A pest is an organism that is a nuisance to the crops. It can cause eventual loss of the crop if it is not tackled properly. Pests are categorised into weed pests, insect pests, birds and mammals such as monkeys and rodents. There are several pests that attack maize. These include stem borers, termites, army worms, cut worms, leaf hopers, birds and mammals (rodents, pigs).
The stem borer: For this pest, the eggs are laid on the leaves and stems of the maize. However, the damage is caused by the young larvae feeding on the young leaves and stems, causing rows of oval perforations in the leaf and stem.
The commonest method of control available to the small-scale farmer is the use of cultural control measures, which involve the management of crop residue and crop rotation. Crop rotation may be practiced, where maize is rotated with legumes like beans in the farm. The rotation tends to reduce infestation by the borers.
Intercropping legumes with maize also helps reduce infestation levels. The stem borer can also be controlled by either burying or burning crop residues. What a farmer needs to do is correct the affected plants and either bury them or burn them.
Furthermore, it can be controlled through habitat management. This is when maize is planted with the legume plant called silver leaf (desmodium incinatum) and with elephant grass on the sides of the maize shamba. The desmodium produces chemicals that repel the borers, which are then are attracted by the elephant grass on the sides of the farm. This means that instead of affecting the maize, the borers enter the elephant grass. Unknown to the borers, while they lay eggs in the elephant grass, the grass has got chemicals that do not allow the eggs to hatch. This way, the prevalence of the borer will be gradually reduced.
The stem borer can also be controlled by using other insects to destroy the eggs. Some of these insects include classes of parasitoids, predators like ladybirds, ants, beetles and spiders which all feed on the eggs of the borer.
There are also maize varieties that are produced with pathogens that kill the borer if it feeds on them. These varieties are already commercially used in Kenya and will be in Uganda soon.
And lastly, borers can be controlled using chemicals. However, according to experts, this should come as a last resort because borers are very difficult to kill with chemicals because they are hidden inside the crop. The insecticide should be applied when they are feeding on the leaves.
