Psa-V thrives in wet, humid conditions; and multiplies quickly in wet conditions. Therefore spring and autumn are high-risk periods for Psa-V to spread. The disease slows down in warm, dry conditions like summer. In an orchard Psa-V can exist as:
An epiphyte, living on plant surfaces without causing high levels of infection; and/or As an endophyte, living within the vine, having entered through natural plant openings or man-made wounds—resulting in severe infection.
Image courtesy of Plant and Food Research Image 47: (left) Psa-V magnified 6000 times (KVH). Image 48: (right) Psa-V is rod shaped with flagella (KVH/ Plant and Food research).
Image 49: (left) Leaf spotting symptom of Psa-V (KVH). Image 50: (right) Exudate (ooze) coming from a kiwifruit plant is another symptom of Psa-V (KVH).
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