The Gazetteers Department

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

Cereals.—Jowar: Jowar stem borer (Chilo Zonellus, Swinh) causes considerable damage to jowar which is frequently found heavily infested by this pest. Creamy white eggs are laid on leaves in clusters which hatch in six days. Young caterpillars bore inside the stems and remain there for three or four weeks after which fully grown caterpillars pupate in situ. Their pupal period varies between seven and ten days while their life-cycle extends over five-six weeks. The pest hibernates as a larvae in stubbles. The pests causes damage to the crop for about 6 months from June to November. During this period the pest completes its life-cycle at least four times.

The caterpillars are dirty white with many spots on the body and with a brown head. The full grown caterpillar measures about ¹/₃'' 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 the drying of the central shoots called ' dead hearts'. This causes reddening of stems and leaves. The extent of damage is about four to five per cent. As the pest is an internal feeder only, preventive and mechanical measures are found practicable and economic. They are as follows:—

(i) The affected plant should be pulled out along with the caterpillars inside and destroyed promptly.

(ii) After harvest of the crop stubbles should be collected and burnt to destroy the hibernating larvae.

(iii) The jowar fodder should be cut into small pieces before it is served to cattle.

Wheat: Wheat stem borer is (Sesamia Inferens Walk) the pest which causes damage to rabi crop of wheat. It also affects maize in dry weather. The caterpillars bore inside the stems which causes drying of central shoots, known as ' dead hearts'. This pest is sporadic in nature and causes minor damage. Young caterpillars enter the stems and start boring. As those stem borers are internal feeders, the preventive measures discussed above in respect of jowar stem borer (Chilo Zonellus, Swinh) arte identically applicable here also.

Insects termes SP. [ Micrptermes obesi (Anandi) H. Odontoter-mes obesus ] 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 monsoon, 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.

Pulses.—Gram: Gram pod borer known as heliothis (armigera) obsoleta F., damages the gram crop. Cotton, tomato, peas, tobacco, safflower, 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 causes damage to the crop for about 5 months 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. is also one of the measures for preventing this pest.

Tur : Tur plume moth (Exelastes attnosa W.), affects tut and wal crops. Fully grown caterpillars bore inside the 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.

Groundnut.—Aphids are tiny, soft bodied insects. It 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 ' rosette' of groundnut. The pest is of sporadic occurrence.

A single apterous female gives birth to about 8 to 22 young-ones called nymphs per day. It takes about four months before they reach the adult stage. Their life-cycle becomes complete in about a week's period. During its latter part, some winged members are produced in most species of aphids.

The pest can be controlled by the following measures:—

(i) Spraying the crop with nicotine sulphate in the proportion of one ounce of nicotine into 22.73 litres of water with 0.113 kg. of soap. Nearly two to three sprayings at weekly intervals are required during late December or early January.

(ii) Spraying the crop with pyrocolloid in the proportion of one ounce pyrocolloid in 22.73 litres of water. This also gives good results.

Cotton.— There are two types of boll-worms—(i) spotted boll-worms (earias fabia, S.E. insulana B.) and (ii) Pink boll-worms (Platyedra gossy-piella, Saunat). The host plants of both of these boll-worms are cotton, bhendi, ambadi and other malvaceous plants. Eggs of these boll-worms are laid singly on leaves, flower buds, bracts, bolls, etc. They hatch within 4 to 6 days. Larval period in case of spotted boll-worms is 9 to 16 days depending upon the climatic conditions. Pupation takes place inside the silken cocoons outside the bolls. In this stage it remains for 8 to 14 days. The total period of a life-cycle is about 22 to 35 days.

In case of pink boll-worms the caterpillars, on hatching feed on developing flowers, seed or lint. The larval period is usually of about 3 to 4 weeks but most of them remain dormant in the seeds for a pretty long time for the perpetuation of the species. Pupation generally takes place inside the bolls or in the soil in silken cocoons from which moth emerges after about 10 days. This pest is active from July to December while the winter is passed in the larval stage.

The adults of the spotted boll-worms have pale white upper wings with a greenish band in the middle. The moth of pink boll-worms is about � inch across the wings and is dark brown in colour. The segment of the antenna has 4 to 6 staff hairs and the palps are long and curved upwards. Caterpillars when fully grown measure ¹/₃'' long and are pink in colour with a brown head. Both the types of boll-worms have a number of black and brown spots on the body. The full-fed larva measures about �'' in length.

In case of spotted boll-worms, caterpillars bore into the growing shoots of the plants in the initial stage of the crop. Later on, when the flower buds appear, the larvae bore into them and then enter the boll by making holes which are plugged with excreta. The infested buds and bolls arc shed but if they remain on the plant, they open prematurely and consequently lint from such bolls 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 some of the measures suggested for controlling the pest:—

(i) Removal and destruction of stubbles to check carryover of the pest to the next season.

(ii) Destruction of all malvaceous plants growing in off season which serve as alternate hosts for the pest.

(iii) Fumigation of seed before sowing with carbon-di-sul-phide at the rate of two ounces per 15 cubic feet or heating the seed at 145�F to destroy the hibernating pink boll-worm larvae.

(iv) Quick removal and destruction of affected parts of plants in the early stage of pest incidence.

(v) Six dustings with mixture of 10% D.D.T., two per cent lindane and 40 per cent sulphur or with one per cent endrine dust.

(vi) Six sprayings at fort-nightly intervals with endrine at the rate of 6 ounces per acre, commencing from a month prior to flowering. Sulphur may. be added to this mixture in equal quantity to avoid.subsequent mite incidence.

Other Minor Pests. Red cotton bug (Dysdercus oingulatus Fabr.) is another minor pest of cotton. Like cotton it also affects the 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. The following two are the measures of controlling this pest:—

(i) Adults and nymphs should be collected in large numbers by shaking them in a tray containing a mixture of water and a small quantity of kerosene.

(ii) In case the pest is serious, which rarely happens, the crop may be treated with five per cent Benzene Hexachloride.

Jassids (Empoasca devaslens 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 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. but the mixture of sulphur and D.D.T. is not sprayed on Indian or Asiatic cotton as sulphur scorches these 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 is very effective against jassid attack.

Aphilds (Aphis 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 the spray of nicotine sulphate at the rate of 0.453 kg in 363.68 litres of water mived with 2.268 kg of soap in quite effective. A spray of parethrum extract in the proportion of one part in 1000 parts of water also gives satisfactory results.

Dahiya, the grey mildew of cotton has assumed serious proportions in recent years. In the case of severely affected plants defoliation takes place which adversely affects the yield.

Chillis: Thrips (Sarto thrips dorsalis H.) and mites are the pest 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.

Citrus Fruits: Citrus shoot and bark borer known as Indarbela quadrinotala walk causes damage to guava, citrus, pomegranate, mango, etc. The bark and the 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 bark.

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 galleries and webbings and to ascertain the live burrows before injecting the solution.

Fruit-sucking moth known as othreis sp. is another important pest of citrus fruits. Moths generally puncture rings of all varieties of citrus. However in this district 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 fruits to rot early.

This type of pest is very difficult to control. Insecticides do not help to 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 this pest can be reduced by removing the hosts of caterpillars.

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