disease – Apples

August 22, 2019August 22, 2019

Powdery Mildew

Powdery mildew can be a persistent disease of susceptible apple cultivars throughout the United States. It is one of the most predominant diseases in the more arid apple growing areas. It is the only fungal apple disease that is capable of causing infection without wetting from rain or dew.

Powdery mildew causes whitish lesions on curled or longitudinally folded leaves, stunted whitish-gray twig growth evident on dormant shoots, and fruit russeting. Economic damage occurs in the form of aborted blossoms, …

August 22, 2019August 22, 2019

Fire blight

Fire blight is a destructive bacterial disease of apples and pears that kills blossoms, shoots, limbs, and, sometimes, entire trees. The disease is generally common in most apple-growing regions of the US; although, outbreaks are typically very erratic, causing severe losses in some orchards in some years and little or no significant damage in others. This erratic occurrence is attributed to differences in the availability of overwintering inoculum, the specific requirements governing infection, variations in specific local weather conditions, and …

August 22, 2019August 22, 2019

Managing Apple Trees and Orchards: Insects, Diseases, Wildlife and Other Challenges

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August 22, 2019August 22, 2019

Disease Management in Apple Trees and Fruit

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August 22, 2019August 22, 2019

Apple Scab

Apple scab is a fungus disease caused by Venturia inaequalis. It is of major economic importance and, if not controlled, can cause extensive losses (70% or greater) where humid, cool weather occurs during the spring months. Losses result directly from fruit or pedicel infections or indirectly from repeated defoliation, which can reduce tree growth and yield.

Symptoms

Apple scab lesions occur on leaves, petioles, blossoms, sepals, fruit, pedicels, and less frequently, on young shoots and bud scales. The first lesions …

August 22, 2019August 22, 2019

Southern Blight in Apple Trees

Southern blight is a fungus disease caused by Sclerotium rolfsii. The disease is a problem primarily in the Piedmont apple growing region in the southeastern United States. S. rolfsii is a widespread pathogen that affects several hundred plant species. The fungus affects the lower stems and roots of apple trees, killing the bark and girdling the trees. The disease is characterized by the presence of a white, weblike mycelium, which often forms at the bases and on the lower stems …

August 22, 2019August 22, 2019

What is Brooks spot, and how do I identify and manage the disease?

Brooks spot is a fungus disease caused by Mycosphaerella pomi. It is a minor disease that occurs throughout the northeastern and mid-Atlantic apple growing regions of the United States and occasionally as far west as Iowa. Some of the more susceptible common commercial cultivars include ‘Jonathan’, ‘Golden Delicious’, ‘Stayman’, ‘Grimes Golden’, and ‘Rome Beauty’. Read more about Brooks Spot in Apple.

Answer provided by Alan R. Biggs, West Virginia University.…

August 22, 2019August 22, 2019

What apple cultivars are resistant or susceptible 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 leaves and fruit of hawthorn. More information, complete with images and a table of cultivar resistance/susceptibility, can be found in this article, Quince Rust of Apple.

Answer provided by Alan R. Biggs, West Virginia University.…

August 22, 2019August 22, 2019

What apple cultivars are resistant or susceptible to fire blight?

Fire blight is a destructive bacterial disease of apples and pears that kills blossoms, shoots, limbs, and, sometimes, entire trees. The disease is generally common throughout the United States wherever apples are grown. Outbreaks are typically very erratic, causing severe losses in some orchards in some years and little or no significant damage in others. This erratic occurrence is attributed to differences in the availability of overwintering inoculum, the specific requirements governing infection, variations in specific local weather conditions, and …

August 22, 2019August 22, 2019

What apple cultivars are resistant or susceptible to powdery mildew?

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. More information, complete with images and tables of cultivar susceptibility and resistance, is available in this article on …