Vascular Streak Dieback (VSD): Oncobasidium theobromae
Symptoms
- The first indication of the disease is a characteristic yellowing of one or two leaves on the second or third flush behind the growing tip.
- Diseased leaves fall within a few days of turning yellow and the other leaves on the shoot show similar symptoms.
- When the infected shoot is split lengthwise there is always a characteristic brown streaking.
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| Yellow leaf |
Defoliation |
Yellowing of leaves on shoots |
Brown streaking |
Management
- The disease can be controlled by disposing diseased branches and regular pruning of chupons on the trunk.
- Cocoa nurseries should not be located near the diseased area.
- Avoid getting seedlings from diseased tracts.
- Kerala Agriculture University has developed some VSD resistant and high yielding varieties CCRP-1 to CCRP-7.
Image Source: Guest., D and P. Keane. 2006. Vascular-Streak Dieback: A new encounter disease of Cacoa in papua new guinea and southeast asia casued by the obligate basidiomycete Oncobasidium therobraomae. Phytopathology, 97 (12), pp- 1654- 1657.
http://www.dropdata.org/cocoa/cocoa_pics/VSD2_s.JPG |
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