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Diseases and Pests

Diseases

i. Powdery Mildew

The disease is caused by Oidium mangiferae Berthet. The disease affects inflorescence, leaves and young fruits. The characteristic symptom of the disease is the white superficial powdery growth of the fungus comprising a large number of conidia borne on conidiophores. The disease can be managed by pruning of diseased leaves and malformed panicles and three sprays of fungicides at different stages starting with Wettable Sulphur (0.2%) at the panicle size of 7.50 -10.00 cm followed by Dinocap (0.1%) after 15-20 days of first spray and Tridemorph (0.1%) after15-20days of second spray. Wettable Sulphur (0.2%) can be used in all the three sprays and number of sprays may be reduced as per appearance time of disease.

ii. Anthracnose

The disease is incited by Colletotrichum gloeosporioides Penz. ( Glomerella cingulata (Stons.) Spauld & Schrenk).It affects all the above ground parts of the plant particularly leaves, petioles, twigs, blossoms and fruits. It is one of the important post-harvest diseases of mango. Disease may be reduced by removal of diseased parts from the tree and its destruction by burning. Infection on blossom could be reduced effectively by 2 sprays of Carbendazim (0.1%) at 15 day intervals. Its foliar infection can be managed by 2 sprays of Copper oxychliride (0.3%), while latent infection of the pathogen on fruits could be reduced by pre-harvest sprays of Thiophanate methyl or Carbendazim (0.1%). Post-harvest infection of this pathogen can be managed by post-harvest dip of fruits either with hot water alone (45 ± 20°C ) or hot water in combination of fungicides, Thiophanate methyl or Carbendazim (0.05%). Covering of fruits on tree, 15-days prior to harvest with news or brown paper bags and use of bio-control organism, Streptisporangium pseudovulgare were also found effective in management of its post-harvest phase.

iii. Dieback

The disease is characterized by drying back of twigs from top downwards particularly in older trees followed by dying of leaves. Dark patches are seen on young green twigs. Cracks are seen on branches and gum exudes from the cracks before its death. Graft union of nursery plants is also affected by the disease and it dies. Nodal infection below growing point results in death of growing twigs. The causal pathogen of the disease is Lasodiplodia theobromae (Pat.) Griffon & Mouble (Botryodiplodia theobromae Pat.). The gummosis is found more prominent during winter after rainy season. This pathogen also attacks ripe fruit in storage at the base of pedicle (stem end rot) and the circular brown area near the stem end further develops towards the lower portion of the fruit. Later entire fruit surface is covered with the dark brown to black area and complete fruit rots in 2 to 3 days. The disease may also start from injured portion on the fruit surface. The disease can be reduced by pruning of infected plant parts from 7- 10 cm below the infection site and pasting the cut ends with clay mixed cow dung or Copper oxychloride or Bordeaux mixture. In case of gummosis diseased parts may be cleaned / removed and pasted either with Bordeaux or Copper oxychloride paste. Application of Copper sulphate (500 g t -1 ) in soil around the tree trunk is also found effective in reducing gummosis. The stem end rot can be minimized by pre-harvest spray of Carbendazim or Thiophanate methyl (0.1%) 15 days prior to fruit harvest. Fruit should be harvested with stalk (5 cm), if not, the opening must be sealed with wax. Post-harvest phase of the disease can also be controlled by dipping the fruit in hot water (52 ± 10°C) with Carbendazim for 5 minutes. Covering fruits with brown or news paper bags and use of bio-control agent, Streptisporangium pseudovulgare have also been found effective in management of stem end rot.

iv. Phoma Blight

The disease is caused by Phoma glomerata (Corda) Woll. & Hochapf and generally noticed on old mature leaves only. Disease initially starts as minute, irregular, yellow to light brown scattered spots on allover the leaf lamina. Characteristic feature of fully developed spots are dark brown margin and dull necrotic grey centers. In severe cases spot coalesce and form big patches resulting in withering and defoliation of infected leaves. The disease can be managed by application of balanced nutrients to the plants. Spraying of Copper oxychloride (0.3%) has also been found effective against the disease.

v. Scab

The causal pathogen of the disease is Elsino mangiferae Bitancourt and Jenkins (= Sphaceloma mangiferae Bitancourt and Jenkins).It affects leaves, panicles, blossoms, twigs, stem bark and fruits. The symptom produced by the pathogen is almost similar to anthracnose but lesions produced are smaller than anthracnose on leaves and down surface is covered by delicate velvety growth. The disease may cause crinkling, distortion and premature shedding of leaves under severe conditions. Some times irregular shot holes are also observed on leaves. The blotches on the stem bark are grayish and irregular in shape. The disease can be controlled by regular sprays of Copper oxychloride (0.3%).

vi. Black Banded

The causal pathogen of this disease is Rhinocladium corticolum Massee (perfect state Peziotrichum corticolum (Massee) Subramanian). Disease symptoms appear in the form of black velvety fungal growth on midribs, twigs and branches of mango tree. Since the disease is seen in to black colour bands, hence named as black banded. The infected portion of the bark contains mycelial growth and cluster of conidiophores which confined to upper layer only. Removal of black growth by rubbing, application of Bordeaux / Copper oxychloride paste and spraying of Bordeaux mixture (1%)/Copper oxychloride (0.3%) helps in management of this disease.

vii. Mango Malformation

The disease is caused by Fusarium subglutinans and it produces two types of symptoms, i.e., vegetative and floral. Vegetative malformation is more pronounced on young mango seedlings and plants. The affected plants develop swollen abnormal vegetative growth with short internodes. Leaves are small, narrow and often produced on the top of seedlings in clusters, giving it a bunchy appearance. The characteristic symptoms of the floral malformation are compact and clustery appearance of flowers. The flower buds transform in vegetative form and leaves. The flower bud seldom opens and remains dull green in colour. Some malformed panicles are not compact but both types of malformed panicles do not bear fruit. Mango malformation can be minimized with removal of malformed panicles and its destruction, removal of late December and early January flowers and application of NAA (200 ppm) in the first week of October.

viii. Mango Bacterial Canker Disease (MBCD)

MBCD is incited by Xanthomonas campestris pv . mangiferaeindicae (Patel, Moniz & Kulkarni) Robbs, Ribiero& Kimura and affects all the above ground parts of plant, i. e., leaves, petioles, twigs, branches and fruits. Lesions on leaves are angular to irregular, dark brown to black, cankerous on lower side but occasionally on both the sides and surrounded by chlorotic halo. Cankers on petioles are raised and dark brown to black in colour, while on twigs and branches are raised with longitudinal fissures. Lesions on fruits are raised and dark brown to black which gradually develop in to cankers. Under favourable condition lesions increase in size and sometimes cover complete fruit. Such lesions often burst extruding gummy substances containing bacterial cells of the pathogen. Fruits may drop off, if infection comes at stem end. MBCD can be minimized by regular inspection of orchards and its sanitation, use of healthy stones for root stock, 3 sprayings of Streptocycline (200ppm) or Copper oxychloride (0.3%) alone or its combination and use of bio-control agents, Bacillus coagulans , B. amyloliquifaciens , B. subtilis and fluorescent pseudomonads.

ix. Red Rust

The disease is caused by an algae, Cephaleuros virescens Kunze and manifests itself in the form of rusty red fructification of the alga on the surface of leaves, petioles and twigs. Initially the spots are greenish grey and velvety in texture which finally turn to reddish brown. After shedding the spore the algal matrix remains attached to leaf surface, leaving a creamy white mark at the original rust spot. The disease can be reduced by supply of balanced nutrients to the plants and two sprays of Bordeaux mixture (1%) or Copper oxychloride (0.3%) in the month of July at 15 days interval.

x. Black Rot

It is a post-harvest disease and caused by Aspergillus niger Van Tiegh. Affected fruits show yellowing with irregular grayish spots, which develops into black necrotic area with growth of black mould. Tissues around and beneath the spots disintegrates and emits foul odour. The disease can be managed by avoidance of injury to fruits and its contact to soil, dipping of fruits in hot water (52±1 0 C) with Carbendazim (0.5%) for 5 minutes and covering of fruits with brown or news paper bags on the tree it self 15 days prior to harvest.

Insect Pests

About 492 insect species are known to infest mango and out of these approximately 45 per cent reported from India . Among these 45 per cent, about a dozen are found more severe causing considerable loss to the crop and mentioned below:

i. Hoppers

Three species of hoppers Idioscoynio chypeabis, I. nitidulus and Amritodus atkintoni are the most important and found on panicles, leaves and stems, respectively. The adult and nymphs of hoppers, suck the sap from tender parts resulting in reduction of vigoure. Heavy infestation causes curling and drying of infested parts. Inflorescence infestation results in complete loss of crop. The hoppers after sucking, excretes sweet sticky substance which facilitate the development of fungi, Maliola and Capnodium spp., commonly known as sooty mould which gives black look to the trees and affects photosynthetic activity. Hoppers are present round the year in the orchard but population used to be high during February to April and June to August. The hoppers can be managed by pruning of dense orchards in the month of December, orchard sanitation and 3 sprays of Carbaryl (0.02%) or Propanophos (0.05%) or Imidachlopid (0.005%) at early stage of panicle formation if, population exceeds from 10 hoppers per panicle. The second spray should be given at full length of panicle but prior to full bloom and third at pea stage of fruits. Nymph predators Mallada boninensis and Chrysopa lacciperda and egg parasite Polynema sp., Gonatocerus sp. and Tetrastichus sp. are found effective in nature against the hoppers. A fungus, Verticillium lacani has also been found effective against this pest but under moderate climate. Spraying of Nimbicidine (0.2 %) is effective at initial stage of hoppers management.

ii. Mealy Bug

It is another major pest of mango in India and widely distributed along the Indo-gangatic plain. The most common mealy bug is Drasicha mangiferae , which causes severe damage to mango crop through out the country. Adults and nymphs both sucks the plant sap and reduce the plant growth, destroy inflorescence and causes fruit drop. Mealy bug excretes honey dew, a sticky substance, which facilitates the development of sooty mould fungi ( Maliola mangiferae & Capnodium mangiferae ). The female insect crawls down in the month of April/May to lay the eggs in soil. The eggs hatch in the following month of November/December and crawls up the tree. Flooding the orchard in the month of October and deep ploughing in November, fastening of alkathene 25 cm wide sheet (400 gauge) afterwards mud plastering of trunk at 30 cm above the ground in the middle of December, loosening of soil around the tree trunk and mixing of Chlorpyriphos dust (1.5%) @ 250 g per tree helps in reduction of mealy bug population. This dust can also be applied below the alkathene band on tree trunk and soil. Spraying of Propanophos (0.05%) or Imidachlopid (0.005%) for control of nymphs already made the way up to tree. The integrated approach (IPM) of above has been found effective in management of mealy bug but spraying of neem products along with soil application of Beauveria bassiana spores will be further useful in population reduction of this pest. Apart from B. bassiana , coccinellid beetles (predator), Minochillus sexmaculatus , Rodolia fumida and Suminus renardi are natural bio-control agents of this pest.

iii. Inflorescence Midge

In recent years, the inflorescence midge ( Erosomyia indica ) became serious in certain mango growing pockets particularly in Uttar Pradesh, affecting both inflorescence and small fruits. It affects the crop at 3 stages, i.e., at floral bud burst, fruit set and tender leaves particularly encircling the inflorescence. The first phase is more damaging as the entire inflorescence destroyed before flowering and fruit set. The inflorescence show stunting growth and its axis has curve at the entry point of the larvae and ultimately die before fruit set. Its attack on inflorescence could be recognized by presence of tiny black spots. Apart from inflorescence midge, 2 other gall midges, Dasineura amramanjarae and Procystiphora mangiferae have also been found infesting mango inflorescence. The larvae of D. amramanjarae are red, while P. mangiferae are orange in colour. Accordingly D. amramanjarae infected parts are red whereas P. mangiferae are swollen and bigger (bud) in comparison to normal. The pest can be managed by ploughing of orchards and spraying of Propanophos (0.05%) or Imidachlopid (0.005%) at bud burst stage of inflorescence.

iv. Fruit-fly

The oriental fruit-fly is one of the most important pests of mango and considered to be a major hurdle in export of fresh fruits. The three species of fruit-fly, i.e., Bactrocera dorsalis , B . zonatus and B. correctus are the most common and causes severe damage to mature mango fruits. The female insert eggs in small clusters inside the mesocarp of the mature fruits and after hatching larvae feeds on the pulp which appears normal from outside but finally drops down. The maggots pupate in soil and flies start emerging from April onwards with maximum population during May to July which coincides with fruit maturity. Collection and destruction of infested and dropped fruits ploughing of orchards, use of trap bottle containing 100ml watery emulsion of methyl euginol (0.1%) + Malathion (0.1%) during April-June) reduce the infestation of this pest. Wooden traps prepared with sex hormone and insecticide has also been found effective against the pest. Bait spray of Carbaryl (0.15%) + protein hydrolysate (0.1%) or molasses at 21 day intervals starting from first week of April found effective in control of adult flies. Early harvesting of mature fruits, selective and need based bait spray and hot water treatment of harvested fruits before storage showed promising result.

v. Leaf Webber

The leaf webber ( Orthaga euadrusalis ) infestation starts from the month of April and continues up to December. Eggs are laid singly or in clusters in the webs on leaves. After hatching, the caterpillar feeds on leaf surface and make web of tender shoots and leaves together and feeds inside. Pupation also takes place inside the web but last generation (December-January) pupates in soil. Pruning and destruction of infested shoots during April to May, ploughing of orchards and loosening of soil around the trees in January and spraying (2-3) with Carbaryl (0.2%) or Propanophos (0.05%) or Imidaclopid (0.005%) at 15-days interval reduces the population of this pest.

vi. Shoot Borer

The shoot borer ( Chlumatia transversa ) is found prevalent in all the mango growing areas of the country. Larvae of this insect bore in to the young shoot which results in its drying. The infestation of larvae has also been noticed on inflorescence stalk. Eggs are laid in tender leaves and after hatching larvae enter in mid rib and afterwards in growing shoot from tip downwards. There are four overlapping generation of this pest in a year. The insect can be controlled by Clipping and destruction of infested shoots and spraying (2-3) of Carbaryl (0.2%) or Propanophos (0.05%) or Imidachlopid (0.005%) at fortnightly intervals. .

vii. Bark Eating Caterpillar

The caterpillar ( Indarbella quadrinotata ) is found to infest a variety of plants including fruit trees and ornamentals in India . Dense, old and neglected orchards are more prone to attack of this pest. Larvae of this pest feed on the tree bark and spin brown silken web which consist of its excreta and wood pieces and make tunnels in the stem and branches. Larvae generally feed from April to December and have only one generation in a year. The population of this pest can be reduced by keeping the orchard clean and removal of webs from tree trunks and filling the insect holes with emulsion of Monocrotophos (0.05%) or DVVP (0.05%) and plugging with mud.

viii. Stem Borer

Stem borer ( Bactocera rufomaculata ) is widely distributed in India and attack a number of fruit trees including mango. The grub of this pest feeds inside the stem, making tunnel upward which results in drying of branches and in severe cases death of tree. Eggs are laid either in the cracks of tree trunk or in the cavities of main branches which covered with viscous fluid. Grub pupates inside the stem and beetle emerges in July/August. There is only one generation of this pest in a year. The pest can be kept under check by maintaining the orchard clean and applying propanophos (0.05%) or Imidaclopid (0.005%) or DDVP (0.05%) in hole of insect and plugging with mud.

ix. Shoot Gall Psylla

The shoot gall psylla ( Apsylla cistallata ) is very serious on mango in Tarai region of India , North Bihar and West Bengal . Infestation of this pest results in formation of green conical galls in leaf axis. The pest becomes active from the month if August and galls dry after emergence of adults in the month of March. The eggs are laid in the midrib as well as on lateral axis of new leaves in March/April, nymphs emerges during August/September and feeds on adjacent buds which later turn in to hard green conical gall. Galls are more prominent during September/October and infested plants usually devoid of flowers and fruits. There is only one generation of this pest in a year The pest can be managed by avoidance of new planting in humid region, removal and destruction of infested plant parts and use of Monocrotophos (0.05%) or Imidachlopid (0.005%) or Propanophos (0.05%) at fortnightly intervals.

x. Scale Insects

In recent years, scale insects ( Chloropulvinaria polygonata, Aspidiotus destructor and Rastococcus sp) became serious on mango. The nymphs and adults of pest suck the sap of leaves and other tender parts which results in reduction of vigour of plants. Scale also secrets honeydew which facilitates in development of sooty mould on different plant parts. Among these scales, C . polygonata is posing threat to mango industry particularly in Western Uttar Pradesh. Pruning and destruction of infested plant parts and spraying with Monocrotophos (0.05) or Imidachlopid (0.005) or Propanophos (0.05%) at an interval of 21-days found effective in population reduction of this pest.

Insect pests of mango, viz. mealy bug, hopper, midge, fruit fly could be managed through IPM schedule involving banding of tree trunk with alkathene (400 gauge) and drenching with Beauveria bassiana (2 g/l) during first week of January and first spray with Neem Seed Kernel Extract (5%) in first week of February followed by second spray of imidadoprid (0.005%) when panicles are of 5 to 7 cm size and third need based spray with Propanophos (0.05%) after fruit set.

xi. Stone weevil, Sternochetus mangiferae (Fab.):

The stone weevil, Sternochetus mangiferae (Fab.) (Coleoptera: Curculionidae) is a direct pest on mango fruits. It is monophagous, and its management has been a challenge to entomologists. The weevil causes a loss varying from 5-80%, depending on the place and variety of mango (Verghese, 1998). The loss is essentially in four folds: One- Affected fruits prematurely fall. Two-Infested fruits result in spoilage of pulp, affecting the canning industries. Three-The weevil has been an hindrance for export of fresh fruits. Four- Seeds with weevil fail to germinate, where root stock is produced through seeds limiting mango propagation as also observed by Johnson, 1989.

The stone weevil, S. mangiferae has a cosmo-tropical distribution. Besides India, it is distributed in Australia, Bangladesh, Hawaii, Indonesia, Japan, Malaysia, Mauritius, Mozambique, Myanmar, New Caledonia, Pacific Islands, Pakistan, Philippines, S. Vietnam, Sri Lanka, Tanzania, Thailand, Uganda, Wallis Island, Zanzibar, etc. (Tandon and Verghese, 1985). In the Americas , it has been reported in the Southern Caribbean region (Johnson, 1989). The adult of S. mangiferae is grayish brown with buffish streaks. It emerges from the seed during harvest by making an exit hole on the seed, and working out its way through the pulp, and subsequently out of the fruit through an exit hole on the rind. During this adult emergence process, the adult drags the faecal matter is responsible for the spoilage of the pulp during pulp processing and canning.

Management:
Cultural control
  • Field sanitation- collection and destruction of all fallen fruits at weekly interval till harvest (This will destroy adults which is a source of infestation for the following year).
  • Rake the soil below the tree in October/ November and March to destroy weevils hiding under clods/ fallen leaves.
  • After harvest destroy all left-over seeds in the orchard, or in the processing industries.
Chemical control
  • Spray main trunk, primary branches and junction of branches prior to flowering (November/ December) with chlorpyrifos 0.05%, to control beetles hiding in the bark.
  • Spray acephate 0.1125% at lime size followed by decamethrin 0.0028% after two to three weeks.
Biological control

Parasitoids are unknown on stone weevil () . The natural enemies recorded on S. gravis include a mite Rhizoglyphus sp. (Acarina: Tyroglyphidae) ants ( Camponatus sp., Monomorium sp. and Oecophylla smaragdina Fab.) (Hymenoptera: Formicidae) and a fungus Aspergillus sp.. On S. mangiferae only a virus has been recordedTherefore, scope for using biological control for weevil management with the existing information is limited. Recently, Beauveria bassiana (Balsamo)Vuillemin was to be pathogenic on mango stone weevil.

Forecasting:

Regular fallen fruit sampling recommended by IIHR, starting from pea size of fruits, can help in forecast of the pest incidence for a geographic region and helps in timing of first spray (This is usually at lime size of fruits or by middle of March, whichever is earlier)]. Prediction models were also fitted for varieties viz., Alphonso, Banganpalli for estimating percent infestation in harvested fruits based on first 3 week's (post lime size) infestation in fallen fruits.

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