Maize larva feeding on male flower
Agriculture Biodiversity

The invasive pest fall armyworm is devastating Tamil Nadu Maize fields

During the Village Stay Programme arranged by our college, we spotted the new invasive pest fall armyworm in Maize fields of Namakkal. Control measures were taken under the guidance of Mr. Mohan, Agricultural Officer (AO) of Namagiripettai  in one of one farmer’s field (Venkatesh Thumpalpatti, Namagiripettai). Initially pyralidin was sprayed to control the pest. Fifty per cent reduction of pest was observed.

Later soil application was tried; it controlled the pest to feed on the central stem of Maize. Then we participated in demo program on control of invasive pest in Kariyampatti village near Mullukurichi and made awareness to nearby villages.

Maize Damaged leaf whorl by Fall armyworm
Maize -Damaged leaf whorl

 

This new invasive pest on maize, Fall armyworm (Spodoptera frugiperda) is a devastating pest of maize crop. It is a native of South America and has been spread into Africa a couple of years back, which has threatened the food security of African countries. This pest has recently spread into India causing huge loss to maize farmers. It was first identified in Karnataka State during the month of May’2018 and now spread into Tamil Nadu mainly in the maize growing areas.

Maize larva feeding on male flower
Maize- Larva feed on male flower

Life cycle of the pest

Like most Lepidopteran insects, this pest also has four life stages viz. Egg, Larva, Pupa and Adult. An adult female moth can lay upto thousand eggs, usually on immature plants. Egg hatches between 3rd – 5th day and the larva grows upto 14-22 days, which involve 6 molts. On maturation the larva crawls down to pupate in the soil. It remains in the pupal stage for 7-14 days. Adult moth lives upto 11-14 days.

Maize -Egg Mass of Fall Armyworm
Egg mass of Fall Armyworm

The total life cycle completes within 30 days during summer and goes upto 60 days during spring/autumn and during winter, its life span goes upto 80-90 days.

Maize Fall Armyworm (Spodoptera frugipedra)
Maize Fall Armyworm

 

Damage Symptoms on the plant

Larvae feed on lower surface of the leaves gregariously. It scarps the chlorophyll content. Third and fourth instar larvae damage the inner portion of leaves and cut the central whorl and make it into pieces. Parallel shot holes on the newly emerged leaves and excreta are observed.

Management of  Spreading Fall Armyworm 

Spray pyridine to obtain fifty percent control of the pest. Later cultural methods like dusting of soil, rock dust, charcoal powder, wood ash, agniasthra, salt and spraying of Ipomoea solution, green chili solution and waste decomposer can be done.

Application of soil slurry in the leaf whorl will give best results. Apply thick slurry of soil into the leaf whorl. The next day, larval excreta could not be seen indicating that larvae cease feeding and it will die in next three to four days. Meanwhile, the affected whorl will recover fast and emerge quickly.

This slurry method of managing Fall armyworm gives multiple benefits, as it is cheap, economical and eco-friendly.

Biological control: Bacillus thuringiensis or NPV (Nuclear Polyhedrosis Virus) @ 2ml per litre will effectively control the pest.

Fall armyworm develops resistance against most insecticides and thus chemical control didn’t yield better results. Also, understanding the residual and other harmful effects of chemicals, farmers start moving to organic pest control methods such as trap crops, intercrop with Cassava and Beans, bio-controls, insect repellents like Neem oil, Neem Seed Kernel Extract (NSKE), ginger garlic extract and Dasakaviya etc. Soil/soil slurry application in the leaf whorl proves to be effective and eco-friendly. 

Sharvankumar. P, Final year B.Sc (Agriculture) is a student of Imayam Institute of Agriculture and Technology (IIAT), Thuraiyur. He shared his experience to IMoT Agri Forum as a part of his RAWE program. And he was guided by Dr. B. Guna Assistant Professor (Agricultural Extension) of the college.

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