November 13, 2005
From: British Society for Plant Pathology, New Disease Reports, Vol 12 [edited] <http://www.bspp.org.uk/ndr/jan2006/2005-93.asp>

First report of Alternaria tenuissima causing leaf spot and fruit rot on eggplant in India
P Raja, AV Ramana Reddy, US Allam, Department of Plant Pathology, Agricultural College, Bapatla-522 10, Andhra Pradesh, India. Accepted for publication 11 Oct 2005.

A leaf spot disease of eggplant (_Solanum melongena_) was observed during 1997-2000 in Guntur district Andhra Pradesh, India. The symptoms recorded were small, circular, brown necrotic spots all over the foliage. The spots
gradually enlarged in size and later became irregular in shape or remained circular with concentric rings or zones. In the later stage of infection, these spots coalesced, resulting in withering, extensive drying and leaf  shedding. On fruit, the symptoms started as small concentric dark brown sunken spots, which coalesced and covered the entire surface of the fruit. Affected fruit rotted completely, causing severe yield losses.

The causal agent of this disease was successfully isolated on potato dextrose agar (PDA) from diseased leaves and fruits. After 4 to 5 days of incubation at 26 C with a 12 hour photoperiod, the fungus produced colonies which were regular and flat, with a rough upper surface. The periphery of the colony was olive-green, with a black center and dull white spots. The growth of the fungus was smooth. The conidiophores were short, arising singly, measuring 81.6 to 163.2 mm in length and were 4.08 to 8.16 mm thick. The size of the conidia varied from 26 to 48.75 mm in length and 9.75 to 16.27 mm in width, with an average beak length of 9.58 mm. Horizontal and vertical septations of conidia varied from 1 to 6 and 0 to 2, respectively.

On the basis of the morphological characteristics of the conidiophores and conidia, the pathogen was identified as _Alternaria tenuissima_. The culture was sent to the Indian type culture collection, located at the Indian Agricultural Research Institute in New Delhi, where its identity was confirmed.

Pathogenicity tests were conducted on 60 day old eggplants (cv. Bapatla Local) by spraying with a spore suspension (500 000 spores per ml) using an atomizer in the late evening. Inoculated plants were covered with a
polythene bag and incubated at 26 C with a 14 hour photoperiod. 30 days after inoculation, the symptoms were similar to those previously observed.

The fungus was consistently re-isolated from the inoculated plants. At the same time, control leaves, sprayed with distilled water, did not develop any symptoms. _A. tenuissima_ is a cosmopolitan fungus already identified in India on several hosts - for example, taro _Colocasia esculenta_, pigeon pea _Cajanus cajan_, and _Ipomoea carnea_.

This is the 1st record of _A. tenuissima_ on eggplant in India.

References:
Solankure RT, Rao VG. Alternaria leaf spot of taro from India. Indian Phytopathology 1972; 25: 457-9.
Kannaiyan J, Nene YL. Alternaria leaf spot of pigeon pea. Tropical Grain Legume Bulletin 1977; 9: 34.
Reddy MN, Rao AS. A new leaf spot disease of _Ipomoea carnea_ Jacq. Current Science 1975; 44: 367.

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[The is the 1st report of this disease in India. The interval between completion of the work and its submission seems inordinately long, but I am overlooking that because the piece involves a 1st report of the disease,
which is worthy of record.

Link: <http://www.bspp.org.uk/ndr/jan2006/2005-93.asp> - Mod.DH]