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Garlic Diseases, Pests and Control Methods

Garlic Diseases, Pests and Control Methods

Garlic Diseases and Pests

Let us discuss today about Garlic Diseases, Pests and prevention methods.

Damping off:

  • Symptoms: the major symptoms are -Pre-emergence damping-off: this results in seed and seedling rot before they sprout.
  • Post-emergence damping-off: The disease attacks the collar region of seedlings on the surface of soil. The collar will rot, and the seedlings collapse and die. 
  • Favorable conditions: The disease mainly affects during kharif season/rainy season.

High soil moisture, moderate temperature along with high humidity leads may lead to this disease. 

  • Prevention: some preventive measures are; Proper preparation of soil bed, Treating the soil before sowing seed, Treating the seeds with warm water before sowing, proper irrigation methods, and improved cultural practices will control this disease to some extent.

Avoid heavy seeding so that there is no overcrowding of seedlings and the seedlings should get proper light without any shade.

Purple blotch

It is soil borne fungal disease.

  • Symptoms: the major symptoms are, the affected plant has small leaves and flower stalks with sunken, whitish flecks with purple colored centers.

You can observe lesions on leaves/stalk and leads to dropping off. The infected plants don’t produce bulbs.

  • Favorable Conditions: Wet foliage, Hot and humid climate with temperature (21-30° C) and high humidity (80-90%) will encourage the development of the disease.
  • Preventive Measures: Long rotations with non-hosts will protect the plants from this disease. And avoid overhead watering and well-drained soil and timing irrigation will control this disease to some extent.

Use fungicides that are effective in controlling this disease. 

Read: Garlic Cultivation Project Report.

Stemphylium leaf blight

It is fungal diseases that survives in plant debris or soil.

  • Symptoms: this disease mainly affects the radial leaves of transplanted seedlings at 3- 4 leaf stage during late March and early April.

You can observe small yellowish to orange flecks or streaks in the middle of the leaves, which gets elongated spindle shaped spots surrounded by pinkish margin.

This disease affects inflorescence stalk may lead to severe damage to the seed crop.

  • Favorable conditions

Warm, humid conditions and wet foliage for long periods will increase the chances of this disease.

Preventive

  • Preventive Measures: Buy disease-free seed and plants, well-drained soil; weeding is compulsory and proper irrigation will control the disease to some extent.

Use come protective fungicides are very useful.

Downy mildew

It is fungal diseases that cause severe damage to the crop

  • Symptoms: You can observe a pale spots or elongated patches on the leaves; gray-purple fuzzy growth on the surface of the leaf; leaves turn yellow and the leaf tips collapse.
  • Favorable conditions: cool temperatures and leaf wetness will encourage this disease.
  • Preventive Measures: select disease seeds and seedlings; rotate the crops for every 3-4 years; Use  well-drained soil and avoid overcrowding; dispose infected crop debris properly; Use  appropriate foliar fungicides.

Rust in Garlic Plants

It is a fungal disease. That affects the crop production.

  • Symptoms: You can observe small white flecks on leaves and stems which turns into circular or elongated orange pustules; severe infestations will turn leaves to yellow and die.
  • Favorable Conditions: High humidity and poor irrigation will encourage this disease, spores can be transported over long distances by wind.
  • Preventive Measures: Use only disease-free seed varieties and use well-draining soil for sowing;regular weeding is compulsory; use protective fungicide that is affective to control this disease.

White rot of Garlic

It is a fungal disease that survives in soil for more that 20 years. This disease damages severely.

  • Symptoms: Yellowing of leaves; stunted growth of the plants; leaf fall; fluffy white growth at the base of the bulb which enters from the bulb to the leaves.
  • Favorable conditions: cool temperatures and dry soils for long periods will encourage this disease.
  • Preventive Measures: Avoid soil changes, treat seed with warm water before sowing and long-term crop rotations with non-allium crop will prevent this disease. Use organic fungicides to treat this disease.

Mosaic Garlic mosaic virus (GarMV)

  • Symptoms: Mosaic lesions on the leaves; streaks or mottling on the leaves, slow growth of the plants and very small bulbs.
  • Favorable conditions: this disease is mainly transmitted by aphids; this disease may not show any initial symptoms.
  • Preventive Measures: Plant virus-free cloves meristem tip culture in virus-free conditions. Use organic fungicides to treat this disease.

Black mould of Garlic:

  • Symptoms: Foliage dies down at maturity, bulb gets discolored black around the neck, and affected scales shrivel. You can observe black spores along the veins.
  • Favorable Conditions: this disease is common in high temperatures in both the fields and storage.
  • Preventive Measures: Prepare soil bed properly, good drainage in the field will prevent development of this disease. Implement crop rotation with crops that don’t belong to an onion/garlic family.

Proper harvest and storage will also prevent this disease. Avoid damaging or bruising the onions while you harvest. Properly cure onions for storage and choose varieties that are good for storage plan.

Read: Frequently Asked Questions About Plant Diseases.

Pests in Garlic:

Bulb mites:

  • Symptoms: Slow growth of the plants; reduced stand; bulb rot; you can also observe white bulbous mites on the lower side of the leaves. Bulb mites can cause bulb rots
  • Preventive Measures: avoid crop rotations with onion or garlic; dispose the crop residues properly; treat the seed gloves with water before plants. Use organic insecticides like neem oil, horticultural sprays to control mites.

Leafminers:

  • Symptoms: Thin, white, winding trails on the leaves; white blotches on leaves and leaves drop off before they mature; early infestation leads to low production rate; adult leaf miner is a small
  • Prevention Measures: Buy good quality disease free transplants; Dispose the crop debris after harvesting. Use organic insecticides as soon as you see the above symptoms.

Onion maggot:

  • Symptoms: Wilted and stunted seedlings; very weak stems and falls on the soil; root rots and bulb rots; bulbs get storage rot post harvesting.

Maggots are grayish flies which lay eggs at the base of the plant; these eggs turn into tiny white larvae that bore into the plants.

  • Prevention Measures: Good sanitation; treating soil with granular insecticides or insecticidal sprays after harvesting is highly recommended.  Cover the plants with floating covers to protect them from female maggots.

Thrips:

  • Symptoms: distorted and discolored tissue; leaves with scars; silvery appearance of the plant.

The thrips are insects being  small are only visible through the lens; adult thrips are pale yellow to light brown and the nymphs are smaller and lighter in color.

  • Preventive Measure: Don’t plant garlic crop near to grain fields; Overhead irrigation will reduce the thrips population. Use organic insecticides at the first sign of thrips damage

Lesion nematode Pratylenchuspenetrans

  • Symptoms: weak and stunted plants; very weak root systems; lesion on the roots.
  • Preventive Measures: treat the bulbs with hot water; use organic pesticides to control nematodes.

Read: Organic Farming Business Plan.

Last Updated: November 20, 2018
Author: Jagdish

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