Cyperus rotundus : adventice graminée vivace

Classification phylogénétique

Vivace à tubercules, Cyperus rotundus est une espèce du genre Cyperus et de la famille des Cyperaceae. Elle est nommée Souchet rond, Souchet d'Asie, Souchet officinal, Herbe à oignon ou Souchet à tubercule. Originaire d'Inde, elle s’est développée de l'Afrique au sud de l'Europe, puis a étendu son aire de répartition sur une grande partie de la planète. Dans les régions tropicales et tempérées chaudes, elle représente un véritable fléau pour beaucoup de cultures. Ses tubercules sont utilisés à des fins médici- nales et alimentaires.

Écologie

Originaire d'Inde, elle s’est développée de l'Afrique au sud de l'Europe, ainsi que dans le sud de l'Asie, l'Océanie, le Sud de l'Amérique du Nord et l'Amérique du Sud. En France, Cyperus rotundus est une espèce rare cantonnée à la zone méditerranéenne.

Elle se développe sur tout type de sols. La limite nord de sa répartition semble être les régions où la tempéra- ture minimale moyenne oscille autour de −5 °C, tempé- rature où le tubercule ne semble pas germer. Le facteur

« température » limiterait l'espèce aux régions tropicales et tempérées chaudes. À l'inverse, elle peut survivre aux plus grandes températures connues en agriculture.

Cyperus rotundus se plaît au sein des zones marécageuses, humides, les cultures de régions tropicales ou tempérées chaudes, les patûres, et les bords des chemins. Les tuber- cules sont également une source alimentaire des oiseaux migrateurs tels que les grues.

Espèce invasive

Cyperus rotundus est une des adventices les plus répan- due dans les régions tropicales et tempérées chaudes. Elle a été élue “la plus grande adventice du monde” en rai- son de son impact dans plus de 90 pays et sur plus de 50 types de cultures du monde entier. Elle est nommée “Mal de tête des jardiniers” car son expansion est très ra- pide et difficilement contrôlable. Cette plante a une crois- sance rapide et peut former des colonies denses en rai- son de la production de son système rhizomatique tubé- reux souterrain d'où elle peut se régénérer et se disper- ser très facilement. Elle réduit les rendements de la canne à sucre, du maïs, du coton, du riz et des légumes.

Guide de lutte intégrée contre les mauvaises herbes dans les cultures

La maîtrise des plantes adventices en agriculture

connaître les adventices pour les maîtriser en grandes cultures

Orobanche spp. (orobanches)

The orobanch (broomrapes) are parasitic plants, devoid of roots and chlorophyll, whose nutrition is totally dependent on their hosts. It has been listed more than 150 species. They attack many plants, whether they are cultivated or not, especially Solanaceae, Fabaceae and Cucurbitaceae, on which they can cause significant damage. The most harmful species are mainly located in the Mediterranean basin, south-west Asia and some other regions whose climate is close to the Mediterranean type (western Australia, California ??).

In France, the orobanche rower (Orobanche ramosa L. Phelipaea ramosa C.A. Meyer), a species with the widest spectrum of hosts, is in recrudescence, especially on hemp, rapeseed and on another olanacea, tobacco. To our knowledge, it does not currently seem to be a big problem for field tomato crops. Note that several other species of Orobanche have been described on tomato; O. aegyptiaca Pers., O. cernua Loefl ??

The appearance of tufts of white, yellow or purple at the foot of the plants characterizes the parasitism of the orobanches (Figures 1 and 2). These tufts correspond to the flower stalks which can have a height of one to several tens of centimeters. These stems bear pale blue to purplish blue flowers in O's case. ramosa, which will produce capsules containing 300 to 500 seeds each (seeds measuring 0.2 to 0.4 mm long).

In fact, the parasitism of orobanches concerns mainly the roots of tomatoes on which they set up suckers, then tentacle anchoring roots, which allow them to absorb the mineral elements essential for their growth. The plants are weakened and are therefore smaller and stunted. In the long term, fruit yields are reduced. In addition, these plants are unable to regulate their stomatal transpiration during the dry period, so they maintain their host in chronic water deficit.

Orobanchae are preserved in the rather superficial layer of the soil by means of their tiny seeds, which perennialize for several years; 10 and more. They can also be maintained and multiply in the soil by means of numerous cultivated hosts (example of vegetables sensitive to O. ramosa: aubergine, lettuce, pepper, Cucurbitaceae, bean, peas, carrot, celery, fennel) and certain weeds (Capsella bursa-pasteuris, Solanum spp., Amaranthus spp.). In the presence of sufficiently moist soil and stimulated by root exudates, the seeds germinate and attach to the roots of their host. Subsequently, the orobanche enter the latter and set up a sucker in connection with the xylem of its host, allowing them to ensure their carbon, mineral and water to the detriment of plants. It is at this moment that the first underground growth of the stem begins. This is not slow to emerge and to form the flower stalk, which blooms thereafter. In the long term, several tens of thousands of seeds will be produced per Orobanche plant. These can be scattered by irrigation water or as a result of floods, wind, animals, agricultural implements, polluted seed lots ??

The fight against these highly polyphagous parasitic plants is often very delicate because of their enormous potential for conservation and dissemination. We advise you to implement the following measures:

to pluck or destroy by all means parasitic plants before their flowering;

- in the presence of an early outbreak, treat orobanches and their hosts with a herbicide such as glyphosate to prevent plants from producing seeds that will return to the soil;

-optimize the fight against certain weeds (brassicaceae ??) that can replace the tomato and perpetuate these parasitic plants in the absence of sensitive crops;

-in some countries soil disinfection with a fumigant is envisaged (methyl bromide). Solarization would destroy part of the seed stock in the first few centimeters of soil;

-The deep burrowing of the seeds is sometimes advisable because it removes them from future tomato roots which will be parasitized only belatedly. This practice is controversial, however, as it contributes to their conservation;

the increase in nitrogen fertilization would reduce infestations by reducing their germination and fixation capacity on their hosts. Ammoniums are more inhibitory than nitrates;

- avoid contaminating new plots with soiled agricultural equipment. For this, we suggest that you always work the infested plots last and wash the material well afterwards.

As an example, let us point out that a resistance to O. aegyptiaca, monogenic, dominant and controlled by the "Ora" gene, was highlighted and worked on tomato in Egypt.

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• Source :
 
• D  Blancard (INRA  France)

Tips and methods for controlling orobanches.

The orobanchs are parasitic plants that graft to the roots of crops, depriving them of all food. They cause considerable losses on leguminous crops, sunflower, tobacco ... With integrated control, it is possible to reduce the infestation on the short but also in the long term.

Orobanche, which is also called Halouk, L'Outed, Ben Nabbou or Farôun depending on the region, is one of the enemies that crop professionals (cereals, legumes, tobacco, etc.) dread the most. It is a holoparasite plant, that is to say, it is non-chlorophyllian, which must take the organic matter, water and mineral salts it needs on a host.

This plant-parasite belongs to the Orobanchaceae family, of which there are four main species:

O. crenata is one of the main obstacles in the cultivation of the bean but also lentils, peas and to a lesser extent chickpeas and green beans;

O. aegyptiaca and O. ramosa mainly attack tomato, tobacco, melon, potato and lentils;

O. cernua and O. cumana infest mainly sunflower but also tobacco, eggplant and tomato;

O.foetida parasitizes alfalfa and bean crops.

This enemy is spread over all regions of Morocco that grow cereals, legumes and other field crops.

From left to right: O. cernua; O. crenata; O. foetida; O. ramosa

Symptoms and damage

The growth of orobanches is at its peak during the flowering of the crops they parasitize. These holoparasites cause the wilting of the plants because they deprive them of their water, their organic matter and their mineral salts. The crops lose their vigor and the flowers fall, which leads to yield losses. In the long term, the plants die. Orobanches can cause up to 100% loss in the most infested plots.

Biology

To fight the orobanche, it is essential to know its biology and its development cycle. The majority of the dwarf species are annual and breed through tiny seeds (0.2 to 0.3 mm).


The cycle of this plant-parasite has two main phases: that of underground development, which begins with germination, and that of aerial development which begins at the moment when the first stems emerge from the soil and ends after the fructification and the maturation of the seeds. .

Fight

Several control methods have been studied. They can be used separately but it is better to combine them in an integrated fight to manage the orobanches.

Manual uprooting

Manual picking of orobanches is an effective means of control provided that it is well done and that the plot is newly or slightly infested. To be effective, we must proceed to the uprooting of the shoots of orobanche after their emergence of the soil but before the maturity of the seeds. This technique also makes it possible to limit the stock of scattered orobanche seeds since the maneuver takes place before the formation and dissemination of the seeds.

In India, where this method was tested, the pulling of O. crenata on tomato culture for 3 years showed an efficiency rate of 100%.

Cultural method

Various methods of cultivation make it possible to fight against the proliferation of orobanchs.

Crop rotation

Crop rotation is an effective means of control especially if it is practiced alternately with trap plants. The trap plants allow the germination of the orobanche seeds but they are unable to attach to the roots of the host plant which causes their death. This process is called "suicide germination". Some pea, clover, flax, coriander, mustard, etc., are effective when used as trap plants.

Planting date

The shift in sowing date is a maneuver that significantly reduces the extent of orobanche attacks. The more the crop sowing is shifted, the more the attacks are reduced. However, the shift in sowing date may affect the development of the crop.

In the case of winter crops, such as legumes, it is recommended to use an early variety and sow it late at temperatures below 8 ° C. Thus, the main root of the crop will not be parasitized by orobanches because they prefer dry soils and higher temperatures to grow. The experiments carried out demonstrate a reduction of infestation of 72.5% in the case of late sowing of 6 weeks for lentils.

Conversely, for spring crops, such as tobacco, it is recommended to sow early, that is to say when the temperatures are still low. Early planting of tobacco reduces the borer infestation by up to 70%.

Fertilization

High potassium and nitrogen fertilization reduce the presence of orobanches by 33 to 50%. On the other hand, this method involves using a large volume of fertilizer which is very expensive.

Other methods

Irrigation helps reduce infestation. In Fez and Meknes, bean crops irrigated with wastewater are less invaded.

Deep plowing also bury the orobanche seeds, which are too far from the roots to germinate and grow.

In addition, the use of resistant varieties should be considered.

Solarize

As mentioned earlier, the orobanche trees do not tolerate too high temperatures. Solarisation consists of covering the floor with plastic mulch (polyethylene) during periods of intense heat, before sowing. The best results were obtained with a solarisation of 30 to 50 days which makes it possible to obtain a temperature of 56 ° C in the first 5 to 10 centimeters of the soil.

This method is however limited to small plots. It is also effective for fungi, nematodes, bacteria and weeds.

Biological control

There are several natural ways to control orobanches, but these are often effective in the long term rather than in the short term:

*Insects: Phytomyza orobanchia attacks orobanchia without damaging the crop. It is found naturally in Morocco. 500 to 1000 insects / ha can reduce the presence of parasitic plants by up to 50%;

*Fungi: Fusarium oxysporum fsp orthoceras, Sclerotinia spp, Rhizoctonia solani, Colletotricum lagenarium and Ulocladium atrum. Fusarium oxysporum fsp o. is the most used mushroom. On tobacco growing, it improves the yield by 80.5%. However, it needs a high relative humidity and temperatures between 10 and 20 ° C;

*Bacteria: orobanches are susceptible to fluorescent Pseudomonas bacteria and Picketti ralstonia;

*Trituration waste of olives: The by-products resulting from the crushing of olives (vegetable and olive-pomace) are very effective in the fight against orobanches, they make it possible to reduce the infestation from 78 to 97% in bean cultures !

Chemical fight

Chemical treatment is the method most often used in the fight against orobanche because it is effective in the short term.

glyphosate

Although glyphosate is a very controversial product, it remains one of the best friends of farmers. The recommended rate is 60 g / ha diluted in 500 liters of water for beans and 40 g / ha for other legumes. The treatment should be broadcast at the tubercle stage of orobanche. Repeat with the same dosage two weeks later.

However, be careful with the dosage because this product can become very harmful. The effectiveness of this treatment depends on the stage at which it is applied, the setting of the sprayer, etc.

sulfosate

The sulphosate should be dosed at 100 g / ha. It is necessary to renew the treatment two with the same dosage. It is appreciated for its efficiency and ease of use.

imidazolinones

Imidazolinones are effective herbicides in the control of orobanches. Imazethapyr (100 g ai / ha) and Imazaquin (25 g ai / ha) are used pre-emergence to control O. crenata.

Integrated struggle


To manage orobanches, it is essential to establish a control program combining cultural methods, biological control and chemical treatments. In this way, the infestation can be reduced in the short but also in the long term.

Source : http://www.agrimaroc.ma

Preventive measures: how to prevent the invasion of the dodder

Since dodder has incredible vitality, the main rule for the gardener is to make sure that the seeds of the plants you plant, the organic fertilizers you use, the tools you work with do not contain the seeds of this pest or yourself.

If a dodder has been noticed on your site, avoid planting the seeds harvested next year (of course, we are not talking about large seeds that are deep in the fruit and that were removed after several days on the edge of the window).

Buy seeds of your favorite flowers in the store - it will cost a lot less: since the standards in our country prohibit the use of seed, dodgy stuffy, conscientious manufacturer before the sale holds a special seed phytopathology examination, so buy stroll with the main crop is virtually impossible.

Do not ask the manure of his familiar grandmother, because you do not know what they should feed his animals. Purchase fertilizer in proven locations and ask the manufacturer or seller if they warrant the purity of their products. It is believed that the manure completely rotten - is a reasonable assurance that the seeds of the weed, and if it was, lost their germination.

The same caution must be applied to the soil used for sowing. Never take the land in a meadow where a lot of weeds, and it is best to buy the finished extract in the store: a basecoat is not very expensive, but they are guaranteed uninfected by parasites and in addition saturated with all necessary plants organic and inorganic substances. There are cases where weed seeds are introduced into the groundwater used for irrigation, but there is much more difficult to defend.


So, be extremely careful and remember: Dodder, as a rule, rage on untilled meadows, and penetrate the date parasite first helps our own carelessness.

If dodder appears in your garden, there are ways to remove the grass without resorting to poison use or long-term quarantine.


Thus, we already know that the main potential hazard of the dodder is its many seeds, able to last long, even if they are deep enough in the soil. Therefore, the main and primary task is not to ripen the seeds of the parasite.

Mechanical removal of the dodder from the plant to which it has been sucked is an ineffective way of controlling the weed - just do not notice a small piece of the stem - and the parasite will recover. Therefore, the diseased plant must be extracted from the ground and burnt without mercy, and the sooner the better

You can try to remove the dodder from the plant only if the parasite has not yet wrapped its prey, and the phenomenon is clearly isolated. However, in this case, several follow-up inspections are necessary because the ragged stems attach easily to the donor plant.

Infected with dodder seeds, the soil can be tried to clean. There are many ways for this.

The first is to bury the seeds to a depth where they can not rise. The uniqueness of the dodder lies in the fact that, as mentioned, it does not have its own developed root system, so its seeds can germinate exclusively in the superficial layer of soil. Therefore, an effective method of fighting dodder is the deep digging (preferably no less than two bayonets of the shovel) with a mandatory overturning of the soil - this allows you to "bury" the seeds accumulated on the surface as well as deeply as possible.


The second method is to artificially stimulate the seeds to dodder as soon as possible in order to destroy their shoots and not attach themselves to the plant-victim (as has been said, without any energy source, the dodder is practically unprotected). Stimulating germination of the remaining seeds on the surface can be abundant watering in autumn and spring for a few weeks before landing in the soil of the main crop.

Sprouted seeds quickly yield seedlings that can easily be removed by surface treatment. However, if the young shoots of a vine a week or a year and a half do not find a plant that could be suckled, they will die themselves because of their inability to develop autonomously.

An additional precautionary measure after soil cleaning is the planting of those crops on which the plant does not parasitize. For example, oats and wheat are quite resistant to this parasite.

Infected meadows of dodder, it is recommended to mow before the flowering of the plant. If we are talking about a vegetable garden, it is necessary to cut at a height of 2-3 cm above the ground as the affected grass (eg in the driveway) and its neighbors in a radius of at least 1 m. reinfection.


Another method for dealing with dodder is fire. To this end, in the second half of the last century, the United States used special flame throwers (flame weirs) to manipulate vineyards and mown grasslands. A similar technique is used in some European countries. In our country, there is no such equipment, and it is not safe to use an open fire in the country.

Finally, another non-chemical way to control dodder is the use of Alternaria fungus mushroom medications; however, in our country, these biopreparations are problematic and, moreover, they only act in a humid environment, that is, the stem of the dodder must be kept for a long time. As soon as the plant dries, it stops being exposed to the mushroom

The use of herbicides for the destruction of dodder

Our recent ancestors, desperate for lime, tried to use iron and copper, vitriol, and even kerosene and sulfuric acid against it. The first two drugs have not shown great effectiveness, as for the third and fourth, then the use of these substances at the dacha, perhaps, is like treating a headache with a guillotine.

Therefore, in particularly difficult cases, when neither the fire, nor the "sword" nor the "like" can defeat the parasite, there is only one way out - the herbicides. We can not say that their choice is too big, but with some persistence, it is possible with their help to overcome the dodder on vegetables, fruit trees and vines. +


If it is necessary to dispose of dodder seeds on the soft bed of the main crop, ethylhexyl salts and ethers may be used. When mixed with ammonium nitrate and ammonium sulfate, these medications will help you avoid weeds. But if there are other plants on the site affected by dodder, especially dicotyledons, they will suffer as drastically as the pest itself.

Safer for glyphosate these crops, but they can not be used after installing rose. Therefore, the drug should be used after provocative watering, as soon as the germs of dodder, but before transplanting the main crop. The second option is processing in the fall, after harvest and again after active irrigation

Important! Herbicides kill a young cuscine much faster. When the parasite starts to bloom, its resistance to chemical preparations becomes much higher. Therefore, in the fight against dodder, time works against you! Another secret: herbicides work best on moist plants, so the treatment is done preferably after rain or heavy watering.
Get rid of weeds that poison vegetables, much more difficult than the news of this pest in prairie grasses.
On potatoes, tomatoes, peppers, tomatoes and other Solanaceae dodder destroy soil herbicides such as "Reiter", "Gezagard", "Liquid Zenkor" and so on. N. (The last drug produced by the German company "Bayer" destroyed the dodder at the beginning of its growth).

But C-metalohlorovye drugs such as "Typhoon" or "double gold" can kill only duscus in a concentration that is dangerous for vegetables too. +

Carrots can be saved from the dodder with a mixture of herbicides "Stompe" and "Reitar".

Among the other herbicides recommended to control dodder, it is possible to identify also Titus (the manufacturer is the Swiss company DuPont) and Targa (a Japanese drug Nisan Chemical).


Dodder is a very dangerous weed. Herbicides help to get rid of them, but for a positive effect, they can only be combined with each other, as well as with other agrotechnical techniques (earthworks, quarantine, planting unaffected crops, etc.). ). Only such persistent and systematic work can give a result of 100%.

Source : https://fr.madlovefarms.com