In late spring, on conifers, most often on spruces and pines, you can notice some deviations from their normal growth and development: yellowing and twisting of needles, white covering of buds and shoots on branches. This suggests that pests, hermes, have appeared on coniferous crops, and plants are in serious danger.
What are hermes
Hermes are very small, no more than 2 mm insects, which are also called coniferous aphids. Outwardly, they look like bugs. They have an elongated torso of green, brown or black, and on their heads they have small antennae. These insects feed on the juice that stands out from the needles and young shoots, and the white fluff on the branches serves as a reliable shelter that promotes the reproduction of larvae.
In summer, coniferous trees infected with hermes are covered with galls - unhealthy growths similar to a spruce cone, which actually serve to protect, grow and breed larvae in them.
Symptoms of the lesion and the main types of pest
Hermes is not one type of harmful sucking insect, but a whole group. The only thing that unites them is that they belong to the order of isoptera and feast on the juices of conifers.
Pests are migratory, that is, developing on two plants of a different species, and they are not migrating, they choose one species and live on it.
Another sign by which pests can be divided is the development cycle. Some species develop one year, and there are those that need as much as 2 years.
For instance:
- Yellow Hermes. Develops in one season. Females feed on the juice of needles and, when laying eggs, form a huge gall, sometimes reaching 20 cm.
- Spruce larch red hermes. Individuals are brown or black. It is a migratory species of coniferous parasite that lives on spruce and pine. Duration of development - 2 years.
- Spruce larch green hermes. Individuals are mostly light shades of green. Develop in one season. The female of green hermes forms galls, in which larvae develop. In the summer they turn into winged individuals and fly away to live and breed on larch. Therefore, the species is also migratory.
- Hermes weymouth pine. A non-migratory species that develops over one or two years.
- Subcortical spruce hermes. These pests live only on spruce and do not migrate. They have no wings, live mainly in the bark of branches and a tree trunk and do not form galls
Non-fertile females on the body have white fluff that resembles a cotton ball, but the fruit-bearing ones do not. Relatives of hermes are aphids, whiteflies, worms and scale insects.
Despite the microscopic size of the pests, the symptoms of tree disease from their life are visible to the naked eye.
After infection, the spruce trees turn yellow and twist, and when there are too many larvae and adults, the needles begin to crumble and galls form. In pine, the crown thins from pests, sometimes the flow of resin begins and the tree can die.
Hermes on a pine, cedar
The main symptom of cedar pine infection with hermes is the presence of white fluff on the plant. Shoots, twigs at the base of the needles are covered with white lumps, and even with a large amount of pest, even a tree trunk. From these fluffs you can easily understand whether a tree has been infected for a long time.
The old fluff is very firmly glued to the tree, it is difficult to remove it, and fresh white lumps are easily removed. If you rub them in your hands, you can find brown spots on the skin - these are crushed larvae that hide and protect with the help of a white soft shell.
Disease of a cedar after damage by hermes can lead to drying out and death. The needles slowly turn yellow, curl and crumble. Shoots become small and bright every year. By the appearance of the tree, you can determine whether it is going to die.
Cedars, which grow in favorable soil, can resist the disease for a very long time and can be completely cured in a few years, while trees growing in lowlands, too moist soil and an unfavorable climate often die because they do not have enough strength to deal with the pest.
Hermes on fir and larch
The primary signs of damage to fir and larch by sherry are the withering of the beauty of appearance. First of all, the crown thins on fir, the needles become red, sparse, dry and have an untidy appearance. Trees begin to hurt from the lower branches.
Also, upon careful examination, you can notice an unhealthy brown coating on the needles of fir and in old shoots, it is there that parasites are first inhabited.
Unlike cedar, on fir it is more difficult to notice the symptoms of the disease, since it is not covered with fluff, and yellowing of the branches can be caused by other infections. In this case, you need to select the treatment very carefully, since a mistake can only aggravate the situation.
As for the larch, we can say that it is sick less often. The needles on this breed are updated annually, so pests settle on it less often. But it is more difficult to detect them, because the larch does not turn yellow, but remains green all summer. Despite this, if it grows next to other conifers, it must also be examined for insects, and in case of illness, treated together with other cultures.
Hermes at Spruce
The main sign of spruce disease is the formation on the shoots of heterogeneous growths called galls. They look like a fir cone and are a refuge for the development of larvae. When an adult female lays eggs, a chemical is released that provokes tissue proliferation - this is how a gall turns out.
After the larvae leave the galls, these growths remain empty for a long time on the tree and gradually dry up.
Methods for the prevention and control of hermes
To prevent the occurrence of insects on young seedlings in the first seasons or when planting, the following prevention rules should be observed:
- When buying a seedling, it is necessary to carefully examine it for small pests. It is advisable to avoid acquiring infected trees. If you still find hermes on the seedling after purchase, you must definitely get rid of them before planting in the soil, clean it from insects and remove galls.
- It is not recommended to plant a seedling in too wet soil, on windy and too light areas, and also close to paths where the soil is very compacted
- It is necessary to plant crops in loose soil with the addition of fallen needles or peat (they serve as an excellent fertile fertilizer)
- After planting, you need to feed the tree with special preparations that strengthen the root system (Radifarm, Kornevin)
- Be sure to use the drug to maintain immunity at least three times after planting a seedling (the recommended interval between treatment is 2-3 weeks)
- It is very useful to cover the soil around the trunk with pine bark. The thicker the mulching layer - the better
- It is important to treat the trunk and crown of the young tree with special preparations - vitamins for conifers. It can be Needle Reak or Joofert
To protect adults, growing trees, there are also some methods of pest control and they need to be produced in spring (but not later than June), until the larvae have grown and left their shelters:
- If galls are found on spruce trees, it is necessary to cut them and burn them along with damaged shoots
- Rinse the trunk and needles with a strong pressure of water in order to wash off insects. The procedure must be performed repeatedly.
- To process a fir-tree with a solution with mineral oil (to part in proportions 200 300 ml on 10 l of water, and to spray a tree).
There are times when all these methods do not bring the desired effect.
Then you have to turn to stronger chemicals, which will certainly help get rid of the annoying pest. This may be the Commander, Mospilan, Prestige, Caesar, etc. It is necessary to breed and use drugs according to the manufacturer's instructions. The frequency of treatment depends on the degree of damage to the plant.
It is recommended to use different drugs in turn for greater effectiveness.
This will not harm the plant, and hermes will probably cease to disturb the tree for quite some time.
Growing conifers in the areas will bring aesthetic satisfaction and a constant feeling of the new year, if you take care of the trees and carry out preventive measures in time.
