Field Crops> Maize> Insect Pests

Maize crop is subjected to attack by a number of insect pests. Some of the major insect pests are as follows:

Stem Borer

Stem borer is a very serious pest of maize. The darnaging.stage of the pest is larvae. The eggs hatch in about two to five days. The freshly hatched caterpillars migrate towards the central shoot where they first feed on the tender leaves for sometime. Later on they bore into top internode and move downwards. In case of younger plants, the growing point and base of central whorl gets badly damaged resulting into the drying up of the central shoot. It is commonly known as 'dead heart'. This condition, however, does not appear when the plant is attacked in the later stages.

Pink Stem Borer

It is a polyphagous pest and is not so serious in north as in south India. It generally attacks the crop in the late stage when cob formation starts in the field. The newly hatched larvae, first feed on the tender leaves and then bore towards the central shoot. This results in drying up of the central shoot and creation of 'dead heart'.

Control Measures: Control measures are same for both the stem borers. Spray 1.5 litre Endosulfan 35 EC or 2 kg Carbaryl 50 WP in 1000 litres of water per hectare. The spraying should be done about 15 days after sowing. After about 30 days of sowing apply 4 per cent Endosulfan or Savin granules at the rate of 15 kg per hectare. The granules should be applied in the leaf whorl.

Shoot Fly

It is a very serious pest of maize in south India. In north India, however; maize crop is not affected much except in the spring season in Tarai area. The attack is maximum when the crop is in seedling stage. Within two days or so eggs hatch and the tiny maggots creep down under the leaf sheaths till they reach the base of the seedling. After this they cut the growing point or central shoot which result in the formation of characteristic dead hearts.

Control Measures: Application of 10 per cent Phorate (Thimet) granules at the rate of 15 kg per hectare at the time of sowing in furrows, will control this pest. If the insecticide is not available at the sowing time then its side dressing after germination may also be adopted.

Maize Leaf Roller

Damage is caused by the caterpillar which is glossy green in colour and becomes pink when fully grown up. The larvae after emergence wander on the tender leaves. They fold the leaves by silking threads and hide themselves inside the rolled leaves. The surface of the attacked leaf becomes white and papery in appearance.

Control Measures: Spray Endosulfan (0.1 per cent) or 0.2 per cent carbaryl (Savin) (4 g of Savin 50 WP in one litre of water) at the rate of 500- 700 lit res per hectare. Spraying of 0.15 per cent oxydemeton methyl (Metasystox) is also effective.

Kharif Grass Hopper

Kharif grass hopper generally does not cause much damage to maize crop. However, in a favorable season, it may prove very harmful and leaves nothing on the plant except stem and midribs of leaves. Both adult any nymph stages of this pest are responsible for the damage. Adults are green or dry grass coloured.

Control Measures: Grass hopper can be controlled to some extent by how weather cultivation, which exposes their eggs to hot sun and natural enemies. Uncultivated area provides a proper place for egg laying, therefore, it should be reduced as much as possible. As the newly hatched nymphs first feed on the grasses around the area where the eggs are laid, they can be easily controlled by dusting with 2 per cent Methyl parathion dust at the rate of 20 kg per hectare. For well grown nymphs and adults, spraying with 0.04 per cent carbaryl (Sevin) at the rate of 500 to Boo litres per hectare proves effective.

Myllocerus

Myllocerus is a greyish weevil pest which attack the crop throughout the season. It is, however, very serious in the early seedling stage and can destroy the whole field in epidemic form. For the control of Myllocerus, 2 per cent Methyl parathion dust at the rate of 20-25 kg per hectare should be used. In the areas where this pest and termite are regular feature, the above insecticides should be mixed in soil before sowing.

Cut Worm

The larvae of this pest cut the seedlings at the ground level. Caterpillars are grey in colour. They live in soil during day and feed at night. The adults of cut worm may be trapped on light source and may be killed later. Dusting of 2 per cent Methyl parathion (Folidol) dust at the base of the plant at the rate of 20-25 kg per hectare will control the pest.

White Grub

This pest is very serious in sandy soils. The larvae are white C-shaped and feed on the roots of the plants. In areas where it is a problem, damage may result in complete failure of crop. For controlling white grub, Phorate (Thimet) 10 per cent granules at the rate of 15 kg per hectare or Carbofuran (Furadan) 3 per cent granules at the rate of 30 kg per hectare should be mixed in the soil before sowing.