1910.] Summary of Agricultural Experiments. 587 



compared with the pollen from the other orchard, and the length of 

 time they took to germinate indicated a lower state of vitality. Close 

 observation also revealed the fact that the flowers in the neglected 

 orchard were much smaller and the stamens and pistils dwarfed and 

 deformed in many cases. The question of the longevity of pollen is an 

 important one to the plant breeder, and it was shown that if kept in 

 a dry place in a temperature ranging from 50 to 65 0 F. apple pollen 

 can be kept for six months or longer; the limit for plum pollen was 

 less, but generally it would seem that pollen can be safely transported 

 and kept for some time without any very noticeable effect on its 

 vitality. 



Under favourable conditions it was found to take from 9 to 32 

 hours for the pollen tube of apples, plums, and cherries to reach the 

 ovary when placed on the stigma or in the germinating medium. 

 Cherry pollen requires a little over 12 hours. Under natural conditions 

 the time would be somewhat greater, but two or three bright, warm 

 days at the time of full bloom is sufficient for the setting of the fruit. 

 These figures show that the danger period from frost is comparatively 

 short, and this accounts for the fact that often a frost during full bloom 

 apparently does very litt!e damage, while at other times a similar frost 

 may completely kill the essential parts of the flower. 



Cross- and Self-Pollination of the Apple (Oregon Agric. Coll. Expt. 

 Stat., Dept. of Horticulture, Bull. 104). — This bulletin contains the 

 results of an inquiry into the value of cross-fertilisation in apples. 

 Many varieties cannot be fertilised with their own pollen, but only 

 with that from another variety. It is important, therefore, that apple- 

 growers should not plant large areas of self-sterile varieties, but mix 

 them with other varieties in order that the opportunities for pollination 

 may be increased. It was found in the course of this inquiry that 

 out of 87 varieties of apples 59 were found to be self-sterile, that is, 

 unable to set fruit when self-pollinated, 15 varieties were self-fertile, 

 while 13 varieties were classed as partially self-fertile. The sterility or 

 fertility of a variety has, however, been found to be greatly influenced 

 by climatic conditions, and consequently conclusions arrived at in one 

 locality as to the behaviour of any variety may not hold good in 

 other localities. The fact that such a large proportion of varieties 

 were found to depend entirely upon cross-pollination is evidence of 

 the practical importance of the question, and, in addition, it was found 

 that even in the case of those that are well able to produce fruit when 

 fertilised by their own pollen, better results were obtained from cross- 

 pollination. 



The Yellow Newtown, an apple that will set fruit without the aid of 

 cross-pollination, was crossed with a number of varieties, and in every 

 case much larger and finer apples were obtained than by self-fertilisatiori. 

 Out of forty apples produced by self- fertilisation, thirty were inferior 

 in size when compared with the apples produced by cross-fertilisation. 

 In the orchards of the district a large number of small malformed 

 apples were found, which were similar to those obtained by self- 

 fertilisation of Yellow Newtown, and which could not be attributed to 

 aphis attacks. 



Considerable variation appears to exist in effect of cross-pollination. 

 All varieties do not cross satisfactorily with each other, while when 



