Pest And Disease Control

9. Pest And Disease Control

In a biologically-managed orchard, pest control should be limited to the use of integrated pest management techniques which include biological controls such as parasites, predators, and diseases. When insect damage is severe, organic growers can make use of certain nontoxic sprays such as dormant oil, retenone, pyrythrum, ryania, pepper juice, and others (see previous lesson on organic gardening for more details). All insecticides should be used only in emergencies, and with caution, because of the possibility of upsetting the natural balance.

The main point in biological pest control is the greater the area under biological and integrated pest control, the greater that control can be. When one orchard under biological control methods is surrounded by nearby, sprayed orchards, it has less of a chance of attaining optimum good effects from biological management. The more growers who can be convinced to retreat from total reliance on toxic chemicals, the more effective the overall program will become.

However, at times you may need to intervene when pest damage is overwhelming. Some insects and types of controls are as follows: The Caribbean fruit fly may cause a problem with citrus. A small brown spot will appear on the rind, and you may find small worms inside the fruit. The papaya fruit fly does similar damage. The only control suggested is bagging the fruit. If you want to do this, use
brown paper sacks, or cloth—not plastic which will cut off respiration. The fruit will still be able to ripen, since the ripening process proceeds through the leaves, not the fruit.

A program to exterminate Caribbean fruit flies in Florida has reduced damage from this pest. Millions of the flies have been captured and sterilized by irradiation. The sterilized flies are released to mate with wild flies, resulting in sterile eggs.

As mentioned in the previous lesson on organic gardening, “Neutral Copper” may be used in controlling certain plant diseases. If used properly, it will control diseases without poisoning the fruit.

Use neutral copper on fig trees only if rust (a fungus disease) becomes a problem (the leaves look like they are covered with a rusty powder). If there is just a little, simply ignore it.

Neutral copper may also give some control to fire blight on loquat trees if sprayed prior to blossoming, and again when the fruit is about the size of a pea. The symptoms of fire blight are drying up of blossoms, blossom stems, or fruit, when the size of small marbles. Remove and destroy diseased parts, then spray with neutral copper three times at two-week intervals.

If you find splitting bark, or gum running from the trunks of your trees, remove the loose bark, spray with neutral copper twice, seven days apart, then apply pruning paint. When the pruning paint wears off, repeat the process.

Ground-up sulfur rock is an organic fungicide. Organic Gardening magazine, August 1980, says it is the best organic fungicide available.