Commelina benghalensis L.

test adding new Brief paragraph

Northern Cameroon: The first germination of Commelina benghalensis appear 15 days after the first heavy rains (early May), but they remain few in numbers until plowing. Just after plowing, a phase of mass germination for a period of 4 to 5 weeks occurs. Thereafter, the saplings are few in unplowed plot; However, tillage (hoeing, hilling) triggers massive appearances of new seedlings. These sprouts become less important as we advance in season. The full germination phase lasts until late September. The first flowers appear in late July, fruiting in August, the first seeds late August. This cycle is delayed by 4 to 6 weeks in row and earthed plots.
Côte d'Ivoire: In the cotton area, the germination of Commelina benghalensis takes place from April to October.
Madagascar: C. benghalensis rises quickly to flower and can grow as from the middle of the rainy season.
Mayotte: C. benghalensis flowers and fruits all the year round. In crops, it grows mainly during the rainy season.

Commelina benghalensis is an annual to vivacious species if the humidity conditions allow it. It is abundantly propagated by rooting at the nodes and by cuttings of fragments of cut branches, very resistant to desiccation. But the plant also reproduces by aerial and underground seeds.  A plant can produce 1,600 seeds.

Commelina benghalensis differ from C. diffusa circulated by the presence of red hairs at the margin of the leaf sheath, by its bracts fused in funnel-shaped and its sessile flowers.

Present in rice fields in altitude of all countries in South and Southeast Asia, C. benghalensis can be found at the sea level up to 1000 m altitude and prefers fertile, moist soil, sunny or lightly shaded . It can withstand in potting soils, sandy or rocky soils.

Northern Cameroon: Commelina benghalensis is a nitrophilous species, very ubiquitous. It grows particularly on sandy alluvial deposits (clay 17%, silt 12%, sand 70%) and on well-structured ferruginous tropical soils. It tends to disappear on degraded ferruginous soils (over 85% sand; pH 6) and on heavy clay soils; (more than 55% clay, less than 25% sand) as vertisols. Its abundance increases with rainfall patterns and soil moisture. It is particularly abundant in areas with annual rainfall exceeding 1100 mm. Virtually absent in fallow, it appears as a weed after 3-4 years of cultivation. From that moment, in intensive culture, its density will grow from year to year to reach a total invasion of the parcel after 10 to 15 years. The combination of some intensification factors favors this species: in cotton cultivation, in biennial rotation, tillage at planting time, repeated use of pre-emergence herbicides of cotton (not very effective against this species), strong contribution  of fertilizers (200-300 kg / ha of NPK compound fertilizer).
Comoros: The species has been observed in the 3 islands, from low to medium altitude in rocky clay soils, It is present in young fallows of vegetable cultivations, in cassava plot, taro and pigeonpea.
Côte d'Ivoire: Commelina benghalensis is a common species in waste lands, rotational crops, perennial crops and grasslands.
Madagascar: The species grows on rich soils, alluvial soils and ferruginous soils, and ferallitic humiferous soil, vertisols.
It is present along the roads and cultures, It is a common weed of rainfed crops (maize, upland rice, cotton) and vegetable cultivation, widespread throughout the island, in soil plots fairly rich in organic matter (crops after recent forest clearing, cultivation plots located around villages) or in the alluvial plains.
Mauritius: Common weed and occupying a wide range of stations.
Mayotte: C. benghalensis is a common native species growing in a wide range of open or secondarized environments, mainly in the north of the island. It grows in crops, wastelands, in villages, in ditches, along roadsides, in agroforests, in edges and along forest roads.
Reunion: The species is common throughout the island. This is a particularly abundant plant in the humid regions, coastal areas or medium altitude. It likes soils rich in nitrogen.
West Indies: Commelina benghalensis grows particularly on recent soils with little clay and becomes more abundant in irrigated and regularly fertilised plots.

Global harmfulness

Commelina benghalensis is a widely distributed herbaceous weed that commonly invades agricultural sites and disturbed areas. Though not commonly reported to invade natural areas, this rapidly reproducing plant is considered one of the most troublesome weeds for 25 crops in 29 different countries.

Local harmfulness

Benin: rare and scarce.
Burkina Faso: rare and scarce.
Northern Cameroon: Commelina benghalensis is a major general species in northern Cameroon, also abundant in the southern half of Burkina Faso and Mali, northern Benin and Ivory Coast and the Central African Republic.
Côte d'Ivoire: Common and generally abundant species. In cotton crop it is particularly abundant in the areas of  Béoumi, Boron, Diawala, Gohitafla, Kani, Koni, Mankono, Marandala, Morondo, Napié, Niélé, Niofoin, Ouangolo, Sarhala, Sinématiali, Sirasso, Tiénigboué.
Ghana: rare but abundant when present.
Kenya: frequent and scarce.
Madagascar: Species of medium frequency that may be locally very harmful to cultures of cotton, pluvial rice, maize and groundnuts. Its abundance is highly variable depending on the richness of soil and cropping systems. It is more common but less intrusive than C. diffusa.
C. benghalensis is very resistant to drying out after manual weeding; if the soil remains moist insufficiently uprooted plants and cut stems can root at the nodes to give new plants.
Mali: rare but abundant when present.
Mauritius: occasional weed in sugar cane crops and in vegetable cultivation where she can have an average to high harmfulness , however, its harmfulness remains low.
Mayotte: C. benghalensis is a weed present in 13% of cultivated plots, mainly in vegetable crops in the north of the island.
Nigeria: common and generally abundant.
Uganda: common and generally abundant.
Reunion: It's more a ruderal species. In pineapple crops, lentil and vegetable cultivation, it is generally infrequent and sparse. In vegetable cultivation or banana plantation on the east coast of the island, it represents an important constraint because weeding and windrowing in spacing does not allow its removal. The stems take root immediately and the plant quickly re-colonize the plot. Single elimination outside of the parcel is effective. All soil works, favors the germination of seeds.
Senegal: rare but abundant when present.
Seychelles: Species very common and often abundant, particularly in vegetable cultivation.
Tanzania: frequent and usually abundant.
Tchad:  rare but abundant when present.
West Indies: Commelina benghalensis is a weed of low importance for some crops but can be very damaging for many fruit, food and vegetable crops. Like Commelina diffusa, it can be a host of cucumber mosaic virus (CMV) and thus allow its spread from plant to plant via insect vectors (mainly aphids).
 

Global control

For weeding advice of broadleaf annual weeds of irrigated rice and lowland in Africa, visit: http://portal.wiktrop.org/document/show/19
 
For weeding advice of broadleaf perennial weeds of irrigated rice and lowland in Africa, visit: http://portal.wiktrop.org/document/show/25
 
Cultural practices: Particularly difficult to control by cultivation, partly because even the smallest fragment of stem or root takes root quickly. When hand pulling, be sure to remove entire root system from the ground.

Biological control: Few natural enemies of Commelina benghalensis were mentioned and therefore only two Agromyzidae, phytophagous originate in America, which seem promising (two Diptera: Amauromyza sp and Liriomyza commelinae).

Chemical Control: Butachlor was mentioned to give good results during germination of C. benghalensis and propanil at 2 kg / ha; 2,4-D in combination with propanil can increase effectiveness. A single treatment with contact herbicides destroys the foliage, but does not prevent regeneration. An application of 2,4-D (1.4 to 2.8 kg / ha), metribuzin (2.5 to 3 kg / ha) and glyphosate (1.8 to 2 kg / ha) allowed to rid plots of this weed for 4 months. Photosynthesis inhibitors (such as paraquat and ametryne) are not effective. (Warning: paraquat is no longer allowed in most countries.)


Local control

Northern Cameroon: In cotton cultivation, Commelina benghalensis was greatly favored and selected by the daily standard technique, consisting of a seeding just after plowing with a treatment og pre-emergence with Diuron and repeated weeding. It is therefore recommended to prepare the soil 4-5 weeks before seeding, to promote the raising of the maximum seed, then at planting, to perform treatment with a total herbicide mixed with classical herbicide. This destroys all the seedlings in place and prevent the lifting of the later species. After sowing, avoid weeding so as not to provoke new germination of C. benghalensis. In case of late weeding stems of C. benghalensis should be removed out of the plot.
In the case of rotation with corn, it is preferred to employ atrazine for weed control in maize. This active ingredient has some effect on the weed.

Côte d'Ivoire: In cotton crop, Commelina benghalensis is not controlled by the pre-emergence herbicides popularized. Two active ingredients allow a good control of this weed (oxadiargyl and trifloxysulfuron). Similarly, post-emergence treatment of weeds and pre-emergence treatment of cotton and directed treatment with shield are effective means of control.
- Pre-emergence treatment of weeds and cotton: on clean soil, the day of sowing or the day after, apply with a backpack sprayer oxadiargyl at 240g a.i./ha
- Post emergence treatment of weeds and cotton: 15 to 21 days after sowing cotton, apply with a backpack sprayer trifloxysulfuron at 11g a.i./ha
- Post emergence treatment of weeds and pre-emergence of cotton: Sow cotton in a lightly weeded field. The day of sowing or the day after apply with a backpack sprayer an authorized systemic total herbicide (glyphosate at 1440 g a.i./ha or sulfosate at 1920 g a.i./ha) to which may or may not be associated a pre-emergence herbicide such as s-metolachlor + prometryn.
- Directed treatment with a shield: In post-emergence of weeds and cotton, apply with a backpack sprayer equipped with a shield and only in the row (without touching the cotton) an authorized systemic total herbicide such as glyphosate.

Madagascar: C. benghalensis is difficult to control by mechanical working, splitting the stems (very resistant to dryness) leading to multiplication. Pulling manual is very long and uprooted plants should be outputs of the plot. C. benghalensis can be relatively well controlled with diuron, atrazine and alachlor pre-emergence, 2,4-D on young plants, provided they treat early. Adult plants are very difficult to control (especially glyphosate tolerant, it would involve Imazethapyr, not available in Madagascar).
C. benghalensis can grow above ground cover that partially controls it.
 

Reunion :

(Doses are expressed in commercial product) - 2014

 Data acquired in Reunion on the effectiveness of herbicide products in the context of herbicide network of sugar cane by eRcane Network with funding from the ODEADOM and ONEMA.

Action led by the French Ministry for Agriculture and Agri-Food of the forest, with the financial support of the National Agency for Water and Aquatic Environments, appropriations from the fee awarded to diffuse pollution the financing of Ecophyto.

West Indies: Some cultivation practices related to vegetable and food crops (weeding, fertilisation,...) can favour the development of Commelina benghalensis. However, it is easily controlled by conventional weed control techniques on certain crops (herbicide and weeding). In banana, only the complete uprooting of the plant and its export out of the plot allows to control it efficiently.

Herbarium pictures ReCOLNAT: https://explore.recolnat.org/search/botanique/simplequery=Commelina%2520benghalensis