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| Idared apple fruit buds, Apr. 6, 2015. The bud on the left is typical of one infected with overwintered powdery mildew, compared to a healthy one on the right. |
Heavy production of condiospores on emerging Idared flower cluster leaves at tight cluster stage, Apr. 6, 2015
Heavy production of conidia was observed on emerging Idared flower cluster leaves and the temperatures was favorable for infection. (Powdery mildew infects susceptible leaves and flowers in dry weather when the temperature is above 53 degrees F).
Apple scab ascospores were first trapped at our AREC March 25 when Cripps Pink (Pink Lady) and Gala apples were just at the earliest green-tip stage. Wetting recorded at our AREC March 26-27 was not quite long enough for scab infection. Scattered shower activity, but with longer drying periods, occurred Apr. 2-3 and probably did not result in scab infection; however, some local areas may have had longer wetting and less drying between showers, and at relatively warm temperatures this could have quickly resulted in infection. With light rainfall risks of scab infection from these wetting events could have been averted with a protectant fungicide such as copper applied March 26. Expect more ascospore discharge and extended wetting at moderate temperatures several days this week.
In central Virginia, weather instruments at Silver Creek Orchards, Tyro, VA, indicated that wetting was more than adequate for early scab infection March 26-27. Uncontrolled scab lesions from infection at that time would be expected to emerge later this week and early next week.
