<h1 style="text-align: justify;">A. Insect pests</h1> <h2 style="text-align: justify;">1. Citrus psylla (<em>Diaphorina citri</em>)</h2> <p style="text-align: justify;">Citrus psylla (<em>Diaphorina citri</em>) is active throughout the year with its peak period of infestation from March to mid October. The population density is more in arid zone. The adult psyllid is grey coloured and fly actively. It rests on the leaves with closed wings and hind end is raised upwards. The nymphs are orange yellow. Both nymphs and adults suck the cell sap from buds, leaves and young shoots and as a consequence, the leaves get curled and shoots start <a title="External website that opens in new window" href="viewcontent/agriculture/post-harvest-technologies/technologies-for-agri-horti-crops/post-harvest-management-of-pulses/drying?lgn=en" target="_blank" rel="noopener" data-page-id="854">drying</a>. It also acts as a vector of greening disease.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Spray 200 ml Crocodile/Confidor 17.8 SL (imidacloprid) or 160 g Actara/Dotara 25 WG (thiamethoxam) or 6.25 litre MAK HMO (<a title="External website that opens in new window" href="viewcontent/agriculture/state-specific-schemes-for-farmers/goa/horticulture?lgn=en" target="_blank" rel="noopener" data-page-id="1321">Horticulture</a> Mineral Oil) in 500 litres of water per acre during March and again in the first week of September.</p> <p style="text-align: justify;">Note:<br>(i) There should not be any water stress in the orchard at the time of spray of MAK HMO.<br>(ii) Time of application may be adjusted with the appearance of the pest.</p> <h2 style="text-align: justify;">2. Citrus leaf miner (<em>Phyllocnistis citrella</em>)</h2> <p style="text-align: justify;">Leaf miner is a serious pest in the nursery and young plantations during flushing seasons. The larvae attack the tender leaves/shoots epidermis by making serpentine mines which are silvery in colour. The affected leaves become distorted and crumpled. Severe infestation causes defoliation. The pest is active from end March to November with its maximum infestation during April-May and September-October. Its attack encourages the development of citrus canker.</p> <p style="text-align: justify;"><strong>Control:</strong><br>Spray 200 ml Crocodile/Confidor 17.8 SL (imidacloprid) in 500 litres of water during April-May and August-September.</p> <h2 style="text-align: justify;">3. Citrus whitefly (<em>Dialeurodes citri</em>) and Citrus blackfly (<em>Aleurocanthus woglumi</em>)</h2> <p style="text-align: justify;">Both nymphs and adults suck the cell sap from tender leaves and shoots and reduce the vigour of plant. Severely infested foliage turns yellowish green, becomes curled and finally shed. Sooty mould developed on honey dew excreted by the whitefly gives black appearance to the foliage. Affected trees have less chlorophyll, nitrogen and crude protein and produce few flowers which may shed. The fruits are insipid.</p> <p style="text-align: justify;">Nymphs of whitefly are small pale yellow with red eyes. Citrus blackfly lays eggs in spiral rings on the lower side of new leaves and nymphs are black in colour. Freshly emerged adults are reddish but later on get covered with a heavy pulverulence of salty bluish look. Both the species are active from March to November with their peak period of infestation during April-May and September-October.</p> <h2 style="text-align: justify;">4. Aphids (<em>Toxoptera aurantii</em>, <em>Aphis gossypii</em> and <em>Myzus persicae</em>)</h2> <p style="text-align: justify;">These aphids are regular pest of Citrus. <em>Toxoptera aurantii </em>and <em>Myzus persicae</em> are active from first week of February to first week of May with their critical period of infestation from first week of March to first week of April. These two species along with A. gossypii also cause damage to Citrus plants from last week of August to second week of November with their critical period of infestation from second week of September to first week of October.</p> <p style="text-align: justify;">The nymphs and adults suck the cell sap from young leaves and tender twigs. This impairs the vitality of the tree and causes severe curling and deformation of young leaves resulting into stunted growth. The honeydew excreted by the aphids also provides a good substrate for the growth of sooty mould, which affects the photosynthetic activity of the plant.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Spray 200 ml Crocodile/Confidor 17.8 SL (imidacloprid) or 160 g Actara/Dotara 25 WG (thiamethoxam) or 6.25 litre MAK HMO (<a title="External website that opens in new window" href="viewcontent/agriculture/state-specific-schemes-for-farmers/goa/horticulture?lgn=en" target="_blank" rel="noopener" data-page-id="1321">Horticulture</a> Mineral Oil) in 500 litres of water per acre during March and again in the first week of September.</p> <h2 style="text-align: justify;">5. Mites (<em>Eutetranychus orientalis</em>)</h2> <p style="text-align: justify;">Mites damage the leaves, flowers and fruits. Their incidence is maximum during dry and hot period (May-June) or sometimes become serious in August-September. The leaves have minute specks left by the feeding of mites. Leaves generally give dusty look.</p> <h2 style="text-align: justify;">6. Leaf folder (<em>Psorosticha zizyphi</em>)</h2> <p style="text-align: justify;">The pest is active in the nursery and young plantations from May to October. The larvae feed inside the leaves by webbing them together and start feeding from top to downwards. The plants become stunted.</p> <h2 style="text-align: justify;">7. Bark-eating caterpillar (<em>Indarbela quadrinotata</em>)</h2> <p style="text-align: justify;">This pest causes damage by boring holes into the stem and branches and feeds on the bark under the cover of its excreta. The pest is active in neglected orchards.</p> <p style="text-align: justify;"><strong>Control:</strong><br>Remove the webbing and inject kerosene oil into the holes during September-October and again in January-February. Treat all the alternate host plants in the vicinity.</p> <h2 style="text-align: justify;">8. Citrus thrips (<em>Scirtothrips citri</em>)</h2> <p style="text-align: justify;">The pest starts appearing in first week of March with the initiation of flowering and causes damage to petals, stamens and subsequently the basal part of the ovary. The attacked flowers dry up and shrivel. Thrips attack occurs upto third week of April. As soon as the petals start <a title="External website that opens in new window" href="viewcontent/agriculture/post-harvest-technologies/technologies-for-agri-horti-crops/post-harvest-management-of-pulses/drying?lgn=en" target="_blank" rel="noopener" data-page-id="854">drying</a>, adults and nymphs within the floral parts start lacerating the developing fruits.</p> <p style="text-align: justify;">At the initial stage, the damage on the rind/skin of the fruits appears as light silvery white abrasion but with the increase in size of fruit, the scarring becomes prominent and deep on the rind of fruits.</p> <h2 style="text-align: justify;">9. Mealybugs</h2> <p style="text-align: justify;">Four species, viz. <em>Planococcus citri, Planococcus lilacinus, Nipaecoccus viridis </em>and <em>Maconellicoccus hirsutus</em> are active in citrus orchards during July-October, but <em>Planococcus citri</em> is a major pest. These species cause damage to leaves, tender shoots, twigs, branches and fruits. The nymphs and females of these mealybugs suck cell sap and reduce the vigour of plant.</p> <p style="text-align: justify;">The severe feeding causes <a title="External website that opens in new window" href="https://agriculture.vikaspedia.in/viewcontent/agriculture/post-harvest-technologies/technologies-for-agri-horti-crops/post-harvest-management-of-pulses/drying?lgn=en" target="_blank" rel="noopener" data-page-id="854">drying</a> of tender shoots and growing point. Heavy infestation also encourages the growth of sooty mould due to which the leaves, shoots and fruits become black in colour. All these mealybugs hibernate on the twigs and branches of trees.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Monitor regularly the infestation of trees by observing the underside of leaves, young shoots, fruits and branches.<br>(ii) Keep the orchards neat and clean.<br>(iii) Do not allow the branches of trees to touch the ground.<br>(iv) Prune or remove the infested branches and destroy them.<br>(v) Destroy the ant nests in the orchards.</p> <h2 style="text-align: justify;">10. Fruit flies (<em>Bactrocera dorsalis </em>and <em>Bactrocera zonata</em>)</h2> <p style="text-align: justify;">The fruit flies punctures the fruit at colour break stage and deposits its eggs below the epicarp. On hatching, the maggots feed on the soft pulp. The punctured fruit portion start rotting and fruit fall down. On pressing, the juice comes out from the punctured portion of the fruit.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Regularly collect and bury the infested fruits.<br>(ii) Fix PAU fruit fly traps @16 traps/acre in the second week of August and recharge the same if required.</p> <h1 style="text-align: justify;">B. Snails</h1> <h2 style="text-align: justify;">1. Brown snail (<em>Macrochlamys indica</em>) in citrus nursery</h2> <p style="text-align: justify;">The peak activity period of snail in Punjab is during rainy season. For its management in citrus nursery integrated practices should be adopted.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Cleaning up debris in/around nursery will remove breeding and hiding places for snails.<br>(ii) Spread papaya leaves in/around nursery area to attract snails. Then, collect the snails and put into a bucket containing common salt water to kill them.<br>(iii) Hand picking and manual killing.<br>(iv) Keep wet gunny bags in the nursery area as snails try to hide under gunny bags. Then, collect the snails and put into a bucket containing common salt water to kill them.<br>(v) Do bait application of Metaldehyde (2.5% dust) bait when population of snails started appearing in nursery plants or nursery plots.</p> <p style="text-align: justify;">Bait immediately following an irrigation or rainy period when the soil is wet and snails are active. Do not irrigate after bait application. For 1 kg bait, add Jaggery (250 grams) in Wheat bran 750 grams and Metaldehyde (2.5% dust) 25 grams.</p> <p style="text-align: justify;">Caution: Metaldehyde bait is highly toxic and should be stored way from reach of children and pets.</p> <h1 style="text-align: justify;">C. Diseases</h1> <h2 style="text-align: justify;">1. Canker (<em>Xanthomonas axonopodis pv. citri.</em>)</h2> <p style="text-align: justify;">Disease appears on leaves, twigs and fruits. On leaves it appears as yellowish spots, which gradually enlarge, turn rough and brownish and become raised on both sides of the leaf. The spots are surrounded by a yellow halo. Fruit lesions become rough and corky confined only to the rind. Kagzi lime and Grapefruit are highly susceptible.</p> <p style="text-align: justify;"><strong>Control:</strong><br>Give three sprays of 50g Streptocycline + 25 g Copper sulphate in 500 litres of water one each in October, December and February. Bordeaux mixture (2:2:250) or 50% Copper oxychloride (0.3%) can also be sprayed. Also spray nursery plants particularly during July-August.</p> <h2 style="text-align: justify;">2. Scab (<em>Elsinoe fawcetti</em>)</h2> <p style="text-align: justify;">It appears as small, dark brown, rough, irregular, raised lesions mostly on under-side of the leaves. Twigs and fruits are also infected.</p> <p style="text-align: justify;"><strong>Control:</strong><br>Clipping of infected leaves in July and apply three sprays of Bordeaux mixture (2:2:250) or 50% Copper oxychloride (0.3%) during last week of June to August at 20 days interval.</p> <h2 style="text-align: justify;">3. Gummosis/Foot Rot (<em>Phytophthora parasitica</em>)</h2> <p style="text-align: justify;">Affected trees show symptoms of foot rot with profuse gumming, trunk girdling, pale green foliage, stunted growth flushes and twig die-back. The gummy lesions may extend downwards as well as upwards on the tree trunk and may also appear on branches/limbs.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Avoid flood irrigation. Do not allow irrigation water to stay in direct contact with the tree trunk.<br>(ii) Avoid deep hoeing. Avoid injuries to the trunk bark and roots.<br>(iii) Decorticate and disinfect wounds on trunk either with (a) disinfectant solution and cover the wounds with, (b) Bordeaux paste, which when dries up apply (c) Bordeaux paint followed by spray preferably (d) Bordeaux mixture (2:2:250). (for different preparation see at chapter-1 at page 10. OR<br>(iv) Give two applications of Curzate M8 as paint (2 g/100 ml of Linseed oil) to the infected trunk portion and drench (25 g/10 litres of water/tree) the soil at the base of the tree in February-March and again in July-August. OR<br>(v) Spray sodium hypochlorite 5% @50ml per tree by diluting it in 10 litres of water. Spray should be given in the foot and basin region of the trees during February-March and again during July-August. OR<br>(vi) Apply 100 g Talc based bioformulation of Trichoderma asperellum mixed with 2.5 kg FYM per plant one week after the spray of Sodium hyphoclorite at foot and basin region of the plant during Feb-March and again during July–August.</p> <h2 style="text-align: justify;">4. Wither tip / Die-back /Anthracnose (<em>Colletotrichum gloeosporioides</em>)</h2> <p style="text-align: justify;">Symptoms include drying of tips and branches and even of large limbs; necrotic circular areas on leaves; fruit-rot.</p> <p style="text-align: justify;"><strong>Control:</strong><br>Remove the infected twigs during February and then spray with Bordeaux mixture (2:2:250) or 50% Copper oxychloride (0.3%) during March, July and September.</p> <h2 style="text-align: justify;">5. Melanose or Stem end fruit rot (<em>Phomopsis citri</em>)</h2> <p style="text-align: justify;">It manifests as dark circular depressions and yellowish margins on leaves, branches and fruits. Later the spots become raised, rough and light brown and yellow margins disappear. Sand paper texture develops on the surface of leaves and fruits.</p> <p style="text-align: justify;"><strong>Control:</strong><br>Spray Bordeaux mixture (2:2:250) or 50% Copper oxychloride (0.3%) during July-August and September.</p> <h2 style="text-align: justify;">6. Sooty mould (<em>Capnodium citri</em>)</h2> <p style="text-align: justify;">It develops on the honey-dew excreted by the whiteflies. The disease produces black velvety superficial coating on leaves, twigs, stems and fruits. The affected leaves exhibit curling and shriveling symptoms. Heavy infestation leads to poor growth flushes, less flowers and fruits in next cropping season. The incidence of the disease is more on shaded and closely spaced trees. The mould deposited on the fruit rind may delay the fruit colouring and also become difficult to remove resulting in poor market acceptability.</p> <p style="text-align: justify;"><strong>Control:</strong><br>Keep the population of sucking pests under check.</p> <h2 style="text-align: justify;">7. Citrus greening (<em>Candidatus Liberibacter asiaticus</em>)</h2> <p style="text-align: justify;">It is caused by a bacterium and manifests as stiff, upright multiple twigs and buds; small chlorotic or mottled leaves; pre-mature defoliation, die-back of branches and greening of fruits.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Use disease free bud wood.<br>(ii) Since it spreads through an insect vector, citrus psylla (Diaphorina citri) keep the same rigorously under check through recommended insecticidal sprays.</p> <h1 style="text-align: justify;">D. Virus and Virus-like Diseases</h1> <h2 style="text-align: justify;">1. Tristeza (<em>Citrus tristeza virus</em>)</h2> <p style="text-align: justify;">It causes veinlet clearing in young leaves, necrosis of cells at bud union, honey combing of main stem, inverse pits on bark.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Use disease free bud wood and only tolerant rootstocks such as Jatti Khatti.<br>(ii) Control the insect vector (aphid) that causes its spread through recommended insecticidal sprays.</p> <h2 style="text-align: justify;">2. Exocortis (<em>Citrus exocortis viroid</em>)</h2> <p style="text-align: justify;">It is not common on Kinnow and sweet orange budded on Jatti Khatti. In some species like Lime, it causes yellow blotches and cracks on shoots with stunting of trees.</p> <p style="text-align: justify;"><strong>Control:</strong><br>(i) Use disease free bud wood.<br>(ii) Use only resistant rootstocks like Jatti Khatti.<br>(iii) It spreads through the cutting tools. Sterilize them after each contact with infected plants to avoid spread to healthy trees.</p> <h2 style="text-align: justify;">3. Ring Spot (<em>Citrus ring spot virus</em>)</h2> <p style="text-align: justify;">The disease appears as yellow rings on mature leaves. The ring number varies from one to several per leaf with variable diameter. These rings may coalesce to form bigger patches by covering the entire leaf. The severely infected plant shows die-back and decline symptoms with low fruit yield. The virus is transmitted through the infected bud wood.</p> <p style="text-align: justify;"><strong>Control:</strong><br>Use virus free plants for raising the citrus orchard.</p> <p style="text-align: justify;"><a href="https://pau.edu/content/ccil/pf/pp_fruits.pdf" target="_blank" rel="noopener">PACKAGE OF PRACTICES FOR CULTIVATION OF FRUITS</a></p> <p style="text-align: justify;"> </p>