Armillaria root rot, also known as shoestring root rot, is a soilborne disease that can affect several fruit crops, but 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 …
What is black pox, and how do I identify and manage the disease?
Black pox is a fungus disease caused by Helminthosporium papulosum. It is considered to be of minor economic importance. When it occurs, the disease can affect apple bark, fruit, and foliage. It is more common from southern Virginia southward than in the northern mid-Atlantic region. The same fungus causes blister canker on pear. For more information, read this article on Black Pox of Apple.
Answer provided by Alan R. Biggs, West Virginia University.…
What is black root rot (dead man’s fingers), and how do I identify and manage the disease?
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 being more common in the southern Appalachian states, and the latter more common in the eastern …
What is Nectria canker, and how do I identify and manage the disease on apple trees?
Nectria canker is a fungus disease caused by Nectria galligena. It is occasionally found on apple nursery stock shipped into the eastern United States. The economic effects of the disease in the eastern United States are minor. 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 cankers. Eventually the cankers girdle the tree, resulting in a dieback of infected limbs …
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 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, …
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 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 …
Are there restrictions to grafting my own apple trees?
Some cultivars of apple are under patent. If the patent is still applicable, then you must contact the nursery (or whoever holds the patent) and pay the royalty for each tree you propagate. Failure to do so could lead to criminal penalties, a monetary judgment (and/or fine), and destruction of the trees you propagated. Apple cultivars that are part of an exclusive club or licensing agreement are also illegal to propagate, and there usually is no avenue for a “non-club …
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 …