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Ministry of Agriculture, Food and Rural Affairs

Verticillium Wilt

Verticillium wilt symptoms Verticillium wilt symptoms showing extensive yellowing, V-shaped lesions Symptoms of Verticillium Wilt on Tomato Plant Symptoms of Verticillium Wilt on Tomato Plant Cross Section through a Diseased (Left) and Healthy (Right) Pepper Stem for Comparison
Click to enlarge.

Beginner

Scientific Name
Verticillium dahliae; Verticillium albo-atrum

Identification

  • Yellow lesions, extending between veins out to the leaf edge, develop initially on the lower leaves
  • Lesions are often V-shaped
  • Symptoms often appear only on one side of the plant or one side of the leaf
  • The vascular tissue becomes brown and discoloured, most noticeably near the soil line
  • Infected plants may wilt, especially during the hot part of the day

Often Confused With
N/A

Period of Activity
Verticillium wilt is present all season.  However, symptoms are often more severe after fruit set or during dry periods.  The presence of plant parasitic nematodes may increase the severity of Verticillium wilt.

Scouting Notes
Diagnose by slicing the main stem lengthwise.  The vascular tissue of the plant will be brown.

Soil samples can be taken to test for Verticillium and nematodes.  The best times to sample are in May/June and September/October.  Try to sample at the same time of year each time, using the same laboratory, so that you can compare the counts from year to year.  Counts will be lower in the spring than in the fall.  The established thresholds are based on spring sampling.

Thresholds
Soil Verticillium, root knot and root lesion nematode counts, will help determine the need for control measures. OMAFRA Publication 838, Vegetable Crop Protection Guide, provides information on pest diagnostic services in Ontario.

Advanced

Scientific Names
Verticillium dahliae; Verticillium albo-atrum

Identification
The first symptom of Verticillium wilt is yellowing on the leaves, followed by wilting (especially during the heat of the day, with recovery at night).  Yellow leaf lesions, extending between veins out to the leaf edge, develop initially on the lower leaves.  The lesions often have a characteristic V-shape.  Tissue in the lesions may die, but this is typically surrounded by an irregular yellow area.  Surrounding leaves may show yellowing, initially without the browning.  This helps to distinguish the disease from early blight.  Lower leaves are affected first.  Symptoms often appear on one side of the plant or one side of the leaf.  When sliced lengthwise, the vascular tissue of the main stem will be brown, especially at the soil line.   

Often Confused With
N/A

Biology
The Verticillium inoculum survives in the soil and on debris from host plants.  Many crop species are hosts, including potatoes, peppers, eggplant, strawberries, raspberries, beets, cucurbits, some crucifers, and alfalfa.  Weed species such as ragweed, lamb’s-quarters, pigweed, velvetleaf, and solanaceous weeds are also hosts.

Period of Activity
Verticillium wilt is present all season.  However, symptoms are often more severe after fruit set or during dry periods.  The presence of plant parasitic nematodes may increase the severity of Verticillium wilt.

Scouting Notes
Diagnose by slicing the main stem lengthwise.  The vascular tissue of the plant will be brown.

Soil samples can be taken to test for Verticillium and nematodes.  The best times to sample are in May/June and September/October.  Try to sample at the same time of year each time, using the same laboratory, so that you can compare the counts from year to year.  Counts will be lower in the spring than in the fall.  The established thresholds are based on spring sampling.

Thresholds
Soil Verticillium, root knot and root lesion nematode counts, will help determine the need for control measures. OMAFRA Publication 838, Vegetable Crop Protection Guide, provides information on pest diagnostic services in Ontario.

Management Notes

  • Follow a 4- 6 year crop rotation.
  • Do not rotate with other host crops.  Cereals and grasses are non-hosts.
  • Keep fields clean of host weeds, such as nightshades.
  • Cultivars tolerant to Verticillium wilt are available.
  • Soil fumigation may be required if Verticillium and nematode counts are high.