Eutypa
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Beginner
Scientific Name
Eutypa lata
Identification
Shoots
- Stunting, shortened internodes and chlorosis are most obvious during the first 2 months of the growing season
- Often shoots on one cane or cordon will have symptoms while others do not
Trunks
- Cankers originating from old pruning wounds
- Cankers often appear V-shaped in a cross-section of the perennial wood
- Cankers have a definite margin between the live and dead wood
- Wood becomes distorted and twisted after a number of years
Leaves
- Basal leaves have small yellow spots that turn dark brown
- Cupped and mishappened with tattered edges
- As the season progresses, new leaves do not have these symptoms
Fruit
- Bunches on stunted shoots appear normal before flowering but often shrivel and die later in the season
- Berries do not size uniformly
Often Confused With
Winter injury – no necrotic flecks on leaves or leaf cupping
N deficiency – foliar symptoms do not dissipate as the season progresses; no leaf cupping or tattered leaves
Severe Zn deficiency: no leaf cupping or necrotic lesions; no trunk cankers
Phomopsis – no shoot stunting or leaf cupping; no trunk cankers
Water logged soils – frequently adventitious roots develop on the trunk; usually occurs in low spots or where tiles are broken in the vineyard and soil appears waterlogged
Crown gall – corky galls present on trunk
Glyphosate injury - leaves are not tattered
Period of Activity
Ascospore discharge is initiated by the presence of free water (either rainfall or snow melt). Most spores are released during winter or early spring, although a few are released during summer.
Scouting Notes
Stunted shoots rarely appear on vines less than six years old. Stunted shoots are most evident during the spring, when healthy shoots are 20-40 cm long. Stunting mainly develops on one side of the vine while the rest of the vine appears healthy. In the spring leaves are smaller than normal, cupped, misshapen, and yellowed. Later in the season (mid-July), stunted shoots may be less obvious if they are overgrown by healthy growth from adjacent shoots.
Cankers generally form around pruning wounds in older wood of the main trunk. These cankers are usually difficult to see and are often much further down the trunk from the stunted shoots. One indication of a canker is a flattened area on the trunk that is most obvious if the bark over and around the canker is removed. This reveals a sharply defined region of darkened or discoloured wood. Cankers may be up to 3 feet long but do not enter one- or two-year wood and seldom extend below ground. When the trunk is cut in cross-section, the canker appears as darkened or discoloured wood extending in a wedge shape to the center of the trunk. Very rarely is the entire cross-section of the trunk affected.
Threshold
None.
Advanced
Scientific Name
Eutypa lata
Identification
Shoots
- Stunting, shortened internodes and chlorosis are most obvious during the first 2 months of the growing season
- Often shoots on one cane or cordon will have symptoms while others do not
Trunks
- Cankers originating from old pruning wounds
- Cankers often appear V-shaped in a cross-section of the perennial wood
- Cankers have a definite margin between the live and dead wood
- Wood becomes distorted and twisted after a number of years
Leaves
- Basal leaves have small yellow spots that turn dark brown
- Cupped and mishappened with tattered edges
- As the season progresses, new leaves do not have these symptoms
Fruit
- Bunches on stunted shoots appear normal before flowering but often shrivel and die later in the season
- Berries do not size uniformly
Often Confused With
Winter injury – no necrotic flecks on leaves or leaf cupping
N deficiency – foliar symptoms do not dissipate as the season progresses; no leaf cupping or tattered leaves
Severe Zn deficiency: no leaf cupping or necrotic lesions; no trunk cankers
Phomopsis – no shoot stunting or leaf cupping; no trunk cankers
Water logged soils – frequently adventitious roots develop on the trunk; usually occurs in low spots or where tiles are broken in the vineyard and soil appears waterlogged
Crown gall – corky galls present on trunk
Glyphosate injury - leaves are not tattered
Biology
Eutypa survives in infected trunks and prunings for long periods of time in the vineyard. Several years after infection occurs the fungus produces reproductive structures (perithecia) on the surface of infected wood. Ascospores are produced in these structures and are discharged into the air within 1-2 hr after wood is wet with at least 2.5 mm of rain. The ascospores can be carried up to 30 m by air currents to open wounds on the trunk. Ascospores are washed into the woody tissue where they germinate and slowly grow into the vine. Large pruning wounds are the most important points of infection. Wounds in older wood are more susceptible than 1-year-old wood, probably because they are also larger and do not heal as well. The stunted shoot and leaf symptoms may not develop for up to three years after a vine is infected. These symptoms are the response to a toxin that is produced in the canker and translocated up the vascular tissue to developing shoots. Eventually, the infected trunk and all growth above it dies.
Period of Activity
Ascospore discharge is initiated by the presence of free water (either rainfall or snow melt). Most spores are released during winter or early spring, although a few are released during summer.
Scouting Notes
Stunted shoots rarely appear on vines less than six years old. Stunted shoots are most evident during the spring, when healthy shoots are 20-40 cm long. Stunting mainly develops on one side of the vine while the rest of the vine appears healthy. In the spring leaves are smaller than normal, cupped, misshapen, and yellowed. Later in the season (mid-July), stunted shoots may be less obvious if they are overgrown by healthy growth from adjacent shoots.
Cankers generally form around pruning wounds in older wood of the main trunk. These cankers are usually difficult to see and are often much further down the trunk from the stunted shoots. One indication of a canker is a flattened area on the trunk that is most obvious if the bark over and around the canker is removed. This reveals a sharply defined region of darkened or discoloured wood. Cankers may be up to 3 feet long but do not enter one- or two-year wood and seldom extend below ground. When the trunk is cut in cross-section, the canker appears as darkened or discoloured wood extending in a wedge shape to the center of the trunk. Very rarely is the entire cross-section of the trunk affected.
Threshold
None.
Management Notes
Prune only in dry weather. Pruning wounds are most susceptible to infection when vines are pruned early in the dormant season (November or December) and least susceptible when pruned later in the dormant season (February through March).
Prune infected trunks to at least 15 cm below areas of old dead wood to ensure that all infected wood is removed. Burn or bury all wood from infected vines as old infected trunks lying on the ground may continue to produce spores for several years.
Renew infected vines with younger shoots that do not show symptoms.
Completely remove the vine if infection has reached crown area of plant.
The double trunk system of training vines can be used to minimize crop losses.
Different cultivars all have different susceptibilities to diseases. See Table 5-5 Relative Susceptibility of Grape Cultivars to Diseases.
Fungicides have different modes of action, and differ in their activity on grape diseases. See Table 5-6 Activity of fungicides on grape diseases.
