Cassava Witches' Broom Disease in Southeast Asia: A Review of Its Distribution and Associated Symptoms

Juan M Pardo; Khonesavanh Chittarath; Pinkham Vongphachanh; Le Thi Hang; Samoul Oeurn; Warren Arinaitwe; Rafael Rodriguez; Sok Sophearith; Al Imran Malik; Wilmer J Cuellar

doi:10.3390/plants12112217

Cassava Witches' Broom Disease in Southeast Asia: A Review of Its Distribution and Associated Symptoms

Plants (Basel). 2023 Jun 4;12(11):2217. doi: 10.3390/plants12112217.

Authors

Affiliations

¹ Cassava Program, International Center for Tropical Agriculture (CIAT), The Americas Hub, Km 17 Recta Cali-Palmira, Cali 763537, Colombia.
² Plant Protection Center (PPC), Department of Agriculture, Ministry of Agriculture and Forestry, Vientiane P.O. Box 811, Laos.
³ Plant Protection Research Institute (PPRI), Duc Thang, Bac Tu Liem, Ha Noi 100000, Vietnam.
⁴ Plant Protection Sanitary and Phytosanitary Department, General Directorate of Agriculture (GDA), Phnom Penh 120406, Cambodia.
⁵ Cassava Program Asia Office, International Center for Tropical Agriculture (CIAT), Vientiane P.O. Box 783, Laos.
⁶ Cassava Program Cambodia Office, International Center for Tropical Agriculture (CIAT), Phnom Penh 120904, Cambodia.

Abstract

Cassava witches' broom disease (CWBD) is one of the main diseases of cassava in Southeast Asia (SEA). Affected cassava plants show reduced internodal length and proliferation of leaves (phyllody) in the middle and top part of the plant, which results in reduced root yields of 50% or more. It is thought to be caused by phytoplasma; however, despite its widespread distribution in SEA still little is known about CWBD pathology. The overarching goal of this study was to review and corroborate published information on CWBD biology and epidemiology considering recent field observations. We report the following: (1) CWBD symptoms are conserved and persistent in SEA and are distinct from what has been reported as witches' broom in Argentina and Brazil. (2) In comparison with cassava mosaic disease, another major disease of cassava in SEA, symptoms of CWBD develop later. (3) Phytoplasma detected in CWBD-affected plants belong to different ribosomal groups and there is no association study available indicating phytoplasma as the causing agent of CWBD. These findings are essential clues for designing surveillance and management strategies and for future studies to better understand the biology, tissue localization and spatial spread of CWBD in SEA and other potential risk areas.

Keywords: cassava witches’ broom disease; diagnostics; phyllody; phytoplasma.

Publication types

Review

Grants and funding

The authors acknowledge financial support from the Australian Centre for International Agricultural Research (ACIAR), the United States Agency for International development (USAID) and the CGIAR Research Program on Roots, Tubers and Bananas (RTB) (https://www.cgiar.org/funders/, accessed on 15 May 2023). J.M.P., R.R. and W.J.C. acknowledge support from CGIAR’s Plant Health (PHI) and Accelerated Breeding (ABI) initiatives.