July 24, 2005
Source: Minda News, Mindanao, 21 Jul 2005 [edited] <http://www.mindanews.com/2005/07/20nws-kamatis.html>


Tomato leaf curl virus (ToLCV) threatens tomato industry in The Philippines

Mindanao's tomato industry is reportedly being threatened by the continuing spread of a plant virus that has been destroying tomato farms in several parts of the island, a government horticultural scientist said.

Dr. Agapito Cabalquinto, a horticulturist of the state-owned University of Southern Mindanao, said tomato production in several parts of northern and central Mindanao has declined over the last 2 years due to infection by Tomato leaf curl virus (ToLCV). According to Cabalquinto, this is a big problem because ToLCV is systemic in infected tomato plants and once virus symptoms appear, there is no other choice but to destroy them.

Cabalquinto said the ToLCV infection, which reportedly first emerged in several tomato farms in the country more than 2 years ago, is expressed mainly by curling of tomato leaves. He said plants which were hit by the virus no longer have the capacity to bear fruits. On average, this virus could wipe out at least 20 to 30 percent of tomato plants per hectare he said.

Diseased plants were recorded on tomato farms hit by ToLCV in Claveria town in Misamis Oriental in Northern Mindanao. According to the Department of Agriculture, Northern Mindanao is the 2nd major producer of tomato in the country, accounting for 13.80 percent of the country's average annual production of over 150 000 metric tons. The area also comprises 9.44 percent of the more than 16 000 hectares of tomato farms in the country. But Cabalquinto said some farmers based in the province, especially those from Polomolok and Tampakan towns, have also complained about ToLCV.

A tomato producer from Tampakan said the tomatoes they planted recently using certified seeds have showed signs of the virus. "This shows that the virus has been spreading mainly through the seeds that had been infected," he said.

Cabalquinto said there is ongoing research about measures to control spread using ToLCV-resistant tomato cultivars. The Agricultural Biotechnology Support Project II, an initiative of Cornell University in the United States, has been developing a multiple virus-resistant tomato for the Philippines and Indonesia.

The project aims to combine near-market transgenic technologies for Cucumber mosaic cucomovirus with conventional resistance against ToLCV to produce commercial tomato varieties with multiple virus resistance within 5 to 7 years. According to Cabalquinto, the project seeks to assist Indonesian and Philippine organizations in gaining regulatory approval, licensing the needed intellectual property, testing the efficacy of resistance against local virus strains, incorporating the transgenic resistance into local varieties, and combining that with resistance to the other viruses to generate commercial multiple-virus-resistant tomato seeds. ToLCV-resistant lines of tomato against ToLCV have reportedly been developed and initial efficacy trials of these resistant lines in Taiwan,
Southern India, and Thailand have showed promising results.

[Byline: Allen V. Esrabillo ]

--
ProMED-mail
<promed@promedmail.org>

[ToLCV is a begomovirus that is mostly restricted to greenhouse tomato production. The virus is vectored by 4 whitefly species: the sweet potato, silverleaf, cotton and greenhouse species. Under Florida conditions,
disease onset appears to occur during the short day-length period of late December-February. No fruit abnormalities have been observed but fruit size and number appear to be reduced by virus infection.

Disease management involves planting virus-free tomato transplants in a whitefly-free production site. Measures to restrict whiteflies include use of tight screens in greenhouse facilities to prevent entry of whiteflies from the field; this can dramatically reduce virus incidence but will seriously limit cooling capabilities, unless houses are structurally redesigned. Judicious vector control using legally available insecticides will slow disease onset and reduce disease severity. Although ToLCV can cause severe crop losses in fresh market and glasshouse-produced tomatoes, damage is generally minor. It also infects several other food crops monitored by ProMED-Plant such as lettuce (_Lactuca sativa_) and potato (_Solanum tuberosum_).

Link:
<http://edis.ifas.ufl.edu/PG059>
- Mod.DH]

[see also in the archive:
Tomato chlorosis, tomato - France (Reunion Island): 1st report 20050605.1566 2004
Tomato chlorosis virus, tomato - Israel:1st report 20041019.2834 2003
Tomato and cucurbit viruses - France 20030503.1107

2002
Tomato chlorosis virus - Morocco 20020731.4904
Tomato criniviruses, detection - Greece 20021130.5939

2001
Tomato chlorosis crinivirus disease - Puerto Rico 20010324.0588 Tomato chlorosis crinivirus - Puerto Rico 20010515.0942 2000
Tomato chlorosis crinivirus - Portugal: EPPO report 20001129.2080 1999
Tomato chlorosis virus, new - USA 19990125.0120]