In sub-Saharan Africa, the rapid growth of the urban population raises the question of the food supply of cities
(Anonymous, 2012). From then on, urban and peri-urban agriculture becomes an option
(Abdulkadir et al., 2012) which attempts to respond to the problem of improving food insecurity among city dwellers, due to the weak performance of rural production systems
(Anonymous, 2010). Although it is often condemned by the authorities, urban agriculture is a reality in most cities in the South
(Mdarhri, 2005). Market gardening is one of the important links in the agricultural sector which can be. Defined as an intensive production activity of vegetables and fruits
(FAO, 2012). Indeed, numerous epidemiological studies have shown that a diet rich in fruits is often associated with a low incidence of several chronic pathologies, including obesity, parasitic infections, cardiovascular and neurological diseases and cancer
(Allane and Benamara, 2010). The joint report of the World Health Organization and the FAO on the prevention of chronic diseases therefore recommends consumption of at least 400 g of fruits and vegetables per person per day
(Anonymous, 2004). In Burkina Faso, market gardening appears today as one of the main components of urban agriculture. Indeed, market garden crops are produced in all regions of Burkina Faso, in urban and peri-urban areas
(Adorgloh-Hessou, 2006). It constitutes one of the main agricultural activities which particularly occupy vulnerable sectors of the population
(Tokannou and Quenum, 2007). However, market gardening production shows its development hampered by numerous biotic and abiotic constraints which lead, among other things, to a drop in yields and therefore to an irregular and insufficient supply to consumption areas.
Market gardening plays a key role in most nutrition and poverty reduction programs and contributes significantly to family income
(James et al., 2010 and
Yolou et al., 2015). The fight against food insecurity, poverty and improving the nutritional status of the population requires an increase in the production of fruits and vegetables
(Vedukola et al., 2019). Strawberry cultivation is one of the most widespread horticultural crops in the world. Strawberries are a fruit consumed either fresh: edible strawberries, or transformed into jam, syrup and beverages or incorporated into other preparations
(Keldibekoval and Knyazev, 2023). This analytical review will allow us to know the main constraints linked to strawberry production in Burkina Faso and to provide a summary of the activities carried out strawberries.
Strawberry production worldwide
Strawberries are produced on five continents. Strawberry cultivation is more intensive on the Asian and American continents than on the European and African continents, despite the fact that Europeans are among the largest consumers of strawberries in the world. In Africa, the consumption of strawberries is until today a luxury in certain West African countries such as Burkina Faso, Senegal, Mali, Ivory Coast even if it is produced locally in small quantities.
The major strawberry producing countries in the world are China with 3.801865 tons; the United States with 1,420,570 tons; Mexico with 468,248 tons. Worldwide 9,125,913 tons of strawberries are produced per year. In Africa, the main strawberry producing countries are: Morocco, Tunisia, Kenya, Burkina Faso and Senegal. Strawberry growing is booming in West Africa with new producing countries such as Mali and the Ivory Coast. Strawberries have seen one of the largest increases in consumption rates of any fruit crop and demand continues to grow rapidly over the past decade. Yields are linked to the very rich soil, the warm temperature, the health of the plants and technical management. In Benin, strawberries remain exclusively an imported crop. Research, nowadays, is oriented towards the adaptation of strawberries to the edaphic and climatic conditions of agro-ecological zones, the identification of abiotic and biotic constraints and the creation of varieties that are increasingly productive and resistant to different stresses.
Agromorphological characteristics of strawberries
The strawberry plant (
Fragaria vesca) of the Rosaceae family produces a fruit from which the receptacle of the flower becomes fleshy after the fertilization of the ovules. The strawberry is a complex fruit (polyakene on a fleshy receptacle). At the base of the strawberry, we can see a floral part (calyx) and the dry stamens of the flower (Photo 1). The strawberry is a perennial herbaceous plants, forming a tuft 5 cm to 40 cm high depending on the species. The plant produces numerous elongated horizontal branches bearing buds, the leaves at the base are trifoliolate, toothed, more or less hairy. Flowers appear naturally in spring. The development, growth and flowering and therefore the fruiting of the strawberry plant depends on environmental factors and photoperiodicity (Table 1). Strawberry plants are classified into four main groups: non-everbearing, semi-everbearing, everbearing and evergreen
(Putti, 2005).
For good strawberry production, we need a soil rich in mineral elements (N,P,K,Ca, NaCl,
etc.). It is important to add compost or manure regularly. Strawberry cultivation is mainly done during the month of October in Africa which corresponds to periods of heat with temperatures varying between 32°C and 37°C. The strawberry plant fears soils that are too clayey, heavy and cold, or too loamy, limestone soils and excess salinity. Strawberries need a pH between 5.5 and 6.5 for optimal production
(Putti, 2005).
Nutritional value and importance of strawberries in the human diet
Strawberries fruit has typical flavour and taste that can be eaten raw or cooked (pies, frozen jams, syrup). Strawberry is a low calorie fruit, but rich in fiber, vitamin C, constitutes an important source of antioxidants and stimulates the immune system. The average energy content is 38.6 kcal, 90.3 g water; 0.63 g proteins and 6.03 carbohydrates
(Saber et al., 2003).
Constraints to strawberry production
The strawberry plant is subject to several constraints, phytosanitary constraints, climatic conditions and the inadequacy of storage techniques which favor the incidence of several pathogens responsible for the depreciation of the strawberry. The symptoms are diverse and can be found both on the aerial parts (Photo 2) and on the underground parts. The strawberry is attacked by: strawberry latent angular spot viruses (SLRV) and necrotic shock virus (SNSV), Mites:
Tetranychus urticae,
Phytoseiulus permilis. nematodes:
Pratylenchus penetrans and
Meloidogyne hapla. Weeds:
Spergula arvensis.
Several control methods are proposed in order to reduce the losses and improve the production. These includes chemical control, cultural control, biological control, genetic control and the use of plant extracts. But the effectiveness of the good method of struggle requires knowledge of the enemy.
Fungal diseases
Botrytis of strawberries is a fungal disease which causes gray rot of strawberries and caused by
Botrytis cinerea (Photo 3). Botrytis symptoms are covered with a dense grayish coating which makes the fruit unsuitable for consumption. Factors favorable to the development of botrytis are high humidity and mild temperatures. Botrytis can infect all plant organs, particularly flowers and fruits. The gray rot can cause the significant loss in yield of strawberry.
Anthracnose of strawberries is a disease caused by a fungi, the causative agent is
Colletotrichum fragariae. Symptoms of anthracnose appear as round lesions measuring 1 to 2 cm on strawberries, with the center of the spot pressed into a “nudge” shape (Photo 4). “Tanned” in color, the necrosis becomes pink then brown. Favorable factors for the development of anthracnose are mild, humid weather and splashing rain. The harm of the disease is significant.
Powdery mildew of strawberries is caused by the fungus
Podosphaera macularis, formerly
Sphaerotheca humuli. The symptoms of powdery mildew are characterized by a fine whitish down on the leaflets of strawberries and a reddish color of the lower epidermis. On heavily affected strawberries, powdery mildew attacks the flower stems and even the fruits (Photo 5). Factors favorable to powdery mildew are short periods of humidification (condensation, dew,
etc.) alternating with periods of sunshine. Powdery mildew is today the most worrying disease, especially above ground in terms of harmfulness.
Phytophthora or strawberry downy mildew, is favored by soil humidity and caused by
Phtophthora fragariae. Symptoms are observed mainly on the leaves, characterized by browning and drying (Photo 6). The plants become stunted and the fruits appear little or not at all and are inedible.
Purple spot disease, favored by humidity, is a less serious disease that often occurs in the fall. Purple spot disease can be caused by various fungi, the most common of which is
Diplocarpon earlianae but also
Mycosphaerella fragaria,
Dendrophoma obscurans and
Septogioeum fragariae. The symptoms are characterized by round spots of 3 to 5 mm which appear on the upper surface of the leaves, reminiscent of burns (Photo 7). They are first purple with a lighter center then they turn black-brown before developing. The foliage eventually dries and the plant wilts.
Strawberry pests
The speckled blaniula
It is also called strawberry iule, a speckled centipede (
Blaniulus guttulatus) with a white body spotted with pink or red on the sides (Photo 8). It feeds on decomposing organic matter but can also attack strawberries.
Strawberry mite
This is a tiny mite (
Tarsonemus pallidus) transmitted by plants, oval in shape and amber in color which feeds on the leaves of the strawberry plant. The female lays eggs in the heart of the plants in March and the generations continue. The leaves become distorted and stunted, embossed and turn brown. The buds and flowers shrivel and dry out.
Aphids
Like many other plants, strawberries can be infested with aphids. Not very harmful in themselves, aphids can however weaken the plants from which they take the sap to feed and, above all, facilitate the introduction of diseases such as sooty mold, leaf curl or marbling. On strawberries, often encounter green or yellow aphids. Symptoms are characterized by leaves rolling up on themselves and flower buds becoming deformed. A sticky liquid called honeydew settles on the leaves.
The raspberry or strawberry beetle
The raspberry and strawberry beetle (
Anthonomus rubi) is a black beetle measuring 2 to 4 mm (Photo 9). In May, the female lays eggs in the flower buds of the strawberry plant. Then, the larva, white and without legs, remains for three weeks in this bud or in the fallen buds before pupating. The adult hybernates in the ground or under dead plant matter and is only active a temperature of 18°C. Symptoms are marked by a flower stalk being bitten, the flower buds drying and falling off.
Slugs
An ambiguous vernacular name designating in French certain gastropods without an external shell belonging to the infraorder. Slugs measure 1 to 30 cm and can weigh 1 to 40 g. Like other Stylommatophora, they have four tentacles, two of which have eyes. They cut the flower bud stalks and attack the fruits.
Birds and rats mainly attack fruits, causing significant damage to strawberry plants
Although Burkina Faso occupies an important rank for strawberry production in West Africa, the fruit is very little known in the country. Little use is made of the product, particularly in processing and few producers cultivate it. Which always makes the fruit expensive and inaccessible for a person with an average income. The kilogram of strawberry fruit is around 3,000 FCFA (4.59 euros) during the availability period between December-March and can reach 5,000 FCFA (5.64 euros) during the lean periodie November and April. Very few scientific studies have been carried out on strawberries
(Putti, 2012). This means that we lack data compared to widely consumed market garden crops such as tomatoes and onions.
Several biotic constraints are at the origin of the drop in strawberry productivity. According to
Saber et al., (2003) Botrytis cinerea and
Alternaria alternata constitute the most dangerous fungal agents on strawberries.
Fusarium semitectum is a species with a very wide host range, it attacks ornamental plants such as
Hibiscus rosa-sinensis (Alarcao-E-Silva et al., 2001) and
Pelargonium sp. It affects different species of banana trees
(Pretty et al., 2011, Probst et al., 2012a). This fungus was also isolated from the seeds of
Vigna unguiculata (Probst et al., 2012b), it is capable of causing damage to young seedlings. It has also been identified as the causative agent of cankers on walnut branches
(Williams et al., 2011). Mildew is a mold growing mainly on straw and hay stored in excessive humid conditions. It is often insulated from building materials with moisture problems.
Yildirim et al., (2001) isolated it from soybean roots where it also appeared pathogenic. Severe infections leading to death of foliage and shoot rot or even mortality of the entire plant have been observed on
Tillandsia tenuifolia. Anthracnose attacks a wide range of horticultural, cereal or ornamental crops and is present in most cultivated soils around the world
(Sharma et al., 2023). Investigations carried out in the locality of Moulay Bouselham confirm the attack on strawberry plants by this pathogen at the stem, crown and roots
(Sharma and Verma, 2019). The results obtained indicate the presence of a fairly diverse fungal complex comprising species with great antagonistic power, others have pathogenic power on several crops and some are weak parasites. The colonization of the different vegetative organs of strawberry plants by these fungal species can have consequences on their health status, their survival and their yield depending on phytosanitary measures exposed to the reluctance of European markets regarding the use of chemicals. Thus, tracing the evolution of the fungal flora and the comparative examination of plants before and after transplantation could determine the origin of infections occurring on cultivated plants and would allow the adoption of more suitable and timely control methods
(Mouden et al., 2013).
The strawberry fruit is rich in antioxidants. Antioxidants play an important role in human health
(Singh et al., 2002). Indeed, it helps reduce cancer, high blood pressure and oxidative stress.
One of the major difficulties in strawberry production is its post-harvest conservation, which lasts no more than 10 days. The genus Mucor has been reported as a post-harvest pathogen of strawberries. These fungi are also found in tomatoes
(Pornsuriya et al., 2008). Many techniques are proposed but are not suitable or often too expensive for producers and traders. There are several methods of control. Such as the use of bio-pesticides, chemicals, cultural practices and the use of resistant varieties. But market gardeners’ current perceptions of aqueous extracts and/or biopesticides have a negative impact on their adoption. The analysis of this impact revealed that it is the perception of aqueous extracts which most negatively affects adoption
(Ahn et al., 2007, Adekambi et al., 2010). This is followed by the perception of the number of treatments required by the use of these aqueous extracts and/or biopesticides. This could be explained by the fact that despite the slowness in their action, these extracts still act very effectively. The promotion of aqueous extracts and biopesticides with a view to increasing their level of adoption undoubtedly requires improving the current knowledge of market gardeners.
