New York AGRICULTURAL EXPERIMENT STATION. 311 
together and away from other vines would produce no fruit. But 
if Cottage, Delaware, Diamond, Diana, Mocre Early, Niagara, or 
any other strongly self-fertile sort be planted beside the varieties 
mentioned, then fruit could be expected. 
When the pollen of different varieties was taken into the labor- 
atory, it was found that under the artificial conditions there given, 
the pollen of the self-sterile sorts would not germinate, while the 
pollen of the self-fertile sorts always showed a high percentage of 
germinations, and it was further found that the percentage of 
germinations was in direct proportion to the capacity of the variety 
for self-fertilizing itself, as indicated in the previous vineyard tests, 
that is, all those varieties which were partially self-fertile showed 
a pollen in which only part of the grains would grow. When 
examined under the microscope it was found that those grains which 
were self-fertile were of different shape from those which were self- 
sterile. From this information we can tell at once whether a variety 
is self-sterile or self-fertile by examining the pollen, without the 
necessity of bagging clusters in the vineyards. 
As a corollary of this work it was found desirable to note the 
blooming season of the various varieties’ since it was evident that 
two varieties must be in bloom at the same time if it is expected 
that the one should fertilize the other. Lists were!® consequently 
published giving the approximate blooming season of all those 
varieties included in the previous investigation. 
COVER CROPS FOR ORCHARD. 
Owing to the fact that in many of the fruit-growing neighbor- 
hoods of New York State orchards have been cultivated for years 
and the humus in the soil more or less exhausted, the renewal 
of this supply of humus is a vital problem to all fruit growers. 
Humus, be it understood, is vegetable mold coming from decaying 
plants and is found in ail soils. Soils in which the humus content 
is deficient are unsatisfactory for the raising of fruit. Supplying 
the humus by hauling barnyard manure or other vegetable matter 
upon the land is not only expensive but in many neighborhoods is 
absolutely impossible owing to the fact that such manure can not be 
secured. Great interest is consequently felt in the question of cover 
crops, cover crops being the term implied to indicate any crop grow- 
ing in the orchard, usually through the latter part of the growing 
* Bul. 169; also in Rpt. 18:361 (1899). 
