# 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.

## 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
* Aster Leafhopper: Macrosteles facifrons
* Southern Garden Leafhopper: Empoasca solana
Whiteflies
* Silverleaf Whitefly: Bemisia argentifolii
* Greenhouse Whitefly: Trialeurodes vaporariorum
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
* Western Flower Thrips: Frankliniella occidentalis
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. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
* 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. p. 631. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
* Cranshaw, Whitney (2004). Garden Insects of North America: The Ultimate Guide to Backyard Bugs. Princeton University Press. p. 602. {{cite book}}: Cite has empty unknown parameter: |coauthors= (help)
* 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. p. 202. {{cite book}}: |edition= has extra text (help); Cite has empty unknown parameter: |coauthors= (help)CS1 maint: multiple names: authors list (link)