Strawberry farming is cherished for its delightful aroma, vibrant red color, juicy texture, and natural sweetness. It can be enjoyed fresh or incorporated into various prepared foods, including jam, juice, ice cream, and chocolate.
Classification
Kingdom : Plantae (Plants)
Subkingdom : Tracheobionta (Vascular plants)
Superdivision : Spermatophyta (Seed plants)
Division : Magnoliophyta (Flowering plants)
Class : Magnoliopsida (Dicotyledons)
Subclass : Rosidae
Order : Rosales
Family : Rosaceae
Genus : Fragaria
Species : ananassa
Out of the 34 species of Fragaria, found across Asia, North and South America, and Europe, only two—Fragaria moschata (musky strawberry) and Fragaria vesca (wood or alpine strawberry)—were historically cultivated for centuries in Europe and Russia prior to the development of Fragaria × ananassa. However, their production has significantly declined due to the overwhelming success of Fragaria × ananassa, a hybrid between Fragaria virginiana and Fragaria chiloensis, which is now the primary cultivated strawberry worldwide.
Fragaria chiloensis
Fragaria chiloensis, also known as the North American strawberry, is a large-fruited species native to the coastal areas of South America. It is a female variety and cannot produce fruit without cross-pollination.
Fragaria virginiana
Fragaria virginiana, also known as the Chilean strawberry, has perfect flowers and is often interplanted with F. chiloensis, which leads to the production of hybrid seedlings.
Origin
Strawberries originate from temperate and Mediterranean climates, with V. virginiana native to the United States and V. chiloensis native to South America.
Soil requirement
Strawberries thrive in sandy to loamy soil with good drainage, and the ideal pH range is between 5 and 7. The depth of the soil is not crucial, as strawberries have a shallow root system.
Climate
Strawberries thrive in cool climates with low optimum temperatures for growth and fruiting, ideally ranging from 10°C to 25°C. They also require chilling for flower induction, with less than 500 hours at or below 7°C. Winter freezing is essential for their development, but crowns can be damaged at temperatures around -7°C. To protect them from harsh conditions, mulching is often used. Frost is a significant issue for strawberry farming, as they grow low to the ground, where cold air accumulates during calm, clear nights. This, combined with their early blooming habit, makes them particularly vulnerable to frost damage.
Even when the official temperature doesn’t drop below 0°C, crop losses can occur, as the temperature measured at 5 feet above the ground can be several degrees higher than at ground level. In such cases, overhead irrigation is often used to protect strawberries from frost.
Photoperiod
Strawberries are a short-day plant, meaning they require a specific photoperiod to trigger flowering and fruiting. The plants need shorter daylight periods, typically less than 12 hours of daylight—to initiate these processes.
Botany
Plant characteristics
Strawberries are herbaceous perennials with a central stem, known as the crown, which is a reduced stem located at the center of the plant. The plant forms a rosette, and axillary buds develop into runners, branch crowns, or may remain dormant. Roots grow at the base of the crowns, supporting the plant’s growth and development.
The strawberry plant is stoloniferous, meaning it spreads through stolons or runners. Each stolon has several nodes, with the first node remaining dormant. Every other node on the stolon produces a daughter plant, which is commonly used for propagation.
Leaves
Strawberry leaves are trifoliate, meaning each leaf consists of three leaflets that arise from the crown. The leaflets are typically ovate or broadly oval in shape, with an obtuse tip. They have a dentate or coarsely serrate margin, giving them a jagged appearance.
Inflorescence
The strawberry inflorescence is a cyme, specifically a sympodium or dichasium. Flowering occurs over several weeks and is induced in short days. However, the flowers are sensitive to frost, making them vulnerable to cold temperatures.
Flower
Strawberry flowers are white and consist of 10 sepals, 5 petals, 25 to 30 stamens, and 50 to 500 pistils. The pistils are borne on raised conical receptacles, and the flower is hypogynous, meaning the ovary is positioned below the other floral parts. Most strawberry flowers are hermaphrodite, containing both male and female reproductive organs.
Pollination
Most strawberry cultivars are self-fruitful and self-compatible, meaning they can produce fruit on their own. However, pollinator activity is still beneficial, as several hundred pollination events are required to produce a well-formed berry. Without proper pollination, deformed berries can result. Insects play a key role in the pollination process.
Fruit
The strawberry fruit is an accessory fruit and is non-climacteric, meaning it does not continue to ripen after being harvested. The fruit is primarily composed of swollen receptacle tissue, while the true fruit, called an achene, is represented by the small seeds on the surface. Achenes are essential for fruit development, and the size and shape of the fruit are heavily dependent on the proper set of achenes.
Propagation
Strawberry propagation typically involves taking daughter plants from rooted runners (stolons) to use as planting material. Special care is necessary during this process to prevent disease and pest issues. An alternative method of propagation is tissue culture, which offers a controlled environment for plant development.
Planting
Strawberries are typically planted on raised beds, with the soil raised 6 to 10 inches. This elevation improves drainage around the roots and provides discrete row spaces, making it easier to manage cultural practices and harvest the fruit.
Mulching
Mulching serves several important purposes for strawberry farming, including protecting the crown from winter chilling, preserving moisture (which is critical due to the plant’s shallow root system), and preventing fruit from rotting. Common mulch materials include straw mulch and plastic mulch.
FERTILIZER OF STRAWBERRY: Best Strawberry Fertilizers
Irrigation for strawberry farming
Two systems
Overhead
Irrigation for strawberries farming typically uses two systems, one of which is the overhead system. The overhead system serves two main objectives: frost protection and evaporative cooling. During cold nights, the overhead system helps prevent frost damage to the plants by providing a layer of water that freezes and insulates the crops. Additionally, it aids in cooling the plants during hot weather by promoting evaporative cooling, which helps maintain optimal temperature conditions. Beyond these functions, the overhead system also supplies necessary moisture to the plants, ensuring their growth and health.
Drip system
The drip irrigation system primarily focuses on supplying moisture directly to the strawberry plants’ roots. In this system, the field is typically covered with either plastic mulch or straw mulch to help retain moisture and control weeds. Unlike the overhead system, the drip system is more efficient in delivering water straight to the roots, making it better suited for providing targeted irrigation. Additionally, the drip system is often used for fertigation, allowing fertilizers to be delivered alongside the water for more efficient nutrient absorption by the plants.
Fruit Development and Maturity
Strawberry fruit matures rapidly, typically ripening 20 to 50 days after pollination. The fruit is harvested at its full ripe stage when it has turned a dark red color. However, for long-distance markets, the fruit is often picked at the white tip stage to ensure it can withstand transportation and reach consumers in good condition.
Harvesting
Strawberry harvesting typically involves multiple pickings over a period of 3 to 4 weeks, with harvests occurring every 2 to 3 days. Only hand picking is used to ensure careful handling of the delicate fruit. The fruit is collected in small containers, each weighing approximately 500 grams, and is then placed directly into shipping containers for transport.
Sorting and Storage
Strawberries are sorted during the picking process, and no further sorting is required afterward. Due to their highly perishable nature, they have a maximum storage life of only 5 to 7 days. As a result, the fruit is sent to the market immediately after picking to ensure freshness.
Mowing Leaves After Harvest
Mowing the leaves after harvest helps promote flowering and reduces the carryover of diseases. However, it’s important to leave a height of about 5 cm to prevent damage to the crown of the plant. This practice ensures healthy growth for the next season while maintaining plant vitality.
Strawberry Diseases
Leaf Spot
- Caused by Mycosphaerella fragariae (Fungus)
- Most common disease of strawberries
Symptoms
Leaf spot disease in strawberries is characterized by small, 1/8-inch lesions with white centers and purple-black margins. These lesions may coalesce or take on irregular shapes and can appear on all parts of the plant. On the fruit, the disease manifests as shallow black spots, affecting its quality and appearance.
Control
- Control is by using resistant cultivars
- Before resistant cultivars were developed, the disease was the most serious disease of strawberries.
- Today, the disease is often a cosmetic problem and typically has little impact on yield or fruit quality
Verticillium Wilt
Verticillium wilt, a fungal disease caused by Verticillium albo-atrum, targets the crowns as well as the root system of strawberry plants. It causes wilting, stunted growth, and yellowing of older leaves, often accompanied by vascular discoloration in the crown. In severe cases, the disease progresses to plant collapse and death, particularly under warm, stressful conditions.
Control
- Soil fumigation and grow resistant cultivars.
Gray Mold
Gray mold, caused by Botrytis cinerea, is a common fungal disease that affects strawberries. Symptoms include soft, brown, water-soaked spots on ripening fruit, which quickly become covered with gray, fuzzy fungal growth. The disease thrives in cool, humid conditions and can spread rapidly, especially during prolonged wet weather.
Control
- Maintain good air circulation by proper spacing and pruning.
- Avoid overhead irrigation during flowering and fruiting.
- Apply fungicides preventively or when conditions favor disease.
- Remove infected plant debris to reduce fungal spores in the field.
