By Joshua Kato
It is the season of the year when maize fields are attacked by all kinds of pests. Below are the common field pests and their control;
- Armyworm (Spodopters exempta)
This can be controlled by: Chemical control at a young stage with contact insecticide e.g. dimethhoate or similar organophosorous insecticide sold under many different brand names.
It can also be controlled by Ambush. Apply a brand spray along the edge of the field to prevent the worms from matching into the field.
- Cutworms (Agrotis spp)
These are grey-looking caterpillars that feed on green plant materials. They eat the maize plants soon after germination at ground level reducing the stand considerably.
These can be controlled by:
Applying pyrethoid sprays in bands over the rows
Leaving the land weed free for about six weeks prior to planting.
- Leaf Hoppers (Cicadulina spp)
These are small, pale yellow and wedge-shaped insects that suck sap from the maize plants. They are important because they are the vectors of maize streak virus. Their control is by farmers clearing field barriers of 10 – 20 m using plant-resistant varieties.
- Termites
These are becoming important maize pests in Uganda. Various species of termites attack and damage maize particularly during drought seasons or in areas with erratic rainfall. They destroy the maize roots and the base of the stem leading to lodging.
Termites can be controlled by the use of Dusban (Chloryrifos) that kills by contact. Apply 20-40 ml using 10-20 liters of water per termite mould/anthill. Other chemicals include Terminator, Pyrintex, Trban, Ebdosulphan, Malataf.
Reagent 3-G (Fipronil). This can be used where there are no moulds in the garden. Mix 50 gm with 2 liters of water and apply to locations of the feeding termites. Apply to several locations of the field. This will kill the workers due to excitement leading to overworking and exhaustion then eventually die. The queen stops feeding and dies of starvation.
Vertebrate pests
The common vertebrate pests include:
• Rodents
Although rodents are generally considered important pests of stored grains, they are also important pests of maize in the fields. They will also damage grains in storage.
Rodents can be controlled by:
Planting 3-4 plants per hill and thinning to two seedlings in the third week to avoid the reduction in stand.
Where possible, maintain clean surroundings by weeding or slashing around the field. Rodents usually invade maize fields from nearby bushes and garbage, but may fear crossing open grounds.
Wild Pigs
These destroy maize at all growing stages. They feed on seedlings, leaves, green cobs and dry cobs. They usually invade fields in large numbers.
They can be controlled by:
Groups of hunters net and kill them with the help of trained dogs. If the hunters are properly organized, they can kill up to 10 wild pigs per day. The killed pigs are usually eaten by the hunters.
Scaring away the pigs by children. The success depends on the faithfulness of the children in doing the job.
- Monkeys
Monkeys will destroy the maize mainly after tasselling equally when the cobs are already formed.
- Birds
Birds can dig out seeds from the ground before they germinate thereby reducing the plant stand. They also feed on the grains as soon as the grain-filling stage begins. This reduces yields but perhaps, even more important, their damage opens avenues for pathogens leading to reduced quality. Birds can be controlled by scaring them away. This is limited due to a lack of sufficient labour to do that. The use of scarecrows and other locally improvised noise devices stationed at different points of the field reduces damage.
- Thieves
Thieves reduce the quality of maize and in extreme cases, losses can go up to 100%.
- Mite
Mite infestation normally occurs in mouldy grains where they feed on the fungi. Occasionally they are predators of some insect pests. Their presence leads to the contamination of grains leading to off-flavors.
