I chuckled when I found this old turn-of-the-century postcard. Imagine promoting the use of sprays in such a proud fashion! “It’s this special care that makes our fruit so good.” Ha! The fruit looks so beautiful, getting a liberal application of pesticide.
Well, I’ve got to go easy on the Heirloom Orchardist. Sure, the chances are pretty good that this old orchard (probably located in Oregon?) was using a noxious insecticide. But some sprays, such as a horticultural oil spray, aren’t so bad. Horticultural oil, used by itself, poses few risks to the environment.
Now is the time to plan your application of a dormant horticultural oil spray. In his 1918 book, Orchard and Garden, here’s what Benjamin W. Douglass suggested:
March in the Orchard - This is the best of all winter months for the application of the dormant spray. Every twig and branch must be well covered with the spray solution. Those portions of the orchard that have been found to be infested with scale insects or with the eggs of plant lice should be given extra attention. The trees should be examined a few days after they have been sprayed and if any exposed areas of bark are found, the work must be done over in these parts of the orchard.
Horticultural oil spray is a high grade oil used to control insects such as scale, whitefly, mealybug, thrips, aphids and codling moths. The oil interferes with gas exchange, and thus, simply suffocates its victims. The timing for an application of dormant oil is critical. It must go on in the late winter, or early spring, before bud-break. The entire tree must be coated.
What happens if the oil is applied too late? Well, your fruit tree is a living organism too…one that also partakes in gas exchange. So, after the tree comes out of dormancy, you don’t want to gum up all the pores (stomata) in the newly unfurling leaves. You could kill the tree.
Horticultural oils pose few risks to people or to beneficial natural enemies of insect pests. This allows the responsible Heirloom Orchardist to integrate the use of oils with biological controls. Toxicity is minimal, at least compared to alternative pesticides, and oils quickly dissipate through evaporation, leaving little residue.
Various oils have been used for centuries to control insect and mite pests (“plant lice” as the Heirloom Orchardist used to say). Here’s what one Heirloom Orchardist discovered in 1865: "I applied common neats-foot oil to a couple of espalier fruit trees, the past spring, which had become very badly infested with lice, and with the best results. I used an ordinary paint brush in applying it, and the oil in moderate quantity. Passing the trees a day or two subsequently, I found the pests all dead, and the trees soon resumed a healthy appearance, and have grown finely through the summer, and with no further trouble from them." Waterville, NY, Country Gentleman, November 23, 1865
Typically used as a conditioning agent for leather, this Heirloom Orchardist probably had a convenient supply of neats foot oil for boots or saddles. He was successful, because it wasn’t sprayed on…he applied it carefully, with a brush.
Today, we’re fortunate to have horticultural oils, specifically manufactured with the proper viscosity, for use on our precious fruit trees.
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