Shot hole disease: Difference between revisions
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'''Shot hole disease''' (also called '''Coryneum blight''') is a serious [[fungal]] disease that creates BB-sized holes in leaves, rough areas on fruit, and concentric lesions on branches. The pathogen that causes |
'''Shot hole disease''' (also called '''Coryneum blight''') is a serious [[fungal]] disease that creates BB-sized holes in leaves, rough areas on fruit, and concentric lesions on branches. The pathogen that causes shot hole disease is ''[[Wilsonomyces carpophilus]]''.<ref>{{cite book|last1=Evans, Kent, et al|title=Cronyism or Shothole Blight|date=2008|publisher=Utah State University Extension}}</ref> |
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== Hosts and symptoms == |
== Hosts and symptoms == |
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The fungal pathogen ''Wilsonomyces carpophilus'' affects members of the ''[[Prunus]]'' genera. Almond, apricot, nectarine, peach, prune and cherry trees can be affected. Both edible and ornamental varieties are vulnerable to infection.<ref>{{cite book|title=IMP Fact Sheet: Shot hole disease (Coryneum blight)|date=25 April 2014|publisher=University of California Extension}}</ref> Shot hole disease produces small (1/10-1/4”) reddish or purplish-brown spots. There may be a light green or yellow ring around these spots. Damaged areas become slightly larger and then dry up and fall away, leaving BB-sized holes in leaves. As the fungus spreads, more leaf tissue is damaged until the leaf falls. Significant infections can reduce the amount of [[photosynthesis]] that can occur, weakening the plant, and decreasing fruit production. The fungi can also affect fruit, beginning as small purple spots that develop into gray to white lesions. [[Gummosis]] may occur. These lesions leave toughened spots on the skin, |
The fungal pathogen ''Wilsonomyces carpophilus'' affects members of the ''[[Prunus]]'' genera. Almond, apricot, nectarine, peach, prune and cherry trees can be affected. Both edible and ornamental varieties are vulnerable to infection.<ref>{{cite book|title=IMP Fact Sheet: Shot hole disease (Coryneum blight)|date=25 April 2014|publisher=University of California Extension}}</ref> Shot hole disease produces small (1/10-1/4”) reddish or purplish-brown spots. There may be a light green or yellow ring around these spots. Damaged areas become slightly larger and then dry up and fall away, leaving BB-sized holes in leaves. As the fungus spreads, more leaf tissue is damaged until the leaf falls. Significant infections can reduce the amount of [[photosynthesis]] that can occur, weakening the plant, and decreasing fruit production. The fungi can also affect fruit, beginning as small purple spots that develop into gray to white lesions. [[Gummosis]] may occur. These lesions leave toughened spots on the skin, and in some cases the fruit may be lost. Infected buds may appear darker than normal. Branches may develop concentric lesions when infected.<ref>{{cite book|last1=Russell|first1=Kate|title=Shot Hole Disease|date=27 April 2016}}</ref> These lesions may girdle a twig and kill it. |
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== Disease cycle == |
== Disease cycle == |
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'' |
''W. carpophilus'' overwinters in infected buds and in twig [[Canker|cankers]]. Asexual spores ([[Conidium|conidia]]) are dispersed in spring when moisture levels increase or as a result of overhead watering. Spores are pigmented and remain viable, in a dormant state, for months. Infection can occur any time moisture is present for at least 24 hours, as long as temperatures are above 36 °F. At higher temperatures, infection occurs more quickly. ''W. carpophilus'' infection takes only 6 hours at 77 °F. |
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== Management == |
== Management == |
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''W. carpophilus'' can remain viable for several months and spores are often airborne. Since the fungi thrive in wet conditions, overhead watering should be avoided. Remove and dispose of any infected buds, leaves, fruit and twigs. In fall, fixed copper or Bordeaux |
''W. carpophilus'' can remain viable for several months and spores are often airborne. Since the fungi thrive in wet conditions, overhead watering should be avoided. Remove and dispose of any infected buds, leaves, fruit and twigs. In fall, fixed copper or [[Bordeaux mixture]] can be applied. |
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== Importance == |
== Importance == |
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Shot hole disease is a major concern of the stone fruit industry. It is estimated that 80% of the California almond crop may be infested with shot hole disease, resulting in a potential yield loss of 50-75%.<ref>{{cite book|title=The Value of Fungicides In U.S. Crop Production|date=September 2005|publisher=Crop Protection Research Institute}}</ref> In the 1930’s, it was found that applications of Bordeaux mixture reduces shot hole disease on peaches from 80% to 9%. |
Shot hole disease is a major concern of the [[stone fruit]] industry. It is estimated that 80% of the [[California]] almond crop may be infested with shot hole disease, resulting in a potential yield loss of 50-75%.<ref>{{cite book|title=The Value of Fungicides In U.S. Crop Production|date=September 2005|publisher=Crop Protection Research Institute}}</ref> In the 1930’s, it was found that applications of Bordeaux mixture reduces shot hole disease on peaches from 80% to 9%. |
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=== References === |
=== References === |
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Revision as of 20:55, 27 April 2016
Shot hole disease (also called Coryneum blight) is a serious fungal disease that creates BB-sized holes in leaves, rough areas on fruit, and concentric lesions on branches. The pathogen that causes shot hole disease is Wilsonomyces carpophilus.[1]
Hosts and symptoms
The fungal pathogen Wilsonomyces carpophilus affects members of the Prunus genera. Almond, apricot, nectarine, peach, prune and cherry trees can be affected. Both edible and ornamental varieties are vulnerable to infection.[2] Shot hole disease produces small (1/10-1/4”) reddish or purplish-brown spots. There may be a light green or yellow ring around these spots. Damaged areas become slightly larger and then dry up and fall away, leaving BB-sized holes in leaves. As the fungus spreads, more leaf tissue is damaged until the leaf falls. Significant infections can reduce the amount of photosynthesis that can occur, weakening the plant, and decreasing fruit production. The fungi can also affect fruit, beginning as small purple spots that develop into gray to white lesions. Gummosis may occur. These lesions leave toughened spots on the skin, and in some cases the fruit may be lost. Infected buds may appear darker than normal. Branches may develop concentric lesions when infected.[3] These lesions may girdle a twig and kill it.
Disease cycle
W. carpophilus overwinters in infected buds and in twig cankers. Asexual spores (conidia) are dispersed in spring when moisture levels increase or as a result of overhead watering. Spores are pigmented and remain viable, in a dormant state, for months. Infection can occur any time moisture is present for at least 24 hours, as long as temperatures are above 36 °F. At higher temperatures, infection occurs more quickly. W. carpophilus infection takes only 6 hours at 77 °F.
Management
W. carpophilus can remain viable for several months and spores are often airborne. Since the fungi thrive in wet conditions, overhead watering should be avoided. Remove and dispose of any infected buds, leaves, fruit and twigs. In fall, fixed copper or Bordeaux mixture can be applied.
Importance
Shot hole disease is a major concern of the stone fruit industry. It is estimated that 80% of the California almond crop may be infested with shot hole disease, resulting in a potential yield loss of 50-75%.[4] In the 1930’s, it was found that applications of Bordeaux mixture reduces shot hole disease on peaches from 80% to 9%.
References
- ^ Evans, Kent; et al. (2008). Cronyism or Shothole Blight. Utah State University Extension.
{{cite book}}: Explicit use of et al. in:|last1=(help) - ^ IMP Fact Sheet: Shot hole disease (Coryneum blight). University of California Extension. 25 April 2014.
- ^ Russell, Kate (27 April 2016). Shot Hole Disease.
- ^ The Value of Fungicides In U.S. Crop Production. Crop Protection Research Institute. September 2005.