Learn about the pests that damage temperate fruits and its control.
1. San Jose Scale, Quadraspidiotus Perniciosus (Comstock) (Hemiptera: Diaspididae):
This insect is world-wide and is the most serious pest in temperate regions on nearly 700 different species of fruits, shrubs and ornamental plants. It usually prefers plants belonging to the Rosaceae such as apple, plum (Prunus domestica L., P. salicina L.), pear, peach (Prunus persica L.) and other closely related species such as the currant, willow, hawthorn and rose.
The damage is caused by nymphs and female scales which suck the sap from twigs, branches and fruits. The scale which forms a covering on the body of the insect is black or brown. Underneath, a lemon-yellow insect is visible when the covering is lifted. The infested fruits also have a scaly appearance and each spot is surrounded by a scarlet or red area.
Life-Cycle:
The pest is active from March to December and passes the winter in the nymphal stage. The overwintering nymphs resume activity in the spring and are full-grown by about April-May. They start to reproduce by mid-May. The San Jose scale gives birth to young ones, which hatch from the eggs developed within the body of the female.
Each female may give birth to 200-400 nymphs. The newly-born nymphs crawl out of the parental scale and lead a free life for 12-24 hours. On finding a suitable place, they insert their mouth-parts into the plant tissue and begin to feed by sucking the cell-sap. They become full-grown in 30-40 days and the females again start giving birth to young ones within the next 10-14 days.
The gravid mothers live for about 50-53 days. The male nymph has an elliptical or oval scale and develops into a winged adult in 25-31 days. The life of the male adult is short and hardly exceeds 24-32 hours, during which it fertilizes the non-winged females. Four overlapping generations are completed in a year and the fifth-generation nymphs overwinter.
Augmentative and inoculative releases of two exotic parasitoids, Encarsia perniciosi (Tower) and Aphytis sp. proclia group have given promising results for the suppression of San Jose scale on apples. The Russian strain of E. perniciosi proved effective in Himachal Pradesh while Chinese and American strains proved better in Uttar Pradesh.
Damage:
All parts of the plant above the ground are attacked and the injury is due to loss of the cell-sap. At first, the growth of the infested plants is checked, but as the scales increase in number, the infested plants may die.
Control:
(i) For effective management of San Jose scale, orchard sanitation should be given priority. Infested pruned material should be collected immediately and burnt.
(ii) The parasitoid, Encarsia perniciosi (Tower) may be released to check the overwintering population on wild host plants growing around.
(iii) Spray diesel oil emulsion + Bordeaux mixture (diesel oil 68 litres + copper sulphate 15 kg + unslacked lime 3.75 kg) to be emulsified and diluted 5-6 times before spraying or spray 7.5 litres of ESSO tree spray oil emulsion in 250 litres of water per ha during the winter season when the trees are in dormant stage and completely defoliated.
(iv) Severe scale infestation under neglected orchard management requires additional summer sprays with 2.0 litres of chlorphriphos 20EC or 625 ml of methyl demeton 25EC in 1250 litres of water per ha.
(v) To protect the plants in nursery, apply carbofuran granules @ 0.75-1.0 g a.i. per plant.
2. Woolly Apple Aphid, Eriosoma Lanigerum (Hausmann) (Hemiptera: Aphididae):
This insect is a serious pest of apple, pear and crab-apple (Pyrus baccata) in India and Pakistan and it also feeds on hawthorn, mountain ash, etc. The infested plants have pale green leaves and whitish cottony patches on the stems and branches. Characteristic galls or knots are formed on roots and other underground portions of the plants.
Life-Cycle:
The pest is most active during March- September and multiplies at a reduced pace during October-December. The development from December to February is extremely slow. The aphids reproduce parthenogenetically and the progeny, thus produced, consists of females only.
Each female may produce up to 116 young ones in her lifetime at the rate of 1-4 nymphs per day in March- April, 1-5 in May-July, 1-6 in August, and only 1-2 per week in winter. There are four nymphal instars and the duration of each varies according to the season. The total duration of the nymphal period is 35-42 days in February, 29.5 days in August-November, and 10.5-19.5 days in April-July.
The winged forms appear in July-September when fresh colonies on new plants or branches are initiated. There may be 13 generations in a year. In December, there is a partial migration from aerial parts to the roots of infested plants and the reverse migration from the roots to the aerial parts takes place in May.
In Himachal Pradesh, the woolly aphid has been controlled by using natural methods by an introduced parasite, Aphelinus mali (Haldeman) (Aphelinidae) which attacks the 4th and 5th stage nymphs. The parasite has to be maintained on cut twigs fixed in moist soil inside wire-gauze cages.
Damage:
The aphids suck cell-sap from the bark of the twigs and from the roots underground. Swellings or knots appear on the roots which hinder the normal plant functions. Owing to the loss of cell-sap, the twigs also shrivel and the young nursery plants, which are affected the worst, may die quickly.
Control:
The management of woolly aphid in apple orchards is a difficult task because of the waxy covering on the body and reinfestation due to local migration from roots.
However, good success can be achieved if following strategies are followed:
(i) Use of resistant root stock seems to be the only answer for subterranean aphid population. Use resistant root stock like Golden Delicius, Northern Spy and Morton Stocks 778, 779, 789 and 793.
(ii) Biological control of woolly aphid has great potential and it can be achieved by the release of an exotic parasitoid, A. mali.
(iii) As the main source of infestation in the orchard is infested plant material from nurseries, select healthy plants from nursery and then before planting in the orchard, treat them with chlorpyriphos 0.05 per cent.
(iv) During leaf-fall, spray the plants with 2.0 litres of chlorpyriphos 20EC in 1250 litres of water per ha against aerial forms. For controlling the root forms, apply oxydemeton methyl 25EC in 1250 litres of water per ha. These chemicals should be sprayed during winter months.
(v) For checking this pest during summer, spray 2.0 litres of malathion 50EC in 1250 litres of water per ha. The insecticidal spray should be avoided where the parasitoid, A. mali, is present.
(vi) Carry out fumigation against root forms with paradichlorobenzene granules in a 15 cm deep trench dug round the infested tree, about 2 metres from it.
3. Apple Stem Borer, Apriona Cinerea Cheverlot (Coleoptera: Cerambycidae):
The grubs of this pest are destructive stem borers of apple, peach, fig and other fruit trees. The insect has been recorded from Pakistan, Afghanistan, Kashmir, Himachal Pradesh and Uttar Pradesh. The adult beetles are 35-50 mm long, grey in colour and have antennae larger than the body.
Life-Cycle:
The beetles appear in July-August after the start of the monsoon and mate soon after. The female when ready to lay eggs excavates an oval patch on a shoot and lays eggs inside the cavity. Thus, she moves from tree to tree and lays a number of eggs. The grubs emerge in 7-8 days and start feeding by boring inside the stem.
As autumn approaches the feeding activity of the grubs becomes very slow and by October stops altogether. It remains quiescent during the winter and resumes feeding in March. As it feeds it makes a tunnel towards the thicker side of the stem and thus by September-October it reaches close to the tree trunk.
As winter sets in the grubs remain quiescent. As the summer season comes it starts activity and when full-fed it pupates inside a tunnel made in the woody tissue. The pupal stage lasts more than a month and the adults emerge in July- August to start procreation. The life-cycle is completed in about two years.
Damage:
As a result of feeding by the grubs, the affected trees may not die for many years, but their vitality and productivity is greatly impaired. The adult beetles feed on bark and have an unusual habit of cutting more than they actually consume.
Control:
(i) Prune and burn all attacked shoots and branches during winter.
(ii) Location of live holes and injection of carbon disulphide or chloroform or petrol and sealing them with mud will kill the pest.
(iii) The borers can be effectively controlled by inserting cotton wick soaked in insecticide solution of about 10 ml of dimethoate 30EC or oxydemeton methyl 25EC or dichlorvos 100EC inside the hole and plugging it by moist soil or mud.
(iv) Placing of 0.2 g aluminium phosphide tablets inside the hole and then plugging with moist soil will also ensure control of the pest.
4. Apple Root Borer, Dorysthenes Hugelii Redtenbacher (Coleoptera: Cerambycidae):
The grubs of this beetle are very damaging root borers of apple in the Kumaon region of Himalayas. Occasionally, it also attacks the roots of apricot, cherry, peach, pear, walnut and a number of forest trees. The full-grown grub is creamy-white with black head and mandibles, and may be 75-100 mm long. The adult beetles are chestnut in colour with head and thorax darker than the elytra.
Life-Cycle:
Adult beetles emerge from the soil with the advent of monsoon, around the end of June and some of them continue to emerge upto the middle of July. Immediately after emergence, they start mating and the males die soon after. The females also live for 10-12 days only, during which they lay eggs to progenerate. A female lays, on an average, 300 ovoid shaped, yellow- white eggs, 8-12 mm below the soil surface. The eggs hatch in 30-40 days.
The grubs, on emergence from the eggs, go down into the soil, 100-250 mm deep and feed on organic matter and also on the roots of a number of plants and trees. The legless, slow moving creatures feed and move gradually, under the soil surface among the root system of host plants.
It takes up to 3.5 years for them to mature and become full-grown, storing huge quantities of food reserves. If the grubs are confined without food they can survive for 24-90 days. When full-grown they pupate inside the earthen cocoons and then emerge as beetles after the first shower of monsoons.
Damage:
As a result of the grubs feeding on roots, the small as well as the major roots are severed from the base. The trees, if young, die immediately whereas the older ones become weak and fall down eventually owing to the action of strong winds.
Control:
(i) Avoid dry sandy soils for planting apple orchards.
(ii) Remove and destroy the grubs from the affected trees,
(iii) Inter-culturing in the soil under the trees helps in killing the grubs,
(iv) Once the infestation has occurred, it is imperative to treat the tree basins with phorate granules @ 100 g a.i. per tree or apply 2% lindane dust @ 200-300g/tree soon after monsoon.
(v) Prune and burn all attacked shoots and branches during winter,
(vi) Location of live holes and injection of carbon disulphide or chloroform or petrol and sealing them with mud will kill the pest.
(vii) The borers can be effectively controlled by inserting cotton wick soaked in insecticide solution of about 10 ml of dimethoate 30EC or oxydemeton methyl 25EC or dichlorvos 100EC inside the hole and plugging it by moist soil or mud.
(viii) Placing of 0.2 g aluminium phosphide tablets inside the hole and then plugging with moist soil will also ensure control of the pest.
5. Peach Stem Borer, Sphenoptera lafertei Thompson (Coleoptera: Buprestidae):
This beetle is widely distributed in Afghanistan, Pakistan and India. Its grubs feed by boring into the stem of peach, almond, apricot, cherry, loquat, pear and plum trees. The beetles which feed on the foliage of host plants are blackish-bronze and are 10-13 mm long. The grubs are smoky dark or black, club-shaped and attain 18-24 mm body length.
Life-Cycle:
The beetles start appearing by the middle of March. After mating they lay small, spherical, white eggs singly, scattered all over the tree trunk and the main branches. The eggs hatch in 20 days. The grubs on emergence feed on the bark and as they grow they bore inside.
The larval stage is completed in two months in summer, but those which over-winter take 6 months. The larva makes a small chamber in the woody tissue about 10 mm deep from the surface. The pre-pupal and pupal periods last 1-2 and 8-12 days, respectively in summer. The winter is passed in the grub stage. Three generations of this pest are completed in a year.
Damage:
The grubs feed under the bark as well as bore deep into the wood. Gum globules ooze out of the entrance holes. Leaves of the attacked plants turn pale and their growth is arrested. The attacked branches dry up and do not bear fruits. With continued damage the tree dies ultimately.
Control:
(i) The dead or heavily gummed branches should be cut and destroyed.
(ii) Drench spray of 2.5 litres of chloroyriphos 20EC in 1250 litres of water per ha during June after harvest of the crop and in October.
6. Tent Caterpillar, Malacosoma Indicum Walker (Lepidoptera: Lasiocampidae):
The insect is an important pest of apple (Mains pumila) in north-western India, being more serious in the Simla Hills. It also damages the pear (Pyrus communis L.), apricot (Prunus armeniaca L.), walnut (Juglans regia L.), etc.
The caterpillars feed gregariously on foliage, leaving behind only the midrib and other harder veins. When full-grown, the larva is 40-45 mm long, with its black head and abdomen. The male moth is light reddish and the female moth is light brown, with a wing expanse of 29-32 mm and 35-37 mm in male and female, respectively.
Life-Cycle:
The pest is active from mid-March to May and passes the remaining 9 months of the year in the egg stage. The eggs hatch by about the middle of March when buds appear on the plants. The larvae live gregariously and, soon after emerging, each spins a silken nest at a convenient and sheltered place on the tree. As the caterpillars grow, the nest is also enlarged until it is 0.3 -0.5 metre across.
During the day, the caterpillars rest in their nests and at night they feed on the leaves. The larval stage lasts 39-68 days and when full-fed, they spin oval, white and compact cocoons, each about 25 mm in length. The pupal stage lasting 8-22 days is passed inside these cocoons in some protected place.
The moths begin to emerge sometime in the 3rd week of May and continue to do so till the beginning of June. The pre-oviposition period lasts 1-3 days and the females lay eggs in broad bands around the branches. Each band may consist of 200-400 eggs. The moths are short-lived and a female in captivity may survive for 3-5 days. The life cycle is completed in one year.
Damage:
In case of severe infestation, the entire plant may be defoliated and subsequently the caterpillars may feed even on the soft bark of twigs. When there is serious infestation, 40-50 per cent of the apple plants in an orchard may be defoliated producing a poor harvest.
Control:
(i) The caterpillars can be killed by mopping up the ‘tents’ with a pole and some rags dipped in kerosene tied on its end. The best results are obtained when the operation is carried out from 12 noon to 3 p.m. on clear sunny days. Kerosenized water in an open vessel should be placed below the tree so that the larvae that fall may also be killed readily,
(ii) Destroy all egg bands at the time of pruning in December-January.
(iii) Spray 2.5 kg of carbaryl 50WP in 1250 litres of water per ha.
7. Apple Leaf Folder, Archips Termias Meyrick (Lepidoptera: Tortricidae):
Apple leaf roller is a black headed grape-green caterpillar of a small buff coloured torticid moth, which is a polyphagous multivoltine pest with apple as its preferred host.
Life-Cycle:
The pest overwinters as larva in fallen leaves or cracks and crevices of trees for about 7 to 8 months. The overwintering larvae resume feeding when foliage and blossom appear in April and adult emergence occurs in May. They lay dorsoventrally flattened eggs in clusters of 35-180 on dorsal surface of the leaf and depressed fruit surface.
Peak moth activity is observed in May, which is followed by high damage to fruit in June. Late maturing varieties suffer more from its attack. At least 2 generations are completed (with egg, larval and pupal stage of 1-2 weeks, 3-5 weeks and 1-3 weeks, respectively) up to September at about 2000-m altitude and third generation larvae overwinter.
Damage:
It not only feeds on foliage after folding young leaves by silken threads, but also damages the fruit on the tree as well as in the storage by scrapping the skin and causes upto 41 per cent fruit loss during storage.
Control:
(i) Bacillus thuringiensis (Bt) is effective against the larval stage. Bt is only effective on small (<1.25 cm long) caterpillars and usually requires more than one application.
(ii) Spray of 2.5 kg of carbaryl 50WP or 2.0 litres of malathion 50EC in 1250 litres of water per ha, three weeks prior to the harvest gives good control of the pest. Apply sprays only when there is evidence of a damaging population, such as large number of larvae early in the spring or large number of egg masses.
8. Indian Gypsy Moth, Lymantria Obfuscata Walker (Lepidoptera: Lymantriidae):
The caterpillars of the Indian gypsy moth defoliate apricot, apple and walnut trees in the Western Himalayas. It is primarily a pest of forest trees and attacks willows (Salix babylonica Linn.) and S. sataz (Peema) and poplar (Populus spp). The caterpillars are 40-50 mm long and are clothed in tufts of hair. The female moths are dark grey and they have atrophied wings. The males are comparatively more active in moving around and in mating.
Life-Cycle:
After being fertilized by a winged male, the female settles on the bark of a host tree for opposition. It lays, during June-July, round, shining and light greyish brown eggs, in batches of 200-400. The eggs are laid under the loose bark and are covered over with yellowish-brown hairs. The eggs over-winter as such and hatch in March-April when the season warms up a little.
The young larvae feed gregariously and as they grow through five instars they become more mobile but remain together in large groups. The larval period is completed in 66-100 days. The pupal formation takes place in soil among debris and this stage lasts 9-21 days from May to mid-July. The male moths live for 4-10 days and the females for 11-31 days. One generation is completed in a year.
Damage:
The caterpillars are gregarious and they eat voraciously at night time. Their habit to defoliate the host trees completely results in the failure of fruit formation.
9. Almond Weevil, Myllocerus Lactivirens Marshal (Coleoptera: Curculionidae):
The almond weevil is polyphagous and besides almond, it has been reported to feed on apple, apricot, ber, citrus, falsa, loquat, mango, peach, plum and pomegranate. Almond and pear are its preferred hosts. The weevils are small 3-4 mm long and pale metallic green in colour. The full-grown grubs are creamy white, 4 mm long, are stout in body which is without legs. They have short erect setae which help them in locomotion.
Life-Cycle:
The adults appear in May and lay eggs from the end of July till the beginning of September in the soil in batches of 40-50 each. The eggs are broadly oval in shape, creamy-yellow, smooth, transparent and shiny. They hatch in 4-5 days and the grubs burrow deep in the soil up to 200-300 mm. They feed on roots of the host plants. When full-grown, they come up on soil surface to pupate in the upper 25 mm of the soil. The grub stage is completed in 10 months and the pupal period lasts 4-5 days. The pest passes winter in the pupal stage in the soil.
Damage:
The weevils congregate on ventral surface on leaves, nibble irregular holes and gradually eat away the entire leaf laminae, leaving only the mid-ribs. The tender leaves are eaten first and then the older leaves are also skeletonized. The pest causes the maximum damage to foliage during the rainy season.
Control:
Soil application of lindane 2 per cent dust @ 30 kg per ha will effectively control grubs.
10. Peach Fruit Fly, Bactrocera Zonata (Saunders) (Diptera: Tephritidae):
The peach fruit-fly is widely distributed in the Indian Sub-continent and feeds on a number of fruits, viz., peach, fig (Ficus carica), guava (Psidium guajava L.), ber (Zizyphus spp.), citrus, apple, cucurbits, tomato, brinjal and pear. This fruit-fly causes heavy damage to peach fruits. The damage is caused by the larvae only and the attack is characterized by the dark punctures, oozing of a fluid and rotting or dropping of fruits.
The maggots found inside the fruits are dirty white, headless and legless. They are elongated wriggling creatures about 1 cm in length. The fly is a small insect about the size of a housefly and is reddish brown with yellowish cross bands on the abdomen. The wings are transparent and have a small brown spot on the tip of each wing.
Life-Cycle:
This pest is active from March to November or December and passes winter in the pupal stage. The adult flies appear in March and breed in a number of fruits like ber, loquat, peach, mango, cucurbits, citrus and guava. When the fruits mature in various seasons, the flies are active and are noticed in the gardens.
They mate a number of times and at 20 days of age, they lay white, cylindrical eggs just under the skin of a fruit, in groups of 2-9. A single female may lay, on an average, 137 eggs in her life-time. The place of oviposition is marked by a resinous secretion. The eggs hatch in 2-4 days in May-Tune and the maggots feed on the fruit pulp by making galleries.
These larvae are full-fed in 4-16 days and, at the same time, the fruits also fall from the tree. The larvae crawl out of the rotting fruits and by jumping movements, reach a suitable place for pupation in the soil at a depth of 25.4-76.2 mm. The flies emerge from these pupae in about one week and the life-cycle is completed in 13-27 days. Many generations are completed in a year.
During spring and summer, the population builds up gradually and reaches a peak in the monsoon. Of all the fruit-flies, this species used to be the most abundant in various fruits, but now it is being replaced by the mango fruit fly. The latter is also displacing the Mediterranean fruit-fly in the Hawaiin islands and other places.
Damage:
The peaches, apricots or other fruits attacked by this pest are malformed, misshaped, and undersized are rotten within. The damage caused is very heavy and the fruits become unmarketable.
Control:
(i) Plant early maturing varieties such as Prabhat, Florida Prince, Earli Grande, Partap, Shan-e-Punjab and Flordasun.
(ii) Hoe the orchard in May-June to expose the pupae which are present mostly at 4-6 cm depth.
(iii) Harvest the ripening fruits and do not let the ripe fruit remain on the tree.
(iv) Remove regularly the fallen fruits from around and bury the infested fruits at least 60 cm deep.
(v) Fix methyl eugenol based PAU fruit fly traps @ 40 traps/ha in the first week of May in peach and first week of June in pear.
(vi) Apply bait spray of yeast hydrolysate (250 g), crude sugar (2.5 kg) and malathion 50EC (250 ml) in 250 litres of water per ha. Spraying should be started two weeks before harvesting.
(vii) In orchards, only with history of severe infestation, spray 3.125 litres of fenvalerate 20EC in 1250 litres of water per ha, in the end of June and repeat the spray at weekly intervals if required. Fruits should be harvested at least on third day after spray.