Fruit Physiological Disorders:
Berry Shrivel By Fred Jenzen Occurrence: Seeded grapes, particularly Emperor & Calmeria Importance: Affects Emperor, particularly on resistant rootstocks, and sometimes older, own-rooted vines. Five to 30% of clusters may be discarded. Occasionally so severe that vineyard is removed. Affects own-rooted Calmerias; up to 20% of clusters may be culled. Both varieties are decreasing in importance. Symptoms: After ripening begins, Emperor berries become flaccid and sunken. Some affected berries develop color; some remain white. The flaccid berries are usually interspersed with normal ones, but occasionally several berries at the tip of a lateral or at the cluster apex are affected. With Calmeria, whole clusters may be involved. Sometimes the disorder is difficult to recognize. The clusters may be a slightly duller green but the berries must be touched to confirm the flaccid condition. The amount of fruit involved usually increases up to harvest. Physiology: The cause is unknown. With Emperor, 16 grams per acre of gibberellin applied about two weeks after fruit set when the berry diameters average 10-15 mm will reduce the shrivel by 50 to 70% compared to the untreated. Similar treatments are not tolerated by the Calmeria variety.
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