In ancient Greece, the food of the gods was called ambrosia. The same name is also given to the malicious quarantine weed - a plant described by the botanist Karl Linnaeus in 1753. The great Swede, of course, could not imagine how much trouble this plant would bring to mankind. So what is ragweed weed?
The ragweed genus has about 50 species and belongs to the Aster family. The most dangerous are several species that are found in our country. Among them are ragweed, tripartite ragweed and ragweed. But the palm, undoubtedly, belongs to the wormwood.
- The height of the plant is from 20 to 30 cm, but under favorable conditions it can grow up to 2 m.
- The root system of the plant is powerful pivotal, easily penetrates even to a depth of four meters.
- The stem of the plant is pubescent, branches at the top.
- Pubescent leaves are pinnately dissected. At a young age, the plant looks like marigolds, which often misleads people, having matured, it looks more like a chernobyl - one of the types of wormwood, for which it got its name.
- The flowers of the plant are unisexual: male - yellow-green, collected in branched inflorescences and female, located at the base of male flowers. It blooms from July to October. The plant produces a lot of pollen, which can be carried over long distances by the wind. Even one weed can give rise to numerous offspring.
- In August, seeds begin to ripen, their number is very large, record holders produce up to 40,000 seeds. The seeds do not germinate immediately. They need a rest period of 4 months to six months. Not only fully ripe seeds germinate, but also those that are in waxy and even milky ripeness. Seed germination is very high, they can wait 40 years or more for germination.
- Favorite habitats of this weed are wastelands, roadsides and railways, landfills.
Photo of wormwood ragweed.
And this is a photo of her relative - tripartite ragweed.
Tripartite ragweed and wormwood are annuals, and holomesle is a perennial and winters well. Here she is in the photo.
Attention! When plowing areas infested with this weed, its roots are cut into pieces. Each of them germinates, so it is very difficult to deal with this type of ragweed.
History of appearance
The natural habitat of ragweed is the southwest of North America. Even 200 years ago, it was relatively rare even there. But population migration made it possible for ragweed seeds to spread throughout the American continent. Sticking to shoes, they penetrated into new areas. In 1873, this malicious weed appeared in Europe. Its seeds ended up in a batch of clover seeds from America. Since then, this quarantine plant has continued its victorious march not only across the European, but also across the Asian continent.
In Russia, the first ragweed plants were seen in 1918 in the Stavropol Territory. The climate of the south of Russia suited her quite well; on the wheels of cars she was carried farther and farther. Now ragweed can be found even in the south of the middle zone. Gradually adapting to new growing conditions, it confidently moves north. Distribution map of this malicious weed.
All types of ragweed are quarantine, that is, especially dangerous, since they have a large potential area of possible naturalization. Why is this weed so bad?
Harm to humans
The pollen of all types of ragweed is a powerful allergen. The degree of allergenicity of pollen of any plant is determined by two indicators: the size and the number of allergens that are included in its composition. Ambrosia pollen is small. Such particles freely penetrate into the human lungs. The number of pollen particles that one plant can excrete reaches several billions.
There is an allergenicity index that determines the strength of the allergen. In ragweed, it has a maximum value of 5. Allergies are caused by the content of 5 units of pollen per 1 cubic meter of air. For other types of plant pollen to cause allergies, their concentration must be much higher. When tested on volunteers, half of the subjects were found to be sensitive to pollen. This is a very high figure. This is what the pollen of this plant looks like when viewed at high magnification.
Attention! Since 2000, even in Moscow during the flowering of this quarantine weed, the pollen content is 8-15 grains per 1 cubic meter of air.
How is ragweed pollen allergy manifested?
- Very severe allergic bronchitis, which can be complicated by pulmonary edema.
- Asthma attacks.
- Temperature increase.
- Itchy skin.
- Sore throat and sore throat.
- Cross-allergic reaction to a range of foods, such as mustard.
Some people may also experience general allergy symptoms.
- Depressed state up to the development of depression.
- Poor sleep and appetite.
- Deterioration of attention and concentration.
- Increased irritability.
Warning! If you are allergic to ragweed pollen, it is very difficult to cure it.
To prevent allergies from becoming a huge problem, it is better to take preventive measures during the flowering of this weed.
- Do not go out into the fresh air in the morning. And it is better to time the walks at a time when the air humidity is high, which happens after a rain. Most of all, ragweed pollen is thrown into the air from 5 am to 12 noon.
- It is better to dry washed things at home, outside pollen can easily settle on wet things.
- Do not ventilate the apartment at night and in the morning; the windows in the car must be kept closed.
- After being outdoors, you need to wash your face, wash your hair, rinse your mouth. It is better to rinse the nose with a saline solution.
- Bathe your pets more often, ragweed pollen can settle on their fur.
- Sun glasses keep pollen out of your eyes.
- Daily wet cleaning is required.
Advice! At the time of flowering of this plant, it is better for allergy sufferers to leave the dangerous region and spend a vacation where there is no ragweed yet.
There are sites that monitor the state of ragweed flowering. There is also data on the concentration of pollen of this plant in each region.
Advice! When going on vacation, check the pollen forecast for the area where you will be vacationing.
The seeds as well as the leaves of this quarantine weed are allergens and can cause dermatitis. The essential oils secreted by ragweed provoke a severe headache, the pressure jumps up to hypertensive crises.
Harm of ragweed to plants and animals
Having a powerful root system, this plant absorbs a large amount of water and nutrition from the soil, taking them away from the cultivated and wild species growing nearby. In just a couple of years, it depletes the soil on which it grows to such an extent that it becomes unsuitable for further agricultural use. Getting into the crops of cultivated plants, ragweed not only takes away their water and mineral nutrition, but also light, as it grows above them. In cultivated plants, the process of photosynthesis slows down, their oppression and even death occurs.
When it gets into livestock feed, this weed degrades the quality of milk. It becomes unpleasant to the taste and acquires the same smell due to the content of bitter substances in this plant. If you make silage from grass containing ragweed, the animals do not want to eat it.
How to deal with ambrosia
Why was the ragweed weed able to capture large areas so quickly? This sturdy and strong plant easily outstrips any competitors. The huge number of seeds and their ability to germinate for many years contributes to the rapid multiplication of this quarantine weed. At home, ragweed has pests and plants that can significantly limit its habitat. But neither Europe nor Asia has them. Only some weeds that live next to it can make a small competition for ragweed. Among them are creeping wheatgrass and pink thistle. These plants are able to significantly reduce the height of ragweed plants, as well as the number of seeds that it can form.
In order to defeat this weed dangerous for humanity, it will take joint efforts of not only specialists, but also ordinary people.
Ambrosia outbreaks in Europe.
There is already a large-scale project in Europe that provides for the environmentally friendly protection of agricultural plants. 200 researchers are looking for insects and plants that could cope with the biological expansion of ragweed. 33 states have already joined the project. It is called SMARTER for short. The project was initiated by the Swiss ecologist Professor Heinz Müller-Scherer. In Russia, there are regional programs that are aimed at combating this malicious weed.
- The most productive method of dealing with ragweed in private estates is manual. Moreover, mowing is effective only during the beginning of flowering of the plant. If you do this earlier, the effect will be the opposite, since the number of plant shoots will multiply many times over. We will have to repeat the mowing of ragweed until the end of the growing season of the plant in late autumn. For ragweed, this method of control is ineffective, since it is a perennial plant.
- Weeding by hand before seed formation has a very good effect. The plant can completely disappear from the site.
- Chemical methods for the destruction of harmful weeds. For the treatment of fields with soybean crops, the herbicide Basagran is used, it is also used in a mixture with another herbicide titus on corn crops. The consumption rates of herbicides for effective weed control are high enough, which does not contribute to the improvement of the ecology. Herbicides Pruner and Hurricane are also used. The best results are obtained with a mixture of these herbicides, the time of its application is the beginning of ragweed flowering. This mixture allows the concentration of both substances to be reduced without compromising treatment efficiency. Ragweed is difficult to treat with herbicides. When handling, a protective suit and respirator must be used.
- Using the method of displacing ragweed with mixtures of cereals and legumes. A good result on farmland gives the correct crop rotation, careful care of crops. There is information about the use of its natural enemies brought from America to control this quarantine weed, namely the ragweed leaf beetle Zygogramma suturalis and the moth Tarachidia candefacta. Experiments with these insects are encouraging. This method of fighting ragweed is successfully used in China.
The ragweed leaf beetle is the brother of the Colorado potato beetle, but unlike it does not recognize any other food, therefore it does not pose a danger to other plants. Since the 80s of the last century, the time when the zygogram beetle was first released on the fields to fight ragweed, amazing metamorphoses have occurred with it. He not only changed his color, but also learned to fly, which he could not do in his homeland. It took only 5 generations of the zygogram to grow the wings. Crop rotation interferes with the reproduction of the beetle, because of which it does not have a permanent habitat.
It should be said that on the basis of ragweed, quite effective drugs have been created for certain diseases, which, oddly enough, include allergies.
The uncontrolled spread of such a dangerous weed is a side effect of the human development process. It was thanks to the improvement of communication links that it became possible not only to relocate this plant to other continents, but also to quickly settle within them.