Mal secco disease caused by <i>Phoma tracheiphila</i>: a potential threat to lemon production worldwide

Abstract

Lemon (Citrus limon (L.) Burm. f) is the most popular acid citrus fruit because of its appealing color, odor, and flavor. World production of lemons was about 7 to 8 million metric tons in 2007. Major producers and exporters of lemon in the world include Argentina, Spain, Iran, the United States, Italy, Turkey, Egypt, Greece, South Africa, Cyprus, Morocco, and Israel (www.cga.co.za). Argentina and Italy are major suppliers of lemon juice, and Spain, Argentina, Turkey, the United States, South Africa, Italy, Chile, Egypt, Uruguay, India, Jordan, Cyprus, China, and Iran are the leading exporting countries of fresh fruit. Mal secco of citrus is a highly destructive vascular disease of lemon, presently confined to the Mediterranean basin, which has a relevant economic impact on the lemon industry in this geographic region. Mal secco is caused by the mitosporic fungus Phoma tracheiphila (Petri) Kantschaveli &amp; Gikachvili (syn. Deuterophoma tracheiphila Petri). The name of the disease stems from the Italian words male (disease) and secco (dry). The term “malsecco,” referring to nonspecific symptoms, was initially used in a broad sense to indicate citrus diseases of various origins. Later, Petri used the term “mal secco of citrus” in a more strict sense to indicate the tracheomycotic disease that was spreading in lemon orchards in Sicily. Mal secco first appeared affecting lemon trees on the islands of Chios and Poros (Greece) near the end of the nineteenth century. In 1929, Petri described the fungus causing mal secco as a new species and named it Deuterophoma tracheiphila, which he proposed as the type-species of the new genus DeuterophomaPetri. The species was transferred to Phoma by Kantschaveli and Gikachvili in 1948. Later, Ciccarone and Russo and Ciccarone, who amended the description of the fungus, confirmed this binomial as the correct name