Why does a cobweb appear on an apple tree and how to deal with it
Spider web source
The source of the cobweb in the case when it is thick and dense are caterpillars. This insect is a pest. It is called apple moth. Such a pest can appear everywhere, and the most important thing is to process plants on time, unfortunately, such a pest can ruin almost all the fruits of your plant. 
There is also a second type of pest - apple sucker. From it, a white and very dense web appears throughout the plant. This insect is winged. Its larvae will suck juices from everywhere - from buds, flowers and leaves of a tree. After that, it will secrete a specific, peculiar substance (excrement), which is very sticky to the touch and, externally, is sugary. This substance sticks together buds, leaves and buds, from which mushrooms can appear on the apple tree. It is these mushrooms that are for our "eyes" a dense white web.
On the photos at the end of the post, you can see this web. In fact, if such a web appears on your apple tree, you urgently need to do something and take certain measures to destroy it and preserve your harvest.
Such a web on an apple tree can also form in the winter season. Many gardeners are interested in what kind of cocoons, which are very clearly visible, hang on the branches of their apple trees, and what to do to get rid of them ?! These are also pests, they are called - hawthorn. They are small caterpillars that prefer to curl up and hibernate during the entire period in their cocoons. If you have a hawthorn, you need to immediately process the plant in order to get rid of this pest as soon as possible.
How to fight
The apple tree is a fruit tree that not only creates a beautiful image in any garden, and at any time of the year, but also gives delicious, healthy, vitamin-rich fruits. But if pests appear on the tree, they must be eliminated immediately. How to deal with them is described below.
With the cobweb that has formed on the branches of apple trees, in general, it will not be difficult to fight. The main thing is to detect the appearance of a cobweb in time and start fighting.
It is also important that the gardener understands why the cobweb appeared. If the apple tree began to become covered with cobwebs in the form of a white mesh, in this case an apple moth started up. To get rid of, you need: where you can get it on your own, reach in the places of the crown - remove the cobweb with your hands. 
It is necessary to process apple trees at intervals of a week, and until you completely get rid of the cobwebs on the trees. You can also use a chemical preparation, which can also be purchased at specialized points of sale - Fitoverm, use it, also, according to the instructions in its packaging.
An important point is the mandatory removal and destruction of caterpillars that look like small worms, as well as their nests, so that new pest larvae do not mature in the future. Leaves and branches that are high should be sprayed on. It is recommended to use a special, for this, infusion of tobacco.Also, you can buy biological products at specialized retail outlets, for example: entobacterin or dendrobacillin, use these products - according to the instructions included in their packaging. 
Gardeners may also have such cases when it is not possible to process trees in time due to frequent and heavy precipitation in the form of rains. And then, instead of flowers, a lot of cobwebs will appear on the apple trees, with which the entire crown of the tree will be wrapped, and the leaves will be eaten by caterpillars that look white with black dots - this is the ermine moth. A butterfly of its snow-white color, lays its eggs in small heaps in the cozy places of the tree, for example: the branches, the bases of the buds. The eggs are laid in the form of scutes. It is under them that caterpillars winter. And when spring comes, they bite into the buds of the apple tree, and when the leaves bloom, the whole brood feeds on the pulp of the leaves for two weeks.
Of course, after that the leaves will dry up, and the caterpillars will make a tent of cobwebs and will live in it (up to 70 pieces in one). Then they eat all the leaves on the tree, and the gardener did not have time to look back, as the apple tree managed to be covered with all the white cobwebs. Then the caterpillars will pupate, butterflies will appear, which will again lay their eggs and everything in a circle ...
It is best to inspect the young branches of the apple tree in autumn, you can even use a magnifying glass. If you find ovules, they need to be scrubbed well and burned. Also do with dry branches, especially those that are heavily eaten. And before the frosts come, it is imperative to sprinkle with milk of lime, after which the apple tree should turn white.
Also, in early spring, it is imperative to cut off and burn all the spider nests so that the caterpillars in no case crawl over your apple tree. Starting from the period when the apple tree is about to become covered with blossoming buds, and then flowers, it is recommended to spray the trees. For example, you can use one of the recommended remedies.
Video "How to get rid of cobwebs on an apple tree"
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