China, News

Intra-specific diversity practices for pest and disease management to reduce pesticides dependency by small holder farmers in China

June 23rd, 2014 | Source: Bai, Keyu from East Asia office, email: k.bai@cgiar.org

Community seedbankMaize and rice are two major crops especially in the southwest of China, which occupy 26% of the farmland. Crop loss from pests and diseases is one of the main limitations for increasing the productivity of these crops and safeguarding the food security in local areas. Increased use of pesticides for pest and disease control in China has made it one of the biggest pesticide consumption countries in the world, which caused a lot of environmental problems and increased the cost of farming to local farmers. Practices for pests and disease management that use intra-specific diversity, have been tested and proven through the three years UNEP-GEF global project on using biodiversity to control pests and diseases in support of sustainable agriculture and three years IFAD global project entitledImproving productivity and resilience for the rural poor through enhanced use of crop varietal diversity in IPPM; implemented in China since 2007.

 One such practice is increasing the intra-specific diversity on-farm and consequently at the landscape level as seen from research findings that show a decrease in rice blast and panicle blast damage with increased varietal evenness and richness in China. This is in agreement with findings from similar studies in Uganda where a general trend in the study sites for banana and common bean showed that when the number of varieties and their evenness increased, the average pests and diseases damage levels decreased. Also households with higher levels of intra-specific diversity in their production systems had less damage to their standing crop in the field compared to those with lower levels.

 Growing varietal mixtures has proven to reduce pests and diseases damage on crops. Experiments showed that the yield from varietal mixtures of rice was higher than that of monocultures and the disease index in the mixtures was lower than in the monoculture which implies that varietal mixture planting reduces the crop loss from disease and pest damage. The three and four varieties mixtures had a better control effect than the two varieties mixture showing that the more the number of varieties in the mixture, the better the control effect.

Community seed banking is another practice that increases the availability of crop diversity in terms of numbers of varieties and quantities available freely for farmers to plant through readily providing seed. After accessing seeds, farmers return twice the quantities taken from the seed bank and they are able to plant whatever varieties that they may be interested in. So far, three community seed bans have been established in Menghai, Zhaojue and Yuanyang.

The table below shows the varieties of rice, maize and other crops in the community seed banks of China

 

Location  (county)/No. of collections

Rice

Maize

Other crops

Menghai

70

10

8 (include coix seed, broom corn, sunflower, white gourd)

Yuanyang

101

 

 

Zhaojue

 

10

 

Total

171

20

8

If farmers are to use crop diversity to manage pest and disease pressures, awareness is very crucial to enable them take on this option with a clear understanding of how the diversity can be deployed. Several ways can be used to create public awareness including diversity fairs, field demonstrations, handbooks, calendars, drama, to mention but a few. Through these activities, the enthusiasm and participation of farmers can be greatly increased.

These are some of the intra-specific diversity disease and pest management practice being promoted in China to reduce the amount of pesticides that are currently being used as they are not only detrimental to human but also ecosystem health.

References:

Wu Shu; Yang Xuehui, Peng Huaxian, 2012, Relating crop damage levels on-farm to crop varietal diversity measured by richness, evenness and diversity for rice in China and maize in Sichuan, Proceedings of an International Symposium 15-17 February, 2011, Rabat, Morocco, Bioversity International, Rome Italy

 Mulumba, J.W., Nankya, R., Kiwuka, C., De Santis, P., Fadda, C., Jarvis, I.D., 2012. A risk minimizing argument for traditional crop diversity use to reduce pest and disease damage in agricultural ecosystems of Uganda. Agric. Ecosyst. Environ. 157:70–86.