< Horticulture
Lactuca

Lettuces
Genus:Lactuca
Family:Asteraceae
Type:Annuals, Perennials, Biennials
Weediness:Most species are weedy
Pollination:Insect

Lactuca, commonly known as lettuce, is a genus of flowering plants in the Sunflower family Asteraceae. The genus includes about 100 species, distributed worldwide, but mainly in temperate Eurasia.

Description

Its best-known representative is the garden lettuce (Lactuca sativa), with its many varieties. But many are just common weeds. They are annuals or perennials. Their height can vary between 10–180 cm. They form heads or capitula in panicles of yellow, brown or purple flowers in ray florets.

The non-edible species may contain bitter elements. Others contain a milky juice.

Growing conditions

Species

  • Lactuca biennis : Tall Blue Lettuce, Wild Blue Lettuce
  • Lactuca canadensis : Canada Lettuce, Florida Blue Lettuce, Wild Lettuce (North America)
  • Lactuca sativa : Garden Lettuce, Lettuce
  • Lactuca serriola : Prickly Lettuce, China Lettuce, Wild Lettuce (Southern Europe)
  • Lactuca tatarica : Blue Lettuce, Chickory Lettuce, Russian Blue Lettuce (Asia, India)

Uses

The garden lettuce is grown as a salad green, other species occur as weeds.

Pests and Diseases

Pests

Aphids

  • Pea Aphid: Acyrthosiphon pisum
  • Bean Aphid: Aphis fabae
  • Brown Ambrosia Aphid: Dactynotus ambrosiae
  • Potato Aphid: Macrosiphum euphorbiae
  • Green Peach Aphid: Myzus persicae
  • Red Lettuce Aphid: Uroleucon pseudambrosiae
  • Cabbage Aphid: Brevicoryne brassicae
  • Lettuce Aphid: Nasonovia ribisnigri
  • Lettuce Root Aphid: Pemphigus bursarius

Hoppers

Whiteflies

Bugs

  • Pale Legume Bug: Lygus elisus
  • Western Tarnished Plant Bug: Lygus hesperus
  • Tarnished Plant Bug: Lygus lineolaris
  • False Cinch Bug: Nysius raphanus
  • Garden Fleahopper: Halticus bractatus

Thrips

Flies

  • American Serpentine Leafminer: Liriomyza trifolii
  • Chrysanthemum Leafminer: Phytomyza syngenesiae

Beetles

  • Banded Cucumber Beetle: Diabrotica balteata

Flea Beetles

  • Palestriped Flea Beetle: Systena blanda
  • Redheaded Flea Beetle: Systena frontalis

Caterpillars

  • Zebra Caterpillar: Ceramica picta
  • Corn Earworm: Helicoverpa/Heliothis zea
  • Variegated Cutworm: Peridroma saucia
  • Beet Armyworm: Spodoptera exigua
  • Yellowstriped Armyworm: Spodoptera ornithogalli
  • Cabbage Looper: Trichoplusia ni
  • Celery Leaftier: Udea rubigalis
  • Alfalfa Looper: Autographa californica Western US
  • Celery Looper: Anagrapha falcifera
  • Saltmarsh Caterpillar: Estigmene acrea
  • Western Corn Rootworm: Diabrotica virgifera virgifera
  • Western Yellowstriped Armyworm: Spodoptera praefica
  • Angle Shades: Phlogophora meticulosa
  • Autumnal Rustic: Eugnorisma glareosa
  • Cabbage Moth: Mamestra brassicae
  • Common Swift: Korscheltellus lupulina
  • Garden Dart: Euxoa nigricans
  • Ghost Moth: Hepialus humuli
  • The Gothic: Naenia typica
  • Grey Chi: Antitype chi
  • Heart and Club: Agrotis clavis
  • Heart and Dart: Agrotis exclamationis
  • Ingrailed Clay: Diarsia mendica
  • Large Yellow Underwing: Noctua pronuba
  • The Nutmeg: Discestra trifolii
  • Setaceous Hebrew Character: Xestia c-nigrum
  • The Shark: Cucullia umbratica
  • Small Angle Shades: Euplexia lucipara
  • Turnip Moth: Agrotis segetum

Slugs and Snails

Diseases

Bottom Rot

  • Rhizoctonia

Downy Mildew

Gray Mold

White Mold

  • Sclerotinia

Other Problems

Calcium Deficiency

References

  • Ann Fowler Rhoads and Timothy A. Block (2000). The Plants of Pennsylvania: An Illustrated Manual. Anna Anisko, illustrator. Morris Arboretum, University of Pennsylvania Press. pp. 225–227. 
  • Staff of the L. H. Bailey Hortorium (1976). Hortus Third: A Concise Dictionary of Plants Cultivated in the United States and Canada. Cornell University Press. pp. 631. 
  • Cranshaw, Whitney (2004). Garden Insects of North America: The Ultimate Guide to Backyard Bugs. Princeton University Press. pp. 602. 
  • Pippa Greenwood, Andrew Halstead, A.R. Chase, Daniel Gilrein (2000). American Horticultural Society Pests & Diseases: The Complete Guide to Preventing, Identifying, and Treating Plant Problems (First Edition ed.). Dorling Kindersley (DK) Publishing, inc.. pp. 202. 
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