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