In 2022, the Philippines produced an estimated 250,000 tonnes of tomatoes, mostly for domestic consumption, and this is a major source of income for many farmers. Major production areas include northern Mindanao, Ilocos Region, Zamboanga Peninsula, and peri-urban areas around the National Capital Region (NCR), among others. However, virus diseases are a major constraint for tomato production.

An important but often looked aspect of the work of WorldVeg is its support to national agencies in identifying vegetable pests and diseases. And this becomes even more crucial when new or emerging organisms are found for the first time.

Surveys were undertaken in March June 2023, led by Ricardo Oliva, WorldVeg plant pathologist and Yuan-li Chan, alongside Filomena C. Sta. Cruz of the Institute of Weed Science, Entomology and Plant Pathology (IWEP) at the College of Agriculture and Food Science (CAFS), University of the Philippines Los Banos (UPLB). The team made a collection of disease samples from farms in areas with year-round production of tomatoes and other vegetables, in the provinces of Nueva Ecija located in Region III (central Luzon), Laguna and Batangas in Region III (southern Luzon), and Bukidnon in Region X (northern Mindanao).

The team recovered more than 40 samples, including viruses, bacteria, and fungal diseases, that will be characterized in UPLB and WorldVeg headquarters in Taiwan.

Fungal diseases (left) and bacterial diseases (right) in Bukidnon, the Philippines

Tomato leaf curl disease

Crinivirus-like symptoms of interveinal chlorosis observed in Batangas (left), Nueva Ecija (center left) and Bukidnon (right)

This work forms part of a collaborative project ‘Developing a decision support system to track vegetable diseases in the Philippines’, funded by the Taiwan Ministry of Foreign Affairs, in partnership with collaborative project by WorldVeg and the Institute of Weed Science, Entomology and Plant Pathology, College of Agriculture and Food Science, University of the Philippines Los Banos. The aim is to improve the understanding of the distribution of virus diseases, to better inform breeders and extension officers about disease status, guide local breeding or deployment decisions, and increase preparedness for emerging threats in local vegetable production systems.

Information on the presence of crop diseases is crucial for informing national breeding priorities. In the case of bacterial wilt for example, WorldVeg are in the process of identifying the specific bacterial populations present, and selecting resistant rootstocks and lines, of which Bwr12 and Bwr6 are already being used. Amongst the begomoviruses, the dominant species are Tomato leaf curl Philippines virus (ToLCPV) and Tomato leaf curl Cebu virus (ToLCCeV), and WorldVeg surveys have recently detected Tobacco leaf curl Yunnan virus (TbLCYNV). So far, one line has been identified with Ty genes that show a high level of resistance to ToLCPV and TbLCYNV variants, that requires confirmation. An emerging crinivirus-like disease was detected in the surveyed sites in Batangas, Neuva Ecija, Laguna and Bukidonon. Work is ongoing to characterize the begomoviruses, and confirm the identity of the crinivirus-like disease.