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Grapefruit Tree Diseases

grapefruit for sale image by David Levinson from Fotolia.com

A ubiquitous part of breakfast, the grapefruit (Citrus x paradisi) possesses a bitter to bittersweet flavor. The sweetest fruit is produced in climates with hot days and warm or hot nights. Grapefruits are evergreen and have short supple thorns. More than 30 viruses or virus-like diseases affect citrus trees, however, including grapefruit trees.

Citrus Tristeza Virus

Citrus Tristeza virus is one of the most damaging diseases that affects grapefruit trees. Symptoms include yellow foliage, cupped leaves, loss of tissue between leaf veins, pitted stems and smaller fruits. If the rootstock becomes infected, the tree will decline and eventually die.

Psorosis

Also known as scaly bark, Psorosis is a virus or virus-like disease that occurs mainly in grapefruit trees. Patches of scaly or peeling bark appear on the branches and twigs of affected trees. As the patches get bigger, the tree suffers stress and becomes less productive.

Sooty Canker

The fungus Hendersonula toruloidea causes sooty canker or limb wilt on grapefruit trees. The fungus enters the tree through an injured area and grows under the bark. The sooty black spores under the bark grow into the sapwood of the tree, causing the foliage to wilt, turn brown and die. Infected branches will die back to the cankered areas.

Rio Grande Gummosis

Rio Grande gummosis is another fungus that attacks injured grapefruit trees. Narrow cracks appear in the bark of affected limbs or trunks. Yellow water-soluble gum oozes from the cracks and forms gum pockets under the bark. The exposed sapwood decays and dies. Rio Grande gummosis can also infect the heartwood of a tree.

Grapefruit Tree Size

The average size of a grapefruit tree is around 25 feet tall, but some trees are known to reach 45 feet tall with age. Most trees are considered moderate growing trees, reaching 20 feet high in 20 years, averaging only 12 inches of yearly growth. Many different types of hardy citrus rootstock are used for grapefruit trees, but the flying dragon rootstock produces the true dwarf size of only 4 to 8 feet tall. Normal dwarf or semi-dwarf grapefruit trees reach 8 to 12 feet high. One dwarf variety is the “Dwarf Redblush” grapefruit tree (Citrus paradisi “Dwarf Redblush”), which grows best in the ground in USDA zones 9 through 10. This 8- to 12-foot-tall evergreen produces red grapefruit with only a few seeds, ripening on the tree in the winter and spring. These trees need plenty of room to expand their large canopies. The canopy spreads out to the width of about 29 feet.

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