AGRICULTURE AND IRRIGATION

PESTS

Agricultural production suffers heavily due to various pests and diseases. A detailed account of the major pests and diseases of important crops in the district is given in what follows. The loss due to different pests in the district cannot be generalised as the damage done by pests depends upon the severity of infestation in any particular year. The remedial measures suggested against different pests described below are such as may be adopted by the cultivators at minimum cost.

Jowar is generally affected by pests such as, stem borer, army worms, deccan wingless grasshopper, flea beetle and aphids. The nauue and extent of damage caused by these pests and their various control measures are given below.

Of Jowar.

Stem-borer (Chilo zonellus).—The caterpillars with dark spots on the body bore into the stems and feed on the whorl causing dead hearts. Moths come out of pupae in 7 to 10 days' time. They are aciive from June to November. Kharif jowar suffers most. The pest being internal feeder, it could be checked by preventive methods only. The affected plants are pulled out and destroyed. After the harvest of the crop the stubbles are collected and burnt so as to destroy the hibernating larvae.

Army Worms (Cirphis imipuncta).—The caterpillars are dull greenish coloured with broad light.coloured stripes running along its length on either side of the body and feed on tender leaves mostly at night. Generally they migrate from one field to another and defoliate the plants. The pest assumes epidemic form when there is a long break in rains after an initial good start and remains active from June to November.

Five per cent BHC dust at the rate of 13.608 kg. (30 lbs.) per acre, which is generally broadcast in the evening, controls the pest. The ploughing of the infested fields after the harvest of the crop also helps much to expose pupae.

The Dcecan Wingless Grasshopper" (Colemania Sphenaroides).— The wingless nymphs and adults feed on leaves and often completely devour them. They remain active during the period from June to December. Dusting 10 per cent BHC at the rate of 9.072 kg. (20 lbs.) per acre controls the pest effectively. Ploughing the land after the harvest of the crop also helps to control the pest.

The pests, surface grasshopper and jowar stem fly, which damage jowar and other millets, are very similar to the deccan wingless grasshopper and the jowar stem.borer respectively. They can be controlled in the same way as the deccan wingless grasshopper and jowar stem.borer are controlled. The flea beetles which feed on the middle part of the leaves can be controlled by 10 per cent BHC dusting.

Aphids which remain stationary mostly on the lower surface of leaves, suck the sap of leaves and secrete sugary substance causing sugary disease. Spraying with nicotine sulphate 1 lb. in 363.680 litres (80 gallons) of water with 2.268 kg. (5 lbs.) soap or 2 to 4 ozs. endrin per acre can effectively control the pest.

Of Bajri.

Blistei Beetle (Lytla sp) (Hinge or Bali).—.The black adult insects with yellowish brown stripes across their wings secrete an acid substance from their body and when crushed on the human body, it causes a blister. They reduce the setting of grains. The pest is active from August to December and can be effectively controlled by 5 per cent BHC dust at the rate of 9.072 kg. (20 lbs.) per acre.

The pests, viz., the deccan wingless grasshopper, the surface grasshopper and army worms also damage Bajri crop. The nature and extent of damage due to these pests and their controlling measures are the same as accounted under jowar.

Of Groundnut.

Aphid.—The pest aphid damages groundnut. It can be controlled by dusting 10 per cent BHC, spraying of 0.16 per cent DDT or spraying of 40 per cent Nicotine sulphate..

Pod-sucking.—Bugs infest young pods and suck the juice. 5 per cent BHC dusting may be tried when the bugs are noticed on the plants.

Of Wheat.

White ants (Termes sp.) valavi, are whitish yellow, soft bodied, Hat insects with mouth parts suited for chewing or biting purpose. The workers of the pest feed on the roots of the plants as a result of which the affected plants die off. They cut and tunnel into plants, wood, timber and reduce the material to powder. The pest can be controlled by fumigating the termitoria with carbondisulphide and chloroform mixture or petrol or methyl bromide.

Of Gram.

The gram-pod-borer.—The caterpillars feed on tender foliage and young pods. They make holes in the pods and eat the developing seeds. The pest is active from November to March.

It can be controlled by 0.2 per cent DDT spray obtained by diluting 1 lb. of 50 per cent water-dispersible DDT powder in 113.650 litres (25 gallons) of water. About 272.760 to 363.680 litres (60 to 80 gallons) on a young crop and 454.600 litres (100 gallons) on a grown.up crop are generally required. Thorough ploughing after harvesting the crop also helps to control the pest.

Of Paddy.

The Stem-borer (Schoenabins bipunctifer).—The caterpillars are pale, yellowish white and smooth, and are about 25.4 mm. (1") long when full-grown with the head having orange.yellow colour. They bore into the stems of paddy plants with the result that empty earheads are produced.

The pest can be controlled by preventive measures only, as the same is an internal feeder. These include (i) collection and destruction of stubbles after the harvest, (ii) removal and destruction of the affected plants showing whitish shoots or dead hearts. The crop is also affected by army worms. This pest is controlled by the same measures as detailed under jowar an my worms.

Paddy Grasshopper (Hieroglyphus banian fb.).—.The adults are uniformly greenish without spots, with the hind tibia coloured blue. Immediately behind the head on the prothorax, of Paddy it has 2 to 3 dark black streaks. Both nymphs and adults eat the foliage of plants and also feed on the developing earheads of paddy and other crops. If the pest occurs annually, it is best to plough the fields and crush the egg masses by clod-crushing with a heavy plank during April and May. The pest is successfully controlled by dusting 5 per cent BHC powder at the rate of 9.072 to 11.339 kg. (20 to 25 lbs.) per acre.

Paddy blue beetle (Leptispa pygmoea) weet.—Beetles feed on leaves and green shoots of the young paddy crop with the result that the plants turn white and dry up. The infestation generally takes place before flowering. The pest can be checked by dusting 5 per cent BHC dust at the rate of 6.804 to 9.072 kg. (15 to 20 lbs.) per acre.

Paddy Gall Fly (Puchydiplosis oryzae) Kane.—The pest gets access to the growing bud, lacerates the tender tissues and thus spoils the bud which cannot produce the normal stem to bear an carhead or leaves. Infestation is highest during the tillering stage of paddy. The pest is active from July to November The 'silver shoots" and alternate hosts like grass on which the pest breeds should be removed.

Rice Hispa (Hispa asmigera) Karpa.—The pest creates patches on leaves which ultimately turn white and dry up. This pest many times appears along with the paddy blue beetle and can he readily controlled by 5 per cent BHC dust used for blue beetle control.

Rice-Earhead Bugs (Leptocorisa acuta).—These suck the juice from milky grains which as a result become shrivelled. The pest can be controlled by dusting with 5 per cent BHC dust at the rate of 6.804 to 9.072 kg. (15 to 20 lbs.) per acre.

In addition to these pests of paddy there are other minor pests such as rice case worm, rice skipper, crabs, leaf hopper, paddy leaf roller, etc.

Of Sugarcane.

Sugarcane Stem.borer (Argyria stiticraspis).—The cater. pillars enter the plants from the side at ground level by making holes in the stalk and bore with the result that the central  shoot dries  up,  causing "dead hearts". The control measures are as follows: —

(1) The affected plants having "dead hearts" should be removed, (2) Ratooning of cane should be avoided, (3) Ploughing the fields and burning the stubbles also help to check the pest.

Sugarcane top shoot borer (Scirpohaga nivella and S. mono stigma).—The punctures on the leaves, the death of the central shoot and the bunchy top are the characteristics of this pest.

Sugarcane Grasshopper.—The details and the controlling measures of the pest are the same as described under paddy.

Sugarcane Leaf.hoppers (Pyrilla).—The bugs suck the sap of cane leaves from the lower surface. The leaves then get dried up. The damaged leaves look pale, sickly and turn black due to the growth of black fungus on them.

Dusting the crop with 5 per cent BHC at the rate of 13.608 to 18.144 kg. (30 to 40 lbs.) and 22.679 to 27.215 kg. (50 to 60 lbs.) per acre in the pre and post monsoon periods respectively destroys the pest. The removal of pachat of the infested crop also helps in controlling the pest.

Of Cotton

Spotted Boll-worm (Earis fabia) Bond ali.—The caterpillars attack buds as well as bolls and stain the lint. The infested buds and bolls are mostly shed, hut if they remain on the plant, they open prematurely. The pest is active throughout the year. Removal of stubbles and destruction of affected shoots and malvaccous weeds are the feasible methods to control the pest.

Pink Boll-worm also affects buds and bolls. The caterpillars feed inside the bolls and make them drop down. The pest can be controlled by fumigating the cotton seeds with carbon.di. sulphide at the rate of 1 oz. to 15 c.ft. The destruction of infested bolls also helps to check the pest.

Cotton Jassid (Tudtude).—The nymphs and adults pierce the plant tissues and suck the cell sap. The pest is active during the monsoon season. Dusting 5 per cent DDT mixed with an equal quantity of sulphur effectively controls the pest.

Cotton Thrips.—The insects suck the oozing cell sap. The pest is more active from August to October. It can be easily controlled,by DDT, BHC or nicotine sulphate. 5 % DDT should be used in admixture with sulphur in the proportion of 1:1. Nicotine sulphate can be used at 1 part in 600 parts of water with 1.814 kg. (4 lbs.) of soap.

Cotton Aphid (Mava).—The damage caused by these insects is somewhat similar to that caused by cotton jassids. The pest can be effectively controlled by spraying it with nicotine sulphate at the rate of 0.454 kg. (1 lb.) in 363.680 litres (80 gallons) of water with 2.268 kg. (5 lbs.) of soap. DDT should be avoided.

Cotton Leaf Roller.—The caterpillars roll up the leaves, and feed from the margin while remaining hidden. Dusting the crop with 5% BHC or 5% DDT effectively controls the pest. The rolled-up leaves should be removed.

Red cotton bug and dusky cotton bug, are of minor importance and can be controlled by dusting of 5°/₀ BHC.

Of Chilli.

Chilli crop is generally affected by the chilli thrips. The infected leaves curl up and symptoms locally known as "murda" appear. They suck the sap of the leaves and stem, causing reduction in size. Spraying with tobacco decoction helps to check the pest.

Tobacco, though the source of nicotine used for insect control, is also infested by insects.

Of Tobacco.

Tobacco Leaf-eating caterpillars.—The caterpillars feed on tender leaves and juicy stems at night.

Insectkidal measures include dusting with calcium arsenate at the rate of ten to fifteen lbs. per acre. After the harvest of the crop the land should be ploughed so as to expose pupae.

Stem borer.—The caterpillars are small and brownish.white in colour with a dark head and are about half an inch long when full.grown. They bore into stems and cause gall like swelling. on them. The plants throw out a bushy growth. The affected siems should be removed.

Cut worm. (Agrotis).—The caterpillars are active during the night. They cut the young plants at the ground level and feed on tender leaves and shoots.

The pest is controlled by the use of poison baits of 5% paris green or benzene hexachloride.

Surface Grasshopper.—They eat leaves and tender shoots of plants. The pest can be controlled by 5% BHC dust at the rate of 9.072 kg. (20 lbs.) per acre and poison bait at the rate of 13.608 to 22.679 kg. (30 to 50 lbs.)"per acre.

White Fly.—The nymphs and adults suck the sap from leaves, which thus turn brownish and affect fruit.setting. The nymphs also secrete a honey.dew which attracts fungus which in turn gives the tree blackish appearance. The pest can he controlled successfully by two applications of good spray of rosin compound at an interval of a week.

Aphid (Mava).—The aphids are tiny, black, soft bodied insects and feed on stems and young shoots by sucking the sap from the tender parts of plants.

Spraying the crop with nicotine sulphate in the proportion of 1 oz. of nicotine into 22.730 litres (5 gallons) of water with 4 oz. of soap gives a good measure of control. 181.840 to 272.760 litres (40 to 60 gallons) of such spray per acre are required. Nearly two to three sprayings at weekly intervals are required during late December or early January.

Of Safflower.

This is one of the most important commercial oilseed crops in the district. The following insects cause damage to it.

Aphid.—The nature of damage and controlling measures are the same as described under tobacco.

Leaf-eating caterpillar.—The caterpillars are green when young and then turn darkish brown. During the early stages of the crop, they eat leaves and cause defoliation. The plants can be dusted with 5 per cent BHC at the rate of 6.803 to 9.072 kg. (15 to 20 lbs.) per acre.

Of Maize.

Pink borer.—The damage done by the pest and the controlling measures are the same as described under jowar. The other pests, viz., army worms, the deccan wingless grasshopper, the banded grasshopper, the surface grasshopper, which damage the crop are described in detail under jowar.

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