20 



BULLETIN 727, U. S. DEPARTMENT OF AGRICULTURE. 



tilled water inoculated with spores and incubated at thirteen different 

 temperatures between 3° and 31° C. secured in an Altmann compart- 

 ment incubator and in other constant-temperature incubators. The 

 results are presented in Table II. 



Table II. — Relation of temperature, oxygen supply, and food supply to spore germination 

 and appressorium formation of Colletotrichum lagenarium. 



[Abbreviations: ab = abundant, ap = appressoria, d = day or days, g = germination, gt = germ tubes, 

 hr = hours, mar = marginal, mini = numerous, pc = per cent, spo = sporulation, sw = swelling, tg = 

 trace of germination.] 





Distilled water. 



Prime decoction. 



Tempera- 











ture (C.). 













Hanging drop. 



Exposed drop. 



Hanging drop. 



Exposed drop. 



2° to 3° 



19 d, no g 



19 d, no g 



19 d, no g 



19 d, some swollen. 



3° to 4° 





10 d, no g 



10 d, no g 



7 d, sw; 19 d, a few 



6° to 7° 



10 d, no g; 19 d, sw.. 



5 d,no g; 7d,sw; 10 

 d, a few budlike 



19 d, no g 



short gt. 

 1 d, no g; 2 d, tg; 5 d, 

 num short gt; 7 d, 











gt. 





50 pc short budlike 

 gt. 

 1 d, no g; 2 d, 3 pc g; 

 7 d, 90 pc g, short gt, 



9° to 10° 





3 d, no g; 19 d, bud- 

 ding gt. 



19 d, no g 

















ap ab. 



11° to 12°... 



2d, sw; 10 d, nog 



2 d, 10 pc g; 3 d, ap 



2 d, sw; 10 d, sw, 



10 hr, tg; 1 d, 1 pc g. 







ab;5d,80pcg. 



nogt. 



short gt; 2 d, 90 pc 

 g; 3 d, ap general. 



12.5° to 14°. 





1 d, 1 pc short slen- 



1 d, nog; 2d, swollen 

 (septate); '7 d, . 95 



10 hr, tg; 1 d, 5 pc g; 

 2 d, a few ap; 10 d, 







der gt; 2 d, 10 pc 







g, ap present. 



pc same, 5 pc nor- 

 mal g. 



acervuli spo. 



14° 



Id, no g; 2d, 5 peg; 



1 d, tg; 2 d, 90 pc g, 



2 d, no g (cell found air 



1 d, 20 pc g, gt robust; 

 2 d, 90 pc g, a few 





5 d, ap formed. 



ap num (mar). 



tight); 5 d, no g. 











ap; 5 d, ap num, 











acervuli forming. 







9 hr, 1 spore germi- 

 nating; 1 d, 5 pc g, 



Id, 1 peg; 2d, 5 peg, 

 long gt; 3 d, no ap; 



9 hr, tg; 1 d, 5 pc g, ap 

 present (mar); 2 d, 









■ 



a few ap. 



7 d, acervuli; 10 d, 

 spo. 



ap. num; 7 d, spo. 



15°tol7°... 



2 d , no g 



1 d, 20 pc g, ap pres- 

 ent; 2 d, ap num 



11 hr, 2 spores germi- 

 nating; 1 d, 1 pc g; 



9 hr, 1 pc g; 1 d, 40 

 pc g, ap present; 3 











(mar). 



2 d, 3 pc g, ap pres- 

 ent; 4 d, acervuli 

 forming; 5 d, no 

 spo. 

 Id, 90 peg; 2d, noap; 



d, ap num; 7 d, spo. 



18° to 20° . . . 



10 hr, 2 peg; Id, 10 



10 hr, 1 spore germi- 



9 hr, 3 pc g; 1 d, 10 pc 





pc g; 3 d, no ap; 4 



nating; 1 d, 5 to 



3 d, apnum. 



g, ap present (mar); 





d, ap num. 



10 pc g, ap num 

 (mar); 2 d, 10 

 peg. 





3 d, acervuli forming; 



4 d, spo. 



22° 



Si hr, 5 pc g; 1 d . 20 



1 d, ab g, ap pres- 



1 d, 90 pc g; 4 d, spo, 



8hr, 10 peg; 1 d, 20 pc 

 g; 2 d, ap; 4 d, spo. 





pc g, gt slender, 



ent; 2 d, ap num 



no ap. 





a few ap (mar); 2 



(mar). 









d, ap num. 









264°to27£°. 



10 hr, 20 pc g; 1 d, 



8 hr, 10 pc g, 1 d, 25 



10 hr, sw; 1 d, 95 pc g; 



8 hr, 10 to 20 pc g; 1 d, 





30 pc g; 3 d, a few 



pc g, ap (mar); 



5 d, noap; 7d, spo. 



75 pc g; 2d, ap pres- 





long-stalked ap. 



2 d, ap num. 





ent; 4 d, spo. 



30°to31°... 



9£ hr, lateral bud- 



8hr, tg; 1 d, 5 pc g; 



9hr, sw; 20 hr, 95 peg; 



8 hr, 10 to 20 pc g; 1 d, 





like gt; 20 hr, 40 



4 d, 50 peg; 5d, no 



2 d, extreme sw of 



95 pc g, colonies visi- 





pc g; 3d ex- 



ap. 



spores and myce- 



ble to unaided eye, 





tremely swollen 





lium; 3 d, no ap. 



no ap; 5 d, no ap, no 





budded spores or 







darkening. 





"involution 











forms"; no ap. 









44° 





No g 





Nog. 











More vigorous germination was obtained in prune decoction than 

 in water, and in either medium the exposed drops furnished better con- 

 ditions for germination than the hanging drops. The latter is 

 attributed to lack of aeration in the Van Tieghem cells, although, in 

 preparing these, care was exercised not to have the vaseline seal con- 

 tinuous around the edge of the ring. At the rather high tempera- 



