First Scab Spray
(Re-printed from Mike Fargione's Tree Fruit Grower Alert Message - Tuesday, April 2, 2013)
The first scab spray should include a protectant fungicide such as mancozeb, captan, copper, or sulfur (if you are growing apples under organic protocol).
The first scab spray should go on before the first infection period once green tissue is visible in a block.
Mancozeb at 3 lbs./acre may be adequate for scab control at green tip in blocks that had little scab the previous season. Tank-mixing mancozeb with copper or captan or Syllit (dodine) may be advantageous if the block had a scab problem in 2012. Other tank mix options if you think you have dodine resistant scab include Scala or Vanguard (these don’t redistribute as well as Syllit).
Copper (mixed with a quart of spray oil per 100 gal of finished spray) has some real advantages as a first spray. Copper reduces fire blight inoculum from overwintering cankers. In addition, an early copper spray does as good a job as 3 lbs./acre of mancozeb at controlling apple scab. Finally, recent observations suggest that annual copper applications may also help reduce the level of resistance to other apple scab fungicides like the DMI’s and Strobies. Some copper formulations do not list apple scab on their label as a target pest at green tip, so be sure to note in your records what the appropriate pest is that you are treating.
The window to use copper is from silver tip or green tip to ¼” green, and this window may be very short once this season gets under way. Do not use Syllit or other adjuvants besides spray oil with copper. Avoid applying copper just before an expected frost.
Editors Note- at Rutgers Snyder Farm we are just approaching Silver tip on apples- Asian Pears are very swollen and on the move. First early plum is just showing white tissue. Peaches are still tight.