الخَسّ

Foodplant / sap sucker
Aulacorthum solani sucks sap of live, slightly distorted and discoloured leaf (young) of Lactuca sativa

Foodplant / open feeder
nocturnal caterpillar of Autographa gamma grazes on live leaf of Lactuca sativa

Foodplant / pathogen
Beet Western Yellows virus infects and damages intensely yellow between veins leaf (outer) of Lactuca sativa
Remarks: season: summer

Foodplant / pathogen
Botrytis dematiaceous anamorph of Botrytis cinerea infects and damages rotten stem of Lactuca sativa

In Great Britain and/or Ireland:
Foodplant / spot causer
mostly hypophyllous colony of sporangium of Bremia lactucae causes spots on live, mainly outer leaf of Lactuca sativa
Remarks: season: 9-10
Other: major host/prey

Foodplant / miner
larva of Chromatomyia syngenesiae mines leaf of Lactuca sativa

Foodplant / pathogen
pale green or mottled, often blistered or crinkly Cucumber Mosaic virus infects and damages Lactuca sativa

Foodplant / pathogen
Ditylenchus dipsaci infects and damages live, swollen, stunted or malformed leaves of Lactuca sativa

Foodplant / pathogen
colony of Erwinia carotovora infects and damages Lactuca sativa

Foodplant / parasite
Golovinomyces cichoracearum parasitises live Lactuca sativa

Foodplant / pathogen
Lettuce Big-vein infects and damages distorted or bubbled lamina leaf (outer) of Lactuca sativa

Foodplant / pathogen
pale green or mottled, often blistered or crinkly Lettuce Mosaic virus infects and damages Lactuca sativa
Remarks: season: spring

Foodplant / sap sucker
Macrosiphum euphorbiae sucks sap of live shoot (young) of Lactuca sativa

Foodplant / open feeder
caterpillar of Mamestra brassicae grazes on live leaf of Lactuca sativa

Foodplant / gall
Meloidogyne causes gall of root of Lactuca sativa
Other: major host/prey

Foodplant / shot hole causer
acervulus of Marssonina coelomycetous anamorph of Microdochium panattonianum causes shot holes on live leaf of Lactuca sativa

Foodplant / spot causer
amphigenous colony of Ramularia hyphomycetous anamorph of Mycosphaerella hieracii causes spots on live leaf of Lactuca sativa
Remarks: Other: uncertain

Foodplant / sap sucker
Myzus persicae sucks sap of Lactuca sativa

Foodplant / sap sucker
Nasonovia ribisnigri sucks sap of live leaf of Lactuca sativa
Remarks: season: 5-summer, (1-12, under glass)
Other: major host/prey

Foodplant / parasite
Olpidium brassicae parasitises live root of Lactuca sativa

Foodplant / sap sucker
subterranean wingless of Pemphigus bursarius sucks sap of live root of Lactuca sativa
Other: major host/prey

Foodplant / feeds on
subterranean larva of Phyllopertha horticola feeds on live root of Lactuca sativa
Other: unusual host/prey

Foodplant / saprobe
effuse colony of Stemphylium dematiaceous anamorph of Pleospora allii is saprobic on dead Lactuca sativa

Foodplant / shot hole causer
pseudothecium of Pleospora herbarum causes shot holes on live leaf of Lactuca sativa

Foodplant / spot causer
colony of Pseudomonas marginalis causes spots on live, shrivelled leaf (edge) of Lactuca sativa

Foodplant / parasite
pycnium of Puccinia opizii parasitises live leaf of Lactuca sativa
Other: major host/prey

Foodplant / saprobe
sclerotium of Sclerotinia minor is saprobic on rotting plant of Lactuca sativa
Remarks: season: 6-12
Other: major host/prey

Foodplant / spot causer
mostly epiphyllous pycnidium of Septoria coelomycetous anamorph of Septoria lactucae causes spots on live stem of Lactuca sativa

Foodplant / internal feeder
larva of Trupanea amoena feeds within capitulum of Lactuca sativa
Remarks: Other: uncertain