SH 



Journal of Agricultural Research 



Vol. Ill, No. 6 



The data secured relative to the duration of ascospore expulsion after 

 certain rains are given in a summarized form in Table XI. As will be 

 seen, all of these, except the results obtained on October 20, bear refer- 

 ence to rains occurring during the progress of exposure-plate tests. 

 Although the exact time of cessation of rain is a very important point, 

 in the cases of September 18, 19, 20, and 22 it could not be more accu- 

 rately determined, because the rains all ceased in the night. A com- 

 parison of the figures presented in these tables with the results obtained 

 in the exposure-plate tests will show a close interrelation. 



On October 20 another opportunity was offered to obtain data relative 

 to duration of spore expulsion. By selecting only a few traps and chang- 

 ing the slides at much shorter intervals more in detail was learned in 

 regard to the activity of the perithecia (Table XI). 



Since the point had been often suggested that these ascospore-trap 

 tests might not yield results typical of natural conditions because of the 

 protection from drying afforded by the glass suspended over the bark 

 and that because of this spore expulsion was greatly prolonged, occasion 

 was taken on October 20 to determine the validity of this contention. 



About two hours after the cessation of rain, when expulsion had appar- 

 ently ceased under most of the ascospore traps that were being tested 

 (Table XI), a number of clean slides were placed at random over other 

 areas of perithecia-bearing bark which appeared still to be damp, to 

 determine whether or not perithecia on bark unprotected by glass slides 

 were expelling spores at this time. Owing to the high south wind and 

 occasional sunshine, such promising areas of bark were found only on 

 the north side of trunks, either where loosened bark about a bad lesion 

 had become soaked or in locations more or less protected by sprouts or by 

 stumps from the drying action of the wind. The slides were held in 

 place by a cord tied around the trunk, and care was taken to prevent 

 contact with the papillas. The results obtained from these 22 test traps 

 are given in Table XII. 



Table XII. — Record of test traps on October 20, 1913, at West Chester, Pafi 



Trap No. 



Time of placing slide. 



I 

 2 



3 

 4 

 5 

 6 



7 

 8 

 10 

 II 

 12 

 14 

 IS 

 16 



17 

 18 

 19 

 20 

 21 

 22 



11.20 a. ra 



11.25 a. m 



11.27 a. m 



11.27 a. m 



11.32 a. m 



11-352. ni 



11.35 a. m 



11.39 3- ™ 



11.34 a. m 



11.47 ^- T" 



11.47 3- rn 



11.55 a. m 



12.00 to 12.04 p. m 

 12.00 to i2.o4p. m 

 12.00 to i2.o4p. m 

 12.00 to i2.o4p. m 

 12.00 to i2.o4p. m 

 12.00 to 12.04 p. m 

 12.00 to i2.o4p. m 

 12.17 P- ni 



Time of colJectiou. 



1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 

 1.30 to 



2.00 p. ra 

 2.00 p. m 

 2.00 p. m 

 2.00 p. m 

 2.00 p. m 

 2.00 p. in 

 2.00 p. m 

 2.00 p. m 

 2.00 p. m 

 2.00 p 

 2.00 p 

 2.00 p 

 2.00 p 

 2.00 p 

 2.00 p 

 2.00 p 

 2.00 p 

 2.00 p 

 2.00 p 

 2.00 p 



Results of examination. 



I faint spot. 

 o. 



I light spot. 



o. 



o. 



o. 



o. 



o. 



I faint spot 



o. 



o. 



o. 



o. 



3 spots; I rather heavy. 



o. 



1 light spot. 



o Kainfall. 0.86 inch. Time of cessation, 9-09 a. m. Wind, high SSW. 



