The Smyrna quince tree, one of the varieties of cydonia oblonga, is often found growing near temples of antiquity in Turkey, Syria and Greece. These trees grow in full sun and in moist, fertile soil. They are commonly recognized by their colorful flowers and edible fruit that begins to ripen in early September. They suffer commonly from the same pests and diseases as other fruit trees.
Powdery mildew is a fungal growth that can cause the fruits to become discolored and growth to be stunted. Symptoms usually begin with small patches appearing on the leaves that eventually spread into black spots that rapidly reproduce on the buds and branches of the tree. Infected blossoms become unable to produce fruit and fall off, and leaves often become distorted. Most fungicides will cure powdery mildew already present on the plant.
Smyrna quince trees, along with many other fruit-bearing trees, often suffer from scabs such as the apple scab. Scabs begin to appear as small dark spots on the leaves that eventually begin to spread. As it develops, the scab will appear on the fruits as raised black spots. This infection will begin to kill the tree's leaves as it worsens. Gardeners often use concentrated dormant oils, which will smother and kill the infectious fungi.
Fire blight, a dangerous bacterial disease, will crack and distort all parts of the tree. It develops in early spring, during rainy, warm weather. The blossoms of the tree begin to shrivel and turn black. The tips of twigs will start to curl and become distorted, and dead leaves will cling to the tree as the infection worsens. As the bacteria spread, they form black cankers along the edges of the bark, giving the appearance of scorched wood. The bacteria are easily transferred between trees through insects and rain. To cure fire blight, all infected twigs and cankers must be cut out, disinfecting all tools as you go.
Apple Maggot Flies
Apple maggot flies will attack the Smyrna quince fruit, laying their eggs beneath the skin of the fruit. The maggots will hatch and and burrow through into the soil to continue their life cycle. Gathering fallen fruits at least twice a week can cut down on the number of flies present around the tree. Common insecticides containing organophosphate will control the apple maggot, though all directions from the manufacturer should be followed precisely when being used as they can be dangerous to humans. Avoid over-spraying within two weeks of harvesting the fruit.
Codling moths are a serious insect threat to quince trees. The larvae of the moth will make the fruit inedible and unable to be stored. The moths are attracted to the flower blossoms of the tree, where they lay their eggs among the developing fruit. The larvae begin eating the fruit immediately after hatching. This reproduction cycle often happens twice a year, further damaging potential harvest. Organophosphate pesticides are an effective way of removing a codling moth infestation, and should be applied every two weeks from the time fruits begin to develop until prior to harvesting.