post harvest diseases of garlic white rot - sclerotium cepivorum white rot - sclerotium cepivorum...
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Post harvest diseases of garlicPost harvest diseases of garlic
White rot - White rot - SclerotiumSclerotium cepivorum cepivorum Blue mold rot - Blue mold rot - Penicillium Penicillium sppspp.. Black mould - Black mould - Aspergillus niger Aspergillus niger Pink rot - Pink rot - Pyrenochaeta terrestisPyrenochaeta terrestis Internal bulb rot - Internal bulb rot - Macrophomina phaseolinaMacrophomina phaseolina Basal rot - Basal rot - Fusarium oxysporum f. sp. garlicFusarium oxysporum f. sp. garlic Neck rot - Neck rot - Botrytis alliiBotrytis allii
White rot - White rot - Sclerotium cepivorum,Sclerotium cepivorum,s. rolfsiis. 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 myceliumRoots and bulbs - covered with a fluffy white mycelium
Affected bulbs may become watery, and the outer scales crack as Affected bulbs may become watery, and the outer scales crack as the bulb dries and shrinksthe bulb dries and shrinks
Small black sclerotia form on and in affected bulb partsSmall black sclerotia form on and in affected bulb parts
Mode of spread and survivalMode of spread and survival Cool weather - needed for germination of sclerotia and hyphal Cool weather - needed for germination of sclerotia and hyphal
growthgrowth
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 Mycelium can grow outwards from the roots of one plant to the roots of a adjacent plant of a adjacent plant
ControlControl Rotating out of Rotating out of AlliumAllium crops for ten years crops for ten years
Destroying infected tissueDestroying infected tissue
Planting disease - free seed stockPlanting disease - free seed stock
Seed dressing with benomyl or carbendazim(100-150g/kg of seed)Seed dressing with benomyl or carbendazim(100-150g/kg of seed)
Micro sclerotia of the White Rot fungus S.cepivorum developing on an infected
garlic bulb
Basal rot - Basal rot - Fusarium oxysporum f. sp. garlicFusarium oxysporum f. sp. garlic
Plants - show reduced emergence, yellowing and/or browning Plants - show reduced emergence, yellowing and/or browning (necrosis) of leaves beginning at tips(necrosis) of leaves beginning at tips
Reduced bulb size, bulb decay, and brown, poorly developed root Reduced bulb size, bulb decay, and brown, poorly developed root systemssystems
In storage - bulbs show spongy, sunken, yellow brown rotting In storage - bulbs show spongy, sunken, yellow brown rotting lesionslesions
In early stages - infected bulbs are softened, brown and watery In early stages - infected bulbs are softened, brown and watery when cut openwhen cut open
White, light pink or reddish fungal growth covering the cloves or in White, light pink or reddish fungal growth covering the cloves or in rot cavitiesrot cavities
Deep cracks form in the cloves, followed by break down of the 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, tissue, which will eventually dry down to a portion of its original size, the cloves becoming crinkled and smallthe cloves becoming crinkled and small
Disease CycleDisease Cycle
Soil borne fungus and can persist for long periods in the soilSoil borne fungus and can persist for long periods in the soil
Transmission - infested soil on tools or equipment, infected debris, Transmission - infested soil on tools or equipment, infected debris, infected seed, or run-off waterinfected 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 Disease develops from the base of the bulb and progresses towards the tips of the clovesthe tips of the cloves
Favored by higher RH and temperatures(20-30Favored by higher RH and temperatures(20-30ooC)C)
Management Management
Avoid rotations with Avoid rotations with AlliumAllium spp.(e.g. onions and leeks) and cereals spp.(e.g. onions and leeks) and cereals
Store bulbs at cool temperatures and low humidity with good Store bulbs at cool temperatures and low humidity with good ventilation ventilation
Avoid storing damaged bulbs Avoid storing damaged bulbs
Blue mold rot - Blue mold rot - Penicillium Penicillium sppspp..
A blue-green color powdery mould is observed on cloves in soil and in A blue-green color powdery mould is observed on cloves in soil and in storage, thus its common name, “storage, thus its common name, “Blue Mold” Blue Mold”
Air-borne spores spread the diseaseAir-borne spores spread the disease
Infection first occurs on wounds sustained when cloves are separated Infection first occurs on wounds sustained when cloves are separated from the parent bulb from the parent bulb
CONTROLCONTROL Bulbs are harvested carefully to avoid wounds and bruising, then Bulbs are harvested carefully to avoid wounds and bruising, then
promptly dried or curedpromptly dried or cured
Black mould (Black mould (Aspergillus niger and A. alliaceousAspergillus niger and A. alliaceous))
Whole tissue become Whole tissue become black powdery massblack powdery mass
Individual bulbs shrivel and become light Individual bulbs shrivel and become light in weightin weight
Under high humid condition the inner Under high humid condition the inner tissues become moderately softtissues become moderately soft
Infected bulbs lose their pungency and Infected bulbs lose their pungency and smellsmell
Rotten garlic cloves show black, brown, Rotten garlic cloves show black, brown, pink or white coloured rottingpink or white coloured rotting
FungusFungus Mycelium - branched, septate thick walled foot cells differentiate and Mycelium - branched, septate thick walled foot cells differentiate and
give rise to a single conidiophoregive rise to a single conidiophore
Conidiophore - globose on which brown sterigmata are formedConidiophore - globose on which brown sterigmata are formed
Vesicle, sterigmata, conidia make up the black head - characteristic Vesicle, sterigmata, conidia make up the black head - characteristic of the fungusof the fungus
ControlControl Rapid and thorough curing Rapid and thorough curing
Storage - good ventilation Storage - good ventilation
Temp - just above 0Temp - just above 0oocc
Pink rotPink rotPyrenochaeta terrestisPyrenochaeta terrestis
Roots are affected and they turn pink or reddish and sometimes darken to a red or purple colourRoots 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 dieBlack spores form on the diseased roots which eventually shrivel and die
Pathogen - Soil borne and infection is mostly from mycelia in the soilPathogen - Soil borne and infection is mostly from mycelia in the soil
Temp - 24-28Temp - 24-28oocc
Internal bulb rot - Internal bulb rot - Macrophomina phaseolinaMacrophomina phaseolina
No external symptom can be observed unless the outer scales are No external symptom can be observed unless the outer scales are removedremoved
Black pin head microsclerotia develop over the fleshy scales which Black pin head microsclerotia develop over the fleshy scales which are light in weight, brown, mostly shrivelledare light in weight, brown, mostly shrivelled
Do not lose their pungencyDo not lose their pungency
ControlControl Dipping of bulbs in formalin 0.03%Dipping of bulbs in formalin 0.03%
Boric acid-2.0%Boric acid-2.0%
After harvest to minimize storage rot
Neck rot - Neck rot - Botrytis alliiBotrytis allii
Found upon the bulbs at the time of harvestFound upon the bulbs at the time of harvest
Affected scale tissue become softAffected scale tissue become soft
Dense layer of grey mould appear at the neckDense layer of grey mould appear at the neck
Infection progresses most rapidly down the scales which have been Infection progresses most rapidly down the scales which have been originally infectedoriginally infected
Garlic with neck rot
Mode of spread and survivalMode of spread and survival Survive as sclerotia Survive as sclerotia Requires cool and moist weatherRequires cool and moist weather Temp -15 to 20Temp -15 to 20oocc
ControlControl Promoting rapid drying at harvest and good aeration in storage is Promoting rapid drying at harvest and good aeration in storage is
best for managing Botrytis on bulbsbest for managing Botrytis on bulbs
Additionally, cooler storage temperatures may help control the Additionally, cooler storage temperatures may help control the diseasedisease