Vegetables - Disease Management          Pat Donald, MU  (573) 882-2716 
                                         Om Sehgal, MU (573) 882-7060

                               KEY
                          1 = Symptoms
                           2 = Control

CARROTS        

Aster yellows   (mycoplasma)   
   1.  Yellowing of young leaves.  Dwarfing and distortion. Outer
       leaves may have reddish or purplish color.     
   2.  Control leafhopper vectors with approved insecticide.
       Destroy golden rod and similar weeds bordering garden,
       because they may be a source of aster yellows.

Cercospora leaf spot (fungus)   Cercospora carotae  
   1.  Occurs in early season. Elongated or circular brown to gray
       spots on the leaves with yellow borders. Whole leaflets may 
       be killed and petioles girdled. Floral parts may be        
       affected, resulting in infected seeds.  
   2.  Use disease-free seed. Fall plowing to cover crop residues
       may be desirable. Use a two- to three-year crop rotation.  
       Check catalogs for partial tolerance in some varieties.    
       Fungicide sprays 3 to 4 times, starting early. Use         
       chlorothalonil (Bravo 500 2 1/4-2 3/4 pt./A, 720 1 1/2-2   
       pt./A, or 90 DG 1 1/4-1 1/2 lb./A, W75 1 lb./A).

Early blight (fungus)   Alternaria spp.     
   1.  May cause seedling loss and stalk blight in early season.
       Dark spots on leaves and petioles, causing yellowing and
       death to leaves.  Reduced growth. May kill entire leaflet.
       Leaf symptoms similar to Cercospora leaf spot, but occur
       later in season.   
   2.  Use a 2-3 yr. crop rotation. Make three to five fungicide  
       applications at 7-10 day intervals, beginning when plants  
       are six inches tall. Use chlorothalonil (Bravo 500 2 1/4-2 
       3/4 pt./A, 720 1 1/2-2 pt./A, 90 DG, or W75 1 lb./A), fixed
       copper or iprodione (Rovral 1 lb./A). Do not apply fungicide
       within seven days of harvest.

Root-knot nematode (nematode)   Meloidogyne spp.    
   1.  Roots tufted or knotted.  Increased in number. Tap roots
       often misshapen.    
   2.  Homeowners:  Rotate to non-host plants or move garden
       spot.  Use balanced fertility in infested areas.           
       Solarization with clear plastic and added water may be     
       beneficial.  Commercial producers:  Use Telone C-17 (see   
       label) or soil fumigants. Use soil fumigation in the fall. 
       If treated in spring, allow 14 to 21 days before planting. 
       Use Vapam or Vorlex.

Soft Rot (bacteria)   Erwinia carotovora  
   1.  May occur in soil following insect injury, but usually in
       storage. Roots have water-soaked appearance, then soft and
       slimy. Sulfurous odor.    
   2.  Store carrots dry and free from bruises. Clean and disinfect
       storage area. Store at cool temperature, below 40 degrees F 
       with a relative humidity of less than 90 percent. Clean and 
       treat storage area with copper-type spray.