How grafting can help citrus farmers beat EU chemical regulations


Kenyan citrus farmers exporting to Europe can now beat tightened EU pesticide laws by planting seedlings or grafting material free of greening disease caused by the African Citrus Trizoid (ACT) pest.

“Planting clean citrus seedlings is an important management strategy. Grafting of seedlings should be done using clean scion [top parts of the plant used in grafting] that have been tested and found to be free from the bacterium that causes greening disease,” said Dr Ivan Rwomushana of International Centre of Insect Physiology and Ecology (ICIPE).

Blow from importer

The new EU laws have lessened the amount of chemical residue allowed in horticultural produce by 10 times calling on farmers to re-think their pesticide use seeing that the region is Kenya’s biggest horticultural export market. In 2014, Kenya earned Sh90 billion from the EU.

The EU is barring entry into its markets of horticultural products with chemical residue of more than 0.02 chemical parts per million. The figure has been scaled down by 10 times from 0.2 chemical parts per million. The regulations were effected following studies that linked some chemical components like guazantine in pesticides to cancer.

Clean citrus planting materials can help farmers cut chemical use in production for export.PHOTO: TWITTER

Big save

 According to Dr Rwomushana, clean planting materials can save between 25 per cent and 100 per cent of the crops affected by the greening disease. The bacteria attacks soft tissues of the plant, leading to reduced photosynthesis and eventual death in severe cases.

To raise clean seedlings for grafting, a farmer can plant seeds in commercially available media like Amiran Kenya’s Peat Moss and Cocopit.

These artificial ‘soils’ are neutral and disease free. A farmer is only required to add mineral nutrients to support growth of the seedlings.

Low lands

Another way to get rid of the ACT pest is by planting in low lying regions as it does not survive in areas of high temperature and humidity. However, most of Kenya’s horticultural farmers are in the high altitude regions such as Rift valley, Nyandarua, Kiambu, Kirinyaga, Meru, among others.

Dr Rwomushana cites that the best way to control the ACT pest still remains the use of systemic pesticides like imidacloprid. This is however not viable for Kenyan farmers as these pesticides contain the chemical component guazantine which has been restricted by the EU.

It is for this reason that pest control is looking to organic farming for the answer. Biopest control remains the only viable route of minimising chemical use in production.

Another pest

The False Colding Moth (FCM)-a horticultural pest that can destroy between 34 and 68 per cent of crop-has been controlled by use of a mating disruption gel. It prevents males from mating with females.

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“ICIPE is testing a range of biopesticides for their efficacy against the FCM. Major in the tests is the Metarhizium anisopliae fungi, which adults will be picking and spreading through mating. Victims with the fungi would die,” said Dr Rwomushana.