Watermelon, commonly known as “pakwan” in Tagalog, is probably native to Africa. It is mainly eaten as dessert fruit. The rind is made into preserves and pickles; the seeds are processed into butong pakwan. In 1982-83, the area planted to watermelon was 15,410 hectares with a total production of 75,650 metric tons of fruits; but area was reduced to 5,370 hectares in 1983-1984 and production went down to 57,000 metric tons of fruits. The demand for watermelon could go up as foreign markets like the USA offered to buy all the watermelon the country can produce.
Varieties commonly grown in the Philippines are Valencia, Meak, Klondyke, Northern Hybrid, Tender Sweet, honey Cream and Mallorca.
Elevation – Watermelon is grown commercially in lowland areas after rice harvest. These provinces are Bataan, Bulacan, Pampanga, Tarlac, Nueva Ecija, Rizal, Batangas and Laguna.
Months of planting – Planting season is from October to January. In some parts of the country, planting is done as early as August to produce an off-season crop which commands better market price.
Plow land at least 20 cm deep to increase soil aeration. Plow and harrow 2-3 times for early growth and development. These are done several weeks in advance of planting to condition soil. Though this is quite expensive, labor cost of weeding will be reduced.
Planting and spacing – Watermelon is grown from seeds directly planted in the field. Plant 3-4 seeds to a hill, 2.5 cm deep. Distance of planting ranges from 1.5 x 1.5 to 2.5 x 2.5 meters apart, depending on variety.
Watermelon is generally grown in rotation with other crops; it is necessary to use manure or any soil-improving crop to maintain organic matter in the soil. Apply 10 to 15 tons of manure per hectare. Apply complete fertilizer the rate of 100 to 150 kilogams per hectare at planting time by hand placement 5 to 8 cm below the soil and 5 to 6 cm away to the side where seeds are placed. If plants show signs of yellowing, apply sidedressing or nitrogenous fertilizer.
Watermelon has a spreading, hairy, tendril-bearing vines reaching 3-5 meters long. Leaves are oblong-ovate 8-20cm long with 3-7 lobes. Flowers are monoecious, yellow in color and about 2 cm in diameter. Fruits are large, green-mottled or deep green. Introduced hybrids and varieties produce much bigger fruits, shapes varying from globular to oblong.
SOIL AND CLIMATE
Watermelon prefers a well-drained sandy loam soil rich in organic matter and which has not been previously planted to watermelon. Watermelon requires more aeration than any other kind of crops, so the field must have good drainage to obtain good yield. In areas where growing season is short, light soil is desirable for early harvest. It grows satisfactorily in heavier soil if properly cared and managed.
Watermelon is tolerant to a wide range of soil acidity with soil pH 5.0 to 6.8 to successful growth. A long period of warm, preferably dry weather contributes to growth. A temperature of 25°C to 30°C is ideal for growth and 25°C is the best temperature for fruit setting.
After plants are well-established, thin to one to two plants per hill. Alternate plant is planting incontinuous rows and thinning the plant to a distance of 1.5 to 2.0 meters. When plants have 3-4 leaves, thin to one plant per hill.
Cultivate and weed to check weed growth. Any implement may be used for the purpose. Avoid injury to roots while cultivating.
Watermelon may suffer injury when exposed to a long period of drought. Apply irrigation water when necessary. Frequent may suffer injury when exposed to a long period of drought. Apply irrigation water when necessary. Frequent light irrigation 5-6 times during growing season is beneficial. During early stage of growth, irrigate sparingly since too much water tends to hinder root development.
PEST AND DISEASES
- Cucurbit beetle – Adults are yellow beetle 6 to 8 mm in length. They eat leaves of young and old plants.
- Aphids – Adults and young are tiny, greenish insects generally wingless and soft-bodied. Insects suck the sap of leaves. Infested plants show curling and distorting of leaves.
- Mites – Very tiny insects usually found on undersurface of leaves. Adults are reddish in color.
- Downy Mildew – Caused by Pseudiperonospora cubensis Berk and Curt. Characterized by the presence of yellow spots on up-per surface of leaves and purplish powdery material on lower surface.
CONTROL OF PEST AND DISEASES
Treat the watermelon seeds with appropriate fungicides to minimize early development of diseases in the field.
Dust or spray the young plants regularly with any suitable insecticides as soon as the false leaves have spread. At the seedling stage, watermelon are easily attacked by insect pests.
Harvest watermelon fruits when mature enough to be sweet. Generally, it takes a watermelon fruit to mature 35 to 40 days from pollination depending on the variety. The old method of determining maturity of watermelon is by “thumping” with a finger. a dull or hollow sound is an indication of maturity. The most practical index,
However, is when the color of the lower part of the fruit that rests on the ground changes from white to creamy yellow. Harvest fruit with a sharp knife.
POST HARVEST ACTIVITIES
Pile newly harvested fruits in shaded areas. Do not bruise fruits during sorting, packing and shipping.
MORE PLANTING TIPS
October is the right time for planting watermelon, (not December when the thrips come out) usually just after the palay harvest when the soil still retains moisture.
Watermelon likes clay-loam soil with good irrigation and drainage.
1. Plant seeds 3 in a hill, with canals in between rows to facilitate drainage. In an area of 2,000 square meters, 1000 hills can be made. If the seeds do not germinate, put seeds again in each hill.
2. Apply fertilizers:
– 4 kilos complete fertilizers
– 2 kilos Furadan (to prevent dumping off disease)
3. After 2 weeks, apply:
– 1 liter of the above mixture
– 1/2 small can Urea put in a pail of water
– Apply 1 liter per hill
4. After another 2 weeks
– 1 liter Urea
– 1/2 liter Triple 14 in a 1 pail of water
– From this, get 1 liter & mix in a pail of water & apply 1 liter of it per hill
5. After 10 days, apply the above mixture every 5 days
6. After 10 days
– 2 liter Urea and 1 liter Triple 14 (in a pail of water)
– Apply 1 liter of this in one pail of water every 5 days
7. After another 10 days:
– 3 liters Urea
– 2 liters Triple 14 in 1 pail of water
– Apply 1 liter to a pail of water; 1 liter for each hill every 5 days.
For fruiting purposes,
– 2 liter Triple 14 and 1 liter Urea (in 1 pail of water)
– 1 liter of this in 1 pail water every 5 days
8. In another 10 days
– 3 liters Triple 14
– 2 liters Urea
– 1 pail of water
– Apply same as above every 5 days
9. Another 10 days, apply
– 4 liters Triple 14
– 3 liter Urea
– 1 pail water
10. Another 10 days:
– 5 liters Triple 14
– 4 liters Urea
– 1 pail water
– Same way as above