Disease Management of Lettuce
Major Diseases Caused By Symptoms Control
Fungal Disease      

Bottom rotlettuce-bottomrot

Rhizoctonia solani Usually wilting of the outer leaves Provide good drainage and weed control

Grey moldlettuce-greymold

Botrytis cinerea Water soaked, then grayish green or brown, and finally turn into a brownish-gray, slimy mass.

-keep the humidity low and the temperature warmand sterilize soil before planting

-Keeping the plants as dry as possible helps prevent infection, so avoid overhead watering

Downy mildewlettuce-downymildew

Bremia lactucae -Symptoms appear first on oldest leaves. -Yellowish or light green blotchy areas appear on the upper sides of leaves Use resistant varieties

Fusarium wiltlettuce-fusarium wilt

Fusarium oxysporum -The first symptoms may occur in seedlings that wilt and die. -Mature plants have a characteristic red-brown streak.

Effective control measure is to avoid planting head lettuce in infested fields for at least several years

Leaf drop lettuce-leafdrop

Sclerotinia minorĀ  & Sclerotinia sclerotiorum First symptom that is noticed is wilting of the outermost leaves

-Use long rotations away from lettuce, beans, celery, or carrots

-Well- drained soil and/or use raised beds

Powdery mildewlettuce-powderymildew

Erysiphe cichoracearum -Covered by the fungal hyphae, giving it a powdery or dusty appearance -Can be managed if tolerant varieties of lettuce are available
Viral Disease      
Alfalfa mosaic Alfalfa mosaic virus   Cultural and biological practices

Lettuce mosaiclettuce-lettuceMV

Lettuce mosaic virus plants are often irregularly shaped and mottled yellow and green Use certified disease-free seed
Cucumber mosaic Cucumber mosaic virus    
Beet western yellows Beet western yellows virus    

Lettuce infectious yellowslettuce-infectious yellows

Lettuce infectious yellows virus Plants are stunted with overall yellowing and leaf margins of older leaves may turn brown Control weed hosts

Big veinlettuce-big vein

Virus-like agent A pronounced clearing of the chlorophyll next to major veins Disease can be controlled by planting tolerant varieties and avoiding fields with known history of disease
Abiotic disease      

Tip burnlettuce-tipburn

Calcium deficiency or excessive nutrients or warm temperature or enhanced light Symptoms are dark brown spots near the leaf margin followed by marginal necrosis of leaves Ca application
Nematode disease Nematode   Crop rotation, cultural practices