September 21, 2005
From: British Society for Plant Pathology, New Disease Reports, Vol. 11 [edited] <http://www.bspp.org.uk/ndr/july2005/2005-65.asp>

Black rot in lettuce: a new disease caused by Ceratocystis fimbriata in hydroponic culture in Brazil
BA Halfeld-Vieira, KL Nechet, Embrapa Roraima, BR 174, km 8, Distrito Industrial, CP 133, 69301-970, Boa Vista-RR, Brazil. Accepted for publication 14 Jul 2005.

_Ceratocystis fimbriata_ is a pathogen reported on 31 plant host species representing 14 families. In April 2004, a large hydroponic lettuce greenhouse reported serious losses due to root rot. The Plant Pathology Laboratory of Embrapa Roraima, Brazil, received samples of _Lactuca sativa_ cv. 'Vera' exhibiting black rot symptoms on roots and hypocotyl. White mycelial growth and partly embedded perithecia was observed on the diseased tissue.

A fungus was isolated as greenish colonies on potato dextrose agar (PDA). Perithecia were dark brown, base globose, 140-210 micrometers, ornamented with brown hyphal hairs; neck erect, 650-890 micrometers, ornamented with divergent ostiolar hyphae; width at the base was 23-33 micrometers and at the apex, 15-18 micrometers. Hyaline acospores were hat shaped, 7.3-7.8 x 2.6-4.7 micrometers, surrounded by a gelatinous sheath. The anamorph corresponded to _Chalara_. These characteristics permitted the identification of the fungus as _Ceratocystis fimbriata_ [Cf].

Pathogenicity tests were carried out on wounded and unwounded 35 day old lettuce plants cv. "Baba de verao". A 40 microliter aliquot of the conidial suspension (80 000 conidia per ml) or ascospore suspension (2 masses from
the top of perithecial necks in 40 microliters sterile water) was deposited on the axil of the bottom leaf. Wounding was done by puncturing the leaf axil with a needle tip through the inoculum droplet. Each treatment consisted of 6 plants; there was also a sterile water control. The plants were kept in a humidity chamber for 24 hours after inoculation and then maintained under greenhouse conditions.

Black rot symptoms were observed after 4 days on wounded plants inoculated with conidia or ascospores. Cf was recovered from lesions. No symptoms were observed on unwounded inoculated plants or on controls.

To our knowledge, this is the 1st report of Cf causing disease in lettuce or any other member of the _Asteraceae_.

References:
Baker CJ, Harrington TC, Krauss U, Alfenas AC. Genetic variability and host specialization in the Latin American clade of Ceratocystis fimbriata. Phytopathology 2003; 93: 1274-84.
Upadhyay HP. A monograph of Ceratocystis and Ceratocystiopsis. Athens, USA: University of Georgia Press, 1981.
Wingfield MJ, Seifert KA, Webber JF, editors. Ceratocystis and Ophiostoma: taxonomy, ecology, and pathogenicity. St. Paul, USA: American Phytopathological Society, 1993.
Walker J, Tesoriero L, Pascoe I, Forsberg LI. Basal rot of Syngonium cultivars and the first record of _Ceratocystis fimbriata_ from Australia. Australasian Plant Pathology 1988; 17: 22-3.
Bertus AL. Quarantine interceptions. In: Plant Disease Survey 1986-87. New South Wales Department of Agriculture, 1987.

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[This report appears to be the 1st instance of Cf being reported infecting an agricultural crop. _Ceratocystis fimbriata_ was 1st detected in Place, VIC, Australia in 1987 on _Syngonium_ sp. It has been reported on White
Butterfly, White Knight, White Wings; as being well established in eastern States when 1st detected; common overseas; with taro importation intercepted in quarantine. It was introduced with _Syngonium_ sp., possibly
in tissue cultures, with taro tubers from Fiji. Other diseases include black rot (sweet potato and _Araceae_), _Ficus_ wilt, mango wilt, coffee wilt and canker, xylem stain and canker (Bitternut hickory), and in Sycamore (California, North Carolina and Wisconsin).

The link to the original piece contains all of the text and graphics and is located at the top of the list of links. Link: <http://www.public.iastate.edu/~tcharrin/FimbDis.html> - Mod.DH]