Apple Project
Incomplete pollination in apples results in smaller and misshapen fruit. Applesrequire inter-varietal cross-pollination. The project has two main phases. The firstinvolves studies of the foraging patterns of honeybees in apple orchards, betweentrees, between varieties, and on trees. The second phase, which has been mostlyconducted by Dr. Paul Kron and Dr. Brian C. Husband in the Botany Department of the University of Guelph, involves chasing genes between varieties to determine how the genes travel. Combining data from both phases is giving insights into pollenand gene movements through pollinator activity and the arrangements in which applevarieties are planted in orchards to maximize fruit set and quality. One of our mainco-operators was "Farmer Jack" near London, Ontario.
Apple Project Facts:
The Grower:
The Ontario Fruit and Vegetable Growers’ Association
355 Elmira Road North, Unite 105
Guelph, ON, N1K 1S5
POINTERS IN POLLINATION B I
Authors: Peter G. Kevan, Brian Husband, Paul Kron
APPLES
Lopsided and small apples cost more to produce than they are worth on the market. The best apples are produced in healthy, well fertilized and watered orchards. But that=snot all that=s needed. Cross-pollination between cultivars is essential. The best apples come from the central "king" blossoms of the flowering clusters when they are fully pollinated. Fully pollinated apples grow symmetrically, with a full complement of seeds all round the core. Incomplete pollination results in misshapen fruit. What can growers do about pollination to produce high quality apples? And, what are the costs and expected returns for pollination?
One mistaken view is that apples are over-pollinated, requiring thinning of the excess fruit. Thinning is part of high quality fruit production, but not to overcome the effects of excessivepollination. Thinning removes inferior fruit from the trees, and those tend to be produced by the lateral flowers, not the king blooms, and those that are under-pollinated. Thus, to obtain the best, largest and most symmetrical fruit, pollination must be as complete as possible. Another commonly encountered grower error is in orchard design. Because cross-pollination between cultivars is required, orchards must be planted so that cultivars are intermixed closely enough for cross-pollination to occur. Large blocks of single cultivars in orchards fail to produce to their maximum potential.
The most useful pollinators for apple orchards are honey bees. How should they be deployed on orchards to satisfy pollination needs? The answer is not simple. Researchers have shown that it is not necessary to place honey bee hives singly throughout orchards. They can be placed in groups. Although there are usually fewer bees at greater distances from the hives than nearby, they tend to disperse throughout the orchard. Research conducted from the University of Guelphhas used genetic fingerprints to chase pollen in orchards in southern Ontario and in the Georgian Bay area. It seems that pollen is moved rather locally on orchards. With honey bee hives deployed at C hives/ha on orchards with cultivars planted in 3 to 4 row blocks, it was found that almost all cross-pollinations take place within 3 or 4 rows of the pollinizer cultivar. Almost no pollen is moved more than 7 rows, nor more than 6 or 7 trees along rows of mixed cultivars. Thus, it should come as no surprise that large blocks of single cultivars produce poorer and fewer fruit in the centre than round the edges. It is possible that deploying more hives couldovercome this sort of shortcoming.
Growers need to be aware of what cultivars are suitable for pollinating other cultivars. Not all bloom at the same time, and synchrony or good overlap in blooming time is important. Some cultivars, such as triploids (names) do not produce much viable pollen and so must be incorporated into orchard planting design with pollination of the adjacent cultivars also in mind. Although not well researched, it seems that some cultivars are especially good as pollinizers because they have vigorous "stud" pollen. Indeed, research is continuing to determine if mixed pollinizer pollen is superior in producing even higher quality fruits than cross-pollination by a single pollinizer.
Some estimates on the economic returns of deploying pollinating hives indicate that no growershould consider pollination as not worth while. By comparing the size and numbers of seeds in apples from an orchard with honeybees and one without, it has been estimated that the better apple crop amounts to a 700% return on the investment in renting pollinating honeybees. Suchpreliminary figures need more investigation and the North American Pollinator Conservation Campaign (NAPPC) is planning to help with that.
Related Photos:
