Jowar Stem Borer: Overview
Jowar Stem Borer
Class – Insecta
Order – Lepidoptera
Family – Pyralidae
Genus – Chilo
Species – zonellus = partellus (Swinhoe)
- Jowar is Maharashtra’s most important staple food crop. Aside from being a staple food crop for the people, it also provides excellent fodder for cattle.
- It is grown in Kharif, Rabi, and in hot weather.
- One of the most serious jowar pests is the jowar stem borer. This pest is typically observed during the crop’s early growth and even after the formation of the earhead.
- This pest is active all year, but it is more noticeable on rabi and hot weather crops. This pest is more prevalent in hybrid varieties.
It occurs throughout India. The jowar stem borer is commonly called a spotted stalk borer or pink borer.
- The adult moth is a medium-sized insect with wingspan of 3 cm. It has straw or light brown forewings with numerous shining brown spots on the margin, and white and paper hindwings.
- Caterpillars (Larvae) are dirty white in colour with a dark brown head and mandibulate mouthparts. On the body, numerous dark spots have appeared.
- Mature caterpillars have four broad and patchy stripes on their bodies and are about 12-20 mm long.
This is primarily a jowar and maize pest, but it has also been observed on bajra, ragi, and other grasses.
- During the months of April and May, a female lays 50-300 eggs in clusters arranged in two rows on the underside of the leaves. The colour of eggs is creamy white. They hatch into young caterpillars after about six days of incubation.
- For a few days, the young caterpillar feeds on tender leaves before boring into the central shoot. The larval stage lasts about 3-4 weeks and has five moults. Pupation occurs within the stem and lasts approximately 7-10 days.
- The adult has a lifespan of 2-4 days. The pest is typically active from June to November, with four generations completed each year.
- During unfavourable periods, the pest hibernates in stubbles as a larva.
Nature of Damage:
- Caterpillars that have just hatched feed on the leaves, causing numerous small holes in the leaf lamina, and then attack all parts of the jowar plant except the roots.
- When the larvae enter the leaf, they whorl and cut it, leaving characteristic pin holes, shoot holes, and longitudinal streaks.
- When the growing point is cut, the central shoot dries out, resulting in the formation of dead-heart.
- The larvae feed on the tissues (pith) after entering the stem, forming tunnels or galleries.
(i)Handpicking or light trapping of adult moths and collection of their eggs for destruction.
(ii) Burning of stubbles and trash, which harbour borers and serve as a source of infestation for the next crop.
(iii) Changing the sowing and harvesting timings reduce infestation.
(iv) Crop rotation is another cultural practice that does not allow the pest of one crop to survive next year for lack of its host.
(v) Growing resistant varieties of jowar like CHS-7, CHS-8, Indian sorghum types IS-5566, 5285 and 5613.
(i) For the Chilo on jowar a spray of 0.05% lindane or 0.1% endosulfan on 15 days old plants has been found effective. This may be followed after another fortnight with a second application of 1.0% lindane or 4% endosulfan granules. A third application with 0.2% carbaryl spray may be carried out, if found necessary.
(ii) If the crop infestation is noticed, dusting of crop in the early stage with 10% BHC at the rate of 25 kg per hectare or spraying the crop with 350-400 ml of aldrin or dieldrin in 200 litres of water helps to control the pest.
(i) The hymenopteran, Trichogramma minutum is employed as an egg parasite.
(ii) Apanteles flavipes and Bracon brevicornis as larval parasites.
(iii) The lady beetles, Coccinella septempunctata and Menochilus.
(iv) Sexmaculata have been recorded predating on early stages of the larvae of this pest.