Apple moth (lat. Cydia pomonella) is one of the most dangerous insect pests of the apple tree.
It is widespread everywhere. Therefore, amateur gardeners need to know the main features of this pest and measures to combat it.
In order to determine the best time for the fight against the codling moth, it is necessary to know the date of the beginning of its summer, and in this regard, the dates of the possible hatching of caterpillars.
Usually, in our conditions, the mass years of the codling moth are observed in the second half of May-early June and coincides with the end of the flowering of the apple tree. 3-4 days after the departure, the females begin to lay their eggs (usually on the leaves, less often on the ovary of the fruit of the apple tree). The duration of egg development is 5-10 days.
A spawning caterpillar is located on the surface of leaves and ovaries for several hours and then bites into the fruit. Naturally, after this spraying the trees with pesticides useless. Most likely, and your neighbor in the area sprayed his apple trees also after this time.
There is an exact method for establishing all phases of codling moth development – this is a method for calculating the sums of effective temperatures. The temperature is considered effective, which is the difference between its average value and the value of the lower threshold for the development of the moth (it’s biological zero).
It was established by observations that the lower threshold should be considered a temperature equal to + 10 ° С: only with the transition of its average daily value above + 10 ° С the codling moth develops in spring, therefore, when organizing observations, the calculation of the sums of effective temperatures should begin in the spring from the moment the average daily last through + 10 ° С. From this date, it is necessary to summarize the effective temperatures daily (the difference between the average daily temperature and the lower development threshold).
So, for example, if the daily average temperature turned out to be + 13.5 ° С, the value of the lower development threshold is + 10 ° С, then the effective temperature for this day is 13.5 ° -10 ° = 3.5 ° С. By the moment of accumulation of 130 ° С (effective temperatures) in the spring, a butterfly hatches from a pupa. By the time of accumulation of 230 ° С effective temperatures (above + 10 ° С), caterpillars develop from the eggs laid by the butterfly, and they are introduced into the fetus.
At this point, the trees need to be treated with appropriate chemicals designed to combat the moth.
The methodology for calculating effective temperatures is simple and quite accessible to every gardener. Moreover, many gardeners live on their plots from spring to late autumn.
Summing up these residual (effective) temperatures from the day when the daily average temperature went over + 10 ° С, we can determine the date of accumulation of 130 and 230 ° С effective temperatures, which will indicate the timing of the protective spraying. Temperature observations are carried out directly in the garden, using a conventional thermometer with a two-time reading of temperature information during the day or special maximum and minimum thermometers.
The sum of two measurements of a conventional thermometer taken at the maximum and minimum hours of the daily temperature and the measurements of the maximum and minimum thermometers divided by two will give the average daily temperature.
To avoid the influence of direct and scattered solar radiation, thermometers are installed under protection in a special box with trellised grids at a height of about one and a half meters. When using the minimum and maximum thermometers, the minimum thermometer is put in the box at night and the maximum on the day. Such a shift is carried out daily during the entire observation period. Such observations of temperature in the garden are very useful for the study of plant phenology.
In addition to the indicated temperature observations, for the successful fight against the codling moth, it is necessary to know the basic biological properties of this pest.
In addition to the fruits of the apple tree, it damages the fruits of pears and plums.
This is a small butterfly with dark gray front wings, on which dark transverse wavy lines are located, and at the top, there is a brown spot with a bronze tint. The hind wings are light, with a fringe at the edges. In the range of the butterfly reaches 20 mm.
Caterpillar is yellowish or pink in color, with a dark head and an occipital shield. Adult caterpillars reach 12-18 mm. Adult caterpillars hibernate in dense spider web cocoons in the upper soil layer, under the lagged bark, in cracks in the trunk, on supports, in packing material, in containers, in premises for storing fruits, where they fall with damaged apples. Caterpillars pupate in cocoons during the period of bud staining, butterflies fly out after flowering at the sum of effective temperatures equal to + 130 ° С.
Butterflies fly at night, and during the day they sit motionless in the crown of trees, where they are difficult to notice. Soon after flowering (usually 10 days after departure) at temperatures above + 16 ° C, the butterflies begin to lay their eggs.
Butterfly egg laying is carried out one by one for 1.5-2 months. This circumstance makes it difficult to conduct a single pest control measure. After a few days (4-12), depending on the air temperature (when the sum of the effective temperatures of + 230 ° C is reached), caterpillars hatch from the eggs, which penetrate into the ovaries and feed there, making moves in the pulp of the fetus and eating seeds.