Fall Army Worm: A Devastating Pest Of Sorghum

Spodoptera frugiperda, commonly known as the Fall Armyworm (FAW) is one of the most important invasive pests worldwide, causing considerable losses to its host crops. It is considered to be a serious pest which feeds on more than 80 crop species. Next to maize, sorghum is the most affected crop by fall armyworm. It is a major pest of sorghum crops and can cause severe damage to the crop if not controlled in time. In this article, we will explore the different methods of integrated pest management that can be used to control sorghum fall army worms. 

The life cycle of a fall armyworm consists of four stages: egg, larva, pupa and adult. The larva or nymphal stage is the most damaging stage of the pest. Initially larvae are green in color, but as they grow, they become brown with longitudinal stripes. Inverted “Y” shaped marking can be seen on the face of the mature larva. Cool, wet and spring weather favours the growth and development of fall armyworm. 

Type of Infestation

Sorghum army worm infestation can be classified into two types: sporadic and epidemic. Sporadic infestations occur in isolated areas and are generally not widespread. Epidemic infestations, on the other hand, are widespread and can cause significant damage to the crop by feeding on all parts of the plant. 

Scientific Name: Spodoptera frugiperda 

Most Affected States

The pest is found throughout the country, but the most affected states are Andhra Pradesh, Karnataka, Maharashtra, Tamil Nadu and Telangana.  

Symptoms of Sorghum Fall Army Worm

The damaging symptoms of Sorghum army worm infestation are as follows:  

• Elongated papery windows: Initially larvae of sorghum fall armyworm feeds on leaf tissues, leaving only a thin translucent layer of tissue intact known as window feeding.
• Ragged edged leaves: As the larva grows, its feeding habits result in the development of ragged edged holes on the leaves that vary in shape from round to oblong.
• The larvae of sorghum FAW excrete a large amount of frass, which can accumulate on the leaves.
• Severe infestation of sorghum fall armyworm can result in defoliation.
• They can also damage the reproductive parts of the sorghum plant.

Control Measures

A combination of different control measures is often important to effectively manage fall armyworm infestation in sorghum plants. The following are some of the commonly used IPM practices for controlling fall armyworm, 

Cultural Measures

• Deep summer ploughing of fields exposes larvae and pupa of sorghum fall armyworm, which are located in the soil, to birds and high temperatures.
• Crop rotation with non-host crops helps to reduce the fall armyworm population.
• Early planting can avoid peak populations of sorghum fall armyworm.
• Removing the weeds and other debris can reduce the incidence of armyworms.
• Harvesting early can avoid consistent damage.
• Proper nutrition management, including balanced fertilization and irrigation can also help to reduce the susceptibility of sorghum plants to fall armyworm attacks.

Physical Measures

• Light Traps play a major role in trapping adult fall armyworm insects. Install Farmoguard Solar Light Trap in the sorghum fields at the rate of one per acre.

Mechanical Measures

• Handpicking and destroying egg masses and larvae by crushing or immersing in kerosene water can reduce FAW damage.
• After the detection of FAW infestation in the field, the affected sorghum plants can be treated by applying dry sand to the affected whorl.
• Tapas Fall Armyworm (FAW) Lure can be used to attract and trap insects. Install Funnel trap with FAW lure at a rate of 15 per hectare for effective trapping.

Biological Measures

• Release egg parasitoids like Trichogramma pretiosum or Telenomus remus at the rate of 50,000 per acre at weekly intervals to control the fall armyworm population.
• Erect bird perches to encourage insectivorous birds.
• Apply Econeem Plus Bio pesticide containing Azadirachtin at the rate of 3ml per litre as oviposition deterrent on one week after sowing.
• Katyayani Organic Larvicide contains Bacillus thuringiensis which produces protein that blocks the digestive system of the insect and kills them. The recommended dosage is 10ml per liter of water.
• Anand Dr. Bacto’s Brave is an ecofriendly biological insecticide containing Beauveria bassiana which effectively controls fall armyworms. The recommended dosage is 2.5ml per liter of water.

Chemical Measures

Chemical measures include the application of commercial insecticides to control sorghum fall armyworm. Insecticides that can be used to control fall armyworm are mentioned below, 

Product Name	Technical Content	Dosage
Coragen Insecticide	Chlorantraniliprole 18.5% SC	0.4 ml/lit of water
Delegate Insecticide	Spinetoram 11.7% SC	0.9 ml/lit of water
EM 1 Insecticide	Emamectin Benzoate 5% SG	0.4-0.5 gm/lit of water
Greenovate Maheru Insecticide	Lambda cyhalothrin 9.5% + Thiamethoxam 12.6% ZC	0.5 ml/lit of water
Starclaim Insecticide	Emamectin benzoate 5% SG	0.5 gm/lit of water
Plethora Insecticide	Novaluron 5.25% + Indoxacarb 4.5% w/w SC	2 ml/lit of water
Ampligo Insecticide	Chlorantraniliprole (10 %) + Lambdacyhalothrin (5%) ZC	0.4-0.5 ml/lit of water

Note: Poison Baiting can effectively kill late instar larvae. To prepare the bait, a mixture of 10 kg of rice bran and 2 kg of jaggery should be left to ferment in 2-3 litres of water for 24 hours. Half an hour before application in the field, 100 g of Thiodicarb should be added to the mixture. The bait should then be applied to the whorl of the plants.