Citrus reticulata ‘Dekopon’ (Sumo Oranges)

Sumo Oranges: The Sweet Giants of Citrus

Citrus reticulata ‘Shiranui’ or Citrus reticulata ‘Dekopon’, commonly known as Sumo oranges, are remarkable hybrid citrus fruits renowned for their large size, easy-to-peel skin, and exceptionally sweet flavor. Developed in Japan in the 1970s, these oranges are a cross between the Kiyomi orange and the Ponkan mandarin. Their distinctive top knot and bumpy rind make them easily recognizable, while their juicy, seedless interior has made them a favorite among citrus enthusiasts.

Sumo oranges belong to the citrus family Rutaceae, which includes other popular citrus fruits such as grapefruit, lemon, pomelo, clementine, mandarin, tangerine, calamansi, kumquat, Kaffir lime, Persian lime, and Key lime.

What are Sumo Oranges?

Description

Sumo oranges are notable for their substantial size, often weighing between 8 and 10 ounces. Their thick, bumpy skin features a prominent knob at the top, reminiscent of a sumo wrestler’s topknot, which inspired its name. Despite its rugged exterior, the peel is surprisingly easy to remove, revealing a tender, seedless, and incredibly sweet flesh inside.

Native Range

Originating in Japan, the Sumo orange was developed through meticulous cultivation techniques. It was introduced to the United States in the late 1990s and is now primarily grown in California’s Central Valley, where the climate is ideal for producing this unique fruit.

Growth Habit

Sumo orange trees are medium-sized, evergreen citrus trees with a rounded canopy. They produce fragrant white blossoms in the spring, which develop into the large, distinctive fruits by winter.

Size

A mature Sumo orange tree typically grows 12 to 15 feet (3.6-4.5 meters) tall and 8 to 10 feet (2.4-3 meters) wide, making it suitable for both orchard planting and large garden spaces.

Flowers

The tree produces aromatic white flowers in the spring, attracting pollinators and signaling the beginning of the fruiting process.

Blooming Season

Blooming occurs in the spring, with fruit maturing and ready for harvest between January and April, depending on the growing region.

Fruits

The fruit is large, round to slightly oblong, with a bright orange, textured rind. Inside, the segments are juicy, seedless, and boast a rich, sweet flavor that sets it apart from other citrus varieties.

Leaves

The tree’s leaves are glossy, dark green, and lance-shaped, contributing to its attractive appearance throughout the year.

Hardiness

Sumo orange trees thrive in USDA hardiness zones 9 through 11. They prefer full sun and well-drained soil, with protection from frost in cooler climates.

Uses

• Fresh Eating: Enjoyed raw for its sweet, juicy segments.
• Juicing: Makes a flavorful, naturally sweet juice.
• Cooking: Used in desserts, salads, and savory dishes for a citrusy twist.
• Garnishing: Adds visual appeal and flavor to beverages and plates.
• Ornamental: The tree’s attractive foliage and fruit make it a decorative addition to gardens.

Toxicity

While the fruit is edible, essential oils in the skin and leaves (limonene, linalool) can cause contact dermatitis or mild poisoning in humans and are toxic to cats, dogs, and horses. The fruit itself is safe for humans, but the plant should be kept away from pets.

Sumo Orange Nutrition

DV = Daily Value based on a 2,000-calorie diet.

Health Benefits of Sumo Oranges

Sumo oranges are not only delicious but also offer several science-backed health benefits, making them a smart and nutritious addition to your diet.

Culinary Uses of Sumo Oranges

Sumo oranges are a culinary dream: sweet, seedless, and easy to peel. Thanks to their low acidity and rich flavor, they’re delicious eaten fresh and versatile in the kitchen. Their firm segments hold their shape well, making them perfect for salads, desserts, and even savory glazes.

• Fresh Snacking: Peel and eat on the go—their segments separate easily, and the sweet flavor is unbeatable for a healthy treat.
• Fruit Salads: Add juicy chunks to fruit bowls or mix with fennel, arugula, or beets for a refreshing salad.
• Smoothies & Juices: Blend into smoothies for natural sweetness or juice them for a rich, pulpy drink that doesn’t need added sugar.
• Baking: Use zest and juice in muffins, cakes, or citrus bars. Their bold flavor stands out in desserts without overpowering.
• Sauces & Glazes: Reduce juice into a glaze for poultry or tofu, or whisk with soy sauce and ginger for a tangy stir-fry sauce.
• Desserts: Top panna cotta, yogurt parfaits, or sorbet with bright segments. Try caramelizing slices for an elegant citrus dessert.
• Cocktails: Muddle segments into citrus-based cocktails, or garnish sparkling water with a juicy wedge.

Whether sweet or savory, Sumo oranges bring a burst of citrus flavor and elegant texture to every dish.

How to Grow and Care for a Sumo Orange Tree

Light Requirements

Sumo orange trees require full sun—at least 6–8 hours daily—to develop their famously sweet and easy-to-peel fruit. Bright, direct light is essential whether planted outdoors or grown in large containers.

Soil Requirements

They thrive in well-drained loamy or sandy soil with a slightly acidic to neutral pH (6.0–7.0). Avoid heavy, waterlogged soils, which can promote root rot and poor fruit development.

Watering

Water deeply once or twice a week during the growing season, allowing the top inch (2.5 cm) of soil to dry out between waterings. Sumo trees prefer consistent moisture but dislike soggy conditions. Reduce watering in cooler months. In sandy soils, increase watering frequency.

Fertilizing

Sumo oranges are heavy feeders. Use a balanced citrus fertilizer rich in nitrogen, magnesium, and micronutrients. Apply 3–4 times per year during the active growing season for optimal fruit size and sweetness.

Pruning

Prune lightly after fruiting to shape the tree and remove dead or crossing branches. Because Sumo oranges produce large, heavy fruit, thin crowded branches to reduce stress and breakage. Avoid removing flowering wood, which produces next season’s fruit.

Mulching

Mulch around the base to retain soil moisture and suppress weeds. Keep mulch 12 inches (30 cm) away from the trunk to prevent rot.

How to Grow Citrus Indoors: From Fragrant Blooms to Homegrown Fruit

How to Harvest Sumo Oranges

When to Harvest

Sumo oranges typically ripen from **January through March**, depending on the growing zone. Wait until fruits are large, bright orange, and aromatic—Sumo oranges do not continue to ripen after picking.

How to Harvest

• Use hand pruners or gently twist fruit from the branch, supporting the heavy fruit with your hand.
• Do not harvest too early—Sumo oranges reach full flavor and sweetness only when fully ripe.
• Test ripeness by sampling a fruit before harvesting your entire crop.

How to Propagate Sumo Orange Trees

Propagation by Grafting

• Sumo oranges are propagated by grafting onto vigorous rootstocks like trifoliate orange or sour orange.
• T-budding and cleft grafting are common and produce fruit in 2–4 years.
• Grafted trees offer better disease resistance and earlier fruiting.

Common Pests and Diseases of Sumo Orange Trees

Pests

Aphids: Small, soft-bodied insects that feed on new shoots and excrete honeydew, encouraging sooty mold.

Citrus Leafminers: Larvae burrow through leaves. Use neem oil or set pheromone traps.

Whiteflies: Feed on undersides of leaves and spread disease. Manage with insecticidal soap or sticky traps.

Spider Mites: Cause stippling and webbing. Increase humidity and apply neem oil.

Scale Insects: Waxy bumps on stems and leaves. Control with horticultural oils.

Mealybugs: Cottony white insects that cluster in leaf joints. Remove manually or treat with insecticidal soap.

Fungus Gnats: Thrive in wet soil. Improve drainage and use traps.

Fruit Flies: Attracted to damaged fruit. Remove fallen fruit and use traps.

Other Notable Pests: Thrips, stink bugs, and leaf-footed bugs may blemish fruit.

Diseases

Citrus Canker: Bacterial lesions with yellow halos. Managed with copper sprays.

Greasy Spot: Fungal leaf spots. Clean leaf litter and spray preventively.

Anthracnose: Causes leaf and fruit lesions. Prune and apply fungicide.

Alternaria Brown Spot: Sunken fruit spots. Prevent with copper fungicide.

Root Rot (Phytophthora): Yellowing leaves, bark peeling, and fruit drop. Prevent with drainage.

Scab: Corky fruit outgrowths. Controlled with copper-based sprays.

Sooty Mold: Black fungus that grows on insect honeydew. Control pests to eliminate mold.

Citrus Tristeza Virus: Spread by aphids. Leads to tree decline. Use certified disease-free stock.

Prevention and Management Tips

• Inspect trees regularly for pests and disease.
• Prune to improve airflow and remove diseased wood.
• Apply neem oil, copper fungicide, or insecticidal soap as needed.
• Encourage beneficial insects like ladybugs.
• Remove fallen leaves and fruit to prevent disease cycles.
• Ensure proper irrigation and avoid waterlogging to prevent root rot.