Fruit IPM Advisory 2019- fruit

Delayed-Dormant Sprays, A Year in Backyard Pest Management

In this Issue

DELAYED-DORMANT OIL SPRAY

Despite the fact that some call it “dormant oil” spray, the timing of the spring horticultural oil spray is not when trees are still dormant. A better term would be a “delayed-dormant” application, because the oil should be applied after bud swell. This timing coincides with the increasing activity of the overwintering insect, including aphid eggs, scale nymphs, and peach twig borer larvae.  (Scroll down for pests that the oil spray targets.)

In the warmest areas of Utah, the dormant oil may already have been applied. But in northern Utah, it is approaching time to apply the spray in some areas.

There are two factors that must coincide to determine when to spray: the bud stage of your fruit trees (pictures of fruit bud stages), and temperature.

Bud Stages

The window for application extends from bud swell to when leaves just start emerging. The last point at which you can safely apply oil for each crop is:

Temperature

Oil should be applied on a clear, non-windy day in the 50 to 70°F temperature range. Only apply oil if the temperature will remain above freezing (ideally above 40°F) for 24 hours after application. Following these guidelines will prevent damage to the flower and foliage tissue.

How to Spray

Commercial growers:

  • Oil should be applied at a rate of 2%, which is 2 gallons per 100 gallons of water.
  • Mix oil with an insecticide such as Warrior or Asana to help improve knockdown of overwintering pests.
  • When spraying apple trees, add in copper for fire blight.
  • Thoroughly cover all cracks and crevices.

Backyard growers:

  • There are many brands of oil, such as All Seasons Oil, Volk Spray Oil, etc.
  • Oil should be applied at a rate of 2%, which is 5 tablespoons in 1 gallon of water.
  • If you are not growing organically, and aphids or scale have been a serious problem and oil alone has not worked in past years, consider adding in an insecticide, such as Spectracide Triazicide, Malathion, or carbaryl.
  • When spraying apple trees, add in copper for fire blight.
  • Thoroughly cover all cracks and crevices.

Insects and Diseases Affected by Delayed-dormant Spray (oil and/or copper)

Click on image for caption information.

 

A YEAR IN BACKYARD FRUIT PEST MANAGEMENT

We presented a webinar in spring 2018 that provides a seasonal “to do” list of pest management activities for backyard fruit trees.

Click on the image below for a pdf document of the slides, showing one slide per page (16 MB in size), or get the black and white version showing 6 slides per page, which is a smaller file size (2 MB).

Click here for the recorded webinar.