Diseases on Citrus Trees

Citrus trees require a well-balanced regimen for abundant fruit production. These trees require well-drained soils, abundant irrigation and plenty of sun for the best results. Still, citrus trees are susceptible to several diseases, even when they are well cared for and experience vigorous growth. Addressing the citrus tree diseases immediately will provide you with a greater opportunity of saving your tree and its fruit.

Greasy Spot

Greasy spot is a fungal disease that is spread by fungal spores. These fungal spores develop on the defoliated debris that lies around the citrus tree. The spores are transported by wind and rain during the warm, rainy days of spring. Once the fungal spores reach the tree, the spores infect the tree through its lower lying stomata, as explained by the University of Florida Cooperative Extension. Infected trees initially develop yellow spots on its foliage. As the disease progresses, the yellow spots begin to brown. The browning then collapses and dies from the infection. The fruit of the infected citrus develops small pin-sized black specks within its oil glands. Progression of the disease causes these spots to coalesce on the fruit, which produces the appearance of greasy-like spots across the surface of the fruit. Greasy spot is treated and prevented with a regular schedule of fungicidal treatments and oil sprays.

Citrus Scab

Citrus scab is a fungal disease that is especially problematic to lemon, tangelo and grapefruit trees, as explained by the University of Florida Cooperative Extension. This fungal disease depends heavily on settling water for successful germination. Citrus scab infects the foliage, twigs and fruit of young trees. Though the foliage quickly develops immunity to the disease, fruit can be susceptible for as long as two months after its initial development. The foliage of infected trees develops scab-like tissue and becomes distorted and crinkled. Infected fruit develops white to yellow colored fungal lesions and masses that quickly cover the rinds of the fruit. Severely infected citrus trees also experience growth stunt and dieback. Infected areas must be pruned and properly discarded to reduce the potential of spread and cross contamination. Fungicidal treatments are also effective in controlling the disease when combined with your pruning schedule.

Phytophthora Root Rot

Phythophthora root rot is a soil-borne fungal disease that attacks the root system of the citrus tree. This disease, also known as foot rot, begins germination after long periods of standing water and moist soil conditions. This rotting disease infects the fine, feeder roots of the root system and destroys the tissue and roots of the system. The root system becomes water-soaked and unable to pass nutrients and water throughout the tree. This lack of transport results in the citrus tree's symptoms that include wilt, dieback, growth stunt, premature defoliation and fruit drop. There are no cures for Phytophthora root rot and infected trees should be removed and destroyed. Maintaining a well-drained environment, selecting disease free planting locations and providing regular fungicidal treatments can prevent this disease.

Keywords: citrus greasy spot, phytophthora root rot, citrus scab

About this Author

Charmayne Smith is a business professional and freelance writer. She has worked in management for successful organizations since 1994. Smith draws on her business background to write articles, and her work has appeared in a variety of online outlets. She holds a degree in business from Cleveland State University.