Kasuy Anacardium occidentale

About Kasuy (Cashew)

Kasuy, the Filipino name for the cashew tree, is a tropical evergreen tree scientifically known as Anacardium occidentale, belonging to the family Anacardiaceae. It is one of the most botanically fascinating food trees in the world because of its unique fruit structure: the true fruit — the kidney-shaped cashew nut — develops not inside a fleshy covering but rather hangs conspicuously outside and below the swollen, colorful cashew apple (which is technically a pseudofruit or false fruit formed from the enlarged flower stalk).

In the Philippines, kasuy is both a backyard shade tree and a significant commercial crop. The tree grows 8 to 14 meters tall with a spreading, irregular canopy that can span 10 to 12 meters in diameter. Its leathery, oval leaves are dark green and arranged alternately on the branches. The tree produces small, fragrant pink-to-red flowers in terminal clusters during the dry season, which develop into the distinctive nut-and-apple combination over the following 2 to 3 months. Each nut hangs from the bottom of its companion apple, connected by a short, tough stem.

The Philippine cashew industry centers on Palawan province — widely recognized as the cashew capital of the country — and the municipality of Antipolo in Rizal province, which has a centuries-old tradition of kasuy cultivation and processing. Roasted kasuy nuts are one of the most popular Filipino snack foods, sold by roadside vendors throughout Rizal and Laguna, while the cashew apple remains a seasonal delicacy enjoyed primarily in growing regions where the perishable fruit can be consumed within hours of harvest.

History and Discovery

Anacardium occidentale was formally described by Carl Linnaeus in his groundbreaking Species Plantarum of 1753. The genus name Anacardium comes from the Greek ana (above) and kardia (heart), referring to the heart-shaped cashew nut that appears to grow above the apple — though modern interpretations note this may reference the shape of the nut itself. The species name occidentale means "western," indicating its New World origins.

The cashew tree is native to northeastern Brazil, where indigenous Tupi peoples had cultivated it for centuries before European contact. Portuguese explorers encountered the tree in the 1500s and recognized its commercial potential. They introduced it to their colonies in East Africa (Mozambique) and India (Goa) during the 16th century as part of a deliberate strategy to establish cash crops in tropical territories. From Goa, the cashew spread throughout Portuguese-influenced Asian trade networks, reaching the Philippines by the late 16th or early 17th century.

In the Philippines, kasuy found ideal growing conditions in the dry lowlands of Palawan, Zambales, and Rizal province. Antipolo became particularly associated with kasuy cultivation, with local communities developing cottage industries for roasting and selling the nuts. By the 20th century, Palawan emerged as the country's primary commercial cashew-producing province, with plantation-scale cultivation supplying both domestic and export markets. Today, the Philippine cashew industry remains largely smallholder-based, with families in Palawan, Antipolo, and parts of Mindanao processing nuts using traditional methods passed down through generations.

How to Plant Kasuy

Propagation methods: Seed, Grafting, Air-layering

Germination time: 15 to 20 days from fresh seed

Best planting season in the Philippines: June to August, at the start of the rainy season

Step-by-Step Planting Guide

1. Select and prepare seeds. Collect fresh, mature cashew nuts that have fallen naturally from a healthy, productive tree. Perform a float test by placing nuts in water — viable seeds sink, while empty or damaged ones float. Plant the whole nut in its shell (do not attempt to extract the kernel). Soak selected nuts in clean water for 24 to 48 hours to initiate germination. Wear gloves when handling raw nuts as the shell liquid can irritate skin.
2. Sow in nursery containers. Plant each soaked nut on its side (flat edge down) approximately 3 to 5 cm deep in large nursery bags (at least 20 x 30 cm) filled with sandy loam soil. Cashew develops a strong taproot early, so deep containers are essential. Place in a partially shaded nursery area and water every 2 to 3 days. Germination occurs in 15 to 20 days.
3. Grow seedlings in nursery. Maintain seedlings in the nursery for 3 to 4 months until they reach 30 to 40 cm in height. Gradually expose them to full sun over 2 weeks before transplanting to harden them off. Ensure consistent watering but avoid waterlogging the nursery bags.
4. Prepare the permanent planting site. Select a sunny location with well-drained sandy or laterite soil. Cashew thrives in poor, dry soils where many other fruit trees struggle. Dig planting holes 50 cm wide and 50 cm deep, spacing trees 8 to 10 meters apart to accommodate the wide spreading canopy. Mix the excavated soil with compost and a handful of complete fertilizer (14-14-14) before backfilling.
5. Transplant and establish. Carefully remove the seedling from the nursery bag without disturbing the taproot. Plant at the same depth it was growing in the bag, firm the soil around the base, and water deeply. Apply 5 to 10 cm of organic mulch (dried leaves, grass clippings) in a ring around the seedling, keeping mulch 10 cm away from the trunk. Water twice weekly for the first 3 months.
6. Long-term maintenance for fruiting. After the first year, cashew becomes drought-tolerant and requires minimal watering. Prune lower branches to shape the tree and improve air circulation. Expect the first flowers and fruit 3 to 5 years after planting from seed (2 to 3 years for grafted trees). A mature tree produces 10 to 20 kg of raw nuts annually and continues bearing for 30 to 40 years.

Care Guide

Sunlight

Requirement: Full Sun

Kasuy requires full, unobstructed sunlight throughout the day — at least 8 hours of direct sun for optimal flowering and nut production. The tree naturally grows in open, exposed areas and does not tolerate shade at any stage of its life. In the Philippines, the dry, sun-baked lowlands of Palawan, Zambales, and Rizal provide ideal light conditions. Shading from neighboring trees or buildings will result in leggy growth, poor flowering, and drastically reduced nut yields. When planning a kasuy planting, ensure no taller trees will shade it as it matures.

Water

Frequency: Once per week (established trees are drought-tolerant)

Cashew is one of the most drought-tolerant fruit trees grown in the Philippines, making it perfectly suited to areas with pronounced dry seasons like Palawan and Zambales. Young trees (first year) need regular watering — once or twice per week during dry periods. Once established, cashew trees rarely need supplemental irrigation and thrive with natural rainfall alone. In fact, cashew produces better nut quality during periods of moderate water stress. Excessive moisture during the flowering period can cause flower drop and increase susceptibility to fungal diseases. The tree's deep taproot system allows it to access groundwater during extended dry spells.

Soil

Type: Sandy, Laterite, Sandy Loam

pH Range: 5.0 to 6.5

Kasuy is remarkable for its ability to thrive in poor, degraded soils where few other commercial trees would survive. It grows well in sandy coastal soils, red laterite (barangay soil), rocky limestone terrain, and eroded hillsides. The key requirement is excellent drainage — cashew roots will rot in waterlogged or heavy clay soils. In Palawan, cashew orchards are established on sandy and laterite soils that would be considered unproductive for most crops. This adaptability makes cashew an ideal reforestation and livelihood crop for degraded land in the Philippine dry lowlands.

Humidity and Temperature

Humidity: 40 to 70% (prefers dry conditions)

Temperature: 27°C to 38°C

Cashew thrives in hot, dry tropical lowland conditions with temperatures between 27 and 38 degrees Celsius. It does not perform well in cool highland areas or locations with prolonged wet seasons and high humidity. The tree requires a distinct dry season of 4 to 6 months for optimal flowering and nut set — this is why Palawan's type I climate (distinct wet and dry seasons) is perfectly suited for cashew production. High humidity during the flowering period promotes anthracnose disease and reduces pollination success. Cashew is not frost-tolerant and will suffer damage below 15 degrees Celsius.

Fertilizer

Young cashew trees benefit from quarterly applications of balanced fertilizer (14-14-14) at 100 to 200 grams per tree during the first 3 years. Once fruiting begins, switch to a potassium-rich formulation to support nut development. Mature trees in good soil often need minimal fertilization — apply 1 to 2 kg of complete fertilizer per tree annually, split between the start of the rainy season and midway through. Organic alternatives include composted animal manure and wood ash (rich in potassium). Cashew responds well to organic mulching, which builds soil organic matter over time.

Pruning

Prune cashew trees during the dry season when the tree is dormant and least susceptible to disease. Focus on removing dead, diseased, or crossing branches to maintain an open, well-ventilated canopy shape. Remove water sprouts (vigorous vertical shoots) and any branches growing toward the center of the tree. For commercial orchards in Palawan, some growers practice heading-back (cutting the main branches to reduce height) to keep trees at a manageable harvest height of 6 to 8 meters. Always use clean, sharp tools and wear protective gloves, as the sap can cause skin irritation similar to the shell liquid.

Growing Medium Options

Kasuy is exclusively a ground-planted tree due to its large size (8 to 14 meters), extensive root system with a deep taproot, and specific requirement for dry, well-drained soil conditions. It cannot be grown in water culture or hydroponic systems. Container growing is only practical for the seedling nursery stage; the tree must be transplanted to open ground for long-term growth and fruit production. The ideal soil for cashew in the Philippines is well-drained sandy loam, sandy soil, or red laterite — the poor, dry soils of Palawan and similar provinces are actually advantageous for this uniquely drought-adapted tree.

Edible Uses and Nutrition

Edible parts: Nut kernel (roasted), Cashew apple (fresh/juice)

Culinary Uses

The cashew provides two distinct food products from a single fruit: the nut kernel and the cashew apple. The roasted cashew nut kernel is one of the world's most popular and premium tree nuts, prized for its rich, buttery, slightly sweet flavor and creamy texture. In the Philippines, roasted kasuy is a beloved snack food sold by roadside vendors in Antipolo, Tanay, and throughout Rizal province. The nuts are roasted in their shells over wood fires (outdoors due to toxic smoke), shelled by hand, and sold warm in paper cones or plastic bags. Commercially, Philippine cashew kernels are used in kare-kare, stir-fries, trail mixes, baked goods, and as a garnish for rice dishes and desserts. Cashew butter and cashew milk are emerging products in Philippine health food markets.

The cashew apple — the fleshy, colorful pseudofruit — is highly perishable and less widely consumed, but is a genuine delicacy in kasuy-growing regions. In Palawan, the fresh apple is eaten as-is or squeezed into juice. Its sweet-tart, mildly astringent flavor is unique and refreshing. The juice is also fermented into vinegar (sukang kasuy), wine, and local spirits. Some communities in Palawan produce cashew apple jam and dried cashew apple snacks for tourist markets.

Nutritional Highlights

Harvest time: 3 to 5 years after planting from seed; fruiting season typically February to May in the Philippines.

Storage: Raw unshelled nuts can be sun-dried and stored for several months in dry, well-ventilated conditions. Roasted and shelled kernels keep for 2 to 3 months at room temperature in airtight containers, or up to 6 months refrigerated. The cashew apple must be consumed or processed within 24 hours of harvest due to its extreme perishability — this rapid fermentation is why fresh cashew apples are rarely found in Philippine city markets.

Air Quality and Oxygen Production

As a medium-to-large evergreen tree with a broad, spreading canopy, the kasuy tree is a significant contributor to local air quality and carbon sequestration. A mature cashew tree with a 10-to-12-meter canopy span provides substantial shade coverage and produces oxygen year-round through its persistent foliage. In Palawan and other cashew-growing regions, cashew orchards serve as effective carbon sinks while simultaneously providing livelihood to farming communities.

CO₂ absorption: Moderate to High

Cashew trees are particularly valuable for reforestation and rehabilitation of degraded lands in the Philippines. Because they thrive in poor soils where few other productive trees survive, they can restore vegetative cover to eroded hillsides, abandoned mine sites, and degraded grasslands. The Philippine government has included cashew in several reforestation programs for this reason. In urban and peri-urban settings, mature kasuy trees planted as shade trees in parks, schoolyards, and along roads contribute to cooler microclimates and improved air quality while eventually producing economically valuable nuts.

Toxicity and Safety

Humans: Cashew apple and roasted kernel non-toxic; RAW NUT SHELL HIGHLY TOXIC

Pets: Roasted kernel safe in moderation; shell and raw nut dangerous

The cashew tree presents a critical safety distinction that every grower must understand. The cashew apple (pseudofruit flesh) and the properly roasted nut kernel are completely safe and nutritious to eat. However, the nut shell contains cashew nut shell liquid (CNSL), a caustic oil rich in anacardic acid and cardol — chemicals closely related to urushiol, the same compound that makes poison ivy and poison oak so dangerous. Direct skin contact with raw shell liquid causes severe chemical burns, painful blistering, and allergic contact dermatitis. The reaction can be worse than poison ivy and may require medical treatment.

Additionally, burning raw cashew shells releases toxic fumes containing these same compounds, which can cause severe respiratory irritation and lung damage if inhaled. This is why cashew nut processing must always be done outdoors in well-ventilated areas, and processors must wear protective gloves, long sleeves, and preferably face protection. The tree sap can also cause skin irritation. Children and pets should be kept away from fallen raw nuts, and raw nut shells should never be burned in cooking fires or disposed of carelessly. Once properly roasted at high temperatures, the shell toxins are destroyed and the kernel inside is perfectly safe to consume.

Common Pests and Diseases in the Philippines

Pests

• Tea mosquito bug (Helopeltis) — the most damaging pest of cashew in the Philippines, causing necrotic lesions on young shoots, flowers, and developing nuts. Control with neem-based sprays during the flowering season. Severe infestations can reduce nut yield by 30 to 50 percent.
• Cashew stem and root borer — larvae bore into the trunk and major branches, weakening the tree structure. Look for frass (sawdust-like material) at bore holes. Remove and destroy severely infested branches; apply wound paste to cuts.
• Leaf miners — larvae create winding trails inside leaves, reducing photosynthetic capacity. Usually cosmetic and not economically damaging unless infestation is severe. Encourage natural predators such as parasitic wasps.

Diseases

• Anthracnose — a fungal disease that attacks flowers, young nuts, and leaves during wet, humid conditions. Causes blackening of flowers and premature nut drop. Apply copper-based fungicide preventatively at the start of flowering. Maintain good tree spacing and canopy ventilation.
• Dieback — progressive death of branches from the tips inward, caused by various fungal pathogens entering through wounds or weakened tissue. Prune and destroy affected branches, cutting back to healthy wood. Apply wound sealant to large cuts. Ensure trees are not stressed by waterlogging.