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Using pulse diversity to manage pests and diseasesPaola De Santis, Agricultural Ecosystems Researcher, Bioversity International 19 April 2016
Smallholder farmers maintain substantial numbers of traditional varieties of pulses.Many are grown for their resistance to major pests and diseases, adaptation to temperature and rainfall extremes, poor soil conditions, reduced cooking time, and taste.
Crop varietal diversity in farmers’ fields
Changes in pest and pathogen populations Unpredictability of rain and temperature/ water scarce poor soils
2009 wet2010 dry
Linking Diversity with disease resistance and climate
Ochoa et al., 2010, unpublished dataPhoto: M. Arbaoui
Central hypothesisGenetic uniformity of monocultures (wide areas planted to
a single pulse variety) leads to genetic vulnerability, Therefore
Increasing intra-specific diversity of pulses on farm may lead to reduced losses from pests and diseases
Only if the diversity exists in relevant traits
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Crops (food security for smallholder farmers; different breeding systems)
• Coverage of different resistance gene system (where resistance is controlled by both major and minor genes)
• Transmission systems: seed-borne, soil-borne, and air-borne• Plant organ affected: leaf, stem, seeds and roots
Is varietal diversity in farmers’ fields reducing pest and disease damage and vulnerability to future loss?
Dive
rsity
Dise
ase ?
Can increasing the level of diversity in a field, in a controlled selected repeatable way, with well chosen components, give a benefit over monocultures, or treatments with less diversity?
Photo: M. Arbaoui
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DI
Number of varieties grown per household
Angular Leave Spot Anthracnose
In times of higher disease incidence (Anthracnose) higher relationship of varietal diversity with reduced damage
Number of varieties grown per household
Common bean and severity of bean fly damage (Uganda)
Ssekandi, W et al. Journal of Pest Science. 2015
Traditional variety
Commercial variety
Dissecting the mixture: %Resistance; % Susceptible; rows vs random
Ssekandi, W et al., Journal of Pest Science. 2015
Random mixture
25%R
75%S
50%R
50%S
75%R
25%S
25%R
75%S
50%R
50%S
75%R25%S
25%R 50%R 75%R 25%R 50%R 75%R
Alternate-row mixture
Key elements of healthy production systemFarmers need access to good quality diverse seeds at the right time and in sufficient quantity.
Formal release of improved traditional cowpea
Good quality seed can be produced by improving traditional pulse varieties through both conventional breeding and participatory crop improvement.
Seed productiono Farmers and scientists assess crop genetic
diversity (local and/or improved varieties)o They monitor the crop cycle through weekly
meetings at the experimental siteo At the end of the cycle, varieties with desired
traits are selected, multiplied and disseminated within and outside the group
Diversity Field Fora
o Improve access to rare germplasmo create public awareness on the value of local crop
diversityo locate prime areas of diversity and identify rare and
unique varietieso promote exchange of community based seed and
knowledge
Diversity Fairs
Seed flow and seed accessDiversifying seed sources (e.g. community seed banks supplying traditional varieties, private suppliers providing commercial varieties)
Key elements of healthy production systemFarmers need access to good quality diverse seeds at the right time and in sufficient quantity.
