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Post harvest diseases of garlic White rot - Sclerotium cepivorum White rot - Sclerotium cepivorum Blue mold rot - Penicillium spp. Blue mold rot - Penicillium.

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Presentation on theme: "Post harvest diseases of garlic White rot - Sclerotium cepivorum White rot - Sclerotium cepivorum Blue mold rot - Penicillium spp. Blue mold rot - Penicillium."— Presentation transcript:

1 Post harvest diseases of garlic White rot - Sclerotium cepivorum White rot - Sclerotium cepivorum Blue mold rot - Penicillium spp. Blue mold rot - Penicillium spp. Black mould - Aspergillus niger Black mould - Aspergillus niger Pink rot - Pyrenochaeta terrestis Pink rot - Pyrenochaeta terrestis Internal bulb rot - Macrophomina phaseolina Internal bulb rot - Macrophomina phaseolina Basal rot - Fusarium oxysporum f. sp. garlic Basal rot - Fusarium oxysporum f. sp. garlic Neck rot - Botrytis allii Neck rot - Botrytis allii

2 White rot - Sclerotium cepivorum, s. rolfsii Leaves decay at the base, turn yellow, wilt, and topple over Leaves decay at the base, turn yellow, wilt, and topple over Roots and bulbs - covered with a fluffy white mycelium Roots and bulbs - covered with a fluffy white mycelium Affected bulbs may become watery, and the outer scales crack as the bulb dries and shrinks Affected bulbs may become watery, and the outer scales crack as the bulb dries and shrinks Small black sclerotia form on and in affected bulb parts Small black sclerotia form on and in affected bulb parts

3 Mode of spread and survival Cool weather - needed for germination of sclerotia and hyphal growth Cool weather - needed for germination of sclerotia and hyphal growth Mycelium - encounters a host root, the fungus will form appresoria Mycelium - encounters a host root, the fungus will form appresoria Mycelium can grow outwards from the roots of one plant to the roots of a adjacent plant Mycelium can grow outwards from the roots of one plant to the roots of a adjacent plantControl Rotating out of Allium crops for ten years Rotating out of Allium crops for ten years Destroying infected tissue Destroying infected tissue Planting disease - free seed stock Planting disease - free seed stock Seed dressing with benomyl or carbendazim( g/kg of seed) Seed dressing with benomyl or carbendazim( g/kg of seed) Micro sclerotia of the White Rot fungus S.cepivorum developing on an infected garlic bulb

4 Basal rot - Fusarium oxysporum f. sp. garlic Plants - show reduced emergence, yellowing and/or browning (necrosis) of leaves beginning at tips Plants - show reduced emergence, yellowing and/or browning (necrosis) of leaves beginning at tips Reduced bulb size, bulb decay, and brown, poorly developed root systems Reduced bulb size, bulb decay, and brown, poorly developed root systems In storage - bulbs show spongy, sunken, yellow brown rotting lesions In storage - bulbs show spongy, sunken, yellow brown rotting lesions

5 In early stages - infected bulbs are softened, brown and watery when cut open In early stages - infected bulbs are softened, brown and watery when cut open White, light pink or reddish fungal growth covering the cloves or in rot cavities White, light pink or reddish fungal growth covering the cloves or in rot cavities Deep cracks form in the cloves, followed by break down of the tissue, which will eventually dry down to a portion of its original size, the cloves becoming crinkled and small Deep cracks form in the cloves, followed by break down of the tissue, which will eventually dry down to a portion of its original size, the cloves becoming crinkled and small

6 Disease Cycle Soil borne fungus and can persist for long periods in the soil Soil borne fungus and can persist for long periods in the soil Transmission - infested soil on tools or equipment, infected debris, infected seed, or run-off water Transmission - infested soil on tools or equipment, infected debris, infected seed, or run-off water Pathogen enters the plant through wounded tissue Pathogen enters the plant through wounded tissue Disease develops from the base of the bulb and progresses towards the tips of the cloves Disease develops from the base of the bulb and progresses towards the tips of the cloves Favored by higher RH and temperatures(20-30 o C) Favored by higher RH and temperatures(20-30 o C)

7 Management Avoid rotations with Allium spp.(e.g. onions and leeks) and cereals Avoid rotations with Allium spp.(e.g. onions and leeks) and cereals Store bulbs at cool temperatures and low humidity with good ventilation Store bulbs at cool temperatures and low humidity with good ventilation Avoid storing damaged bulbs Avoid storing damaged bulbs

8 Blue mold rot - Penicillium spp.  A blue-green color powdery mould is observed on cloves in soil and in storage, thus its common name, “Blue Mold”  Air-borne spores spread the disease  Infection first occurs on wounds sustained when cloves are separated from the parent bulb CONTROL Bulbs are harvested carefully to avoid wounds and bruising, then promptly dried or cured Bulbs are harvested carefully to avoid wounds and bruising, then promptly dried or cured

9 Black mould (Aspergillus niger and A. alliaceous)  Whole tissue become black powdery mass  Individual bulbs shrivel and become light in weight  Under high humid condition the inner tissues become moderately soft  Infected bulbs lose their pungency and smell  Rotten garlic cloves show black, brown, pink or white coloured rotting

10 Fungus  Mycelium - branched, septate thick walled foot cells differentiate and give rise to a single conidiophore  Conidiophore - globose on which brown sterigmata are formed  Vesicle, sterigmata, conidia make up the black head - characteristic of the fungus Control  Rapid and thorough curing  Storage - good ventilation  Temp - just above 0 o c

11 Pink rot Pyrenochaeta terrestis Roots are affected and they turn pink or reddish and sometimes darken to a red or purple colour Roots are affected and they turn pink or reddish and sometimes darken to a red or purple colour Black spores form on the diseased roots which eventually shrivel and die Black spores form on the diseased roots which eventually shrivel and die Pathogen - Soil borne and infection is mostly from mycelia in the soil Pathogen - Soil borne and infection is mostly from mycelia in the soil Temp o c Temp o c

12 Internal bulb rot - Macrophomina phaseolina  No external symptom can be observed unless the outer scales are removed  Black pin head microsclerotia develop over the fleshy scales which are light in weight, brown, mostly shrivelled  Do not lose their pungency Control  Dipping of bulbs in formalin 0.03%  Boric acid-2.0% After harvest to minimize storage rot

13 Neck rot - Botrytis allii Found upon the bulbs at the time of harvest Found upon the bulbs at the time of harvest Affected scale tissue become soft Affected scale tissue become soft Dense layer of grey mould appear at the neck Dense layer of grey mould appear at the neck Infection progresses most rapidly down the scales which have been originally infected Infection progresses most rapidly down the scales which have been originally infected Garlic with neck rot

14 Mode of spread and survival Survive as sclerotia Survive as sclerotia Requires cool and moist weather Requires cool and moist weather Temp -15 to 20 o c Temp -15 to 20 o cControl Promoting rapid drying at harvest and good aeration in storage is best for managing Botrytis on bulbs Promoting rapid drying at harvest and good aeration in storage is best for managing Botrytis on bulbs Additionally, cooler storage temperatures may help control the disease Additionally, cooler storage temperatures may help control the disease


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