The Effect of Distance from Pollinizer Varieties on the Fruit Set on Trees in Plum and Apple Orchards

The fruit set on plum trees decreased greatly with increase in distance from pollinizer trees, and less so with increase in distance from honey-bee colonies. Trees adjacent to pollinizers had a greater set on the sides facing the pollinizers than on their far sides. Parts of trees touching “ bouquets ” had a greater set than parts without bouquets.

In an apple orchard with main variety and pollinizer trees in separate blocks, the fruit set was greater on the main variety trees adjacent to the pollinizers than on trees farther away. In an apple orchard with a pollinizer tree as every third tree in every third row, main variety trees had a greater fruit set, more seeds per fruit, and more carpels with seeds per fruit, on the sides near to their adjacent pollinizers than on their far sides. The fruit set, number of seeds per fruit, and number of carpels with seed per fruit, were greater the nearer the trees were to the adjacent pollinizer.

These results are discussed in relation to the foraging behaviour of honey-bees and to methods of arranging pollinizer and main variety trees in orchards.