The question is, whether alternative approaches can reduce pesticide application and its undesired side effects on human health and the environment and at the same time increase economic benefit? One potential approach is called „Push - Pull“. It uses either repellent intercrops or repellent plant extracts on the crop and plants attractive to the pests at the field boundaries. The latter can be selectively treated, so that no harmful pesticides need to be used on the crop itself. Is this a feasible procedure under West African on-farm conditions?

The Nobere case study

In Nobere, southern Burkina Faso, tomato is a major cash crop in the off- season. It is cultivated under irrigation around an artificial water reservoir. The local farmer organisation UDPN is engaged in these activities. During a visit the potential to introduce the „push - pull“ approach was evaluated.

Together with CIRAD/ICRISAT entomologist Alain Ratnadass first the principal pest problems were listed and discussed.  On the following field trip it was tried to identify species and symptoms. The moth Helicoverpa armigera on tomato  and  Tephritid fruit flies on cucumber and courgette could be identified as the major pests. It turned out that farmers are not aware of the life cycle of the pests and that they normally treat the crop when they see crop damage or their experience indicates that a certain pest could  occur at a certain development stage.

For the case of tomato 10-12 applications within 3 months are standard, and only two pesticides are used. Costs for pesticide use are about 10.000 FCFA per 400 m2, while gross returns amount to 20.000 to 200.000 FCFA. So only under low crop price conditions pesticide application becomes an economic problem.

After explanation of the pests‘ biological cycle, Alain Ratnadass proposed two potential approaches to control the major pests.

„Push - Pull“ against Helicoverpa caterpilar in tomato

Neem kernel extract can be applied as repellent on the tomato crop. In addition, pigeon pea (alternatively cotton) is proposed as attractant for Helicoverpa around the tomato field. On pigeon pea plants the caterpilar can be controlled either manually or by applying plant-derived or conventional insecticides.

„Push - Pull“ against Tephritid fruit flies in cucumber and courgette

In principal the same approach, but maize as preferred trap crop. Maize serves as roosting host. In order to make it more attractive to the flies it is necessary to add food attractants combined with a non repellent biological insecticide.

In general, farmers were open to test the proposed approaches but asked for more detailed information. Whether these approaches work out? Let‘s see in the next season with three test plots for each crop.

LH

Your comments?

Email to: herrmann@uni-hohenheim.de or ratnadass@cirad.fr

More information? See:

http://www.push-pull.net/

http://farmradio.org/english/weekly/2008/01/28/notes-to-broadcasters-on-push-pull-pest-control/

http://www.rothra.org/Newsletters/16%20January%202005%20Newsletter.pdf

http://www.cirad.bf/fr/ravageurs.php