Sustainable fall armyworm control measures needed


THE fall armyworms (FAW) have made Zambia their home and continue to ravage the staple crop, maize. In response, Government continues to prescribe the use of pesticides which it procures en masse to combat the pest. However, in view of the harmful effects of pesticides on the environment and the possibility of the pesticides to induce immunity in the pests, does the wholesome use of pesticides guarantee effective FAW control that is environmental friendly?
On January 12, 2019, the Zambia Daily Mail reported the looming threat of FAWs in 18 districts. The notorious pests that have developed an avaricious appetite for maize were reportedly poised to attack 24,000 hectares of the staple crop. To counter the threat, Acting President Inonge Wina was reported to have announced the purchase of initially 41,666 litres of pesticides worth US$500,000 from the US$3 million committed by the African Development Bank.
The FAW (Spodoptera exempta) were first sighted in Zambia in December 2012. They, however, caused the heaviest damage to the maize crop in the 2016/2017 farming season. The nation reacted by purchasing pesticides at a great cost using emergency funds.
Six years since the armyworms were first sighted in Zambia, Government still relies heavily on the use of pesticides to control the pests. Although Government revealed the collaboration between all SADC member states working in conjunction with FAO in developing an armyworm control and management system, the current over-reliance on chemical control, centrally to the principles of pest control strategies and FAO recommendations, may not be the best way to combat the FAWs.
Apart from being expensive, pesticide use on FAW is only effective when the worm is still young between day three and six of their four-week life cycle. Pesticides also pose a danger of polluting the environment, especially when their residues are washed into natural water bodies. Like any other pest, FAW develops resistance against pesticides if not varied.
The most effective management and control tool for armyworms is early detection.
Hence, Zambia must draw lessons from the experiences of the Americas and collaborate with her neighbours to develop pest surveillance and monitoring measures.
The Ministry of Agriculture can do better to organise farmers in community-based armyworm forecasting units. In this regard, investing in Geographical Information System (GIS) and Remote Sensing (RS) technologies is a must. GIS and RS technologies are effective in predicting the occurrence of pests and diseases in the fields and are in use in many African countries.
Because of the negative impact of pesticide use, the recommendation from FAO is to minimise the use of the same drastically to prevent a build-up of resistance and to avoid damage to the environment. FAO stresses implementation of Integrated Pest Management (IPM) strategies to combat FAW and so farmers must embrace all good crop management practices that can holistically control the pest.
Continuous growing of maize on the same piece of land promotes FAW infestation, and hence practising crop rotation avoids a build-up of the FAWs.
Crop residue in affected fields must be burnt to reduce food and hiding places for the caterpillars. Farmers must be vigilant and scout for early signs of the FAW and immediately notify the authorities. Deep ploughing in crop fields that have a history of FAW infestation brings the young pupae to the surface.
To avoid periods of heavy infestations later in the farming season, farmers must sow the seeds as early as possible. Good crop nutrition also enhances crop resistance to pest damage.
Meanwhile, extension officers, together with local farmers in North-Western Province, have come up with an effective way to control FAWs with soil. Soil is put into the maize foliage, where FAWs are suspected to hide, using a funnel, and this controls the notorious pest.
In their brochure; Integrated management of the FAW on maize (ISBN 978-92-5130493-8 Copyright FAO, 2018), FAO warns of possible panic by farmers and policymakers that may result in bad decisions on control and management of FAW. According to FAO, the maize plant is able to compensate for foliar damage, especially if there is good plant nutrition and moisture.
FAO asserts that damage of the maize plant is not devastating contrary to what so many believe. While a few of the FAO field studies show yield reductions due to FAW of over 50 percent, the majority of field trials show yield reductions of less than 20 percent.
The long-run recommendations by FAO are the investments in the research of breeding resistant maize varieties that cannot be attacked by FAW.
Investment in the research on biological control such as the use of locally available natural FAW pest enemies like wasps is also encouraged.
Because of the negative environmental impact of pesticide use, purchase and prescription of wholesome use of pesticides to control FAWs in Zambia does not, after all, guarantee effective and sustainable control of the pest.
More efforts must instead be channelled into early warning, research and tutoring farmers in IPM strategies where cultural and biological control and management of the pest is the norm.
The author is an expert in sustainable agriculture and rural development.

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