Tag: apples

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Red Color Development in Apple Fruit

A key quality attribute of apple fruit is its peel or skin color, which affects consumer preferences. Immature fruits are green, and as the fruit ripens the green may fade partially or completely, resulting in very pale cream to green background colors. Red cultivars result from a superimposed accumulation of the red pigment anthocyanin. Anthocyanin accumulation in apple fruit can be affected by environmental, nutritional, and orchard management factors, the stage of maturity of the fruit, and by the microenvironment …

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Apple Rootstock Info: M.9

Characteristic Detail Description
Rootstock M.9

The pedigree is unknown and it was selected in England from a group of French genotypes known collectively as “Juane de Metz” in the late 1800s. M.9 is the most widely planted dwarf apple rootstock in the world and at least 30% of the trees in the U.S. are on M.9. M.9 EMLA is free of known viruses and is slightly more vigorous than the original M.9. Over the years European nurseries have selected clones

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Apple Skin Russetting

Apple skin russet is light brown in color and rough to the touch. Russetting may be limited to small areas of the fruit or may cover nearly the entire fruit. During early-season, cells in the waxy layer, known as the cuticle, are not expand adequately as internal fruit tissues grow and very small cracks may develop in the fruit skin. Cells under the cracks die and cork cells form. Cultivars with thin cuticles are most likely to russet. Most cultivars …

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Apple Maggot


Figure 1. Adult apple maggot Rhagoletis pomonella (Walsh). (Joseph Berger, Bugwood.org)

Apple maggot (Rhagoletis pomonella (Walsh)) is a potentially serious pest of many types of fruit trees. Preferred hosts for apple maggot are apple, especially early maturing and sweet varieties, and the native hawthorns (Crataegus spp.).  In addition, apple maggot will attack apricot, cherry, sweet cherry, sour cherry, crab apple, cotoneaster, flowering dogwood, mountain ash, plum, peach, pear, roses, and serviceberries.

The adult fly (Fig. 1) is …

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Apple Fruit Cracking

Fruit of some apple cultivars tend to crack during the second half of the growing season. Sometimes cracking is limited to the stem end, and other times, the skin will split on other areas of the fruit surface. Cracking occurs most frequently during periods of high humidity following rains. Absorption of rain water through the skin, combined with the uptake of water from the roots, results in rapid enlargement of cells within the fruit. The internal pressure from the enlarged …

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Bitter Pit and Calcium Deficiencies in Apple Fruit

Calcium deficiencies contribute to certain fruit disorders in apple, including bitter pit.  Bitter pit is a physiological disorder of apple fruit that has caused serious losses in certain apple varieties for many years. The visible signs may be only slight indentations in the skin with no change in color. The skin over these depressions usually takes on a deeper green color than the surrounding skin, and finally, the disorder appears as small, brown, desiccated pits. The pits may be few …

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What causes my apple and pear trees to look like they have been burned with a torch?

A disease called fire blight, caused by a bacterium (Erwinia amylovora), has these symptoms. The causal bacteria are spread by wind-blown rain and insects. Fire blight is difficult to control in highly susceptible varieties. Avoid excessive nitrogen fertilizer. The blighted shoots and blossoms can be pruned out as they appear if you sanitize the pruning shears by dipping them in a 10 percent bleach solution or 70% isopropyl alcohol (rubbing alcohol) between cuts. Otherwise, prune the blighted shoots …

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Tarnished Plant Bug

The tarnished plant bug, Lygus lineolaris (Hemiptera: Miridae), is found in agricultural and disturbed areas throughout the United States. It has one of the broadest host ranges of any insect pest, feeding on 385 plants, 75 of which are economically important crops.  Tarnished plant bug has reached key economic pest status in several crops, including strawberry and cotton, and can be responsible for significantly reducing yields in apple.

BIOLOGY


Tarnished plant bug adult (Russ Ottens, University of Georgia, Bugwood.org )

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Apple Rootstocks: Understanding and Choosing the Right Rootstock

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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, …

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