First Report of Alternaria Brown Spot of Minneola Tangelo in Turkey

Abstract

Minneola tangelo, a hybrid of Dancy tangerine and Duncan grapefruit, is widely grown in Turkey for export to Europe. In 1995, 2,000 ha of diseased Minneola tangelo trees were observed in the Cukurova region. Ninety percent of orchards in this region were diseased but disease severity depended upon the location and the disease control strategies employed in each orchard. Symptoms were typical of Alternaria brown spot (1). Fruit symptoms included light brown, slightly depressed spots to circular and dark brown areas on the external surface. On leaves, symptoms ranged from small brown circular spots to irregular blighted areas with characteristic yellow halos. The apices of some young shoots were defoliated. Infected young fruit and leaves often dropped from the tree and the mature fruit were unmarketable due to lesions on the fruit. Alternaria was consistently isolated from diseased leaves and fruit on potato dextrose agar and produced dark brown mycelia and pigmented septate conidia similar to those described previously (1). Detached immature Minneola leaves were inoculated with aqueous conidial suspensions of 15 isolates and maintained in a chamber at near 100% relative humidity for 3 days at 26°C. Thirteen of these isolates caused necrotic lesions on the leaves similar to those observed in the field, i.e., dark, necrotic spots with necrosis extending outward on some veins. Alternaria was reisolated from all infected leaves. This is the first report of Alternaria brown spot of Minneola tangelo in Turkey. Reference: (1) Z. Solel. Plant Pathol. 40:145, 1991.

Molecular, ecological and evolutionary approaches to understanding Alternaria diseases of citrus

“…In much of the Mediterranean area, rains are rare after flowering and fruit set. Nevertheless, prolonged dews apparently provide sufficient moisture to allow infection (Canihos et al ., 1997; Solel, 1991). Manipulation of some cultural practices can help to reduce brown spot severity.…”

“…Alternaria brown spot disease was first reported on Emperor mandarin in Australia in 1903 (Cobb, 1903) and the causal agent was identified as a species of Alternaria in 1959, after a number of organisms had been investigated as possible pathogens (Kiely, 1964; Pegg, 1966). The disease later appeared in the USA (Whiteside, 1976), and now occurs in Israel (Solel, 1991), South Africa (Schutte et al ., 1992), Turkey (Canihos et al ., 1997), Spain (Vicent et al ., 2000), Brazil and Argentina (Peres et al ., 2003). Due to the morphological similarity between the brown spot and black rot pathogens, the former was identified as A. citri Ellis & Pierce (Pegg, 1966; Whiteside, 1976), a fungus that had been first described as the cause of citrus black rot.…”

Population Genetic Structure and Host Specificity of Alternaria spp. Causing Brown Spot of Minneola Tangelo and Rough Lemon in Florida

“…Brown spot of citrus occurs in most citrus-producing regions of the world and is a serious problem on many tangerines, tangors, and tangelos grown for the fresh market. MIN is particularly susceptible, and brown spot is very difficult to control on this cultivar in Florida (50), Turkey (6), Israel (46), South Africa (38), and Colombia (7).…”

Diversity among Isolates of the Tangerine Pathotype of <i>Alternaria alternata</i>

“…(mainly Alternaria alternata) are important diseases with worldwide distributions. They have been documented in the USA [1], Turkey [2], Spain [3], Argentina, Brazil [4], China [5] and Iran [6]. Different diseases caused by Alternaria spp.…”