AGRICULTURE AND IRRIGATION

PESTS OF CROPS

Of cereals: Jowar: Stem-borer, ' khodkida' (Chilo zonellus, Swinh): The caterpillars are dirty white with many spots on the body and with a brown head. The full-grown caterpillar measures about to inch in length. The moths are straw-coloured with fore-wings pale yellowish grey having minute dots on the apical margin and white hind-wings.

The caterpillars bore inside the stems causing thereby drying of the central shoots called ' dead hearts'. The stems also become red. Besides kharif and rabi jowar, the pest affects maize. Being an internal feeder only preventive and mechanical measures are found practicable and economic. They include pulling out the affected plants and also the stubbles after harvest and burning them to destroy the hibernating larvae.

Stem fly, khod mashi (Atherigona indica) : Its maggots feed inside the stems of young plants and cause ' dead hearts '. The adults are comparable to house-flies but are very much smaller in size and on their dorsal side, there are a few dark spots.

As the pest is an internal feeder, mechanical methods, though laborious, have been found to be more useful. They consist of removing the affected seedlings and destroying the larvae and increasing seed-rate to make up the loss. For hybrid varieties which are more susceptible to the pest, the chemical control measures such as soil application of 10 per cent phorate granules at the rate of 7 kg. per acre prior to sowing, and if phorate is not available four sprayings with 0.05 per cent endrin at 10 days interval starting from 7 days after germination could be applied with advantage.

Army worms, lashkari alya (cirphis unipuncta) : The full-grown caterpillars are 1 to 1 inches long, smooth-bodied, dull greenish coloured with broad light coloured stripes running along its length on either side of the body. They are found in the central whorl of plants or may remain under stubbles. The moths are of two types. One type of moth is brownish red with prominent spots on the anterior margin of the wings. The hind wings are pale in the middle with dark borders. The other type of moth is dusky brown. A pest called swarming caterpillar which is a little darker and with longitudinal bands is also known to infest jowar. Besides jowar, the pest affects maize, bajri, paddy and other cereals.

The caterpillars feed on leaves mostly at night, while during the day they remain hidden in the whorl or in the clods under-ground. They migrate from one field to another like an army and hence the pest is called ' army worms'. The disease can be controlled by adopting such measures as collection of egg masses and their destruction, deep ploughing of the infested fields after the harvest of the crop to expose the hibernating pupae, and dusting the crop with 10 kg. of 10 per cent BHC or spraying it with 0.2 per cent BHC.

Bajri: Blister beetle, hinge or bale (Zonabris pustulata): The beetles are black with yellowish brown stripes across their wings and over an inch long and about half an inch thick. When crushed on the human body, it causes a blister and hence it is called blister beetle. The beetles feed on the pollen and petals of flowers and thus reduce the setting of grains. The pest also affects jowar, cucurbits and beans. It can effectively be controlled by dusting 5 per cent BHC at the rate of 20 lb. per acre. The beetles can also be collected and destroyed.

Wheat: Pink borer, khod kida (Semamia inferens, Wlk): The caterpillar is fleshy in colour and smooth with dark spots on the body. Each spot bears a hair. A full-grown caterpillar measures about 2.5 cm. in length. Moths are small having straw-coloured fore-wings with a marginal dark line and white hind-wings. Besides wheat, they affect maize and sugarcane. The young larva bores into the stem causing the death of the central shoot. The caterpillars migrate from one plant to another. As the pest is an internal feeder preventive measures like removal of the affected plants and destruction of the larvae, and removal of stubbles after the harvest of the crop and their destruction may help to minimise the pest infestation.

Of pulses: Gram: Pod-borer, ghatyatil ali (Heliothis armigera) : The moths are stout, light yellowish brown, with a wing expanse of 3.7 cm. The fore-wings are pale brown with some black dots and the hind-wings are lighter in colour with smoky dark margins. The caterpillars are greenish with darker broken grey lines along the sides of the body. They are 3.7 to 5 cm. in length when full-grown. They feed on tender foliage and young pods. They make holes in the pods and eat the developing seeds by inserting the anterior half portion of their body inside the pods. Besides gram, the pest affects cotton. tomato, peas, tobacco, ganja, safflower etc.

The pest can effectively be controlled by spraying the crop with 0.1 per cent carbaryl or 0.06 per cent isobenzan or 0.2 per cent DDT or 0.03 per cent endrin at the rate of 250 litres per acre. The preventive measures such as picking of caterpillars during initial stages of attack would help in reducing the future infestation and ploughing the field after the harvest of crop would destroy the pupae.

Tur: Pod-caterpillar, pisari patang or turichya shengatil ali (Exelaster atomosa): The moths are slender, not more than 12 mm. in length and are grey with long, narrow wings. The front wings are divided into two parts and the hind-wings are cut into three parts and provided with a fringe-like border. The full-grown caterpillar is about 12 mm. in length, greenish brown in colour and is fringed with short hair and spines. The caterpillars bore into green pods and feed on the developing seeds. The pest also affects wal.

Spraying the crop with 0.2 per cent DDT at 250 litres per acre or dusting it with 1 per cent telodrin or endrin or 5 per cent BHC per acre have proved effective in controlling the pest. The preventive measures such as collection of the infested pods and their destruction during the early stages of attack and avoiding leguminous crops consequently in the same field also help in controlling the pest.

Pod fly, shengatil mashi (Agromyza obtusa): Newly-hatched larva is white with dark brown mouth-parts. A fine brownish stripe runs along the entire mid-dorsal line of body. Full grown larva is creamy white measuring 3.5 to 4 mm. in length and 1.25 to 1.5 mm. in breadth. Adult flies are glossy black with pubescent eyes and strong legs with femur slightly thickened. Young larvae enter soft seeds and feed on them. At first the damage resembles that of leaf miners as their galleries run just under the epidermis of seed. Later they burrow deep down resulting in decaying of the grains which become unfit for either consumption or germination. As high as 80 per cent of the pods and 63 per cent of the grains may be damaged. In advance cases of damage, the pods present a twisted appearance. The adult flies can be killed by spraying the crop with 0.2 per cent DDT or 0.02 per cent endrin at the rate of 300 litres per acre. Removal of affected pods of first brood during winter also helps to reduce the population of the pest.

Pod bug, shengavaril dheknya (Clavigralla gibbosa): The adult bugs are about 12 mm. in length, greenish brown in colour, having a spined pronotum and swollen femur at the apical end. Both the nymphs and adults suck the sap from pods and cause the infested pods to shrivel. The pest can be controlled by spraying the crop with 5 per cent BHC powder at the rate of 8 kg. per acre. The preventive measures mentioned in the case of the pod caterpillar may be adopted with advantage.

Of oil-seeds: Ground-nut: Aphids, mava (Aphis craccivora, Koch): They are small, black, soft-bodied insects found on the lower side of leaves. The pest reduces the vitality and yield of plants by sucking the sap and also acts as the vector of a serious virus disease commonly known as ' rosette' of ground-nut. The pest can be controlled by spraying the crop with 10 per cent BHC at 15 to 20 lb. per acre. It is necessary to mix equal quantity of sulphur which besides preventing the incidence of mites keeps tikka disease under check. The crop may also be sprayed with other insecticides such as 0.05 per cent malathion, 0.02 per cent thiometon and 0.03 per cent formothion.

Sesamum : Gall fly, pili or kane (Aspondylia sesami) : The adult is like a small delicate mosquito. It is legless in its larval stage. The larva remains inside the gall. The maggots cause gall formation inside the flower-buds and interfere with the process of pod formation. The buds therefore wither without bearing fruit. Insecticidal measures are not yet worked out. Hence, only preventive measures such as destroying the growth of stray plants and also the infested buds could be resorted to.

Sphinx moth, pane khanari ali (Acherontia styx): The moth is large with a dark grey, bluish thorax. The abdomen is yellow with black bands. The fore-wings are dark brown. The full-fed larva is 90 mm. in length and stout, with a rough skin and with an anal born at the abdominal end. It is light greenish in colour and has eight yellow stripes on its body. The caterpillar feeds extensively on leaves. As the caterpillar is very large hand-picking can be practised with success. The pest can also be controlled by dusting the crop with 5 per cent BHC.

Safflower: Aphids, mava (Dactynotus Compositae theb): Both winged and wingless forms are common, the former being noticed especially in the beginning or towards the maturity of the crop. An adult is a shining black, soft-bodied insect measuring about 1.5 to 2 mm. in length. In case of winged insects, the wings are thin and transparent and are held like a roof over the body. The nymphs are smaller in size and are reddish brown in colour.

Nymphs as well as adults suck the cell-sap from the lower surface of the leaves and tender shoots and impair the vitality of the plant. The insects also excrete a honey-dew like substance which attracts a black sooty mould that adversely affects the photosynthesis. The pest can be controlled by spraying the crop with nicotine sulphate ( kg. of 40 per cent emulsion in 350 litres of water plus 2 kg. of soap) or pyrethrum emulsion (1: 800) or fish oil rosin soap ( kg. in 40 litres of water) or 10 per cent BHC at 8 to 10 kg. per acre. However, the recent experiments of dusting the crop with 5 per cent malathion and 2 per cent methyl parathion proved more effective.

Of cotton: Boll worms are of three types, viz., spotted boll worms (Earias fabia S. E. insulana B), hipkyanchi bond ali; pink boll worms (Pectinophora gossypiella S), shendri bond ali; and Heliothis sp. The adults of the spotted boll worms have pale white upper wings with a greenish band in the middle while the pink boll worms have the upper wings completely greenish. The caterpillars of both the species, however, are brownish white and have a dark head and prothoracic shield. They have a number of black and brown spots on the body and hence the name. The full-fed larva measures about ," in length. The moth of pink boll worm is about " across wings and dark brown in colour. The caterpillars, when full-grown, measure " in length and are pink in colour with a brown head. The moths of heliothis are light yellowish brown with a wing expanse of 1.5 inches The fore-wings are pale brown with some black dots and hind-wings are lighter in colour with smoky dark margins. The caterpillars are greenish with darker broken lines along the sides of the body.

The caterpillars of spotted boll worms first bore into the growing shoots of the plants and later on into bolls. The infested buds and bolls are shed but if they remain on the plant, they open prematurely. Unlike the spotted boll worms, the caterpillars of the pink boll worms never attack the shoots. They feed inside the bolls and make them drop down. The pest is more harmful to American cotton varieties than Indian ones. As the caterpillars bore the bolls, the entrance holes get closed and it becomes difficult to spot out the affected bolls until such bolls drop down, or open prematurely. Newly-hatched larvae of heliothis initially feed on the leaves and enter into growing shoots and this internal feeding causes the drying of the growing shoots. In case of heavy infestation, the caterpillars also feed on the bolls.

The boll worms being internal feeders are extremely difficult to control. Therefore, to keep their incidence under check, both preventive and curative measures are necessary.

Preventive measures include removal and destruction of cotton stalks, shed bolls, and other plant debris after the last picking, avoiding growing of bhendi and other malvaceous crops during off-season which serve as alternate hosts of the pest and fumigation of seed with carbon di-sulphide at 1 oz. per 15 cubic feet space or heating the seed to 145 F. to kill the hibernating larvae of pink boll worms. For uprooting the cotton stalks, plant-pullers devised by the Agriculture Department can be used.

The pest can also be effectively controlled by giving six sprays of 0.03 to 0.04 per cent endrin plus sulphur (1:1) or 0.2 per cent carbaryl plus sulphur mixture (1:1) or 1 kg. of 50 per cent carbaryl plus 1 kg. of wettable sulphur in 300 litres of water at fortnightly interval starting from 8 to 10 weeks after sowing an irrigated cotton. In case of unirrigated cotton, three dustings with 10 per cent carbaryl at 15 days' interval starting from 8 weeks after sowing are found quite useful.

Red cotton bug, tambadi dhekni (Dysdercus cingulatus Fabr): The adult is about half an inch long and bright red in colour. A series of white transverse bands are present on the ventral side of their abdomen. The nymphs resemble the adults in colour but are wingless. Both, adults and nymphs, suck plant-sap and greatly impair the vitality of the plant. They also feed on the seeds and reduce their oil-content. Due to the excreta of these insects, the lint gets spoiled. The adults and nymphs can be collected in large number by shaking in a tray containing kerosene oil and water. The pest can also be controlled by dusting the crop with a mixture of 10 per cent BHC plus 10 per cent DDT.

Jassids, tudtude (Empoasca devastens Dist.): The adult is wedge-shaped about 2 mm. long and pale green in colour. The front wings have a black spot on their posterior parts. The nymphs are wingless and are found in large numbers on the lower surface of leaves. They walk diagonally. Both the nymphs and adults suck the cell-sap from the leaves as a result of which the leaf margins turn yellowish and in case of excessive infestation reddening and drying up of leaves followed by stunted growth are seen. For controlling the pest 5 per cent DDT dust at 8 to 10 kg. per acre in case of Asiatic cotton varieties and 5 per cent DDT plus sulphur dust mixture in case of American cotton varieties were recommended in the past. However, in recent years treatments with 0.02 per cent endrin plus sulphur (1:1) (300 c.c. of 20 per cent E. C. endrin in 300 litres of water plus 300 gm. of wettable sulphur) and phosphamidon, methyl demeton, thiometon, dimethoate, parathion and diazinon at 0.02 per cent concentration have also been found effective against the pest.

Aphids, mava (Aphis gossypii Glover): The adult is about 1 mm. long, dark yellowish green in colour and has two projections on the dorsal side of the abdomen. It is mostly found in the wingless stage. The nymphs and adults suck the cell-sap from leaves due to which the leaves turn yellowish and dry. The pest can be effectively controlled by spraying the crop with nicotine sulphate at the rate of one pound in 80 gallons of water with five pounds of soap. About 80 to 100 gallons of spray are required per acre. 2 ozs. to 4 ozs. of endrin or 0.01 to 0.02 per cent parathion per acre are also effective against the cotton aphids.

Mites, mati (Eriophes gossypii Bank): Its larva is flesh coloured with three pairs of legs. The adults are minute creatures with an oval body and four pairs of legs. They are usually found on the lower surface of leaves. Both nymphs and adults feed on the lower surface of leaves as a result of which they become silvery white and ultimately dry. In case of severe infestation complete defoliation of plants is caused. The pest can be effectively controlled by spraying the crop with 0.05 per cent aramite, 0.03 per cent dichlorobenzilate (akar), 0.02 per cent parathion or 0.2 per cent sulphur.

Of sugarcane: Stem-borer, khod ali (Chilotraea infuscatellus Sn): The adult moth is greyish brown or straw-coloured and measures about 1, inches when its wings are spread out. The newly-hatched larva is greyish in colour having a dark head and translucent body with spots and hair. The tiny spots develop into spines later. A fully-developed larva measures about 1 inches and is greyish white in colour. The pest is mainly injurious to young cane. The caterpillars enter the plants from the side at ground level by making holes in the stalk and may bore either downwards or upwards or both ways causing ' dead hearts '.

Top shoot borer, shenda ali (Scirpophaga nivella, F.): Its moth is creamy white in colour having a wing span of a little over an inch when spread out and with orange hair-like structures at the tip of the abdomen of a female. The first pair of wings of certain males has a single black spot on each wing. Fully-developed caterpillars measure about 1 to 1 inches in length and are yellowish white in colour. This is a very serious pest of sugarcane. It breeds throughout the year and is capable of attacking cane at a later stage. The newly-hatched caterpillar enters first the mid-rib of the leaf and bores downwards into the shoots from top. The central shoot, therefore, dries up in characteristic way, which later results in giving off side-shoots, which form a bunchy top.

Both the borers being internal feeders are extremely difficult to control. Both preventive and curative measures are necessary to keep them under check. Mechanical and cultural methods of control include collection and destruction of egg-masses, removal of infested plants, early earthing up of canes, changing the planting time to November or December in the case of cane plant and to August or September for adsali cane, planting of sets in deep trenches, etc. The pest can also be effectively controlled by spraying the crop with 0.3 per cent DDT three times when it is 4, 6 and 9 weeks old. The application of insecticides like 0.05 to 0.2 per cent endrin and 0.25 per cent BHC have been observed to be quite effective against the pests.

Leaf hopper or pyrilla, tudtude (Pyrilla sp): The adult pyrilla bug is a straw-coloured insect with two pairs of wings, folded roof shaped on the back and with its head extended like a pointed beak which is quite readily visible. The young nymphs that hatch out from the eggs are pale brown in colour having a pair of long characteristic processes covered by wax. They are active and are found in large numbers on cane. Both the nymphs and adult bugs suck the sap of cane-leaves from the lower surface as a result of which the leaves lose turgidity, begin to wither and ultimately get dried up. The bugs secrete a honeydew-like substance that spreads on the leaves on which a black fungus develops. The pest thus reduces the sucrose content of the juice.

The pest can be effectively controlled by dusting the crop with 5 per cent BHC at the rate of 15 kg. and 20 kg. per acre in the pre-monsoon and post-monsoon periods, respectively. Spraying 0.12 to 0.25 per cent BHC or DDT at the rate of 300 litres per acre for young cane during the pre-monsoon period and over 400 litres during post-monsoon period gives considerable relief. Similarly application of 0.02 per cent endrin effectively controls the pest.

Of citrus fruits: Lemon butterfly, pane khanari ali (Papilio demoleus L): The adult is a beautiful butterfly with yellow and black markings on wings, which have an expanse of about 2 to 2 inches. The young caterpillar is darkish brown in colour with irregular whitish stains. When full-grown, it turns deep green in colour and cylindrical in form and measures about 1 inches in length with a hump-like appearance in front. The caterpillars usually feed on tender leaves right up to the mid-rib and thus defoliate the plants. The pest can be controlled by spraying the crop with 0.2 per cent DDT or 0.02 per cent endrin (1 kilo 50 per cent W P of DDT in 250 litres of water or 250 millilitres of 20 per cent endrin E. C. in 250 litres of water).

White fly, pandhari mashi (Dialeurodes citri R and E): The adult is a minute insect measuring about mm. in length having white or greyish wings, a yellowish body and red medially-constricted eyes. The nymphs and adults suck the sap from leaves as a result of which the leaves wither and later turn brownish and fruit-setting is affected. The nymphs also excrete a honey-dew which attracts fungus which in turn gives the tree a blackish appearance. Before the advent of modern insecticides, the pest was controlled reasonably well by spraying the crop twice with rosin compound at an interval of a week. Now, the pest can be effectively controlled by spraying the crop with 0.02 per cent endrin or 0.02 per cent parathion (250 ml. of 20 per cent endrin E. C. in 250 litres of water or 100 ml. of 50 per cent parathion in 250 litres of water).

Of vegetables: Of brinjal: Shoot and fruit borer, shendyatil or phalatil ali (Leucinodus arbonalis G): The moths are of medium size and have whitish wings with large brown patches all over the body. The head and thorax are blackish brown. The caterpillars are pale white about 12 mm. long when full-grown. The caterpillars bore into the stem and riddle it and eat the internal tissues and thus cause the plants to wither. When the shoots are infested they bend down and wither. They attack fruits when they are young and leave no signs of infestation. The large holes seen on fruits are usually the exit-holes of the caterpillars. The affected shoots and fruits should be removed and destroyed. Continuous cropping of brinjal and potato in the same field should be avoided. The pest can also be checked by spraying the crop with 1 per cent DDT or 0.08 per cent endrin three and six weeks after transplanting of seedlings.

Of chilli: Thrips, murdya, or bokadya (Anaphothrips dorsalis) : The adults are minute delicate insects, about 1 mm. in length and are light yellow in colour. These insects have mouth-parts suited for scraping the epidermis of leaves and sucking the oozing sap. The plant tissues damaged by insects initially become whitish but later turn brown and ultimately dry. The leaves curl and become small, such symptoms are locally known as murda or bokadya. The pest can be effectively controlled by spraying the crop with 0.2 per cent DDT or 0.02 per cent endrin or telodrin, methyl etc.

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