18 NUT CULTURE IN THE UNITED STATES. 



be found to be due to the different dates of blooming of the flowers of the two sexes, 

 or to a deficiency in the number of male flowers, or a lack of potency in the pollen 

 produced by them. 



There is a lack of accurate data on the comparative season of blooming of indi- 

 vidual trees and varieties of the leading species. Until more exact infonnation can 

 be had upon this subject it will be impossible to lay down definite rules to govern the 

 commercial planter in this regard. It may be said in a general way that most cases 

 of lack of fruitfulness of nut-bearing trees in regions where the trees make a thrifty 

 growth seem to be due to two causes: (1) The untimely blooming of the male, or 

 staminate, blossoms (on the Persian walnut they are frequently more than two weeks 

 earlier than the pistillate ones) ; (2) to a deficiency in the amount or potency of their 

 pollen. This deficiency may be due to an actual deficiency in the number of staminate 

 buds found, as on young trees; to the destruction or weakening of the staminate buds 

 by the cold of winter; to the washing away of pollen by heavy or long-continued rains 

 at blooming time; or, as has been long believed by California almond growers, to a 

 lack of potency of the pollen of a variety upon its own pistils. 



Though the exact causes of the lack of fruitfuluess have not been demonstrated 

 in all cases, precautions which have been found to insure fruitfulness in many locali- 

 ties may be taken. These consist mainly in the mixing of the varieties planted, as 

 with the almond, or of planting trees of other allied species in close proximity, as in 

 the case of the walnuts. The object is to provide a continuous supply of pollen during 

 the whole blooming period, and thus insure the pollination of the pistillate flowers. 

 With a few trees this could doubtless be accomplished by tying branches of staininate 

 blossoms secured from other trees, in the tops of the trees when in bloom. This 

 practice is common in England, in the case of the hazel, where branches of staminate 

 catkins secured from wild trees are often depended on to supply pollen deficiences in 

 the cultivated varieties. 1 



With other nuts the record of experiment is wanting, and trial alone can determine 

 whether choice varieties will be benefited by the close proximity of trees of allied 

 species possessing greater hardiness and virility, or producing their pollen at a more 

 opportune time. 



HARVESTING. 



The gathering of Persian walnuts, butternuts, and perhaps some of the other 

 species for making pickles, catsup, or other culinary products, is done when the fruit 

 is about half mature or when the shell is soft enough to yield to the influence of cook- 

 ing. The proper stage can be determined by piercing the nut with a needle, a certain 

 degree of hardness being desired. 



Nuts mature on individual trees with as much irregularity of season as do most 

 other fruits. Contrary to common belief, the frost that precedes the opening of the 

 bur of the chestnut or of the hull of the hickory does not ripen the nut. It has no 

 more to do with it than it has with the maturing of a winter apple that hangs on its 

 tree at the same time. The frost may cause all the nuts to fall to the ground at once 

 by checking the growth of the tree; this, occurring about the time that the nuts 

 mature, precedes the opening of the bur or hull. A check in the circulation of sap 

 through the outside of the bur or hull causes the outer surface to dry very rapidly, 

 while the inner surface next the full-grown nuts remains more or less moist. The 

 natural result is a shrinking of the outside of the involucre and the consequent separa- 

 tion of the parts, thus liberating the nuts. 



Varieties differ several weeks in the time of ripening under apparently identical 

 conditions, and specimens on the same tree vary in time of ripening, quite as much as 

 do apples or pears. It is a matter of considerable importance in harvesting that trees 

 which mature their fruit at the same time stand in proximity to each other, as the 



1 Arboretum et Fruticetum, Vol. Ill, page 2027. 



