Content
In ancient Greece, ambrosia was the food of the gods. Malicious quarantine has the same name. weed - a plant described by botanist Carl Linnaeus in 1753. The great Swede, of course, could not imagine how much trouble this plant would cause humanity. So what is ragweed weed?
Biological features
The genus Ambrosia has about 50 species and belongs to the Asteraceae family. Several species that are also found in our country are considered the most dangerous. Among them are ragweed, ragweed, tripartite and sea ragweed. But the palm undoubtedly belongs to ragwort.
- The height of the plant is from 20 to 30 cm, but in favorable conditions it can grow up to 2 m.
- The root system of the plant is powerful and taprooted, easily penetrating even to a depth of four meters.
- The stem of the plant is pubescent, branches in the upper part.
- Leaves are pubescent, pinnately dissected. At a young age, the plant looks like marigold, which often misleads people; when mature, it is more reminiscent of Chernobyl - one of the types of wormwood, for which it got its name.
- The flowers of the plant are unisexual: male flowers are yellow-green, collected in branched inflorescences, and female flowers are located at the base of male flowers. It blooms from July to October.The plant produces a lot of pollen, which can be carried by the wind over long distances. 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 mature seeds are germinating, but also those that are in waxy and even milky ripeness. The germination rate of seeds is very high; they can wait 40 years or more for their time to germinate.
- The favorite habitats of this weed are wastelands, the sides of highways and railways, and landfills.
Photo of ragwort.
And this is a photo of its relative - ambrosia tripartite.
Ambrosia tripartite and wormwood are annuals, while ragwort is a perennial and overwinters well. Here she is in the photo.
History of appearance
The natural habitat of ragweed is the southwest of North America. Just 200 years ago, even there it was relatively rare. But population migration made it possible for ambrosia seeds to spread throughout the American continent. Sticking to shoes, they penetrated into ever new areas. In 1873, this malicious weed appeared in Europe. Its seeds ended up in a shipment of clover seeds from America. Since then it's quarantine plant continues its victorious march not only across the European, but also across the Asian continent.
In Russia, the first ragweed plants were noticed in 1918 in the Stavropol Territory.The climate of southern Russia suited her well, and she traveled farther and farther on the wheels of cars. Now ambrosia can be found even in the south of the middle zone. Gradually adapting to new growing conditions, it confidently moves north. Map of the distribution of this harmful weed.
Harm to ragweed
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
Pollen from 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 part of it. Ambrosia pollen is small in size. Such particles freely penetrate into the human lungs. The number of pollen particles that one plant can produce reaches several billion.
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, sensitivity to pollen was detected in half of the subjects. This is a very high figure. This is what the pollen of this plant looks like when viewed at high magnification.
How does an allergy to ragweed pollen manifest?
- Very severe allergic bronchitis, which can be complicated by pulmonary edema.
- Asthma attacks.
- Conjunctivitis.
- Rhinitis.
- Headache.
- Temperature increase.
- Skin itching.
- Sore and sore throat.
- Cross allergic reaction to a number of foods, for example, 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.
To prevent allergies from becoming a huge problem, it is better to take preventive measures during the flowering of this weed.
- Don't go out into the fresh air in the morning. It’s better to time your walks at a time when air humidity is high, which happens after rain. Ambrosia releases the most pollen into the air from 5 a.m. to 12 noon.
- It is better to dry washed items at home; outdoors, pollen can easily settle on wet items.
- At night and in the morning, do not ventilate the apartment; the car windows should be kept closed.
- After being outdoors, you need to wash your face, wash your hair, and rinse your mouth. It is better to rinse your nose by preparing a saline solution.
- Bathe your pets more often; ragweed pollen can settle on their fur.
- Sunglasses will prevent pollen from getting into your eyes.
- Daily wet cleaning is required.
There are websites that monitor the state of ragweed blooms. There is also data on the concentration of pollen of this plant in each region.
The seeds as well as the leaves of this quarantine weed are allergens and can cause dermatitis. The essential oils released by ragweed provoke severe headaches, and blood pressure rises to the point of hypertensive crises.
Harm of ragweed to plants and animals
Having a powerful root system, this plant absorbs large amounts of water and nutrition from the soil, taking them away from 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. When ragweed gets into the crops of cultivated plants, it not only takes away their water and mineral nutrition, but also light, as it grows higher than them. In cultivated plants, the process of photosynthesis slows down, they are inhibited and even die.
When this weed gets into livestock feed, it deteriorates 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 ambrosia, animals do not want to eat it.
How to deal with ragweed
Why was the weed ragwort able to take over large areas so quickly? This strong and strong plant easily displaces any competitors. The huge number of seeds and their ability to germinate over many years contributes to the rapid proliferation of this quarantine weed. In its homeland, ragweed has pests and plants that can significantly limit its habitat. But neither in Europe nor in Asia they exist. Only some weeds living next to it can compete with ragweed. Among them are creeping wheatgrass and sow thistle pink. These plants can significantly reduce the height of ragweed plants, as well as the number of seeds it can produce.
In order to defeat this dangerous weed for humanity, the joint efforts of not only specialists, but also ordinary people will be required.
Ambrosia foci in Europe.
There is already a large-scale project in Europe that provides for 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's called SMARTER for short. The initiator of the project was the Swiss ecologist Professor Heinz Müller-Scherer. In Russia, there are regional programs that are aimed at combating this harmful weed.
Control measures
- The most productive method of combating ragweed on private property is manual. Moreover, mowing is effective only when the plant begins to flower. If you do this earlier, the effect will be the opposite, since the number of shoots of the plant will multiply many times over. You will have to repeat mowing the ragweed until the end of the plant's growing season in late autumn. For ragweed, this method of control is ineffective, since it is a perennial plant.
- Manual weeding before seeds form gives a very good effect. The plant may completely disappear from the site.
- Chemical methods for destroying harmful weeds. To treat fields with soybean crops, the herbicide bazagran is used, and it is also used in a mixture with another herbicide, titus, on corn crops. The consumption rates of herbicides for effective weed control are quite high, which does not contribute to environmental improvement.The herbicides Secateur and Hurricane are also used. The best results are obtained by a mixture of these herbicides, the time of its application is the beginning of ragweed flowering. This mixture allows you to reduce the concentration of both substances without reducing the effectiveness of the treatment. Ambrosia does not respond well to herbicide treatment. When processing, you need to use a protective suit and a respirator.
- Using a method of displacing ragweed with mixtures of grains and legumes. Good results on farmland are achieved by correct crop rotation and careful care of crops. There is information about the use of its natural enemies brought from America, namely the ragweed leaf beetle Zygogramma suturalis and the moth Tarachidia candefacta, to combat this quarantine weed. Experiments using these insects are encouraging. This method of combating ragweed is successfully used in China.
The ambrosia leaf beetle is a brother of the Colorado potato beetle, but unlike it, it does not recognize any other food, so it does not pose a danger to other plants. Since the 80s of the last century, the time when the zygogram bug was first released into the fields to combat ragweed, amazing metamorphoses have occurred to it. He not only changed his coloring, but also learned to fly, which he could not do in his homeland. It took only 5 generations of the zygogram to grow wings. The reproduction of the beetle is hampered by crop rotation, due to which it does not have a permanent habitat.
It must be said that quite effective medicines for certain diseases have been created on the basis of ambrosia, which, oddly enough, includes allergies.
The uncontrolled spread of such a dangerous weed is a side effect of human development.It was thanks to the improvement of communication connections that it became possible not only for the relocation of this plant to other continents, but also for the rapid settlement within them.
