||Malus pumila, Malus sylvestris and Pyrus pumila
||The exact origin of the common apple grown for fruit is quite obscure, but almost certainly contains the genes of several species. Many consider the main gene source to have come from Malus pumila possibly hybridized with M. sylvestris, but a recent writing claims that the main germ plasm came from M. sieversii. Whatever the case, the main body of germ plasm seems to have come from Asia. To avoid this taxonomic mess, many prefer to call the common apple Malus x domestica or simply Malus domestica. This is what I have done.
||Given the mix of germ plasms in the common apple, it is not surprising that the “species” exhibits a great deal of variability. In older orchards or in the wild, the trees commonly known as standard trees can grow to 40 ft in height, but in more recent orchards, where the trees are being grown on dwarfing rootstocks, they frequently are 10 feet and under. Depending on size, these trees are generally referred to as semi-dwarf and dwarf trees. The blossoms are generally pinkish, a characteristic that generally distinguishes them from the white blossoms of pear. There are five petals, five carpels and many stamens. Many years ago, botanists placed both pears and apples in the genus Pyrus (see synonyms above). For purposes of classification, the main distinction between apple (Malus) and pear (Pyrus) is that in apple, the styles are fused at their base and in pear they are not (see diagrams). The shapes of the two fruits are generally different, but not always, and the flesh of the pear generally has a more gritty texture than that of apple.
||The map provided is intended to provide information only about the documented presence of the common apple in the wild and not the presence of apple per se, for the “species” is grown over much of the U.S. and southern Canada, in at least home gardens. You will notice that the map is labeled Malus pumila and not M. domestica. This is because the reference from which the map was generated considers M. domestica to be a synonym for M. pumila. Common apple generally does better in more northern than southern climates because it usually requires the prolonged cold period provided by winter for flowering to occur in the spring. The main commercial apple production in the U.S. is located in Washington, Michigan and New York (in order of descending importance). In Canada, the main commercial producing province is Ontario followed by British Columbia, Quebec, Nova Scotia and New Brunswick. Interestingly, the largest national producer of apples is China, followed by the U. S. Blooming period: Common apple generally blooms in the early spring after the other
deciduous tree fruits have bloomed. In Michigan this usually occurs in late April and early May.
||While apple in generally considered to be a better nectar producer than most other deciduous tree fruits, the “species” has several things working against it as a major honey producer. These include its short blooming period, which can be as little as only a few days, and the frequently inclement weather during its blooming period. While at times, perhaps one out of five seasons, apple produces a surplus (see below), most beekeepers agree that the main benefit of the species to the beekeeping industry, excluding commercial pollination of course, is in its spring stimulation of brood rearing.
||Crane supplies the following data concerning honey potential.
Nectar secretion 1.3-7.09 mg/fl/day
Sugar secretion: 0.596-3.0 mg/fl/day
Honey yield: 2.9-8 lbs /colony/day; 80 lbs/colony/season. These values, while they represent actual yields, were considered exceptional. The original data for this report apparently came from Lovell) and was provided by beekeepers in Maine and British Columbia respectively.
In addition to the above yield data, Crane also provides honey potential data that presumably are based on floral sampling and nectar analysis. In this case, the reported range is 17.7-37.4 lbs/acre.
Pellett provides yield data from an 1883 report of hive weight gains of 36 lbs in ten days and 10 to 15 lbs per day on exceptional days.
||Crane reports a apple honey Pfund rating of amber, and that the honey has the aroma of apples.
||Crane supplies ratings for pollen production that represent the full spread of her three point pollen rating scale indicating that in importance, it can range from being only a minor source to being a major pollen source. She also provides the information that the pollen load is pale yellow with sometimes a hint of a greenish tint.
||Pollination considerations for apple
Most apple cultivars require cross pollination and even ones that are partially self-fruitful are benefited significantly by cross pollination. While cross-incompatibility is relatively rare between cultivars, triploids , for example ‘Winesap’, ‘Mutsu’ and ‘Jonagold’ are not effective pollinators of diploid varieties. Color and spur strains (reds, double reds etc.) of the same variety are incompatible. Of course, the pollinator variety should flower at the same time as the main variety every year.
Trend toward smaller trees
There has been a movement from planting large “standard” trees to planting trees on dwarfing and semi-dwarfing root stock that causes the tree to be smaller, in some cases (dwarfing rootstock), much smaller. Not only are these trees easier to manage (harvest, prune and spray, for example), the yield per acre is potentially considerably larger than for standard trees. This increased yield translates into the need for more pollination, and pollination recommendations for different planting densities and designs logically might well be different. Where dwarf trees are grown, they are often grown as supported “hedgerows”. In these cases, the pollinizer variety is usually one or more varieties of dwarfed crabapple that are severely pruned so they take up as little space as possible. They generally are planted at intervals in every hedgerow to take advantage of the bee’s tendency to work among the blossoms within a row rather than fly through open space to another row.
Pollination recommendations for apple
While one hive per acre is often given as a pollination recommendation, a recent treatise on apple recommends four hives per acre distributed throughout the planting. Here the philosophy is that weather conditions during pollination are often inclement, and trees that are over-pollinated can easily have apples removed with appropriate chemical applications, but apples cannot be put on poorly pollinated trees. Be sure also to read the pollination discussion that is presented in the accompanying sidebar that discusses pollination considerations that are generally applicable to the deciduous rosaceous tree fruits.
Solitary bees as pollinators
Much work has been done using solitary and other native bees as pollinators. Bees in the genera Osmia, Andrena, Halictus and Bombus are the most often mentioned. The rationale for considering and even relying on these organisms is based on several premises. First, because these insects do not overwinter as large colonies and, therefore, do not need to provide winter stores, they have less interest in nectar than do honey bees. Their main interest is in pollen to feed their developing brood. When it comes to harvesting nectar, honey bees are renowned for their efficiency. As an example, honey bees have frequently been noted standing on a petal and reaching through the stamens to the nectar with their tongue rather than using the less efficient method of reaching down through the “canopy of anthers and stigmas” to reach the nectar. This more efficient foraging behavior is frequently referred to as “sideworking”. Sideworking can result in the removal of the reward the flower offers (nectar) without the bee coming into contact with the stigma to which pollen must be applied if cross pollination is to occur. Because bees are capable of learning, during pollination the incidence of this behavior increases significantly over time. This behavior has been discussed in the literature for many years, especially in connection for the variety ‘Delicious’. In ‘Delicious’ the stamens are not equally spaced around the area of nectar deposition, and the honey bee quickly learns that it is more efficient to obtain nectar through the breaks in the “stamen barricade” than to probe for it through the barrage of anthers and stigmas above. It has been proposed that this behavior at times results in poor pollination of ‘Delicious’. In studies done by DeGrandi-Hoffman et al., however, by the time this sideworking behavior became important, pollination had already occurred and thus tends to throw some doubt on the behavior’s importance at least under the circumstances in which this research was done. The proposed replacement pollinators mentioned above, on the other hand seem to “revel” around over the top of the flower gathering pollen, and in the process, frequently come in contact with the stigma. The second feature that is frequently mentioned about the advantages of these alternative pollinators is that they tend to work in more inclement weather and earlier in the morning and later in the evening than honeybees. Third, the advent of the parasitic mites in North America has greatly spurred interest in the use of these organisms for pollination.
Because of the narrow window of opportunity in which pollination can occur, the trick to using these organisms for pollination will be to get them without fail to emerge from their overwintering state at exactly the right time in large numbers. This has already been accomplished in some cases. Osmia cornifrons, for example, has been used commercially in Japan as a pollinator for many years. While these organisms have some advantages, they are also prone to some of the same problems that occur with honey bees. First, while we often think of these organisms as being wild and therefore unmanaged, just like honey bees these organisms need to be managed if they are to be made available in large numbers at pollination time. Because of the heavy pesticide loads that most commercial orchards receive, the main part of the colony must be maintained outside of the orchard with the yearly foraging force essentially being sacrificed for pollination. While I recognize that honey bees have many pests (parasites, pathogens and predators), I also believe that when we start to raise other pollinators in large numbers they will also acquire more pests. This seems to me to be nature’s way—large concentrated resources are not allowed to remain “uncropped” forever. This has apparently already begun to happen where alternative populations are being managed in large numbers. While these pollinators probably have a use, they seem to me not to be the panacea that some of their proponents seem to claim.
||1 Ayers, G. S. and J.R. Harman. 1992. Bee Forage of North America and the Potential for Planting for Bees. Inventory and Relative Importance of Nectar and Pollen Plants of North America. In The Hive and the Honey Bee, (J. M. Graham Editor). Dadant and Sons. Hamilton, IL.
2 Crane, E. The Flowers Honey Comes From. 1975. In: Honey A Comprehensive Survey (E. Crane Ed.). Crane, Russak and Company, Inc. New York, NY.
3 Crane, E., P. Walker and R. Day. 1984. Directory of Important World Honey Sources. International Bee Research Association. London.
4 DeGrandi-Hoffman, G., R. Hoopingarner and K. Baker. 1984. Pollen transfer in apple orchard:tree-to-tree or bee-to-bee? Bee World 65:126-133.
5 DeGrandi-Hoffman, G., R. Hoopingarner and K. Baker. 1985. The Influence of Honey Bee "Sideworking" Behavior on Cross-pollination and Fruit Set in Apples. HortScience 20(3):397-399.
6 Dennis, F. 2003. Flowering, Pollination and Fruit Set and Development. In: Apples Botany Production and Uses. (Ferree, D. C. and I. J. Warrington. Eds.) CABI Publishing. Cambridge, MA.
7 Dirr, M. A. 1998. Manual of Woody Landscape Plants. Their Identification, Ornamental Characteristics, Culture, Propagation and Uses (Fifth Edition). Stipes Publishing L.L.C. Champaign, IL.
8 Free, J. 1993. Insect Pollination of Crops. Academic Press Limited. London
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10 Lovell, H. B. 1966. Honey Plants Manual. A Practical Field Handbook for Identifying honey Flora. A. I. Root Co. Medina, OH.
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12 McGregor, S. E. 1976. Insect Pollination of Cultivated Crop Plants. Agricultural Handbook No 496, Agricultural Research Service. United States Department of Agriculture. Washington DC. This publication is being updated and is available on the web at: gears.tucson.ars.ag.gov/book.
13 Nyéki, J. M. Soltész. 1996. Floral Biology of Temperate Zone Fruit Trees and Small Fruits. Akadémiai Kiadó, Budapest.
14 Pellett, F. C. 1978. American Honey Plants. Dadant and Sons, Hamilton, IL.
15 Ramsay, J. 1987. Plants for Beekeeping in Canada and the Northern USA: A Directory of Nectar and Pollen Sources Found in Canada and the Northern USA. International Bee Research Association. London.
16 Roberts, J. The Origins of Fruit and Vegetables. Universe Publishing. New York.
17 USDA, NRCS. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA
18 Wyman, D. 1997. Wyman's Gardening Encyclopedia. Scribner, New York, NY.