Jowar Shoot Fly & Jowar Stem Borer – Pests of Jowar
A. Jowar Shoot Fly
Scientific Name: Atherigona soccata Rond.
Class & Order: Anthomyidae – Diptera
Economic Importance: It is one of the serious pests of sorghum in India. The Pest attacks the crop only in early stage of growth and infestation goes up to 80%. The high yielding hybrids are more susceptible to the attack of this fly. The total loss in yield is sometimes as high as 60%. The pest is very serious on kharif and Rabi crops in Maharashtra State.
Marks of Identification: Adult fly is dark grey, like the common house fly but much smaller in size, 6 & 4 dark spots on abdominal segments of female & male respectively (arranged in rows of two) Maggot are legless, tapering towards head, pale yellow, small ( 10- 12 mm in length ).
Host plants: Jowar and grasses like Andropogan sorghum, Cynodon dactylon and Panicum spp.
Life history: Eggs: Eggs are average 40 eggs are laid by a female singly on lower surface of leaves & tender stem. Incubation period is of 2-3 days. Larva: larval period 10 to 12 days. Four larval instars are present. Pupa: Pupation in stem. Pupal period is about a week. Adult longevity is 12-1 4 days. Life cycle completes in 2-3 weeks. Several generations in a year. Carry over -The pest over winters in adult stage on grasses.
Seasonal occurrence: The insect attacks the seedlings and late sown crops are attacked badly. The attack is severe during July to October. Cloudy weather favours multiplication of the insect. In rabi, early sown crop suffers more and hence sowing should be delayed possibly
Nature of Damage: Maggots on hatching from the eggs bore into the central shoots of seedlings and kill the growing point, producing "dead hearts". They feed on the decaying core of the shoots. Subsequently on death of central shoot, plant gives out tillers and plant gets bushy appearance.
Sow the crop as early as possible i.e. immediately after the onset of rains or within 15 days after receiving of rains. Increase the seed rate to make up the loss.
- Use the seeds treated with carbofuran 50 SP @ 5% a.i. by wt. of seed (Gum Arabic as sticker) or carbosulfan 25 STD @ 200 gm / kg of seed OR 3% carbofuran granuals @ 5 kgs /50 kgs of seed by using slurry of wheat flour as sticker. OR Application of phorate 10 gm @ 10 Kg / ha in soil at sowing OR Spray the crop with 0.05% endosulfan soon as 10% seedlings are infested or 1 egg / 10seedlings are noticed.
- Removal and destruction of affected shoots along with the larvae.
- Use resistant (Maldandi 35-1) or less susceptible varieties like R.S. V.9 R (Swati), S.P. V86 for planting.
B. Jowar Stem Borer
Scientific Name: Chilo partellus S.
Class & Order: Pyralidae – Lepidoptera
Economic Importance: It is one of the major pests of Jowar and has a wide distribution. The infestation is noticed till harvest and the grown up plants when damaged loose their vigour and put forth week ears. The infestation is more pronounced on rabi and hot weather crops.
Marks of Identification: Moths – medium sized, straw coloured, yellowish grey forewings. The hind wings are whitish. Caterpillar – ditty white, brown head, many dark spots on the body, 12- 20 mm in length.
Host plants: Although principle hosts are Jowar and maize, it has also been recorded on Sugarcane, Ragi and certain grasses.
Life history: Eggs – about 300 eggs are laid, on leaves in clusters, incubation period about 6 days larval period: 3-4 weeks. Pupa: pupation in stem. Pupal period 7-10 days. Before pupation larva prepare a hole on stem at ground level for the moth to escape / come out. Adult longevity 2-4 days
Life cycle: completed in 6-7 weeks. About 4-5 generations are completed in a year.
Carry Over: The pest hibernates in the larval stage in stubbles. Seasonal occurrence: The pest is generally active from July to November. The infestation is more on rabi & summer crops.
Nature of damage: On hatching from the eggs, the larvae initially feed on tender leaf whorls causing series of holes in the leaf lamina and later bore into the stems, feed on the central shoots causing their death, commonly known as “dead hearts”
Management Practices: Preventive and curative measures.
Collection and destruction of stubbles after the harvest of crop to kill hibernating larvae
Increase the seed rate to compensate the loss.
Follow proper crop rotation (with non host crop).
Use of light traps.
Removal & destruction of affected shoots along with the larvae.
Spraying with 0.05% endosulfan or 0.2%carbaryl OR whorl application of endosulfan 4G @ 10kg/ha, when 10% plants are infested.