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Conidiophores solitary, fasciculate, or forming loose synnemata 12-45 µm wide, unbranched, septate, smooth, pale-brown to brown, (60-)120-240 x 4.5-7 µm, usually arising from a dark stroma, 30-60 µm diameter.

Recoginition

The lower sides of leaves should be examined for the dark sporulation of the fungus in grey to brown sunken lesions with yellow halos;the lesions are also visible from the upper surface (Kuate, 1998). Mature fruits also bear sunken brown lesions with a yellow halo, with sporulation occurring under wet or humid conditions.

Related invasive species

  • Pseudocercospora angolensis

Related Farm Practice

  • Defoliation
  • Light
  • Hosts
Impact

P. angolensis is a dematiaceous hyphomycete occurring in sub-Saharan Africa and Yemen. This fungus requires moisture for infection and the production of wind-borne conidia and causes a devastating fruit and leaf spot disease of cultivated species of Citrus. Losses of 50-100% of yield can occur and growers may cease production where the disease is endemic. Although species and cultivars of Citrus vary in susceptibility, no source of resistance is known (Kuate, 1998). An A1 quarantine pest for Europe and the Mediterranean region (EPPO, 2009), this fungus is also of concern for other warm humid regions where citrus is grown, such as Florida, USA. Other than by wind, conidia can be transported on infected fruit or propagated material.

Has Cabi datasheet ID
12184
Symptons

On leaves, the fungus produces circular, mostly solitary spots, which often coalesce, up to 10 mm in diameter, with a light-brown or greyish centre when dormant and non-sporulating during the dry season, but becoming black with sporulation after the onset of the rainy season (Sief and Hillocks, 1993). The lesions are usually surrounded by a dark-brown margin and a prominent yellow halo;occasionally the centre of the lesion falls out, creating a shot-hole effect. At first glance, the young lesions appear similar to those of canker (caused by Xanthomonas campestris pv. citri), but differ in being flat or shrunken. Leaf spots, especially on younger leaves, often coalesce and together cause generalized chlorosis, followed by premature abscission and defoliation of the affected tree. Young leaves and fruit appear to be more susceptible than older mature leaves (Sief and Hillocks, 1999), but whether the leaves or fruit are more affected varies with the host species and variety (Bella-Manga et al., 1999) and location (Derso, 1999).
On fruit, the spots are circular to irregular, discrete or coalescent, and mostly up to 10 mm in diameter. On young fruits, infection often results in hyperplasia, producing raised tumour-like growths surrounded by a yellow halo;these develop central necrosis and collapse (Kuate, 1998). Lesions on mature fruit are normally flat, but sometimes have a slightly sunken brown centre. Diseased fruits ripen prematurely and drop or dry up and remain on the tree (Kuate, 1998). Infection by the fungus seems to predispose the fruit to secondary infection by Colletotrichum gloeosporioides (De Carvalho and Mendes, 1952;Seif and Kungu, 1990);it is common to find a dark-brown to black sunken margin of anthracnose around the fruit spots.
Stem lesions are not frequent and mostly occur as an extension of lesions on the petiole. Occurrence of several such lesions at the stem tip results in dieback;those on other parts of the stem coalesce, become corky, and crack. At the base of the dead stem there is usually a profuse growth of secondary shoots (Menyonga, 1971).

Hosts

All species of cultivated Citrus appear to be susceptible, although the lime (Citrus latifolia) and smooth lemon (Citrus limon) are often reported to be relatively resistant. Of the other members of the Rutaceae in Africa, Citropsis tanakae is known to be infected (Kuate, 1998). The susceptibilities of the many wild Citrus species in Asia (USDA-ARS, 2009) remain unknown.

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