Philippine researchers addressing the threats of cassava phytoplasma disease

Cassava phytoplasma disease (CPD) is a current serious threat to the country’s cassava industry.
 

When the plant is CPD-infected, it shows yellowing or reddening of leaves, shrinking of the internodes resulting in stunted growth, excessive multiplication of shoots, and production of smaller leaves, among other symptoms, until the plant eventually dies.
 

CPD can reduce yield to about 50-70% when its symptoms appear four to six months after planting or during the middle of the growing season. Yield can be reduced to 100% when infection ensues during the first three months from planting.  
 

Becoming prevalent and continuing to spread in several parts of the country, CPD threatens cassava supply amidst its high demand for food, feeds and industrial uses. Worse, it is also feared to decrease export volume to as much as 30% to the detriment of the country’s 1.5 billion dollar cassava industry.
 

Addressing this concern, a group of researchers initiated the formulation of a management program to combat the disease through a research project, Management of Cassava Phytoplasma Disease: Survey, Diagnosis, Characterization, and Control, which is composed of three studies. Dr. Erlinda A. Vasquez, Director of the Philippine Root Crop Research and Training Center (PhilRootcrops), based in the Visayas State University, Baybay, Leyte, leads the project.   
 

The first study, Survey of the Occurence and Incidence of CPD and Associated Insect Pest, illustrated that Regions 1-13 and Autonomous Region for Muslim Mindanao showed high CPD susceptibility for three cassava varieties (‘KU-50,’ ‘Rayong 5,’ and ‘Rayong 72’).
 

All planting materials from Bukidnon showed heavy CPD infection, which spread to areas where these are planted. Because of this, former Department of Agriculture (DA) Secretary Proceso J. Alcala imposed a quarantine memo order in Bukidnon in 2015.
 

The second study, Detection, Diagnosis, and Characterization of CPD, developed an improved protocol for Phytoplasma DNA extraction and PCR analyses. Of the 29 samples collected from Visayas and Mindanao subjected to PCR analysis, 16 were found positive to the infection.
 

Lastly, the third study, Screening and Evaluation of Antibiotic Solution and Resistance Inducers, developed a modified DNA extraction protocol which provides quality DNAs considered important towards an effective diagnosis and characterization of the disease.
 

Results also showed that treatment of cassava cuttings for six hours in 100 ppm Streptomycin solution before planting was the most effective method in lowering mortality and increasing germination rate of cassava planting materials. The treatment using Streptomycin increased root yield (77-187%), dry matter (8-29%), and starch content (12-21%) of the cassava plant compared with the control, wherein only water was used. 
 

The project is one of the finalists in the research category of the National Symposium on Agriculture, Aquatic and Natural Resources Research and Development (NSAARRD). 
 

Initiated by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology (DOST-PCAARRD), NSAARRD recognizes the outstanding contributions of individuals and institutions in improving the state of agri-aqua research and development in the country.