Push-Pull technology can control fall armyworm Instead of using expensive and harmful chemicals to control the fall armyworm, the Push-Pull method has been shown to be effective in controlling the pest.

The impact of the fall armyworm is already being felt across Africa after its invasion of the region in the last two years. The fall armyworm is a heavy feeder that quickly destroys a wide range of crops such as maize, sorghum, rice, wheat and sugarcane, including a number of horticultural crops. It can spread very fast and can fly over 30 kilometres in one night assisted by the wind. The adult moth lays about 150 eggs in one day. Within as little 10-12 days, the worm changes into a moth and the young adult flies away in search of new regions and other fresh crops to consume. The larval stage burrows into crops, destroys and eventually kills them.

Chemicals are harmful and pests develop resistance

Synthetic pesticides are mostly used to control the pest. The chemical sprays however contaminate the environment and cause major health risks to human, livestock and the biodiversity especially the non-targeted organisms. The adult lays the eggs mostly at night therefore the infestation is only detected after damage has been done to the crop. This makes the control difficult. “The pest also has a diverse range of alternative host plants that enables its populations to persist and spread. Moreover, the fall armyworm has been shown to develop resistance to many insecticides, while the performance of such chemicals is also hindered by limited knowledge and purchasing power of farmers, resulting in the use of low quality, and often harmful products,” says icipe scientist, Dr Charles Midega.

Other benefits push-pull technology

Desmodium is a perennial cover crop which is able to exert its Striga control effect even when the host crop is out of season, and together with Brachiaria or Napier grass, protect fragile soils from erosion. It also fixes nitrogen, conserves soil moisture, enhances insect abundance and diversity and improves soil organic matter. Desmodium enables cereal cropping systems to be more resilient and adaptable to climate change while providing essential environmental services. It also makes farming systems more robust and sustainable. In addition, Push-Pull also controls maize ear rots and mycotoxins, while improving soil health, producing high quality fodder for livestock. Therefore, the technology facilitates crop-livestock integration thus expanding farmers’ income streams. Farmers using ‘push–pull’ technology not only use it for pest control but also to reduce the devastating effects of the parasitic weed Striga hermonthica through the effects of desmodium. The technology is appropriate and economical to the resource-poor smallscale farmers in the East Africa region as it is based on locally available plants, no expensive external inputs, and fits well with traditional mixed cropping systems in Africa.

Trials in Kenya, Uganda and Tanzania

In a recent study by Dr. Midega and others published in Crop Protection journal, entitled “A climate-adapted push-pull system effectively controls fall armyworm, Spodoptera frugiperda (J. E. Smith), in maize in East Africa, 2017” indicates that climate-adapted pushpull tool developed for control of cereal stemborer in drier regions can be used for the management of fall armyworm. The technology comprises intercropping maize with drought-tolerant Greenleaf desmodium, Desmodium intortum (Mill.) Urb. and planting Brachiaria cv (Mulato II) as a border crop around this intercrop. Protection to maize is provided by repellent chemicals that are emitted by the intercrop that repel (Push) stemborer moths while those released by the border crop attract (Pull) them.

In this study, 250 farmers who had adopted the technology in drier areas of Kenya, Uganda and Tanzania were randomly selected for the study during the long rainy season (March-August, 2017). Each farmer had a set of two plots, a climate-adapted Push-Pull and a maize monocrop. In the climate-adapted Push-Pull plot, maize was intercropped with greenleaf desmodium and Brachiaria cv (Mulato II) was planted around this intercrop at a spacing of 50 cm within and 50 cm between rows. Greenleaf desmodium was planted in between rows of maize. Maize was planted at inter and intrarow spacing of 75 cm and 30 cm, respectively, in both plots.

Results

“This study was done on the basis that over the past several months they received information from Push-Pull farmers that their fields were free of fall armyworm infestation while neighbouring monocrop plots were being ravaged by the pest. Therefore, we evaluated the climateadapted version of the technology as a potential management tool for fall armyworm in Kenya, Uganda and Tanzania,” explains Prof. Zeyaur Khan, Push-Pull leader at ICIPE. The study revealed fall armyworm infestation to be more than 82.7% lower in plots where the climateadapted Push-Pull was being used, with associated increases in grain yields (2.7 times), in comparison to monocrop plots. The findings were supported by farmers’ perceptions through their own observations where the presence of fall armyworm was low in Push-Pull plots.

In conclusion, ICIPE Director General, Dr Segenet Kelemu said that the ability to manage such a devastating pest clearly demonstrates Push-Pull’s importance as a platform technology in addressing the multitude of challenges that affect cereal-livestock farming systems in Africa.

Donors involved: The European Union; Biovision Foundation for Ecological Development, Switzerland; UK’s Department for International Development (DFID); Swedish International Development Cooperation Agency (SIDA); the Swiss Agency for Development and Cooperation (SDC); the Kenyan Government amongst others. For more information follow this link: http:// www.sciencedirect.com/science/article/pii/S0261219417303216

For more reading on Push-Pull: http://www.infonet-biovision.org/ PlantHealth/Intercropping-and-Push-Pull