Horticultural Oil-Lime Sulfur Combinant Applications

What is Horticultural Oil and when to use?

-Horticultural oil is a mineral oil that is applied as a low-impact natural contact pesticide to treat trees and shrubs vulnerable to attack by insects especially scale insects and mites. Insects do not breathe thru their mouths but thru pores on the sides of their abdomens called “spiracles”. Oil will coat the insects and their eggs and smother them thus a very effective contact pesticide.

-Dormant oil applications need to be applied whilst trees are dormant before buds open when outdoor temperatures are at least 4 degrees C and there is no chance of precipitation or frost for 24 hours following the application. For the most effective results it is preferable to wait until the daytime temperatures reach 12 to 15 degrees C for 3 to 4 days in a row. Applying too soon will not produce satisfactory results. Frost adversely affects the emulsion of the oil mixture.

-Oil applications during growth can be applied in lower concentrations but only when outdoor temperatures are less than 30 degrees C. Higher temperatures can be associated with drought stress and spraying during plant stress can damage the plant. Never apply during wet conditions or conditions where relative humidity is greater than 90%.

What is Lime Sulfur used for?

-Spraying with lime sulfur kills and prevents the spread of fungal spores that can lead to diseases. Lime sulfur can be used alone during the growing season as a wonderful anti-fungal

-Combination dormant horticultural oil and lime sulfur with kill many over wintering insects and diseases and thus prevent problems from arising through the growing season. With a pesticide ban in place this is now more important to use horticultural oil with lime sulfur combination as a dormant spray.

-During growing season one must wait 30 days between applying horticultural oil and lime sulfur. Lime sulfur can be used alone during the growing season as a wonderful anti-fungal when temperatures are 30 degrees or less.

Insects and Diseases controlled by Horticultural Oil-Lime Sulfur Combination

Scale insect nymphs:
-Magnolia scale
-Fletcher scale on evergreens (Thuja, Taxus)
-Cottony maple scale (Acer, Viburnum, Prunus)
-European fruit lecanium scale (Acer, Quercus, Fraxinus)
-European elm scale nymphs (Ulmus)
-San Jose scale (fruit trees, prunis, acer, salix)
-Tuliptree scale (Liriodendron)

Mite Eggs:
-European red mite eggs (Malus, Pyrus)
-Maple spider mite eggs (Acer- red & silver-red hybrids)
-Spruce spider mite eggs (Abies, Picea)
-Pear leaf blister mite (Pyrus)
-Rosa spider mites (Roses)

Fungal Diseases:
-pear psylia
-apple scab
-black knot
-peach leaf curl
-powdery mildew
-downey mildew
-rust/fungus
-anthracnose

Horticultural Oil with Lime Sulfur as a dormant spray can be applied to the rosa family which includes roses, raspberries and fruit trees. Do not use lime sulfur on Apricots. Do not use Horticultural oil on sugar maples, Japanese maples, beech, butternut, Colorado blue spruce, Douglas fir, hickory, walnut and holly.

Contact Harmony Gardens Landscaping Inc. for all your horticultural oil and lime-sulfur applications. March onwards is the time for us to prune and spray dormant horticultural oil-lime sulfur combination to your roses, fruit trees, deciduous shrubs and raspberries.

To schedule a Harmony Gardens Landscaping on-site visit or to request a quotation, please connect with us. We’re always at the ready to help make your landscape #greenforlife!