Apple rootstocks have traditionally been divided into three groups: standard, semi-dwarf, and dwarf.
A standard size tree refers to trees growing on seedling rootstock. If trees on seedling rootstocks are not pruned to limit tree size, the trees will reach a height of about 30 feet and have a crown diameter of about 30 feet. Orchards planted before the 1960s often had only 40 trees per acre and were spaced 40 feet by 40 feet. With good pruning, standard size …
Nectria canker is a fungus disease caused by Nectria galligena. Occasionally, it is found on apple nursery stock shipped into the eastern United States; however, the economic effects of the disease in the region are minor.
| Figure 1. Nectria cankers on trunk of ‘Delicious’ apple. Photo: Alan L. Jones, Michigan State University. |
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The fungus grows deep into the wood and kills new wound callus as it develops. This annual killing of successive layers of callus results in perennial, target-like, zonate …
Strong wind, especially wind associated with tropical storms that saturate the soil, can cause fruit trees to lean and sometimes be totally uprooted. Due to small and brittle root systems, dwarfing rootstocks tend to be prone to wind damage.
Susceptibility to wind damage appears to be related to the combination of rootstock and scion cultivar. Some brittle cultivars, such as ‘Gala’ and ‘Golden Delicious’, when propagated on brittle rootstocks, such as G.30 or M.26, may snap at the bud union. …
Sooty blotch and flyspeck are surface blemish diseases caused by fungi that commonly appear together on apple or pear in late summer and fall. Although these diseases may shorten the storage life of fruit due to increased water loss, they do not cause decay, and losses are attributed to unacceptable appearance. During wet growing seasons, losses of 25% or higher commonly occur, even in orchards treated with fungicides. Many fungi are involved in this complex of pathogens, including Peltaster fructicola, …
Tree death or decline may be caused by several factors. For new trees, roots can dry out or freeze during shipping, or after shipment or purchase, they can become desiccated if not planted, healed-in, or watered immediately. In this case, trees generally fail to produce any new growth or develop only a few leaves and subsequently collapse. Lack of water after planting, usually greater in areas with higher soil temperatures during the growing season, will result in foliar wilting and/or …
Order trees from a nursery as far in advance as possible, and research the choices before placing your order.
Nurseries become overloaded in late winter with last-minute orders. They may not be able to get your trees to you until it is too late to plant. Ordering early will also give you a better choice of cultivars and rootstocks.
Some nurseries will custom bud or graft a particular cultivar from your orchard …
Please note: With the proper guidelines, rootstocks, equipment, and practice, most people can successfully bud or graft apples. However, due to patenting restrictions, it may be illegal to propagate some cultivars without paying the royalty fee. Many nursery catalogs list whether a cultivar is still in patent and how much the royalty fee is. Cultivars that are trademarked, licensed, or “clubbed” are not legal to propagate.
Because the seeds (sexual propagation) produced by apple fruits are the result …
Dwarf apple tree supported by single wire and conduit with wooden posts no more than 50 ft. apart within the row. Photo: Jon Clements, University of Massachusetts Amherst. |
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When propagated on dwarfing rootstocks, most apple cultivars will lean or fall over as they start to fruit. Trees on dwarfing rootstocks tend to produce heavy crops relative to the size of the tree, and the tree cannot support the weight of the crop. Many dwarf rootstocks also produce relatively shallow, brittle …
White-tailed deer in the eastern United States are one of the leading causes of damage to crops, including many perennial crops such as apples (figs. 1, 2). Deer feed on dormant shoots as well as growing trees. Much research has gone into controlling deer by excluding them from orchards using fencing; frightening them with loud sounds; repelling them through different compounds, some as common as soap; and reducing the herd through contraception and, as a last resort, hunting.
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Burr knots are root initials that appear on the aboveground portion of the apple tree trunk. Some rootstocks, such as M.7, M.9, M.26, MM.106, and MM.111, are more prone to developing burr knots than others. Conditions that favor burr knot development include low light, high humidity, and temperatures between 68°F and 95°F.
Burr knots are problematic in a couple of ways. They can be an entry point for organisms, such as dogwood and plum borers, woolly apple aphids, fire blight …