watermelon). I Cucurbita pepo L. (squash). 

 Cucumis sativus L. (cucumber). 



Gloeosporium musarum Cke. and Mass. 



Conidia only produced: 

 Musa paradisiaca sapientum (L.) Kuntz (banana). 



METHODS OF STUDY. 

 DEVELOPMENT IN MOIST CHAMBER. 



Apparently normal and healthy leaves, twigs, and fruits taken from 

 plants showing a slight infection or suspected of being infected with 

 anthracnose in a dormant or hibernating condition were found in most 

 cases to develop typical spots of rot with acervuli and frequently 

 perithecia when kept in a moist chamber. Such material was first 

 immersed from 5 to 15 minutes in a 1 to 500 or 1 to 1,000 solution of 

 corrosive sublimate to destroy any spores of the fungus which might 

 be present. That this treatment is sufficient to destroy all the 

 known reproductive bodies of Glomerella has been demonstrated by 

 treating conidia, appressoria, and ascospores with these solutions for 

 different periods. Treatment with a 1 to 1,000 solution of corrosive 

 sublimate for three minutes has been found to kill all the spore forms. 



After the foregoing treatment the specimens were rinsed in sterile 

 water and placed in sterile glass moist chambers. 



CULTURES. 



Cultures have usually been started from conidia or ascospores 

 obtained from fresh material from the field or greenhouse or from 

 spores developed on parts of the host kept in a sterile moist chamber 

 in the laboratory. To obtain pure cultures of the organism and to 

 isolate single spores, poured plates of corn-meal agar have been gener- 

 ally used. Various solid or liquid media have been tried, but none 

 has proved more satisfactory than corn-meal agar, which is pre- 

 pared as follows: To four teaspoonfuls of corn meal add 1 liter of dis- 

 tilled water. Keep in water bath for one hour at a temperature 

 below 60° C. Strain through gauze and to the filtrate add 1 per cent 

 of agar flour. Steam three-quarters of an hour. Filter through filter 

 paper. Tube and autoclave for 15 minutes at 115° C. 



In isolating single spores to obtain pure-line cultures, special Petri 

 dishes with very thin bottoms are used. After the plates have been 

 poured and the agar cooled, the dishes are placed upside down on the 

 microscope stage and single spores located with an objective of sufli- 



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