Aphids on lettuce: symptoms, causes, control

Aphids are harmful insects that infect lettuce plants, leading to deformed leaves and a decline in crop quality. This article from the “WORLD OF PLANTS” website presents strategies for combating aphids on lettuce and methods of preventing them.

Cause of aphid disease on lettuce

• Aphids
• Scientific name: Aphidoidea
• Type of disease: insects
• The cause of the pest: Black aphid - or - The Green Prach Aphid

As a result of absorbing the juice, the content of antioxidant vitamins and nutrients in lettuce leaves decreases. The plant tissues die with time and the leaves turn yellow. The leaves are lost and become unsuitable for preparing salads or for fresh food.

Host of aphid disease on lettuce

It is also found in apples, pears, grapes, beans and lettuce, peppers and hot peppers, eggplant, cherries, apricots, peaches, peas, cucumbers, pumpkin, zucchini, tomatoes, cabbage, potatoes, green and black cowpeas, Indian peas and red peas, peas and chickpeas, cotton, wheat, soybeans, onions, garlic, rice, millet, almonds, sorghum, corn, strawberries. Currants, olives, bananas, sweet potatoes, okra, citrus fruits (citrus, peanuts, mango, papaya, cow, sugarcane, barley, coffee, watermelon, roses, sugar beet, pomegranate, canola, lentils, cauliflower, pistachios, ornamental plants, guava, turmeric, ginger, karela, bitter cucumber) tobacco.

 Suitable conditions for aphids on lettuce

Although lettuce aphids are more common in the spring, factors associated with climate change, with milder winters, make them more likely to appear in cooler seasons. Their ability to reproduce and develop slows down at temperatures below 10°C, but is much faster when temperatures exceed 20°C.

Effect of aphid disease on lettuce

The lettuce aphid is one of the sap-sucking, plant-piercing insects that spreads in fields and is found anywhere in the world. It has a wide range of plants that are its primary host. It infects thousands of species of plants such as tobacco, onions, garlic, leeks, peaches, apples, tomatoes, and others. Its harm is very strong, as its main task is to suck the plant's cellular juices, and thus it weakens the plant and deprives it of the products of photosynthesis and food. Likewise, the lettuce plant does not benefit from the added fertilizer, so the yield of mature leaves (leaves used for food and making useful delicious salads) is reduced, and the crop is also weakened. . Aphids are widespread in all parts of the world, with a very large number of generations, which makes it difficult to prevent them. These insects infect lettuce and cause economic losses to the farmer, sometimes amounting to 80% of leaves when ignored and not cared for.

Life cycle of aphids on lettuce

The lettuce aphid spends the winter as a nymph or an entire insect hiding on the lettuce plant or parts of herbaceous plants in the field. The life cycle of the lettuce aphid begins with the appearance of the first generation in the cultivated fields with the appropriate temperature rise for the development of the nymphs. After that, the insects mate and new nymphs appear with the availability of temperature of 22-23 Celsius and the ideal humidity 75%. With the emergence of generations, the insects develop from nymphs into full-fledged insects, and then they begin to feed on the juice of the lettuce plant in the leaves, which gradually dies and weakens and becomes in the stage of economic uselessness and agricultural uselessness. .

Symptoms of aphid disease on lettuce

• Small nymphs and adult insects attack the leaves (small and large leaves) of lettuce plants, preferring the young and young ones.
• Insects suck the plant juices from the leaves, causing the lettuce plant to weaken and become in a state of general weakness, dryness, gradual wilting, and a clearly visible paleness of the leaves.
• As the injury progresses.
• As a result of absorbing the juice, the content of antioxidant vitamins and nutrients in lettuce leaves decreases.
• The plant tissues die over time and the leaves turn yellow. 80% of the leaves are lost and they become unsuitable for preparing salads or for fresh food.
• The productivity of one hectare of lettuce grown also decreases, and production decreases by 60-70%.
• Aphids weaken nutritional processes in the plant's body, and the lettuce plant does not benefit from fertilizer, so food assimilation, transport, and distribution within the plant are reduced.
• The weakness of the plant itself attracts other dangerous insects, such as thrips that infect lettuce, root worms that chew and damage the roots (wireworm), nematodes, nematodes, and others.

Preventive measures for aphids on lettuce

• Basic plowing to a depth of 30 cm, adding organic fertilizers, followed by softening and breaking up the soil for growing lettuce to a depth of 12-15 cm using rotary mowing machines, or special disc plows for that purpose.
• Separate the cultivation of lettuce from the cultivation of other vegetables, such as tomatoes, cucumbers, garlic, and onions, and also separate the cultivation of vegetables from the cultivation of fruit trees such as citrus, almonds, and apples.
• The farmer monitors the lettuce fields periodically in the spring and winter by observing the leaves and the vegetative system and ensuring that they are free of aphids and their symptoms.
• The farmer also seeks to get rid of the weeds surrounding the lettuce field, because they ensure that pests can move and hide among the components of these weeds (locust pests, worms, etc.).
• The farmer also depends on balanced fertilization with nitrogen, N, and phosphorus, P (especially potash, K for lettuce, to give the plant an immune boost against pests, including aphids). Potash is added to lettuce at a rate of 60 kg per hectare, and phosphorus is added at a rate of 80 kg per hectare.
• Nitrogen is added in batches, not all at once. Once when planting, it includes 2/3 of the amount, a second time 1/3 of the amount when hoeing lettuce plants, and a third time when setting flowers, it includes 1/3 of the amount at a rate of 30-60 kg/ha of nitrogen.
• The farmer takes as much care as possible to take general care of the lettuce plants, including irrigation and hoeing and other agricultural services. He hoes to a depth of 12-15 cm and repeats three times until the nodes are set and the required parts are obtained (leaves for salad or fresh food).
• Adopting drip irrigation for lettuce (which is highly recommended) combined with water-soluble fertilizers; This technology ensures regulation of irrigation and the killing of insects through the pesticide added to the irrigation water.
• Adding organic carbon or biochar to improve soil properties, provide the lettuce plant with food, strength and vitality, and increase productivity and yield

Organic control of aphids on lettuce

Prevention is carried out by planting lettuce at appropriate distances, which are 20 cm between plants and 25 cm between lines, avoiding high density per unit area, using the technique of soluble fertilizers in irrigation water with drip irrigation, and not increasing nitrogen fertilization.

Chemical control of aphids on lettuce

Aphids on lettuce are permanently treated by using the pesticide Parathion, Malathion, Parathion methyl, or Dimeton s Methyl by spraying the buds and leaves on the lettuce plant. These mentioned pesticides give effective results in lettuce fields infected with aphids.

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References:

^ a b “Aphid”, www.britannica.com, Retrieved 25-11-2019. Edited. ^ A B C D C H “Aphids Management”, Ipm.ucanr.edu, Retrieved 11-25-2019. Edited. ^ a b “INTEGRATED PEST MANAGEMENT (IPM) FOR APHIDS”, hgic.clemson.edu, 8-7-2019, Retrieved 25-11-2019. Edited. ↑ Ron Patterson, Ricardo Ramirez, “digitalcommons.usu.edu”, digitalcommons.usu.edu, Retrieved 11-25-2019. Edited. ↑ “Biological Control of Aphids”, Ipm.uconn.edu, Retrieved 11-25-2019. Edited. ↑ “Aphids on Shade Trees and Ornamentals”, extension.colostate.edu, Retrieved 11-25-2019. Edited. ^ A B C “Aphids in the home yard and garden”, extension.umn.edu, Retrieved 25-11-2019. Edited. ↑ “Aphids In the home yard and garden”, extension.umn.edu, Retrieved 11-25-2019. Edited. ↑ “Aphididae”, www.itis.gov, Retrieved 11-25-2019. Edited.