International Solutions to fight Nematodes and Insects

Nematodes

Amongst nematodes Radolphus similis is the most damaging species. It was seen parasitizing banana plants for the first time on the Fiji Islands, at the end of the nineteenth century. This pest can now be found all over the world in all the important banana regions, with high infestation levels.

Yield can be reduced by between 15 and 50 and bunch weight reduction can vary from 1.5 to 2 kg per year. The nematodes cause damage to the root system, leading to the plant's collapse through root loss. They cause a necrosis which reaches the interior of the root's central cluster. They survive endoparasitically, feeding on cellular cytoplasm during its migration through the root cortex, where all stages of the nematode's life cycle can be seen. If necrosis accompanies cell breakdown, the nematodes either migrate through the tissue in advance of the necrosis or move out of the root into the soil to re-infest the root at another site. Eggs are often found in necrotic tissue.

By wounding the host and inducing histological changes nematodes may provide infection sites for other micro-organisms and particularly root diseases.

There are generally 1 to 3 cycles ofnematicide application around the stem per year.

Weevil

Cosmopolites sordidus is the most significant species of weevil in banana cultivation. Losses in production can reach up to 40%. The adults are attracted by volatile substances emanating from the host plants.

The adult lays her eggs on the upper part of the stem and rhizome. The maggots make galleries in the corm, which can reach the pseudostem. The damage can be made more acute through the introduction of other organisms such as fungi, bacteria or other insects.

The slit corms present a particular attraction: The pest interferes with the formation of roots, kills existing roots, limits the absorption of nutrients, reduces plant vigour and crop stand, delays flowering, and increases susceptibility to other pests and diseases.