Sorghum shoot fly (Atherigona soccata) is one of the most destructive insect pests of sorghum.
It causes significant losses at seedling stage of the crop. Adults resemble small houseflies.
Hosts
The main host is the Sorghum.
Alternative hosts include Maize, Finger millet, Bullrush millet, Rice, Wheat, among other grass species.
Life Cycle
The female lays/ deposits whitish eggs singly on the central surface of the leaves, usually on the underside. The eggs hatch in 1-3 days and the maggots which are yellow in colour migrate to the dorsal surface of the leaf, enter the space between the leaf sheath and the axis and make a clean cut at the base of the leaf. The growing point of the plant dies and decays on which the maggots feed. The larval period lasts for 6-12 days. Pupation takes place in the base of the dead shoot, but sometimes in the soil, and the period takes about 7 days, after which adults emerge.
Each female fly is capable of laying 30 eggs during its life time.
Life cycle is completed within 17-20 days.
This pest is found throughout the year when hosts are available at the right stage.
Identification
The eggs are whitish, have an elongate shape, and measure about 0.8 x 0.2 mm
The fully grown larva is 8-10 mm long and has a white or yellowish colour.
The adult fly is about 4 mm long and looks like a small house fly. Head and thorax of the female are pale grey and the abdomen is yellowish with paired brown patches. Males are more blackish.
Feeding & Damage Symptoms
The larva migrates to the upper side of the leaf, and moves along the leaf whorl till it reaches the growing point. It first makes an incision at the growing point, and as a result, the central leaf begins to dry up. The larva feeds on the decaying tissue of the central leaf inside the shoot causing the production of deadheart. Such symptoms are evident 2-3 days after infestation.
Plants of 5-30 days old are the most susceptible to shoot fly damage. However, under conditions of high humidity during the rainy season, shoot fly infestation may occur in older plants, but the infested plants do not produce the typical deadheart symptoms. The damaged leaf becomes thin and papery, and wraps around the other leaves. As a result, the plants may fail to grow normally.
Late infestations may also damage the panicle in the formative stage, resulting in rotting or drying up of a portion of the panicle affected by shoot fly damage.
Shoot fly-damaged plants also produce axillary tillers, which often serve as a means of recovery for the plant unless the tillers are not exposed to another spell of shoot fly-infestation in the susceptible stage.
When a “deadheart” is plucked, it releases an obnoxious smell.
Control
Chemical control method
The following insecticides are recommended for use against shoot fly.
- KINGCODE ELITE 50EC 10ml/20l
- LEXUS 247SC 8ml/20l
- PENTAGON 50EC 10ml/20l
- PRESENTO 200SP 5g/20l
- BACIGUARD 16WDG 15g/20l
- SINOPHATE 750SP 20g/20l
- EPITOME ELITE 500SP 10g/20l
- ESCORT 19EC 10ml/20l
- LEGACY 50EC 15ml/20l
- PROFILE 440EC 30ml/20l
- TRUMPET 200SC 15ml/20l
Note
- Whenever spraying any insecticide, it is highly advisable to mix it with INTEGRA 3ml/20l, which helps to improve the efficacy of the insecticide. It is a sticker, spreader and penetrant.
- Timely application of the insecticide is very critical for effective control of shoot fly.
- In order to prevent the pest from gaining resistance over any of the insecticides, several of them should be alternated throughout the crop’s season instead of using only one.
Non-chemical methods
- Early sowing.
Use of shoot fly resistant varieties - Use of natural enemies like parasitic wasps and several species of spiders which feed on their eggs.
- Collect and destroy crop residues after harvest to reduce carry-over from one season to the other.
- Proper weed control
- Maintenance of field hygiene/ sanitation
- Rotations with non-host crops
