12 



BULLETIN 1053, IT. S. DEPARTMENT OF AGRICULTURE. 



The longest periods during* which any spores of the species 

 studied have given germination are shown in Table 2. 



Table 2. — Maximum period of retention of viability of the basidiospores of 

 liensites sepiaria, Leninites trabea, Trametes serialis, Fomes roseus, and 

 Lentinus lepideus. 



Species and source of sporo- 

 phores. 



Period of retention of viability. 





Dates. 



Spores germinated 

 after— 



Germination. 



Lenzites sepiaria: 



Madison, Wis., Novem- 

 ber, 1917. 

 L. trabea: 



Apr. 13, 1918, to Feb. 10, 1921 . 



February, 1920, to February, 

 1921. 



November, 1916, to Febru- 

 ary, 1921. 



June, 1917, to December, 

 1918. 



June, 1919, to Feb. 10, 1921 . . . 

 July 5, 1918, to Feb. 10, 1921 . . 



2 years 10 months a 



25 per cent. 

 60 per cent. 



R. I., February, 1920. 

 Trametes serialis: 



Madison, Wis., Novem- 

 ber, 1916. 

 Fomes roseus: 





2 per cent. 



on tamarack (Larix). 



Minnesota, June, 1919, on 

 Prunus. 

 I.entinus lepideus: 



Cotton mill, New Bed- 

 ford, Mass., July 5, 1918. 





Less than 1 per 

 cent. 



Do. 



a These figures refer to the last tests; further tests may show that these spores survived longer periods. 

 >> These spores gave no germination in 20 months. 



viability; of basidiospokes dried at different temperatures. 



Because of the lack of sufficient quantities of basidiospores, tests 

 upon the effect of drying are neither complete nor entirely satisfac- 

 tory, because only one series has been conducted. It is to be expected 

 that the age of the spores will make some difference in their resistance 

 to drying and that, as pointed out previous^, individual casts of 

 spores may vary, hence the tests here reported are only indicative. 

 For example, it will be noted (Table 3) that spores of Trametes 

 serialis 2 years old succumbed sooner at 28° C. (82° F.) than at 32° 

 C. (89° F*.). 



At 28° and 32° C. the spores of Trametes serialis and Lentinus 

 lepideus of the ages given ceased to germinate after an exposure of 

 about 10 weeks to dry incubator conditions. At 36° C. (97° F.) it 

 took about a month to kill all or most of the spores. 



At 40° C. (104° F.) it will be noted (Table 4) that in one week 

 there was a decided drop in the percentage of germination of the 

 spores of the three species tested. Those of Fomes roseus did not 

 survive one week at 40° C. In two months, however, the spores of 

 Lenzites sepiaria were not all killed, nor those of Trametes serialis 

 in six weeks. These spores were fresh, while those in the teste at 

 36° C. were not absolutelv fresh. 



