Common Citrus Damaging Pests: Symptoms, Treatment, Prevention, and Management

Welcome to our blog post on common citrus-damaging pests! Citrus trees are vulnerable to various pests that can wreak havoc on their health and productivity. In this article, we will explore the symptoms of these pests, the best treatments available, and prevention and management strategies. By understanding these pests and how to deal with them, you can ensure the well-being of your citrus trees and enjoy a bountiful harvest.

Overview of Citrus Farming and Production

India ranks fifth in citrus fruit production, making it an important agricultural sector. Spain, USA, Israel, Morocco, South Africa, Japan, Brazil, Turkey, and Cuba produce citrus with India. Many citrus species originate in North East India, a tropical and subtropical region of Southeast Asia that includes India and China. India produces 7,464,000 metric tons of citrus on 846,000 hectares. Its vitamin C and juice are prized.

Orange (mandarin or tantra), sweet orange (mosambi, malta, or study), and lime/lemon (known as ‘Pati lime’ or ‘Kagzi lime’) are India’s commercial citrus types. India’s citrus-growing states are Maharashtra, Andhra Pradesh, Punjab, Karnataka, Uttaranchal, Bihar, Orissa, Assam, and Gujarat. About 250 bug and mite species infest citrus orchards in India. Pests, including citrus butterflies, leaf miners, blackflies, whitefly, psylla, and scales, harm plant development, especially during the fresh flush period.

Citrus is grown in over 52 countries. Brazil, China, India, Mexico, and Spain produce the most citrus. Citrus species’ primary and secondary centers of origin are in India’s North Eastern Region. Citrus Medica, citron (C. medica), sweet lime (C. lamittoides), sour orange (C. aurantium), sweet pummelo (C. grandis), sour pummelo (C. megaloxycarpa), Khasi paid, and rough lemon are native citrus species in this region.

Most Common Citrus Damaging Pests

Citrus Psylla (Diaphorina citri): Both adults and nymphs of this pest suck sap from buds, leaves, and branches, injecting a toxic substance. Severe infestation results in distorted leaves, defoliation, and the spread of ‘citrus greening’ disease.
Bark Borer (Inderbela tetraonis, Inderbela quadrinotata): The caterpillars bore into branches, weakening the tree. Webby masses of chewed wood particles and excreta on trunks indicate their damage. Translocation of cell sap is disrupted, affecting growth and fruiting.
Citrus Leaf miner (Phyllocnistis citrella): Larvae mine tender leaves, causing silvery appearance, distortion, and crumpling. Infestation leads to yellowing and drying of leaves and promotes citrus canker disease.
Citrus White fly / Citrus Black fly (Dialeurodes citri, Aleurocanthus woglumi): Nymphs and adults suck sap, secreting honeydew and causing sooty mold on leaves. Severe infestation turns fruits black and affects their taste.
Aphids (Toxoptera citricida, Myzus persicae, Aphis gossypii): Nymphs and adults suck sap, resulting in yellowing, curling, and deformation of leaves. Aphid infestation during flowering reduces fruit set. Some aphids are vectors of the citrus tristeza virus.
Citrus or Lemon Butterfly (Papilio demoleus): Caterpillars feed on young foliage, causing defoliation. They leave only the midrib of the leaf. Severe infestation occurs in nurseries and on grown-up trees.
Fruit Sucking Moths (Eudocima fullonia, Eudocima maternal): Nocturnal moths that feed on ripening fruits, causing damage and exposing them to secondary infections. Affected fruits usually fall within days.
Fruit Flies (Bactrocera zonata, Bactrocera dorsalis): Female fruit flies puncture ripening fruits to lay eggs. Maggots feed on the pulp, leading to rotting, premature fruit fall, and fungal or bacterial infections.
Citrus Mite (Eutetranychus orientalis): Mites damage fruits by causing russetting, making them unfit for export. They feed on leaves, leaving multiple grey spots.
Scale Insects: Armoured scales (Aonidiella auriantii, A. citrina, A. orientalis, Chrysompahlus aonidum) damage fruits and trees. Soft scales (Coccus hesperidium, C. viridis) secrete honeydew, promoting sooty mold growth.
Mealybug (Planococcus citri): Nymphs and females suck sap, excreting honeydew and causing flowers, fruits, and nursery seedlings to dry up and fall. Ants are often associated with mealybug infestation.
Citrus thrips (Scirtothrips citri): Thrips damage flowers, leaves, and fruits by lacerating, rasping, and sucking cell sap. Leaves become distorted, and fruit necks develop silvery-white irregular patches.

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Citrus Aphid Pest Damage and Control

The citrus aphid is a small insect that reproduces through live birth. It goes through four nymphal stages before becoming an adult. Adult females are oval-shaped, ranging in color from black to reddish-brown, and can have wings or be wingless. They feed on citrus foliage, causing wilting and flower dropping, and hinder plant growth.

The aphid is temperature-dependent, with optimal development occurring between 20 to 25°C. It can transmit the Citrus Tristeza Virus. Controlling measures include spraying with insecticides like Parathion, Malathion, Monocrotophos, or Phosphamidon and conserving coccinellid populations.

Citrus/Lemon-Butterfly Pest Damage and Management

The lemon butterfly, known as Papilio demoleus, goes through different stages. The eggs are yellowish-white and hatch within 3 to 8 days. The caterpillars are initially dark brown and develop white markings on their body. They feed extensively on tender leaves, defoliating seedlings or trees, leaving only the midribs. After feeding, they transform into pupae and remain in this stage for 2-3 weeks before emerging as adults.

The adult butterfly is large and beautiful, with yellow and black markings on its wings. The larval population is highest from October to December, and their activity is most favorable from July to December. The butterfly can survive winter temperatures below freezing. Management methods include handpicking larvae and spraying with Monocrotophos insecticide.

Citrus Psylla Pest Damage and Management

The citrus psylla, or Asian citrus psyllid, is a small, winged insect that causes damage to curry leaf plants. The eggs are pear-shaped and initially orange to yellow, turning darker before hatching. The nymphs with flattened bodies are yellow, orange, or brown and secrete honeydew, attracting sooty mold. The adult psyllids are mottled brown, with red eyes and short antennae.

They feed on the leaves, causing damage, twisting, and curling. Heavy feeding can lead to shoot reduction and failure to develop new flushes. Management includes using natural enemies like coccinellids and ladybird beetles and spraying with insecticides like Phosphamidon, Parathion, Monocrotophos, or Malathion. Application timing should be adjusted based on pest appearance.

Citrus Leaf Miner Pest Damage and Management

The citrus leaf miner is a small fly that lays its eggs inside the leaf tissue of citrus and related plants. The eggs are tiny and hatch in about three days, giving rise to small yellow maggots. The larvae create winding tunnels or mines within the leaves as they feed. After their larval stages, they pupate on the leaf surface or in the soil. The adult flies are greyish to black with yellow markings. The favorable conditions for their development include temperatures between 70º to 85ºF and high humidity.

The damage caused by citrus leaf miners includes distorted and curled leaves. While mature citrus trees can tolerate leaf damage without significant impact, young trees may experience growth retardation. Pruning affected parts during winter and spraying with insecticides like Methyl Demeton, and Phosphamidon can help manage the pest population. Additionally, applying Phorate 10 G before planting can reduce the larval population.

Bark Borer Pest Damage and Management

The Bark Borer, specifically Inderbela tetraonis and Inderbela quadrinotata, are caterpillars that bore holes into tree branches, weakening the tree. Their presence can be identified by the webby mass of chewed wood particles and larvae excreta on tree trunks. To manage these borers, the webbing should be removed, the holes plugged with cotton wool soaked in Dichlorvos 76EC solution or injected with kerosene oil, and then sealed with mud. Management should be carried out in September-October and repeated in January-February.

Citrus White Fly Pest Damage and Management

Citrus White fly, and Citrus Black fly, specifically Dialeurodes citri and Aleurocanthus woglumi, suck the sap of plants, leading to the secretion of honeydew and the development of sooty mold on leaves. Severe infestations can cause the entire orchard to appear black, and fruits may turn black and taste bland. Effective management involves drenching the trees with sufficient Monocrotophos, Phosphamidon, or Acephate solutions.

Fruit Sucking Moths Pest Damage and Management

Fruit Sucking Moths, specifically Eudocima fullonia and Eudocima maternal, are nocturnal pests that hide in fallen leaves and weeds during the day, becoming active at dusk. They swarm in large numbers when citrus fruits are about to ripen and pierce the fruits to suck the juice, causing significant damage. Management involves:

Eliminating alternate host plants.
Collecting and destroying affected fruits.
Using poison baits.
Bagging fruits.
Creating smoke in the orchards.
Spraying with carbaryl.

Fruit Flies Pest Damage and Management

Fruit Flies, specifically Bactrocera zonata and Bactrocera dorsalis, are pests that puncture ripening fruits with their ovipositors to lay eggs. The hatched maggots feed on the fruit pulp, causing damage and rotting. Infested fruits exhibit dark green depressions and enlarged yellow areas around the punctures. Management involves collecting and destroying infested fruits and using flytraps containing Methyl Eugenol and Malathion mixed with sugar syrup. These measures help reduce the population of fruit flies and minimize fruit damage.

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Scale Insect Pest Damage and Management

Scale insects, including armored scales (Aonidiella auriantii, A. citrina, A. orientalis, Chrysompahlus aonidum) and soft scales (Coccus hesperidium, C. viridis), damage citrus trees and fruits. Armored scales cause blemishes on fruits and severe damage to trees, while soft scales secrete honeydew leading to sooty mold growth.

Soft scales can be managed by spraying Monocrotophos (0.1%). Mealybugs, such as Planococcus citri, suck sap, excrete honeydew, and cause fruit and flower damage. Sanitation practices, uprooting weeds, and drench spray with chlorpyriphos can help control mealybug infestations.

Citrus Mites pest damage and management, specifically Eutetranychus orientalis, damage fruits by causing russetting and leaf defoliation. Control measures involve applying Dicofol, Wettable Sulphur, or Monocrotophos to manage the mite population.

Citrus Thrips Pest Damage and Management

Citrus thrips (Scirtothrips citri) are tiny insects that cause damage to flowers, leaves, and fruits by lacerating, rasping, and sucking cell sap. They result in dried-up and shriveled flowers, distorted and wrinkled leaves, and peculiar circular ring patterns around the neck of fruits. Management involves spraying Hostathion 40 EC (triazophos), Metasystox 25 EC (oxydemeton methyl), or Fosmite 50 EC (ethion) twice in 500 liters of water in mid-March and mid-April.

Conclusion

Common citrus-damaging pests include citrus leaf miners, bark borer, white fly/black fly, fruit-sucking moths, fruit flies, citrus mites, scales, mealybugs, and citrus thrips. Symptoms vary but include leaf damage, fruit discoloration, and reduced yield. Effective treatment involves targeted insecticides and cultural practices such as pruning, sanitation, and eliminating alternate hosts. Regular monitoring and early intervention are crucial for prevention and management.