Pollination of Pecans 103 



and fallen. It is possible, at least in some seasons, for the 

 pollen of these two varieties to shed before all the pistillate 

 flowers are fertilized. This is especially true if there should 

 be heavy winds and rains at the time most of the antlers are 

 dehiscing, for during such weather the pollen is either washed 

 or blown away. 



In Group II the interval between the receptive stage of the 

 stigmas and the first shedding of the pollen varies from four 

 to nine or even more days, thus making the pollination of the 

 stigmas by pollen from the same tree rather difficult. In 

 fact it is a frequent occurrence to find trees in the second 

 group with dried stigmas and nuts already formed before the 

 first pollen has shed off the trees. As a rule, the stigmas of 

 Group II dry and callus over from one to five days before 

 the first pollen is shed, thus practically precluding the pol- 

 linating of the stigmas by pollen from the same tree. How- 

 ever, in the case of the Curtis and Stuart, a considerable num- 

 ber of belated pistillate flowers will show fresh stigmas on 

 the date when the first pollen is shed. In such cases when these 

 varieties are grown alone, one would not expect complete 

 sterility, but a light crop. 



No experiments have been conducted as to just how long 

 pecan pollen remains viable, under various conditions. How- 

 ever, a determination was made of the viability of the pollen 

 under natural conditions, i.e., exposed to the weather in the 

 catkins as they hang on the tree, and it was found to be 80 

 per cent for Alley, 65 per cent for Jerome, and 100 per cent 

 for Nelson when the pollen was taken directly from the de- 

 hiscing anthers. None of the pollen from the same varieties 

 germinated when taken from the dried catkins on the same 

 tree ten days later. 



When varieties of Group II are planted, those of Group I 



