Crop Genebank Knowledge Base

Crops

Cassava

Conservation

Field bank

Viability and monitoring

Viability and monitoring in cassava field banks

Contributors to this page: IITA, Nigeria (Dominique Dumet), Bioversity International/ILRI, Ethiopia (Alexandra Jorge); INIA, Peru (Llerme Rios); independent consultant (Clair Hershey).

Health diagnosis in field banks

Preferably, test the source plants to identify healthy plants as a source of cuttings.
If possible, do random health tests during field monitoring and checks.
Follow recommendations from the cassava health diagnosis menu for detailed procedures.

Routine monitoring methods

Assures the viability, adequate growth and good health of the plants during field growth.

Secure and protect the field against theft, vandalism and damage by animals.
Weekly or bi-weekly (maximum) surveying of the collection is essential, to be aware of any problems that arise and need to be corrected.

Check regularly for plant vigour and survival rates.
Check regularly for mixtures due to handling mistakes: look for uniform characteristics, such as colours of young apical leaves (expanded and non-expanded), petiole, cortex and external stem as well as pulp, cortex and external root colours; flowering and branching types, pubescence of young leaves, shape of the central lobe, internode length (leaf scars), storage root peduncle and surface texture.
Check regularly for pests and diseases. Contact plant health experts to identify symptoms and recommended appropriate control measures.
Weed the field regularly.

Recording information during routine monitoring in field banks

The following information should be recorded for each step:

Site name and map/GPS reference.
Name of collaborator.
Field bank site name (a code to identify the site location).
Plot reference (the plot number at the field site).
Accession number; population identification.
Date of monitoring (date when data is collected).
Date of test (the date that the test was carried out).
Results of tests and action taken (removal of plant or application of insecticide or quarantine measures).
Name of staff (name of staff recording the data).
Survival rates (number of plants alive).
Details of plants removed (due to type mixtures or pests or diseases contamination).
Damage [a score of 1-5 (where 5 is most damaged) or qualitative assessment of damage (insect, disease etc)].
Vigour [assessment of vigour of the plants on a scale of 1-5 (where 5 is high)].
Field management details (watering, fertilizer, weeding, pest and disease control, stresses recorded, others).

References and further reading

Fukuda WMG. 1996. Banco de germoplasma de mandioca: manejo, conservação e caracterização. Cruz das Almas, BA: EMBRAPA-CNPMF. 103p. (EMBRAPA-CNPMF, Documento, 68).

Hershey C. 2008. A Global conservation strategy for cassava (Manihot esculenta) and wild Manihot species. A consultancy report to CIAT, on behalf of the Global Crop Diversity Trust, Rome. (Final report under review).

IITA Genebank Manual Series, Cassava field bank operations at the International Institute of Tropical Agriculture (IITA). International Institute of Tropical Agriculture, Ibadan, Nigeria.

Mohd SS, Rao VR, editors. 2001. Establishment and Management of Field Genebank, a Training Manual. IPGRI-APO, Serdang. 121 p. Available here.

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