Ritters Florist & Nursery, Garden Center, Floral and Greenhouse

Dormant Spray Guide

In our business the word “dormant” refers to that time of the year when the plants drop their leaves and are not actively growing – which applies principally to deciduous perennials, shrubs and trees.

Dormant sprays are sprays that are applied to the bare limbs and trunks of the dormant plants. The importance of dormant sprays lies in the fact that they can be made more “kicky” or concentrated (because there are no leaves or foliage to harm) and consequently can do a superior job of cleaning up existing infection of certain diseases and insects. In the event only one spray per year can be applied, this spray by all odds should be the dormant spray.

Liquid Lime Sulphur. A liquid lime sulphur is formulated with an activator to increase effectiveness through better, more even coverage, increased penetration into cracks and crevices and more positive contact with the offending organisms.

As a dormant spray, Lime Sulphur is used on a basis of 6 gallons in 100 gallons of water, (this translates to 1 Pint in 2 Gallons of water or 4 Tablespoons in 1 Quart) and is effective against infection of powdery mildew, black spot (scab), rust, peach leaf curl and some mite species.

Word of Caution: Never use Lime Sulphur or other sulphur sprays on apricots. More about this later.

Superior Type Spray Oil. Superior Type Spray Oil is special petroleum oil to which plants have a tolerance. The effect is that of an insecticide:

A. By coating and smothering insects.
B. By softening or dissolving away the resin or outer cover of insects so they dry out.
C. Assists penetration of other toxicants into the insect’s body.

Another effect of spray oil is that it renders some insect eggs unhatchable. During the dormant season the important use of spray oil is in combinations with Lime Sulphur. By way of information on absolute correctness of time for application, any dormant spray containing oil should be made during the temperature rise, not during the temperature drop. Falling temperatures during the winter tend to “drive” the oil into the tree or shrub. If this occurs damage can result.

Lime Sulphur Plus Spray Oil combination. For this combination the correct mixture is based on 3 Gallons Lime Sulphur plus 2 Gallons Spray Oil in 100 Gallons of water; which boils down to:

1 1/2 Quarts Lime Sulphur plus 1 Quart Spray Oil in 12 1/2 Gallons water or

3/4 Pint Lime Sulphur plus 1 Cup Spray Oil in 3 Gallons water or

8 Tablespoons Lime Sulphur plus 5 Tablespoons Spray Oil in 1 Gallon water.

The resulting mixtures are effective clean-up sprays for a long list of overwintering insects. (Check your Spray Oil and Lime Sulphur labels.) Some insect eggs and several common diseases such as powdery mildew, black spot, scab, moss, etc.

Tribasic Copper is a finely ground sulphate formulated with wetting and dispersing agents for super ease of mixing and applying. (Tribasic Copper Sulphate is sometimes referred to as a “Bordeaus” substitute and falls into the broad class of compounds referred to as “fixed copper” or “copper spray”.

The product is a true wettable powder; that is, not soluble in water, and requires minimum agitation, stirring or shaking up during use. A big use of Tribasic Copper as a dormant spray is for coryneum blight on stone fruits and their flowering cousins or for peach leaf curl. You should also enlarge upon this by checking the label for just pre-dormant uses and just post-dormant uses.

By the way of useful information – we suggest Tribasic Copper for dormant use on Apricots. This tree is sensitive to sulphur compounds and can be harmed by Lime Sulphur.

Word of Caution: Sprays containing Tribasic Copper and Lime Sulphur should not be made on the same plant within 6 weeks of each other. Possible phytotoxicity may result.

Spreader Sticker is a superior sticking agent for use with Tribasic Copper only. (Use with other spray materials will almost surely bring on some compatibility problems.)

Spread sticker is a sticking agent that insures the effectiveness of certain sprays. When mixed with Tribasic Copper sprays, applied to shrubs or trees and allowed to dry, it becomes a virtual gluing agent to hold the Tribasic Copper through considerable wet or snowy weather. From the standpoint of results and consumer satisfaction, it is important to insist that Spread Sticker be included in dormant sprays of Tribasic Copper.

Pruning Sealers They come in aerosols, paints and sealants or resins. The function of Pruning Sealers after being applied to a pruning cut is: 1) To slow the drying of the exposed wood and so reduce cracking and 2) To prevent entry of foreign bodies into the wound so normal healing can take place.