AGRICULTURE AND IRRIGATION

PESTS

A brief account of various pests of crops in the district is given in the following paragraphs. The extent of damage caused by them cannot be gauged accurately as it depends upon the severity of infestation in the year of attack. Remedial measures mentioned against different pests are such as are within the means of the average cultivator.

Of Cereals.

Chilo Zonellus , Swinh.

Jowar stem borer (Chilo Zonellus, Swinh) causes considerable damage to summer jowar, which is frequently found heavily infested by this pest. Caterpillars bore inside the stems. This causes drying of central shoots, known as 'dead hearts'. This results in reddening of leaves and stems, the extent of damage being four or five per cent.

The period of activity of this pest is from June to November. Young caterpillars bore into the stems where they remain for three-four weeks. Their pupal period varies between seven and ten days while their life cycle extends over five-six weeks. As stem borers are internal feeders, only preventive measures, noted below, are found practicable and economic-

1. The affected plants bearing caterpillars inside the steins are pulled out and destroyed promptly.

2. After harvest, the stubbles of crop are collected and burnt to destroy the hibernating larvae.

3. The jowar fodder is cut into small pieces before it is served to cattle.

Sesamia Inferena Wlk.

Wheat stem borer (Sesamia inferena Wlk.) is a pest which causes damage to rabi crop of wheat. It also affects maize in dry weather. The caterpillar bores inside the stem. Thereby the central shoot dries up forming 'dead hearts'. This pest is sporadic in nature and causes minor damage. On hatching, the young caterpillars enter the stems and start boring. As this pest also is an internal feeder, the control measures discussed above in respect of jowar stem borer (Chilo Zonellus, Swinh) are identically applicable here also.

Termites or White ants.

Insects termites or white ants are polymorphic. The host plant of this insect is polyphagus. The workers feed on the roots of the plants as a result of which the affected plants die off. At the advent of monsoons, a few members from the colony possess wings and leave their nests for a flight. After a short flight, the wings break off and pairing and mating takes place. The female (queen) settles in burrow. She establishes a new colony and lays eggs rapidly. The newly hatched nymphs are fed by royal parents till they develop into workers.

Effective control measures include locating the termitoria. digging it out, collecting the queen and eggs and destroying them.

Of Pulses. Heliothis (armigera) obsolata.

Gram pod borer known as Heliothis (armigera) obsolata damages the gram crop. Cotton, tomato, peas, tobacco, saffower, opium, etc. are also its principal host plants, The caterpillars feed on tender foliage and young pods. They make holes in the pods and eat the developing seeds. This pest is active from November to March.

Caterpillars are handpicked and destroyed in the first stage of infestation as a preventive measure. Thorough ploughing after harvesting the crop is also resorted to in order to expose pupae. Spraying the crop with two per cent D.D.T. spray obtained by diluting 0.453 kg. (1 lb.) of 50 per cent water dispersible D.D.T. powder in 113.65 litres (25 gallons) of water; 277.76 (Sixty) to 363.68 Litres (eighty gallons) of spray is sufficient for a young crop and a 454.60 Litres (hundred gallons) for grown-up crops.

Exelustes atomosa.

Tur plume moth (Exelustes atomosa) affects crops of tur and wal. Full grown caterpillars bore into green pods and feed on developing seeds. On hatching, they scrape the surface of pods, gradually cut holes, feed on seed and become full-grown in about four weeks.

Preventive measures include collection of caterpillars, by shaking shoots and pods, in small trays containing a mixture of kerosene and water. Similarly, leguminous crops are not taken in the same fields during successive years, Insecticidal control measures mentioned under 'gram pod borer' [Heliothis (armigera) obsolata] may also be tried with advantage.

Of Groundnut.

Aphids.

Aphids is an important pest which reduces the vitality and yield of plants by sucking the sap. It also acts as the vector of a serious virus disease commonly known as 'Resette' of groundnut. This pest is of sporadic occurrence in most parts of the State except in Jalgaon and Dhulia districts.

The following control measures are adopted to check the pest:-

1. Spraying the crop with nicotine sulphate in the proportion of one ounce of nicotine into 22.73 Litres (five gallons) of water with 0.113 kg. (four ounces) of soap. This is a good measure of control. The total quantity of spray required per hectare is 454.60 to 681.89 Litres (100 to 151 gallons) at a time. Nearly two to three sprayings at weekly intervals are required during late December or early January.

2. Spraying the crop with pyrocolloid in the proportion of one ounce pyrocolloid in 22.73 Litres (five gallons) of water. This also gives good results. About 454.60 to 568.25 Litres (100 to 125 gallons) of spray is required to spray one hectare of cropped land.

Of Cotton,

 Boll worm.

Boll worm, a pest of cotton, is of two types viz., spotted boll worm (Earias Fabia S. L. insulana B) and pink boll worm (Pectinophora gossypiella, S.). The caterpillars of the spotted bell worms bore into the growing shoots of the plants in the initial stage of the crop. Later on, when flower buds appear, the larvae bore into them and enter bolls by making holes which are plugged by them with excreta. Infested buds and bolls are shed but they remain on the plant. Bolls open prematurely as a result of which lint of inferior quality is produced. Such lint naturally fetches low price in the market.

Unlike the spotted boll worms, the caterpillars of the pink boll worms never attack shoots but feed inside the bolls and cause them to drop down. The pest is more harmful to American cotton varieties than to Indian ones. They bore holes and plug them. Thus it becomes difficult to spot out the affected bolls until they drop down.

The following are the main measures of controlling this pest: -

1. Removal and destruction of stubbles to check carryover of the pest to the next season.

2. Destruction of all malvaceous plants growing in off season which serve as alternate bests for the pest.

3. Fumigation of seed before sowing with carbon-di-sulphide at the rate of 0.057 kg. (two ounces) per 425 cubic metres (15 cubic feet) or heating the seed at 145F. to destroy hibernating pink boll larvae.

4. Quick removal and destruction of affected parts of plants in the early stage of pest incidence.

5. Six dustings with a mixture of 10 per cent D.D.T., two per cent lindane and 40 per cent sulphur or with one per cent endrin dust.

6. Six sprayings, at fortnightly intervals with endrin at the rate of 0.425 kg, (six ounces) per 0.405 hectare (acre) commencing from a month prior to flowering. Sulphur is added to this mixture in equal quantity to avoid subsequent mite incidence.

Dysdercus singulatus Febr.

Red cotton bug (Dysdercus singulatus Fabr.) is another minor pest of cotton. Like cotton, it also affects bhendi (lady's finger) crop.

Adults and nymphs suck plant sap and greatly impair the vitality of the plant. Besides, they also feed on seeds and lower their oil content. Lint is soiled by the excreta of these insects. The infected seeds become useless for sowing.

Two measures may be mentioned for controlling the pest, viz., (1) Adults and nymphs can be collected in large numbers by shaking them in a tray containing a mixture of water and a small quantity of kerosene. (2) In case the pest is serious, which rarely happens, the crop may be treated with five per cent Benzene Hexachloride.

Empoasaca devastans, Dist.

Jassids (Empoasaca devastans, Dist.) cause considerable damage to cotton. Both the nymphs and adults suck the cell sap from the leaves as a result of which leaves turn yellowish at the margins. When the infestation is excessive, etiolation and drying up of leaves take place. This is followed by stunted growth of plants. Besides affecting the cotton crop it also causes damage to bhendi (lady's finger), brinjal and potato. The extent of jassid infestation on Asiatic varieties is less due to their relative resistance to jassid attack. Wingless nymphs of this pest are found in large numbers on the lower surface of leaves. The pest is active particularly during the monsoon season.

Spraying the crop with five per cent D.D. T. at the rate of 16.783 to 22.68 kg. per hectare (15 to 20 lbs.) is found effective. However, the use of D.D.T. alone is undesirable as many a time it leads to excessive increase in aphid or mite population.  Hence, sulphur is mixed with D.D.T. Hut the mixture of D.D.T. and sulphur is not sprayed on Indian or Asiatic cotton as sulphur scorches these varieties severely. This mixture can be safely sprayed on American varieties which are also prone to jassid attack. A combined 0.2 per cent spray of 50 per cent water dispersible D.D.T. and sulphur (also water dispersible) is very effective against jassid attack. A cheaper and equally effective mixture consists of 0.01 per cent to 0.02 per cent parathion. Spray of 0.057 kg. to 0.113 kg. (two ounces to four ounces) of endrin is also resorted to.

Aphids Gossypii,Glover.

Aphids (Aphids gossypii, Glover) is another pest of cotton. The nymphs and adults of this pest suck the cell sap from the leaves due to which leaves turn yellowish and dry. It has been found that a spray of nicotine sulphate at the rate of 0.453 kg. (one pound) in 363.68 Litres (80 gallons) of water mixed with 2.268 kg. (five pounds) of soap is quite effective. A spray of pyrethrum extract in the proportion of one part in 1,000 parts of water also gives satisfactory result. The method of spraying the crop with fish oil rosin soap at the rate of 0.227 kg. (eight ounces) in 18.18 Litres (four gallons) of water is also resorted to. A hectare of land can be sprayed with 909.19 to 1136.49 Litres (200 to 252 gallons) of this spray.

Of Chillis.

Thrips and Mites.

Thrips and mites are the pests of chillis. These pests suck the cell sap due to which the leaves get badly curled. This symptom is locally known as Churda Murda disease. Thrips and mites are considered major pests since they cause damage to the extent of about 25 per cent.

Spraying the crop with two per cent Benzene Hexachloride with sulphur (wettable) is found to give very effective control.

Of citrus Fruits.

Indarbela quadrinota.

Citrus shoot and bark borer known as Indarbela quadrinota causes damage to guava, citrus, pomegranate, mango and rasuarina. The bark and stems of these host plants are bored by the freshly hatched larvae. As a result of this, the trees put on a sickly appearance and ultimately wither. Presence of this pest can be readily detected by the appearance of frass covered areas on the hark.

Injecting the borer solution containing two parts of carbon-di-sulphide with one part each of chloroform and creosote helps to control the larvae of the borer. However, due care has to be taken to scrape off gallaries and webbings and to ascertain the live burrows before injecting the solution.

Of Citrus Fruits,

Othreis sp.

Fruit-sucking moth known as othreis sp. is another important pest of citrus fruits. Moths generally puncture rinds of all varieties of citrus. However, in this region it particularly causes serious damage to grapes and sweet-oranges. The moths cause direct damage to citrus fruits. Part of the fruit on which the moths feed themselves is exposed to bacterial attack which causes the fruit to rot early.

This pest is very difficult to control. Insecticides do not help control the adults of moths. Therefore, bagging of fruits is at present the only reliable method of control. Moths are also attracted to fermented poison baits and to torch light. They are thus detected and killed. The damage caused by the pest can be reduced by removing the hosts of caterpillars.

Citrus psylla.

In addition to the pests of citrus fruits described so far. recently the outbreak of the pest citrus psylla (Diaphornia citria) has been recorded in this region. Eggs are laid inside the folded leaves of the buds, in leaf axils or similar other suitable places on the tender parts of plants. Both the nymphs and adults suck the juice from the tender leaves and buds. When the pest is severe, it results in non-setting of the fruit. It causes damage to fruit of "Mrig Bahar" between July and August and to "Ambia Bahar" between January and March. The estimated damage is placed at 15 per cent.

Tobacco decoction, resin compound or crude oil emulsion help control the pest. Cultural methods to increase the vigour of the plants should also be practised since they help ward off the damage.

In addition to damage done by pests, various diseases of crops also inflict considerable damage. The following account briefly enumerates the various diseases of crops.

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