Take a quick trip into the home orchard and see that the buds are swelling and growing. Timely attention to pest control will help keep early season pests from attacking your trees and fruit. Pest control on fruit trees must be applied at the right time. Apply controls too early and you will miss the pests because they are not out and attacking the fruit. Wait too long and you will find that the insects have already attacked and destroyed the fruit and possibly the tree. Knowing what to spray and when to spray are two of the challenges of fruit production.
The changeable spring weather has caught many gardeners off guard. The challenge has been to fit the sprays between snow storms, showers, wind and cold temperatures. By now the delayed dormant spray should have been applied to early blooming trees such as apricots. Apply the spray before the blossoms start to open. Never spray trees that are blooming because the insecticides will kill the bees. The delayed dormant spray is most often used in orchards but can give equally good results when used on ornamental plants that develop pest problems.When trying to grow fruit you must practice integrated pest management techniques. This is essential because trees offer unique challenges. Unlike vegetables, flowers and other annuals that are easily rotated from one place to another, trees remain in their permanent positions. Skipping a year is not an option. With many other crops you can easily stop growing them for a season and let pests subside but trees remain in place and are subject to repeated attacks from the pests. Trees also represent a longer term investment. If pests destroy the fruit, you have lost out for that year. If they destroy the trees, it will be several years before new plants can replace the damaged or-chard.
Look for easy ways to control the pests. Contrary to what many gardeners imagine, pest outbreaks do not happen overnight. Pest populations build as these creatures reproduce. Higher temperatures and a readily available food supply let the pests grow and flourish. Early intervention helps control the pests before the outbreak occurs. Since trees are permanent and do not move, it is possible to anticipate outbreaks and deal with them accordingly.
The delayed dormant spray is a mixture of spray oil plus an insecticide. Spray oil is sold under various brand names including Superior, Supreme and Volck. Oil sprays are "organic" and will satisfy the organic chemical criteria. The oil is usually mixed with diazinon to make it more effective but using it means the spray is no longer organic. Gardeners who are fighting pear psylla need to use thiodan with the oil. Pear psylla causes the leaves and buds to be extremely sticky and turns them black.
Timing is critical. Apply the spray when you see the green tips on the apple buds or the flower color on the stone fruit trees. Use the same guidelines for ornamental plants. For plants on which the leaf buds emerge first, spray when the green tips appear. For those on which the flower buds emerge first, spray when the flower color shows on the ends of the buds. Delay spraying the pears until they reach the fingerling stage. This means that the bud clusters start to separate but the blossoms have not started to open.
Under ideal conditions, the spray is best applied on a warm spring day. Choose a day when the temperatures will not drop much below freezing nor will there be any rain within a 24-hour-period. The conditions I described mean the insects are active and crawling on the buds and branches of the trees. Applications at this time smother the adult insects because the oil coats their bodies. Since insects breathe through openings in their bodies, anything that plugs their breathing opening will kill the pests. The coating also coats the insect eggs and smothers them. This is important because there are few products that work on insect eggs.
The delayed dormant spray is very effective against aphids, scale and spider mites. Aphids often attack the newly emerging foliage, causing it to curl. This makes any sprays applied later in the season much less effective because the aphids are curled inside the leaves and the insecticides will not contact them. The delayed dormant spray controls the pests prior to the time the leaves emerge so the aphids do not curl the leaves.
Scale insects are so unusual that they are not even recognized by many gardeners. Scale is a nonmobile insect and in contrast to most crawly insects, these creatures do not move. They hatch, find a spot and attach themselves to the leaves, stems or fruit. They then cover themselves with a waxy material that protects them from drying out or from pesticides. Because they still breathe through their bodies, an oil coating kills the pests. Scale insects range in size from the size of the head of a pin to the size of a pencil eraser. They are often mistaken for natural plant parts but they are sucking insects that drain the juices from the plant, thereby affecting its growth.
Spider mite problems do not show up until later in the season. They love hot weather and populations explode under the right conditions. The oil smothers both the adults and the eggs. Killing the pests now reduces the problems later in the season. Light oil spray can also be used as an insecticide or miticide during the summer.
As soon as the weather starts to cooperate, get the spray applied. Remember this spray does not keep the worms from getting into apples or cherries nor does it prevent any diseases. Information on controlling those pests will be the subject of future articles.