Gardeners arise and unite; it's time for the annual battle against the pests. High-quality, insect-free fruit is difficult to grow and requires careful pest control. Difficulties in controlling pests are minimized by a preventive delayed dormant spray of specially prepared oil. Oils are available at nurseries under various brand names, including superior, supreme or Volck oils. The oils are mixed with water and applied as sprays. Oil sprays are organic and compatible with those who would like to reduce synthetic pesticide usage.
The effectiveness of the spray is enhanced by adding an insecticide to the spray solution. Diazanon is used by most gardeners, but thiodan gives better control of pests on pear trees. Pear psylla is a serious pest that causes sticky leaves and branches and causes burning on the fruit.Timing is critical for the spray. It's a delayed dormant spray because it is applied when you see color on fruit buds of stone fruit trees or green tips on apple and pear trees. Delay spraying until bud scales start to open and pests become active. Pests hide underneath those bud scales. Target pests include spider mites, scales and aphids. Properly applied, the spray controls both the adult and egg stages.
The oil is effective because insects and their eggs must breath through their outer covering or exoskeletons. The oil clogs the exoskeletons and suffocates the pests. Complete spraying prior to blossom, as the oil and insecticide may damage blossoms or bees.
As mentioned, there are three primary target pests. Aphids suck the juices from newly emerging leaves and cause the leaves to curl abnormally. Early control is essential to control leaf distortion.
Scale insects are often not noticed by gardeners. Scale might be thought of as the armored tanks of the insect world. These sucking insects are closely related to aphids. The insects develop during a short crawler stage lasting about two weeks and then attach themselves to the bark or leaves. They cover themselves with a waxy, protective covering. Again, the oil spray works very well because it clogs the pores and prevents the pests from breathing.
Oil is also effective against spider mite adults and eggs. Failure to control this pest often means a long battle with more expensive and often unavailable pesticides. Spider mites are closely related to spiders but feed on plants rather than insects. Dormant spray is the most effective way of reducing populations of some spider mites. It's important it be applied correctly to avoid killing predator mites. They are your best ally for controlling mites. Predator mites hide on the bark on the lower branches and trunk. Sprays applied now go only on the twigs and upper branches. Don't soak the trunk or the lower branches, as you kill off beneficial predator mites.
Small dwarf trees will require less than a gallon of finished spray solution, while large apricot, cherry or shade trees require two to five gallons per tree for effective coverage. In addition to fruit trees, consider spraying susceptible ornamental plants. Flowering plums, snowballs and many maples have aphid problems each year. Check junipers and other plants susceptible to spider mites and scale.
One caution on oil sprays is to avoid using them on blue spruces. The oil will discolor the blue coloring on the spruce trees and cause them to turn green.
Always spray any plants before they bloom, and spray when temperatures are on the upswing. Allow 24 hours between storms if possible so the spray will dry on the tree.
Don't become confused on which dormant spray to use in Utah. The only effective sprays are the spray oils plus the insecticide you mix yourself. Premixed products labeled as dormant sprays are dormant disease controls. The products control peach leaf curl, apple scab and similar diseases that are very rare in Utah. They are lime sulfur or calcium sulfide, and have a rotten egg odor. They do not control pests we have in northern Utah. Delayed dormant spray is one of the most important sprays to control fruit pests. Remember, it does nothing to keep the maggots out of the cherries or the worms out of the apples. Those sprays come later, so keep reading and I'll let you know the proper time to control those pests.
- ROSE PRUNING DEMONSTRATIONS by the Utah Rose Society, Saturday, March 30, 9 a.m. to 1 p.m., 1602 E. 2100 South. No charge.
- THE ANNUAL UTAH GLADIOLUS SOCIETY BULB AUCTION will be held Thursday, March 28, at the Garden Center in Sugarhouse Park, 1650 E. 2100 South, at 7 p.m. Standard varieties along with a nice selection of recently introduced glad varieties will be sold.
- I WILL BE TEACHING a home landscaping class on Thursdays, April 4, 11, 18, 25, 2-4 p.m. or 7-9:30 p.m. The class is limited to the first 40 participants. To register, send a $10 check to USU Extension, 2001 S. State, Room S1200, Salt Lake City, UT 84190-3350.
- "FRUIT IN THE HOME GARDEN" will be the topic for a session in the Granger Bishop's Storehouse, 3548 W. 7200 South, upstairs meeting room, on Thursday, March 28, 7-8:45 p.m. Intensive gardening techniques, proper care and planting of fruit trees in the landscape, pest control and pruning will be reviewed. "Vegetables in the Home Garden," with tips on growing techniques to improve vegetable production in the home garden, will be the subject there on Tuesday, April 9, 7-8:45 p.m.
- SPRING 1991 GARDEN WORKSHOPS are being offered by the USU Extension Service in the County Government Center, 2001 S. State, S1007. Classes, from 2-4 p.m. or 7-9 p.m., will include "Lawn Care: Saving Time and Money on Your Lawn," Tuesday, April 2; and "Budding and Grafting Techniques," Tuesday, April 16, which requires a $2 material fee. Pre-registration requested. Call 468-3170.