Learn about how to control pests of sugarcane!
1. Sugarcane Leaf Hopper:
Pyrilla Perpusilla Walk. (Homoptera- Fulgoridae):
This is a serious pest of sugarcane and it prefers the board leaved succulent variety as the food plant. Both the adults and nymphs are voracious feeders which ingest the sap from the underside of leaves. This results in the shrivelling and drying up of the leaves. A serious attack affects the quality and yield of the crop and the sucrose content is reduced to 50% and Gur becomes tasteless.
The adult hopper is normally dull yellow in colour with a head produced anteriorly into an upwardly turned snout. The two pairs of wings are folded and rest over the back, a characteristic feature of Homoptera.
The female lays greenish yellow eggs about 300-530 in clusters on the lower surface of leaves or in leaf-sheaths or on stem. The number of eggs in each cluster vary from 20-60. All these eggs are covered over with white cottony waxy filamentous threads as a safeguard from parasite attack. Hatching occurs in about 7-29 days depending on temperature and pale brown nymphs are released.
These are covered on their anal processes with waxy filaments. The nymphs undergo five moults after which fully developed adult individuals are formed. The entire life cycle takes about 46-59 days. In a year, the first brood crops up in April to June, the 2nd in July to September and the 3rd in September to November.
Occasionally mechanical control by collection and destruction of eggs between fingers on the leaves or by burning is applied. Adaptation of biological control through the medium of certain Hymenopterous parasites and the larvae of certain coccinellides is another successful measure of lowering the pests incidents. Chemical control involves the use of endosulfan or dimethoate or fenitrothion 0.025% spray or malathion 50 EC or endosulfan 35 EC @ 1.25 litres/ha in 1000 litres of water.
2. Sugarcane White Fly:
Aleurolobus Barodensis Mask. (Homoptera- Aleurodidae):
It is quite a serious pest damaging atleast 50% of the crop from July to November. The insects which are generally found on the lower surface or on the apices of the unopen leaves desap the plant, bringing down their vigour and turn them sticky and pale. As in Pyrilla, a heavy infestation reduces the sucrose content of the plant. The adults are active creatures with prominent black eyes and a pair of mealy white wing.
The female deposits dull brown or orange eggs in a line near the mid ribs or in any part of the lower surface of leaves during winter.
The number of eggs laid vary from 60-65; the eggs have a broad pedunculated base and a pointed tip. They are found in groups of 15- 20. They hatch in about a week or so into dull yellow nymphs. In course of time the colour of nymphs changes to shiny black. The locomotory legs of the nymphs which are functional for a short duration atrophy immediately after the first moulting, and the insect fixes itself to some point on a leaf and remains there till it completes its life history.
There are usually four instars after which the nymph enters into a “pupal” stage, an unusual features in the metamorphosis of Hemiptera-Homoptera lasting about 10-15 days. Finally the pupa transforms into the adult whitefly which lives 24-48 hours only. The whole life cycle occupies 25-55 days. This pest is very active from August onwards. There are several generations in a year.
Both mechanical and biological controls are commonly employed. The pest can be controlled by spraying the crop with malathion 0.1% or endosulfan 35 EC or monocrotophos 40 EC @ 1.5 litres/ha mixed with 800 litres of water.
3. Sugarcane Top Shoot Borer:
Scirpophaga nivella Fabr. (Lepidoptera: Pyralididae):
It is a major pest of sugarcane attacking the crop at all stages of growth and causing a heavy damage in July and August. The larva usually attacks the top-shoots of the cane and hence is known as ‘top shoot borer’. This results in the curling and drying up of leaves and formation of spiral structures known as dead-hearts. The adult insect is a silvery white moth with dark black eyes and tufts of yellow, orange, brown or red hairs over the anal segment in females.
The female lays 60-80 eggs, oval or elongate in shape, in 5 – 8 clusters on the underside of leaves. Hatching occurs in about 6-12 days and very small shiny caterpillars are released. Immediately after emergence, these caterpillars start attacking the rolled up leaves. Gradually they bore into the mid rib of an upper unfold leaf and enter the terminal shoot through the rolled base of the top leaves.
The entire larval period in this manner is passed either on leaves or on top shoots and in about 22 days the larva becomes full grown possessing a creamy white colour with dark streaks and a few scattered hairs all over the body. It is in this larval stage characteristic tunnels are made inside the terminal shoots.
The cavity thus formed is lined with silken threads secreted by larva. It is in this cavity the larva changes into a pupa and remains in this condition for 7-11 days. At the end of this period the adult moth emerges. The whole life cycle takes about 40-50 days but varies when conditions become unfavourable. The pest completes 4 to 5 generations in a year.
Control:
As in the case of other pests, both mechanical and biological controls are employed. Biological control is brought about by the introduction of Hymenopteran parasites like a Braconid wasp or a Chalcid wasp e.g. Trichogramma minutum. Spraying the crop with 1.5 litres of endosulfan 35 EC or monocrotophos 40 EC mixed in 1000 litres of water on leaf whorl from the top is very effective.
4. Sugarcane Root Borer:
Emmalocera Depressella Swinh. (Lepidoptera- Pyralididae):
The greatest amount of damage is caused by the caterpillars. The attack is confined to the base of the newly formed stem. Presence of the dead hearts or dry central shoot among the young cane is the first symptom of this pest. The damage done by root borer is very characteristic because the caterpillar enters at the base of the stem, close to the surface soil.
These borers are confined to base of the shoot which is bored across sideways or round about. On pulling the whole of the affected shoot or even the entire cane breaks exposing the caterpillars. In grown up canes, they may bore the thick roots but seldom attack the base. Damage is serious from the end of April to the end of September or middle of October.
The young canes die and the older ones dry up and fall down. Sugar contents are greatly reduced. The moth is cryptically coloured hence cannot be easily detected even in worst infested, fields. The female moth measures about 30-35 mm. along wing expanse. The hinder wings are shorter and wider having a dark longitudinal stripe.
Creamy white, scale like flattened eggs are laid singly or in groups on leaves and stems in the first week of May. A female lays as many as 277-355 eggs. Young larvae hatch out in about 4-8 days which are 2 mm. long with yellow body and yellowish brown head. They bore the base of the young seedlings, getting entrance through sides near or below the surface of the soil.
They are confined to the new stems where they grow, and fully mature larva measures about 30 mm. in length with a creamy white wrinkled body with brown head. The larval duration is about 30-50 days. The borer when left underground, attacks other side shoots and plants. The caterpillar is active in cane from the time, the cane is three weeks to a month old.
Before pupation the caterpillars come up above the ground level in the stem, makes an exit hole in the form of silken tube which reaches the surface of the soil. The pupae are reddish brown in colour. Pupal stage lasts about 9-14 days. They hibernate in winter months in the larval stage in roots. The complete life cycle takes about 56-69 days. There are about 4 generations in a year.
Prompt removal of dead hearts is quite effective and the moth can be destroyed by light traps. Ratooning should be avoided by burning the stubble in the fields. Chemical control is very difficult. However, spraying 1.5 litres of endosulfan 35 EC or monocrotophos (Nuvacron) 40 EC in 600 litres of water when eggs or moths are visible in the field, controls the pest.
5. Sugarcane Mealy Bug:
Saccharicoccus Sacchari (Cockerell) (Homoptera- Coccidae):
A large number of mealy bugs are seen clustered at the basal nodes of the sugarcanes and are exposed when a leaf sheath is removed. Nymphs and the wingless female adults cause damage by sucking the cell sap. They are inert pink insect which have a rotund sac like segmented body covered all over with a white mealy powder. The size among the full grown females varies to a great deal but large female measures about 5 mm. in length and 2.5 mm. in width. The male are sluggish, have one pair of wings and short lived and harmless.
The pest breeds throughout the year and lays a large number of eggs at short intervals. The eggs are very small yellowish smooth, cylindrical and rounded at both the ends and measure 0.35 mm. in length and 0.16 mm in width. Within a few hours the crawlers emerge. The tiny young ones are pinkish in colour and very active. On finding a suitable host plant they force themselves below the leaf sheaths near the basal node.
As the canes grow taller, the older bugs remain at the lower end and the crawlers reach the higher nodes. Nymphs feed voraciously and pass through 6 stages before they are full grown in 2-3 weeks. The life of a full grown female is approximately 3-5 days. The entire life cycle is completed in about a month during summer. The pest completes several generation in a year.
The pests can be controlled by spraying the crop with malathion 0.05% or diazinon 0.03%.
6. Sugarcane Black Bug:
Cavelerius Excavatus (Dist.) (Heteroptera- Lygaeidae):
The black bug is distributed throughout India. In addition to sugar cane, as with many pests, it has also been recorded feeding on rice, maize, wheat, jowar and grasses. The damage is caused by both the adults as well as nymphs which suck the cell sap. The leaves become chlorotic, bearing brown patches. The tips and the margins of the leaves start drying up gradually. In severe infestation the whole plant may wither. Further, as a result of heavy infestation the quality of juice is also severely affected.
The insect breeds throughout the year but very common in winter. In summer, each bug lays 55-478 eggs in groups or clusters on the inner side of the leaf sheaths of the sugarcane. Each cluster may contain 14-67 or more eggs. The eggs are creamy white in colour which hatch in about 9-11 days during summer and in about 3-5 months during the winter. The nymphs passes through 5 instars and complete their development in about 4-10 weeks depending on the climatic conditions. The adult bugs are black in colour and about 6-7 mm. long.
The wings are provided with white patches which extend beyond the abdomen. The insects complete about 3 generations in a year. Adults have a long life. Males may live for 4-7 months while the females live for 4-8 months. In winter eggs are laid in the soil about 5-7 cm. below the surface near the plant base which hatch during next spring. Thus in the spring season, the new nymphs and old adults are seen feeding side by side.
The pest can be controlled by spraying the crop with malathion 0.05%. Spraying should be directed from the top to down, towards the central whorl and the leaf sheath. Similarly, spraying endosulfan 35 EC or monocrotophos 40 EC @ 2 litres/ha mixed in 800-1000 litres of water is effective to control the pest. Furthermore, burning of the stubbles has also been found to be very useful in controlling the pest population.