By Murimi Gitari
Dr. Frank Chidawanyika is a scientist in the Push-pull Program under the Plant Health Theme at the International Centre of Insect Physiology and Ecology (icipe), discusses how the pushpull technology, originally used to control the stemborer in maize and sorghum is evolving as an effective tool in managing more pests in more crops and promoting soil health.
Can you explain the basic principles of the push-pull method and how it works in pest and disease management?
The push-pull method is a sustainable pest management strategy that uses companion cropping where non-host plants of the Desmodium family are used to repel pests whilst simultaneously attracting their natural enemies. Brachiaria or Napier grasses are then planted around the plot where they lure pests away from the crop for laying eggs. These grasses impede the full development of the caterpillars emerging from the eggs, leading to a dead-end trap. The push-pull method does not directly control diseases but reduces infections by limiting activity of vectors or pest damage that leads to secondary infections.
What specific pests and diseases are most effectively managed using the push-pull method?
Originally, the push-pull method was designed to manage stemborers in cereals such as maize and sorghum but was later found to effectively control the fall armyworm. More recently, we introduced vegetables into the push-pull method, and it has proved substantially effective against some of the key vegetable pests, including Diamondback moth, Tuta absoluta (leaf miner) and aphids.
How does the push-pull method contribute to the management of mycotoxins in maize?
Push-pull enhances microbial activity in the soil that degrades mycotoxin development. As with crop diseases, push-pull reduces the predisposing factors of mycotoxin development following pest damage.
What are the main benefits of using the push-pull method compared to traditional pest control methods?
So far, I have mentioned only the pest control benefits of push-pull, which help to reduce economic costs associated with pesticides together with the health risks. Other major production constraints in most of our smallholder farming systems is poor soil fertility and parasitic Striga weeds that poach nutrients from the main crop.
The Desmodium in the push-pull addresses this by triggering suicidal germination of the Striga, which depletes its soil seedbanks. The Desmodium also fixes nitrogen and helps to restore soil fertility. These companion plants are also harvested as supplementary fodder for livestock and help to improve herd count and milk productivity.
Can you share any recent research findings or case studies that highlight the effectiveness of the push-pull method?
A recent study is from a research article titled “Sustainable intensification of vegetable production using the cereal ‘push-pull technology’: benefits and one health implications” that delved into the innovative application of pushpull technology (PPT) in vegetable farming.
Originally designed to combat stemborer pests and the parasitic weed Striga in cereal crops, PPT has been adapted to enhance soil health, fertility, and crop protection in vegetable production. This adaptation not only promotes human and animal nutrition but also ensures food safety. The study underscores the significance of agroecological farming strategies as sustainable alternatives to conventional methods that often rely on inorganic inputs. By integrating PPT into vegetable farming, the research aims to mitigate environmental degradation and biodiversity loss, presenting a viable solution for sustainable agriculture. The ‘One Health’ approach is a central theme, addressing interconnected health issues across human, plant, animal, and environmental domains. By incorporating vegetables and legumes into the PPT system, the study seeks to improve nutrition, food safety, and environmental stewardship. Recent findings highlight the benefits of the adapted PPT system for farmers, particularly those in resourceconstrained regions of sub-Saharan Africa.
The system has shown to improve crop yields, enhance pest management, and boost soil health, offering significant advantages for sustainable farming. The research also calls for further exploration into the full potential of PPT in vegetable production, including its impact on pest and biodiversity management and its role in combating zoonotic diseases.
What challenges have you encountered in implementing the push-pull method in different regions?
Climate extremes, particularly erratic rainfall and prolonged dry spells, have limited our success in some regions. The high costs of the companion plants also sometimes limit farmer-led lateral diffusion and adoption of the push-pull.
How does the push-pull method impact soil health and overall crop yield?
By reducing parasitic weeds and fixing nutrients in the soil as earlier mentioned. It, however, also helps with locking organic carbon in the soil, which helps crops to utilise even added nutrients better. Generally, the yield increases among practising farmers increases as high as three-fold (up to 6.4 t/ ha). But of course, this depends on other good crop husbandry practices such as good quality seed, maize variety, and access to rain/irrigation.
Are there any specific crops or environments where the push-pull method is particularly effective or less effective?
Yes, the push-pull is very effective in cereal (maize and sorghum) systems and now select vegetables. As for environments, push-pull tends to do well where the target crops thrive. However, we have noted that Napier grass tends to do well in high rainfall areas whilst the Brachiaria grasses are a bit hardier to withstand more arid environments. Similarly, the Desmodium types can be grouped on their water requirements to ensure optimal performance.
What role do farmers play in the successful implementation of the push-pull method?
Since we rely heavily on participatory approaches, farmers are at the centre of the push-pull technology. They are the ones who validate and sometimes make slight adjustments to suit their needs and priorities. The farmers also are the ones who help with scaling the adoption by hosting demonstration plots and training of their peers at village and district level.
How do you see the future of the push-pull method evolving with advancements in agricultural technology?
Push-pull will greatly benefit from modern advancement in ICT technologies in agriculture by use of climate services to optimise productivity. Farmers can also benefit from information services, including training material, input availability and even market linkages.
We are also now heavily relying on geoinformatic tools and machine learning for precise targeted interventions in areas where low soil fertility, Striga weeds and pests are rampant. In future, labour requirements can also be reduced by mechanisation using micro-equipment suitable for smallholder farming. Most importantly, the PPT is very compatible with many other regenerative farming practices where the integration will not only help in controlling pests, but also meet other societal needs, including nutritional diversity, soil health and development of rural circular bioeconomy