Apple union necrosis and decline is caused by tomato ringspot virus, which also causes disease in other fruit trees, small fruits, and many herbaceous plants. Symptoms appear as infected trees reach bearing age. Bud break is often delayed in the spring, and leaves are small and sparse with a dull, pale green color. Terminal shoot growth is reduced, with shortened internodes. Infected trees flower heavily and set large numbers of small, highly colored fruit. Leaf discoloration and leaf drop occur …
What is X-spot, and how do I identify and manage the disease on apple trees?
The names X-spot, X-rot, and Nigrospora spot have been applied to a small, circular, depressed, necrotic spot typically on the calyx end of apple fruit in the mid-Atlantic region. Although uncommon, incidence of X-spot as high as 86% was reported on unprotected ‘Golden Delicious’ and ‘Rome Beauty’ fruit in 1950. Other susceptible cultivars include ‘Jonathan’, ‘Stayman Winesap’, and ‘York Imperial’. A fungus has been associated with X-spot lesions, but the typical lesion symptom has not been duplicated by controlled inoculation, …
Black Root Rot of Apple
Black root rot, also called dead man’s fingers or Xylaria root rot, is occasionally observed on mature apple and cherry trees. Although trees of all ages can be infected, most trees that die from black root rot are at least 10 years old. Black root rot is caused by two species of the fungus Xylaria: X. mail and X. polymorpha, with the former more common in southern Appalachian states and the latter more common in eastern states. The disease …
What are burr knots?
Burr knots are root initials that develop above ground. Rootstocks are selected for their ability to produce roots, but some rootstocks try to produce roots above the ground. The severity of burr knot development differs depending on the variety and region. In several rootstock trials, trees in Virginia tended to produce more burr knots than trees in most other locations. Sometimes several burr knots will coalesce and partially girdle the tree. Burr knots are considered undesirable because they can be …
Armillaria Root Rot of Apple
Armillaria root rot, also known as shoestring root rot, is a soilborne disease that can affect several fruit crops. However, it is most common in the eastern United States on peach and apple trees. Its host range also includes numerous species of deciduous and evergreen trees, shrubs, and woody vines. The greatest prevalence of the disease is in orchards planted on newly cleared land in which the soils are sandy and well-drained. In these locations, pieces of wood invaded by …
How should I choose among dwarfing rootstocks for my apple orchard?
Choosing the best dwarfing rootstock for your orchard will depend on multiple factors. Probably one of the most important is the cultivar that will be propagated on the rootstock. Cultivars vary greatly in vigor, with some being very weak growing (‘Honeycrisp’) compared to others that are very vigorous (‘Cripps Pink’/’Pink Lady’). You should select the cultivar/rootstock combination that will give you the desired tree size for your desired tree density, support system, soil, and management system.
The disease sensitivity of …
I grafted 10 apple trees in the spring and only a few of the grafts started growing. Can I reuse the rootstocks? What kind of grafting can I do now?
If your bench grafts do not take but the rootstock is healthy and growing, you certainly can re-graft them in the same season.
► The earliest option is chip budding and is done as early as late spring to early summer.
1. Remove a “chip” of scion tissue which includes a healthy axillary bud.
2. Remove a chip of comparable size from a healthy section of rootstock.
3. Place the previously crafted chip of scion in the place where the …
What is blister spot, and how do I identify and manage the disease?
Blister spot is a bacterial disease of apple fruit caused by Pseudomonas syringae pv. papulans. This disease is of economic importance mainly on the cultivar ‘Mutsu’ (‘Crispin’) but can be seen on ‘Golden Delicious’ when grown adjacent to ‘Mutsu’. Even though fruit grow to maturity and no detectable yield loss occurs, severe infection results in ugly fruit and greatly reduces fresh market quality. For more information and images, read this article on Blister Spot of Apple.
Answer provided …
How do I determine the spacing between trees on a given rootstock for my apple orchard?
Determining the correct spacing for a rootstock/variety combination in a particular orchard is worth a lot of pre-planting thought and effort. Trees that are planted too close together for their vigor will be a struggle to maintain during every year for the life of the planting. Additionally, the amount and quality of fruit production will decline when inadequate light is available throughout the tree. On the other hand, trees that don’t have enough vigor to fill their spacing will result …
What is Nectria twig blight, and how do I identify and manage the disease?
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 it is often confused with fire blight, which requires different control measures. For more information and images, read this article on Nectria Twig Blight of Apple.
Answer provided by Alan R. Biggs, West Virginia University.…