NEW this year. Please report local apple bud stages here to make our reports more accurate: https://go.uvm.edu/22applebudstage

Upcoming weather this coming week looks warm, above freezing, anyway, for the Champlain and Connecticut Valleys. Orchards at UVM Hort Farm are at not quite at silver tip, but warm weather this weekend and early next week should advance tissues pretty rapidly. My students are wrapping up pruning today. I recommend pushing your pruning brush or flail mowing in-place for high density plantings with smaller pruning wood as soon as possible to get ready for the spray season.

Calibrate your sprayer. As soon as you can get into the orchard, an application of urea to the leaf litter (44 lbs feed-grade urea in 100 gallons water per acre directed at the ground, especially under trees) may be warranted to reduce overwintering apple scab inoculum, too. That is not an organic-acceptable practice, so if you are certified, consider applying granular lime or compost tea instead if you wish to improve leaf litter decomposition, but those need to happen sooner than later to have an effect on overwintering inoculum.

Get your early season spray materials ordered and on-hand for when the season starts. No, really, calibrate your sprayer. Be ready to properly oil the orchard if you have had any issues with mite flareups or oystershell / San Jose scale, the latter of which I have seen not only in orchards but also on fruit in grocery stores. Remember that oil should go on at full dilute or no more than 2x concentration to be most effective. So when you calibrate your sprayer, be sure to reserve a setting for high-volume applications, either by switching to higher-output nozzles, reducing travel speed, or both.

The window between silver tip and green tip is perfect for applying copper to suppress fire blight and to act as your first scab spray of the season. Dave Rosenberger pulled together an excellent summary of the use of early season copper for scab and fire blight management in the March 25, 2013 issue of Scaffolds. But, while early season copper can be an excellent management tool, copper materials can be phytotoxic. That is why the early season spray is made before much green tissue is exposed. If applied when buds are closed, however, then cold temperatures immediately before or after spraying are not a huge concern. In fact, I have in many years had my airblast sprayer fan shroud ice up while applying copper- not an ideal situation, but it can happen at 5 AM when the temperature is 31 F and the velocity of air coming through the shroud contributes to rapid cooling, much like a snow gun on the ski slopes.

Oil, however, is a different story when it comes to applications before or after freezing weather. Delayed dormant, silver tip, and green tip are common times to apply an oil spray to help manage mites, aphids, scales, and other overwintering arthropods pests. When oil penetrates cells, it causes phytotoxicity that can affect fruit development, especially when cluster leaves which supply most of the carbo0hydrates to developing fruit early in the season are damaged. Oil is often applied at dilute rates, and the goal for a grower should be to fully saturate the tree as best possible. Application of oil just after or before freezing events (24 hours either way definitely, possibly 48 hours) can cause damage, so if you have seen or are expecting freezing temperatures, put the oil away for a couple of days.

Fortunately, oil can be applied right up to tight cluster-early pink bud stages, and in fact may be more effective then. We should be out of frost risk by then (otherwise we have bigger problems than oil on fruit cluster leaves), so maybe delaying your oil application would be prudent, so long as you can fit it around Captan sprays later in the season. Oil should not be applied within 7-10 days of a Captan or Sulfur spray. For more details on spring oil applications to manage mites and other pests, including rates and spray incompatibility issues, please refer to the New England Tree Fruit Management Guide.

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