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Healthy Fruit 2009 Vol. 17:0

Mar 31, 2009

Last chance to chop leaves

To improve scab control, chop your apple leaves now. We've spent some time formalizing this idea, and have a Fact Sheet that describes the process:

F-134 Reducing Apple Scab Risks and Saving Scab Sprays

We recommend that all growers consider leaf chopping and/or urea applications to reduce scab.

Urea applications are best applied 3 or 4 weeks before bud break, so it's getting late. But they'll still be useful, just not as effective. And it might get cold again.

D. Cooley

Early season apple sprays

As usual at this time of year, it's time to remind people that copper is a good idea. Primarily, a copper spray on apples is targeting fire blight. However, it will also do as much to protect against possible green tip scab infections as an early application of Dithane or Penncozeb. One school of thought suggests that it also gives an early season nutritional boost to developing buds, and may kill ice-nucleating bacteria! We're not sure about those last two suggestions, but copper won't hurt unless it's applied too late, after green tip. We recommend it.

D. Cooley

Don't forget the peaches

Leaf Curl on PeachThere are two peach diseases that should get some attention while trees are in a late dormant stage – peach leaf curl and bacterial spot. Bacterial spot can be treated with a copper, and fortunately, so can leaf curl. So, the most efficient approach for these diseases at this time of year is a relatively dilute copper spray. It is important to get thorough coverage of the tissue, so that the solution will get into the cracks and crevices in the buds and bark tissue, where the fungus that causes leaf curl and the bacteria that cause bacterial spot have overwintered.

While most copper formulations are labeled for both diseases, check to make sure. Use a relatively high rate. For example, C-O-C-S should be applied at 5 lbs./acre, or Kocide 2000 at 7.1 lbs./acre.

Bacterial Spot on PeachIf your peaches and nectarines haven't had a bacterial spot problem, and you aren't growing susceptible cultivars such as Autumnglo, Babygold 5, Redhaven, or the California sub-acid types, then you could still use copper for leaf curl. Or, you could use one of several other fungicides, including Bravo or other chlorothalonil products, Echo, Ferbam, Thiram or Ziram. Whatever is used, it has to get on before the buds break to be most effective.

D. Cooley