Plant Parasites of Europe

leafminers, galls and fungi

Allium fistulosum

welsh onion

organ parasitic mode stage note taxonomic group parasite
leaf hidden Thripidae Thrips tabaci
flower predator Aeolothripidae Aeolothrips intermedius
leaf vagrant Aphididae Neotoxoptera formosana
leaf down Peronosporales Peronospora destructor
leaf leaf spot Capnodiales Cladosporium allii
leaf leaf spot Capnodiales Cladosporium allii-cepae
leaf miner Agromyzidae Liriomyza cepae
leaf miner Glyphipterigidae Acrolepiopsis assectella
leaf pustule aecia Pucciniales Melampsora allii-fragilis
leaf pustule aecia Pucciniales Puccinia fragosoi
leaf pustule aecia Pucciniales Puccinia gaudinianae
leaf pustule aecia Pucciniales Puccinia laguri-chamaemoly
leaf pustule aecia Pucciniales Puccinia sessilis
leaf pustule aecia uredinia telia Pucciniales Puccinia allii
leaf pustule Urocystidales Urocystis cepulae


the part of the plant that most conspicuously is hit by the parasite

all buds: both flower buds and leaf buds
flower: also inflorescence
leaf: also needle, phyllodium, petiole
leaf bud: also unfolding young leaf
fruit: also seed
root: also root stock, runners
root collar: also the lowest part of the stem
stem: also culm, the lower part of the peduncle, in grasses also leaf sheath
systemic: the entire above-ground plant.


borer: larva living internally, almost no outwards signs
down: 0.5-2 mm high fungal down
film: very thin cover of fungal tussue
gall: swelling and/or malformation
grazer: feeding at the outside of the plant
leaf spot: discoloured, often ± necrotic, generally not galled, sign of a fungus infection
miner-borer: larve initially makes a mine, lives as a borer later
pustule: plug of fungal tissue, generally brown-black and < 2 mm
stripe: longitudinal line of fungal tissue in a grass leaf
vagrant: (aphids, mites) living freely on the plant, at higher densitiy causing malformations.


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The host plant spectre of a parasite is rarely known exhaustively; this applies in particular at the species level. It is advisable therefore to check at least also the list of all parasites of this genus.


Last modified 16.ix.2023