This tool is part of the Citrus Resource

Citrus Diseases

 

Sweet orange scab

 

Scientific name

 

[Fungus] Elsinoe australis Bitancourt and Jenk.

Anamorph Sphaceloma australis Bitancourt and Jenk.

Disease cycle

 

Sweet orange scab forms spores on the surface of the scab pustules. This species of scab attacks mainly fruits. The conidia (asexual spores) are similar to those of E. fawcettii, require moisture for spore production and are primarily spread by splashing rain. Fruits are susceptible for 6 to 8 weeks after petal fall. The role of ascospores (sexual spores) is uncertain.

Symptoms

 

Sweet orange scab does not usually form lesions on leaves or twigs in contrast to the more common Citrus scab.

Fruit- the rinds of young fruit display relatively large flat or warty outgrowths (windscar) which vary in color from a light pink to a grayish-brown with age. Sweet orange scab lesions are flatter than those produced by E. fawcettii (Citrus scab).

Host range

 

Grapefruit, sweet orange, lemon, and tangerine cultivars.

Distribution

 

Rio Grande Valley-Texas, Arizona, Florida, Brazil, Argentina, Bolivia, and Uruguay.

Easily confused with

 

Citrus scab (Elsinoe fawcettii)

Negative Images

 

Below are fruit and leaf lesion on various Citrus spp. that either tested negative for sweet orange scab or the test results were inconclusive. These lesions look very much alike the lesions that tested positive for SOS.

 

Citrus Diseases
March, 2013
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