By Blake Jackson
With warm, wet weather forecasted, apple growers in Pennsylvania are alerted to imminent apple scab infection events. Effective disease management is crucial during this period, particularly for trees with green tissue.
For the half-inch green tip stage, growers who recently applied dormant copper are protected. Otherwise, mancozeb (3 lb/A), sulfur (6-10 lb/A), or potassium bicarbonate (3 lb/A) can be used.
Tank mixing mancozeb with Syllit (1.5 pt/A) is also recommended. Rainfast mancozeb formulations are preferred for their longer persistence during wet conditions.
Non-rainfast mancozeb can be made rainfast with a spreader sticker (4 fl oz/100 gal). Captan, already rainfast, doesn't require a sticker, nor does a captozeb mix. Ziram users should add a spreader sticker.
As trees progress to tight cluster, consider tank mixing mancozeb (3 lb/A) with Axios (3 fl oz), Cevya (5 fl oz/A), Indar (8 fl oz/A), Inspire Super (12 fl oz/A), Procure (16 fl oz/A), Scala (5-10 fl oz/A), or Vangard (5 oz/A).
Axios, a new product, offers excellent apple scab and powdery mildew control. Growers should avoid FRAC Group 7 fungicides during this time, reserving them for peak disease pressure later in the season.
Powdery mildew, favored by dry days with 50-77°F temperatures and high humidity, requires specific management. Products like Axios, Cevya, Rally/Sonoma, Rhyme, Procure, Torino, Gatten, and sulfur are effective.
Even in dry conditions, a broad-spectrum fungicide like mancozeb is advised to manage scab during intermittent rain events. Low-risk options include sulfur and potassium bicarbonate.
Organic growers can control apple scab and powdery mildew with sulfur, potassium bicarbonate, or EcoSwing (2 pt/A) from green tip through tight cluster.
Local weather monitoring is essential for timely application of fungicides. Adhering to product label instructions is vital for effective and safe disease control.
Photo Credit: gettyimages-richard-7
Categories: Pennsylvania, Crops, Fruits and Vegetables