Farmers must rotate pesticides against the fall armyworm every 30 days to prevent resistance, experts have warned in a new advisory.
The guide was compiled by US non-profit Feed the Future, Usaid and the International Maize and Wheat Improvement Centre (Cimmyt).
They said the worm completes its life cycle in 30 to 40 days in tropical climates and successive generations should not be treated with the same active ingredient.
The insect has a long history of developing resistance to insecticides and this would render the few chemicals recommended in Kenya useless.
In April, the government named five chemicals that farmers should use to control the worm.
Experts say if farmers fail to adhere to instructions, the country could suffer the resistance experienced in countries like Zimbabwe.
"Misuse can lead to the insect developing resistance to the active ingredient, besides causing damage to natural enemies and the environment," says the newly-released guide for integrated pest management, titled Fall Armyworm in Africa.
The guide highlights scientifically proven management practices that could be relevant for smallholder farmers in Kenya.
"Readers are encouraged to identify and combine appropriate options from each of the chapters, applying or adapting them as necessary in their local context," the authors say.
FAW has been confirmed in over 30 African countries and it is likely to become endemic in many.
It has affected 800,000 hectares of land in nearly all counties in Kenyan since it was first reported in 2016.
Kenya lost more than one million bags of maize in the last harvest season following the armyworm infestation, according to the Ministry of Agriculture.
Cabinet Secretary Mwangi Kiunjuri recently said the government will spend Sh600 million to fight the invasion.
Kiunjuri said the money will be disbursed through the newly formed Fall Armyworm Multi-Institutional Technical Team which is made up of scientists from the government and local and international research organisations.
Another Sh1 billion will be set aside for research and the purchase of pesticides for continuous fight against the pest.
"Last year, the armyworm destroyed maize crops worth Sh3 billion, about 20 per cent of the total harvest. The current invasion could be worse, hence the need to look for a long-term solution," Kiunjuri said.
The Cimmyit guide notes the best strategy to fight the worm should employ an effective IPM (integrated pest management) strategy and should employ a variety of approaches including host plant resistance, biological control, cultural control, and safer pesticides, to protect the crop from economic injury while minimising negative impacts on people, animals and the environment.
The report says because FAW is recently introduced in Africa, the dynamics of the pest on the continent is still unknown.
"The lessons learned from the invasive FAW pest should be identified quickly because they are important for monitoring and interception of future invasive pests," says the guide.