Tag: apple article

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Thread Blight of Apple

Thread blight is a fungus disease caused by Corticium stevensii. Primarily, the disease is a problem in poorly managed orchards in the southeastern United States.

Thread blight symptoms are noticeable in early summer. Leaves wilt and turn brown (fig. 1), usually on the interior or shaded portions of the tree. Dead, curled leaves cling to blighted branches, frequently mid-branch, with unaffected leaves remaining on both sides of the diseased area (fig. 2). In well-managed orchards, the disease usually does not …

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White Rot of Apple

White rot is often referred to as Botryosphaeria rot or Bot rot and is caused by Botryosphaeria dothidea, a serious fungal pathogen of apple wood and fruit. The fungus causing white rot is ubiquitous in nature, occurring on a wide variety of woody plants, including birch, chestnut, peach, and blueberry. The canker phase of the pathogen can cause considerable loss in many parts of the South, Midwest, and Northeast. Fruit rot infection is most common in areas of the southeastern …

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Wood Rots in Apple Trees

Wood-rotting fungi cause losses over longer periods of time than most other apple diseases. Losses result mainly from breakage of branches and trunks due to a decline in the structural integrity of the wood. Fungal pathogens that colonize wood alter its structural integrity through enzymatic digestion of wood cell wall components. Some of the same fungi that cause wood rot can cause dieback as well.

The two most common symptoms of wood rot are the breakage of limbs or main …

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Latent Viruses in Apples

A large number of latent viruses have been identified in apple. More common latent viruses include apple chlorotic leaf spot virus, apple stem pitting virus, and apple stem grooving virus. These viruses also cause diseases in other fruit crops. Apple chlorotic leaf spot virus causes pear ring pattern mosaic and has been found in all pome and stone fruit species. Apple stem pitting virus is the causal agent of pear vein yellows.

As the designation “latent” implies, these viruses are …

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Table of Apple Cultivar Susceptibility to Bitter Rot

 

Bitter rot is a fungus disease that causes fruit rot during the summer and the preharvest period. The bitter rot fungi are almost worldwide in distribution and cause an especially economically important disease in the southern United States. Outbreaks can occur rapidly, and losses can be severe, especially under prolonged warm, wet weather. This table lists the bitter rot susceptibility rating of many popular apple cultivars.

Apple cultivar

Bitter rot
susceptibility ratingz

 Apple cultivar

Bitter rot
susceptibility ratingz

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Table of Apple Cultivar Susceptibility to Quince Rust

 

Quince rust is a fungus disease caused by Gymnosporangium clavipes. The fungus infects fruit, but not leaves, of most apple cultivars. It infects both fruit and leaves of hawthorn. This table lists the quince rust susceptibility of numerous apple cultivars.

Apple cultivar Quince rust
susceptibility ratingz		 Apple cultivar Quince rust
susceptibility ratingz
Ambrosia HS Milton R
Arkansas Black HS Mutsu R
Arlet S Northern Spy R
Baldwin R Orin R
Ben Davis R Paulared R
Braeburn S Pinova
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Apple Root Suckers

Root suckers are apple tree sprouts that emerge from the rootstock. They grow around the base of the tree. The point of origin of the suckers is the root. This makes them distinguishable from water sprouts, which originate from aboveground parts of the tree. Root suckers cause problems for the main tree in three significant ways:

  • They compete with the main tree for water and nutrients.
  • They are a prime feeding site for woolly apple aphids.
  • They are a potential
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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 …

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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 …

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Quince Rust of Apple


Figure 1. Quince rust often forms orange tubes for spore dissemination. Photo: Alan R. Biggs, West Virginia University.Quince rust is a fungus disease caused by Gymnosporangium clavipes. The fungus infects fruit, but not leaves, of most apple cultivars. It infects both leaves and fruit of hawthorn.

Typically, an infection on apple fruit shows up first as a slightly raised purplish area on the calyx end of the fruit. On mature fruit, the lesion is sunken and dark green or purple …

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