October 28, 2015 Volume XI No. 8

Orchard Vole Management and Rodenticides

Fall is traditionally the time that New Hampshire orchardists consider rodenticide application to control meadow voles (and, to a degree, pine vole). If you plan to do this, please read my vole management publication, especially the rodenticide section.

If you use one of the anticoagulants, I strongly recommend that you use some type of bait station. That maximizes the likelihood that the target organisms (usually meadow vole or pine vole) will be killed, rather than many other things. We have two types registered in New Hampshire, Diphacinone (Ramik Brown) and Chlorophacinone (Rozol). The Ramik label specifically states the stuff is applied after harvest is complete (including drops), before spring growth, and when 3 days of rai/snow free weather are expected.

Brodifacoum is a second-generation anticoagulant available to people with restricted use permits (for use in and around buildings… not in the orchard), but I STRONGLY ADVISE AGAINST USING PRODUCTS WITH THIS TOXICANT. I think it poses too great a wildlife risk to be used.

Zinc phosphide is the toxicant most commonly used in NH orchards, and it has almost zero risk of secondary poisoning, because it kills quickly and the material breaks down quickly. But it has a high risk of PRIMARY poisoning…killing an organism that directly eats the bait. So if you plan on using ZnP, minimize the risk of killing non-target organisms by avoiding corn as the bait (birds and others readily spot it and eat it), and avoid broadcasting it on bare spots.

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PAD Assessment Reminder

PAD is an acronym for potential ascospore dose, and it is a measurement that can be very important to us trying to manage apple scab. Many decisions about whether or not a fungicide is required are affected by how many bazillion spores threaten your trees. If your PAD is high, you may have to do more fungicide spraying than you’d like, to protect your fruit. If PAD is very low, you can eliminate some of those sprays.

Measuring PAD is an activity that is done in the fall, before many apple leaves have fallen. Instructions are on pages 66 and 67 (section 6.23 of the 2015 New England Apple Pest Management Guide. If you do not have a copy of the 2015 guide, the 2014 version is available on line). It is not difficult. If you have had scab problems, it may be wise to measure the PAD of your orchard.

Fall SJS Spray?

Two growers asked me about a fall insecticide for San Jose scale. I had never heard of that timing, but last week heard a presentation by Dave Combs from New York’s Hudson Valley Lab. He looked at that option. The data suggested to me that it might work at that time, but it did not seem to offer advantages over our standard options. I looked at pesticide labels for the products he tested. They do not appear to currently allow you to try it at that time.

Apple IPM For Beginners

My colleagues at Cornell Cooperative Extension produced a color guide (about 35 pages) called Apple IPM for Beginners – A guide for new apple growers to protect apple orchards from pests, in fact sheet format. You can view it online. If you have a color printer, you might wish to download the entire 3.2MB guide. I think they did an outstanding job, and I’ve learned some new things from it already. You can, too. BTW… it is free.

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