CHENNAI: The State government is waging a ‘war’ against fall armyworm (Spodoptera frugiperda), an invasive pest from the United States which has been wreaking havoc in farmlands in the State with maize crops as its main target.
The State Agriculture Department, which has been conducting awareness programmes among farmers about the measures to control this pest, has drawn up a multi-pronged strategy to do away with this problem.
Armyworm, a deadly invasive pest spread to countries including Brazil, Argentina and Africa, was observed in maize varieties in June last, in Karnataka, and around six months ago, it spread to Karur in Tamil Nadu. Though the Agriculture Department took early preventive measures and advised the farmers accordingly, the spread has increased.
“Sometime ago, the pest was noticed in one lakh hectares of maize. But now due to various measures taken, the infestation has been brought down to around 50,000 hectares. We are working on a war-footing to root out this pest with multiple strategies and by providing relevant pesticides free of cost to the farmers. For this purpose, Rs 4 crore has been sanctioned,” Agriculture department officials told Express.
The government will be supplying pheromone traps free of cost to maize cultivating farmers in 30,000 hectares, besides, Entomopathogenic Fungai, namely, Metarhizium anisopliae WP, a bio-control agent for maize crop cultivated in 20,000 hectares. Block Assistant Director of Agriculture may be contacted for any further clarification.
When asked why the infestation had increased, the officials explained that the sudden changes of climate atmosphere during the recent months, became conducive to the breeding of this pest. It seems to multiply at a faster rate during the winter season and during intermittent rainy days.“It is a nocturnal pest.
During the daytime, it hides itself in the stems of the crop and comes out only after 6 pm. This is also another impediment in controlling this pest. However, we have designed appropriate strategies to eliminate this,” the officials added.
The officials pointed out that Armyworm is under control in Tamil Nadu, compared to states such as Andhra Pradesh, Telangana, Maharashtra, Bihar, and Assam.
Now this invasive pest is noticed primarily in maize crop in the districts of Perambalur, Ariyalur, Cuddalore, Vellore, Villupuram, Tiruchy, Dindigul, Madurai, Virudhunagar, Thoothukudi, Tirunelveli, Coimbatore, Tirupur and Salem.
The Armyworm attacks the emerging leaf whorl of a 15-day-old crop. Due to its feeding habit, the leaves are found with small and big round-shaped holes or sometimes, with holes of irregular shape which are aligned in a straight line. This pest also attacks tips and shank of the corn.
“Among the various strategies, the government is planning to use bio-control methods to eliminate this invasive pest, i.e., by releasing predator insects such as Trichogramma chilonis which eats this Armyworm. Besides, numerous awareness programmes are being conducted among the farmers about this method to control this pest,” the officials said.
Measures to control armyworm:
Deep summer ploughing to expose the pupae of Armyworm to sunlight and avian predators thereby, thus curtailing the chances of emergence of the next brood of this insect that may attack the next crop/maize crop during the next season.
Application of neem cake at 50 kg per hectare in soil at the time of final ploughing to reduce the emergence of adults from pupae.
Seed treatment with Beauveria bassiana @ 10 gram per kg of seed or Imidacloprid 70 WS or Thiamethoxam 70 WS @ 10 gram per kg of seed.
Adopting spacing of 60 x 25 cm for irrigated maize and 45 = 20 cm for rainfed maize. Closer planting always facilitates quick movement or spread of the larvae from one plant to other.
A rogue spacing of 75 cm for every 10 rows of maize is recommended, mainly to facilitate easy access for spraying or plant protection operations during cob formation and maturity stages of maize crop.
Use of solar light trap/battery rechargeable light trap/ordinary incandescent or fluorescent bulb fitted over a wide pot or bowel containing kerosene mixed water, is recommended at 2 to 3 traps per hectare at random just above the crop canopy in the length and breadth of the field.
Cultivation of short duration varieties of cowpea, sunflower, gingelly, sorghum and marigold as border crop to attract, conserve and enhance the activity of natural enemies of this pest like parasitoids and predators.
As the smell of Desmodium Triflorum (Siruullati in Tamil) plant could repel adult moths of armyworm, cultivation of this as intercrop in maize is suggested. Similarly, the smell of Brachiaria could attract adults in Armyworms. So, it can be planted as border crop.
Manual collection of destruction of egg mass found on the upper surface of the leaves near the inner whorl. Also manual killing of various stages larvae of Armyworm also useful.