Nectria twig blight is a fungus disease that results in dieback of apple twigs. It is caused by the fungus Nectria cinnabarina.
Recognition of the disease is important because the disease is often confused with fire blight, which requires different control measures. In late May to early June, shoot growth on infected twigs begins to wilt and die (fig. 1). Small, sunken cankers are found at the bases of the wilted shoots. Leaves on infected shoots appear to die from …
Powdery mildew on apple is a fungus disease caused by Podosphaera leucotricha. It can be a persistent disease of susceptible apple cultivars wherever apples are grown. It is the only fungal apple disease that is capable of infecting without wetting from rain or dew. Mildew severity and the need for control measures are related to cultivar susceptibility and intended fruit market. (Note: Many other powdery species occur on a wide variety of plant hosts.)
Powdery mildew causes whitish lesions on …
The dogwood borer, Syanthedon scitula (Harris) (fig. 1), is from the Family Sesiidae, the family of clearwing moths. Adult clearwings are colorful, day-flying moths that bear close resemblance to wasps. Although they cannot sting, this mimicry no doubt protects them from birds and other predators. They live in all parts of the United States east of the Rocky Mountains.
| Figure 1. Adult dogwood borer moth. Photo: Henry W. Hogmire, Jr., West Virginia University. |
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The dogwood borer has been considered an …
Powdery mildew on apple is a fungus disease caused by Podosphaera leucotricha. It can be a persistent disease of susceptible apple cultivars wherever apples are grown. It is the only fungal apple disease that is capable of infecting without wetting from rain or dew. Mildew severity and the need for control measures are related to cultivar susceptibility and intended fruit market. The table below lists the relative powdery mildew susceptibility of numerous apple cultivars.
| Apple cultivar | Powdery mildew susceptibility rating |
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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 …
