WHY FRUIT DOES NOT SET

Sun (Auckland), Volume III, Issue 625, 30 March 1929, Page 24

WHY FRUIT DOES NOT SET

The pollination of the blossom is one of the most interesting subjects in connection with fruit trees. It has been a common experience with fruitgrowers that individual varieties of apples, pears, plums, and cherries bore little fruit, though the trees were lusty and making good growth, and the blossoms plentiful and healthy. It has therefore been necessary to look for causes for the condition of fruit sterility. It has been found first that the sterility is most noticeable in certain places in large orchards where the varieties have been planted in groups, or secondly in connection with trees isolated from all others. This has given investigators a clue, and both in England and America horticultural scientists have for the past 20 years come to the conclusion that, while climatic conditions and the general vigour of trees have a good deal to do with the pollination of blossom and the setting of fruit, there are not a few varieties of all the hardy fruits which are self-sterile, and which therefore need the pollen of other trees to help them to set and bear fruit. In an instructive lecture given re-

cently to the East Kent Beekeepers’ Association. Mr. C. H. Hooper, F.L.S., a well known authority on the subject, pointed out that the study of the insect visitors to fruit blossoms, and the construction and habits of the insects, might tell us why a certain orchard or plantation made a profit or a loss. Gooseberries, currants, raspberries, and loganberries all mature their fruit perfectly with pollen of the same variety, but they all need insects to carry the pollen. With apples, pears, plums, and cherries, a large proportion of the varieties will not mature fruit with pollen of the same variety, but need pollen of another variety in order to bear fruit. No variety of apple or pear is sufficiently self-fruitful for it to be planted alone with safety. The most self-fruitful variety may mature, say. 10 per cent, of its flowers with its own pollen, but will yield double with pollen of another variety, while Cox’s Orange and Prince Albert may mature one fruit per 1,000 blossoms with their own pollen. In plums, some 10 varieties are Ten* self-fruitful, but the yield of each of these is slightly increased by another pollen. Half the plums are absolutely or for practical purposes self-sterile.