Canola - Disease Management       Jeanne Mihail, MU  (573) 882-1471
                                  Wayne Bailey, MU  (573) 882-2838

                               KEY
                          1 = Symptoms
                    2 = Registered Pesticides
                           3 = Control


Alternaria Black Spot   Alternaria brassicae, A. raphani
   1.  Black, brown or grayish spot on leaves, stem or pods. Pods 
       splitting may occur. Severe early infection may kill plant. 
   2.  None.
   3.  Sow clean seed. Rotate out of canola at least 3 years. Early 
       swathing may reduce seed loss. Control volunteer canola and 
       cruciferous weeds.

Aster Yellows   mycoplasma-like organism (MLO)
   1.  Plants are stunted. Leaves become red and deformed. Infected 
       pods are blue in color, deformed and sterile. Infected     
       plants are usually scattered throughout the field.
   2.  None. 
   3.  The pathogen is carried by several species of leafhoppers. 
       Control is based on reducing vector populations in the crop 
       and in nearby weeds. 

Blackleg   Leptosphaeria maculans
   1.  Lesions are first seen on seedlings as white or gray       
       circular spots on cotyledons. Infection may spread to      
       leaves, stems and pods. Lesion on older plants are         
       surrounded by a dark purple margin. Infected pods usually  
       produce infected seed. Crown invasion from infected        
       cotyledons or leaves results in ring-barked plants at ground 
       level.
   2.  None.
   3.  Destroy crop residues by plowing, grazing, burning. Rotate
       out of canola for at least 4 years. Avoid sowing into
       adjacent fields for 2 years. So far, this disease is very
       rare in Missouri. 

Seed decay and seedling blight   Pythium, Fusarium, Rhizoctonia
   1.  Seeds fail to germinate and become soft and pulpy
       (pre-emergence damping-off). Seeds germinate but roots
       decay; rot extends rapidly up into hypocotyl and the emerged
       seedling topples over (post-emergence damping- off).
   2.  Captan 30-DD, 300 1.25 oz/cwt 400-D, 1-2 fl oz/cwt. 
   3.  Maximize conditions favoring rapid germination and seedling
       establishment, warm soils and proper fertilization. Do not
       plant seed deeply; 1-5 inches is optimal. Excessive
       fertilizer placed with the seed or early seeding in soil
       that stays cold for more than 10 days favors damping off.

Stem rot   Sclerotinia sclerotiorum
   1.  Premature ripening of plants. Stem bleached and tend to
       shred. Hard, black sclerotia inside stem near base of stalk.
   2.  None.
   3.  Rotate out of canola a minimum of 4 years. Plant certified
       seed. Maintain good weed control. Crop residue management.