It’s been a long pruning season but finally after hundreds of labor hours spent pruning the fruit trees, we have been able to put the equipment away for another year. With limited fruit production last year, the trees put their energies into limb and branch growth. We had to spend extra hours pruning this year to get the trees back into shape for this season’s production. Extra pruning created extra brush and we are now in the final stages of orchard clean up. The brush and smaller prunings were mulched twice, debris was raked from under the trees, mulched again and now we’re picking up what was missed by the flail mulcher or too large for the mulcher to grind,
After the orchards are cleared of brush and cuttings, we begin applying pre-emergence herbicides for early weed control under the trees. If pre-emergence herbicides are properly applied, there is a major reduction in weeds, grasses and vines under the trees. Some species of vines are becoming quite invasive and the earlier these vines can be controlled in their growth patterns, the better the outcome.
The first chemical application of the season is dormant oil. The name itself identifies what type of spray it is and the timing of its application. The timing of this chemical is when the trees are dormant and not running sap, prior to bud swell but after pruning is completed. This product is oil based, typically petroleum, containing surfactants that enable the oil to be mixed with water. Mixing the oil with water enables it to more adequately provide a complete coverage of the plant’s leaf and limb surfaces. After dormant oil is applied the trees look oily for a few days. After several rains, however, the “oily” look disappears.
Fruit trees harbor pests and these pests “overwinter.” Dormant oil is used to provide effective control of insects such as aphids, mealybugs, thrips, whiteflies, caterpillar eggs, leafhoppers, scale and mites. Application of dormant oil eliminates most of the pest population by suffocating insects and their eggs which are nesting in the branches and also interferes with insect feeding. The spray if properly applied covers and penetrates the surfaces of the insects’ outer shells and thus suffocates it by not allowing oxygen to get through.
The actual date of the dormant oil’s application changes every year but the conditions for its application are always the same. Apply when daily temps are between 40 degrees and 70 degrees and temperatures need to stay in this range for at least 24 hours as emulsifiers aren’t effective in low temperatures and coverage becomes uneven. Apply during a period when no rain or high winds are predicted. Trees should be dry.
Dormant oils do not leave a toxic residue and dissipate quickly making them a good and safe product. For fruit trees, the application of dormant oil is one of the most important sprays of the season. The product can be purchased from nursery stores and horticultural centers. As with all chemical products ALWAYS read and follow the label directions. The product’s label is provided so you, as the consumer, can get maximum benefit from its use.