The Content Of The Article:
- Development and life cycle of the pest
- Affected plants
- Preventive measures
The plum moth (Grapholita funebrana) is a butterfly species of the family Winder (Tortricidae). The moth can be up to 0.8 inches long, the wingspan of its wings is about 12 to 15 millimeters. The forewings have a dull purple to gray color, while the hind wings are gray-brown. Head and breast part of the animals are also dark gray to brown colored. The male and female butterflies of this genus hardly differ in their appearance.
The initially white caterpillars turn crimson at a later stage of development and are then in possession of a dark brown head. They reach a length of 10 to 15 millimeters and usually overwinter under the bark of the affected trees. The doll of the winder is 6 to 7 millimeters long and light brown. Especially in commercial fruit growing the plum moth is one of the most important pests.
Development and life cycle of the pest
After fertilization, the nocturnal moths lay their eggs individually on the underside of the fruit. This is preferably done at temperatures above 16 degrees Celsius. In total, up to sixty glassy-looking eggs can be deposited. After about two weeks, the first generation of young caterpillars hatch. These begin to drill into the young fruits of the affected plants. After the larvae have finished their ripening - that is about the fifth instar - they leave the fruits again. As long as the young plum-worms feed on the inside of the fruit. Some of the animals now go into the so-called winter diapause - this is a temporary break in the development of insects. The other part of the animals pupates again and after about fourteen days brings out a second generation. The pupation of the pest occurs with a web, which is created by the caterpillars in the moss, on the tree trunk, between fallen pieces of bark or on rotten wood, which is stored on the ground.
The first-generation caterpillars fall to the ground with the fruits that have been prematurely rejected on the trees. The second generation can be dropped in this way to the ground or ropes off with a fine silk thread. The adult moths occur from late April to September, then fly in the evening and at night. In June and July, the small caterpillars infest the heart shoots of the food plants; In August and September, mainly the fruits of the plants are attacked. Most of the first overlaps with the second generation and it comes to a simultaneous moth flight. However, as butterfly development is strongly temperature-dependent, a second generation can be avoided in cool summers.
The first-generation caterpillars provide early violet discolored fruits that fall off the tree in June and July. Since the fruit waste is often considered natural, it is rarely associated with the plum moth.
The second-generation caterpillars cause prematurely ripe and soft fruits as well. A common symptom of fruits are also fine Miniergänge that lead directly to the stone. On the underside of the fruit a drill hole can be seen, which is provided with a colorless gelatinous drop. If you look into the fruit, you often see the caterpillar and its dung deposits. Secondary damage, such as the appearance of the monilia fungus, is increasing. The mushroom penetrates into the eaten fruits.
Inside the infested fruits one often finds the plum moth larvae and their dung deposits
Especially in commercial fruit growing a strong infestation with the plum-winder can lead to significant yield losses, which brings a huge economic damage.
The plum moth is commonly found in Europe, North Africa and Asia. There he mainly colonizes forests, gardens and orchards.
The pest is increasingly found in apricots, sour cherry, common bird cherry, pears and rose plants - such as the plum. It mainly affects late and mid-late varieties.
To prevent the plum wrapper, you should regularly check your trees for larvae nests and remove them if necessary. To monitor the Falters serve so-called pheromone traps. The principle of these traps is based on the propagation behavior of the plum moth. The artificial trap contains a sex attractant, which attracts the males. These fly into the trap and stick to the glue paper located there. As a result, fewer females are fertilized and the offspring thus decreases. The cost per case is about ten to fifteen euros.
With the help of pheromone traps male plum moths are caught and as a result fewer females are fertilized
As soon as you notice an infection with the plum moth on your fruit trees, you should act immediately.Eliminate all affected fruit as well as the fall to prevent the spread of the pest.
A helpful method against the plum wrapper are so-called fishing belts. At the end of July, place the catching belt about 20 to 40 centimeters above the ground around the trunk of the endangered trees. Check it regularly on existing caterpillars until the end of September and collect them if necessary. The belt acts preventively against the next generation by caterpillars crawling up the trunk for wintering. An advantage of this method is that the capture belt is safe for other beneficial insects.
If the caterpillars have not yet left the affected fruit, collecting the affected fruit also helps to reduce the infestation pressure in the following year.
Web wasps of the species Trichogramma are the natural antagonists of the plum moth and thus serve for biological pest control. The beneficial insects are - depending on the plum variety - exposed two to three times a year. The parasitic wasps are 0.4 millimeters in size and are released by means of cardboard cards. The females of the animals lay their eggs in the eggs of the pests and thus successfully prevent a development of the plum moth. A female can parasitize up to 120 pest eggs during its lifetime. On a map about 2,000 parasitic wasps are glued on. In order to fight the plum moth, the cards are hung from June in the intervals of three weeks in the fruit trees.