<h1 class="pgc-h-arrow-right" > preface</h1>
A few days ago we talked about the Japanese turtle wax fly, green blind aphid and apple cotton aphid, these pests, today I and I will discuss another valuable apple tree is seriously harmful, but not easy to find the pest - string clam.
In recent days, many of our growers here have been scraping the bark, and the best time for the control of clams is at this time, when we shave the bark, we must pay more attention to observation and seize this opportunity to eliminate these pests.
<h1 class="pgc-h-arrow-right" > first learn about string clams</h1>
Let's first understand this pest, the string clam is actually a name for our larvae, there are some names called spinworms, and their adults are called apple-winged moths. We are now mainly studying their larvae, so we will call them string clams below.
Larvae: The larvae of the string clam are similar to other clams, the head is yellowish brown, the body is milky white or light yellow, if you look closely, they have 8 pairs of feet, the dorsal line is light red, and the larvae can reach 2 to 2.5 cm in length in the later stages.
Adult: The adult of the string clam is the apple transfiguration moth, although called moth, but they look like a bee, the body is blue-black, the length is about 15cm, shiny; there will be two yellow-colored maculas on the abdomen, these two maculas are next to each other, look like a relatively wide macula, the web is also yellow-colored; their wings in addition to the wing veins and edges are black, the rest are transparent, so it is called the transmember moth.
The string clams photographed on May 8, 2019, at this time their body length has reached about 2cm
String clams occur only one generation a year, with larvae overwintering under the branch cortex of apple trees;
Around the beginning of April of the following year, the activities began to harm the fruit trees, generally in the late May to the beginning of June pupate, we can often find them in the young fruit stage of the apple, because their pupae time is relatively late;
When they pupate, they will bite out a circular hole under the bark, but they will not bite through the bark, pupate in this circular hole, after 10 to 15 days or so, they begin to feather, generally in June feathering the most, the earliest in mid-May can see adults, can last until about July;
After the feathering of the winged moth, the male and female mate, and then after 2 to 3 days or so to start laying eggs, a female adult can lay more than 20 eggs, although the number is not much, but their eggs are scattered, each time is 1, 20 eggs are laid in different places, the eggs are mainly laid on the branches of the apple tree, and there are more easy places to enter such as cracks and wounds in the branches;
The egg stage of the string clam is about 10 days, and after hatching, it enters the bark of the apple tree and begins to be harmful, and begins to overwinter around November.
Adult apple-winged moth of string clams
By understanding the habits of the string clams, we can find that they spend most of the year in the bark of apple trees. This pest is very interesting, called the winged moth looks like a bee, most of the other moths like branches, this winged moth prefers trunks and branches, their larvae are also called clams, the clams of the celestial cow to drill into the xylem, this clam can only be in the bark, it is a pest more unusual.
String clams will continue to nibble in the bark of apple trees, causing damage to the transport tissue of the bark of apple trees, affecting the transmission of nutrients, and it is very easy to cause the weakening of tree potential; at the same time, the wounds of string clams are an important way for apple tree rot disease bacteria to infest, which can easily cause the occurrence of apple tree rot disease.
The string clams are hidden under the bark most of the time, they do not have moth holes and excrement like the larvae of the celestial cow, they have almost no abnormality in appearance when they are harmful, and by the time they find it, they have reached the point where the harm is very serious.
Wounds caused by the infestation of clams on the trunk of apple trees can only be seen after the epidermis has been shaved open
< h1 class="pgc-h-arrow-right" > the occurrence of overwintering string clams in Jiaodong area</h1>
According to my observations from the Spring Festival to the present and the previous few years, the string clams here have become more and more serious in recent years, and traces of string clams have been found in many orchards, in terms of quantity, it is not particularly much, but in the orchard is relatively concentrated, as long as one is found on a tree, then more than 10 pests can be found elsewhere on this tree, and the harm is particularly serious.
In the orchard, the string of clams mainly occurs in the fruit trees with decay disease or dry rot, the main trunk and large side branches have more wounds, the fruit trees with weak trees, at the same time, in the management of previous years, the spraying does not pay attention to spraying the trunk, especially the medicine on the main trunk of the Qingyuan medicine is not well medicated, and it occurs more in the orchard where the bark is not carefully scraped in the spring, and it occurs less on some young trees and fruit trees in the early fruit stage, which is more consistent with the way the string clams invade the bark.
A few days ago in an orchard photographed a bunch of clams at the saw of an apple tree, in front of the wintering astragalus
<h1 class = "pgc-h-arrow-right" > control of string clams</h1>
We have a very important work in the spring Qingyuan - scraping the bark, this work can be found in time in the bark of the string clams, for the control of the string clams is a very critical period, which requires us to be careful when scraping the bark, especially the rot disease dry rot serious old tree weak trees, as long as a string of skin clams are found, then the main trunk and large side branches of the fruit tree are carefully searched, the found string clams in time to eliminate the found string clams.
Now is the best time to control string clams when scraping bark
It is difficult to have an effective drug control of string clams, and serious orchards can be used to eliminate residual larvae by drying them with chlorpyrifos and silicone additives from March to April; in addition, in severe orchards, according to the specific conditions of the orchard and production arrangements in June and July, spray chlorpyrifos or parathrin insecticides, in general, during this period, it is also necessary to consider spraying Bordeaux liquid to prevent early defoliation, and you can spray water medicine after bagging and add insecticides to the fresh water medicine that is rotated with Bordeaux liquid.
Old and weak trees, rotten and diseased fruit trees with serious rot should take measures to restore the tree momentum, minimize the wounds on the main trunk and large side branches, it is recommended to increase the application of organic fertilizer, combined with disease and pest control, reasonable fruit retention, reasonable pruning and other ways to promote tree recovery, which is the basis for the prevention and control of string clams, which can reduce the opportunity for the harm of string clams.
String clams near rotten spots in apple trees photographed on February 3 this year
The string of clams is hidden in the tree, there are few natural enemies, but woodpeckers can find them, and now some orchards have set up bird repellent anti-bird devices, it is recommended that even if the apples are not endangered by birds, even if they are removed, especially some fruit farmers set up bird nets, must not be wanted, so that woodpeckers can enter the orchard, can play a certain auxiliary role in the control of string clams.
< h1 class="pgc-h-arrow-right" > summary</h1>
The string clams on the apple tree, in general, the number of occurrence is much less than the several pests mentioned above, but the harm to the apple tree is very serious, it is recommended that the fruit grower friends focus on checking it when they are clearing the garden now, and seize the best time for prevention and control.
I am the seventh brother of the farmer, the above is just a personal opinion according to the situation of the string clams that occur in our orchard here, the level is limited and inevitably insufficient, welcome to leave a message to criticize and correct!