Plant extracts show positive results in containing fall armyworm

Tephrosa vogilii tree. james Mocheche Nyamira.JPG

Nyamira County farmer James Mocheche stands beside tephrosia vogelii tree, whose roots he says, discourage moles from destroying maize and sweet potatoes . Farmers are turning to terephosia vogelii and neem extracts to control fall armyworm.

Farmers in Africa are turning to tree extracts in search of affordable and effective alternative to synthetic pesticides to the fall armyworm, which is threatening to wipe out more than 87.5 million acres of maize and more other crops.

The farmers are banking on positive reports on neem and tephrosia vogelii extracts of neem reducing the population of the FAW in maize fields in Zambia.  

Apart from maize, the worm feeds on more than 80 types of crops including wheat, sorghum, peas, pastures, beans, potatoes, among others.

Although synthetic chemicals have not failed in controlling the pest, Zambian Researcher Mathew Matimelo said farmers are not sticking to the recommended dilution ratios. This makes the farmers feel the organic pesticides are not working.

Matimelo, who is the principal research officer at the Zambia Agriculture Research Institute, was speaking in Nairobi during a two-day global meeting of agriculture stakeholders. The meeting is seeking strategies of containing the pest that can lead to 100 per cent crop loss if uncontrolled.

Although the trials on the efficacy of the extracts from the two trees are ongoing, the researcher said positive results have been seen.

Besides the cost of organic chemicals being expensive for weekly application for most small-scale farmers, overdose out of desperation to contain the pest is not only increasing the cost of production, but also leading to emergency of resistance from the survivor worms.

 “Pests develop resistance to (synthetic) pesticides if the doses are doubled. Neem extracts have shown some effectiveness in controlling FAW. The test results so far are very impressive,” Matimelo said.

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farmers in Malawi are already using the neem extracts, though it has not given the intended results with a number of factors like rate of application influencing the positive outcome. The pest is hard to control because it burrows into the whorls, stems and cobs mostly in the day.

The two trees have been used for centuries in the control of pests. They are still used in the commercial manufacture of other pesticides and other drugs.

In neem, azadiractin A is one of the active elements that blocks production and release of molting hormones in pests, according to a research published in the US NCBI resource centre.

 This interferes with the lifecycle of the pest, which gradually reduces in population.

The tephrosia tree was applied in the control of field and storage pests for centuries until the introduction of the DDT, whose was discontinued due to its threat to safety.

The rotenone - the active ingredient in the tephorosia extracts - is poisonous to insects and a number of animals like fish.

One kilogramme of the leaves is crashed for mixing with five litres of water, according to the World Agroforestry Centre. The rotenone is naturally degraded after five to seven days, therefore, reducing its danger to humans.

Although they are derived from plants locally, farmers must exercise caution since they are equally poisonous to human.

The FAW covers 100km per day. After the first case was reported in Nigeria in January 2016, the pest had colonised the Southern African region by January 2017. It was first detected in Kenya in March 2017.

Affected countries include Angola, Zambia, South Africa, Malawi, Zimbabwe, Mozambique, Botswana, Tanzania, Swaziland, Uganda, Rwanda, Burundi, Democratic Republic of Congo, Nigeria, among others.

The meeting was organised by the Alliance for a Green Revolution in Africa (AGRA), the International Maize and Wheat Improvement Center (CIMMYT) and the Food and Agriculture Organisation of the United Nations (FAO)

It can cause up to 70 per cent losses, and if uncontrolled, the damage can reach 100 per cent. The larvae feed on leaves, tassels and ears of maize. The leaves have ragged continued holes.