Growing Tomatoes – High Value Crop

Tomatoes have an annual average growth rate of 2.33% in the Philippines for the period of 1998 to 2002. Major producers of tomato in the Philippines include Pangasinan (22.811.40 tons, average for 1998-2002), Bukidnon (17,297.20 tons), Ilocos Norte (14,489.40 tons), Iloilo (10,476.80 tons), Ilocos Sur (10,001.20 tons) and Nueva Ecija (7,900 tons).

Tomatoes are considered as a hot weather crop. Tomatoes like heat and humidity. Tomatoes need light, fertile soil with a lot of organic matter. Too much nitrogen can reduce tomato yields.

Make sure that the soil is loose and at least 12″ in depth. Tomatoes are heavy feeders so mix in compost or chopped leaves to enrich the soil. Tomatoes do well in soils with a pH of 5.8 to 7. Tomatoes need high amounts of nitrogen, phosphorus, and potassium.

Tomato plants have two distinct growing habits – determinate or indeterminate.

Determinate tomato plants need staking or cages to help hold the tomato plant up so spacing should include room for the stakes or cages. Tomato plants may be spaced 12″-24″ apart. Air circulation must be considered between tomato plants.

Indeterminate tomato plants will spread out on the ground or climb a trellis if offered one. Space indeterminate tomato plants 24″-36″ apart if unsupported. If trellis is used for indeterminate tomatoes, they may be spaced at 14″-2o” inches apart. Keep at least 2″ between the rows of tomatoes.

Tomato seeds are not normally sown directly into beds. But they may be planted directly into moist prepared beds after the soil has reached 8o°. Sow tomato seeds 1/2″ deep, 6″-8″ apart in rows 2′ apart. Thin tomato plants to proper spacing after the seedlings are established. Water the tomato seeds evenly.

For transplants, sow tomato seeds indoors 1/4″ deep in cell trays. Keep tomato seeds evenly moist and place the trays under grow lights if available. Transplant tomato seedlings to larger, peat pots when they reach 3″-5″ tall. Bury the tomato seedlings with soil so only 1″ of the tomato plant is above the soil line. These seeds germinate best in soils around 8o-90°F. Germination takes 6-8 days.

Harden-off tomato seedlings two weeks before planting time. Choose a planting date when the soil has warmed to 8o°F. Bury the tomato plants so that only 4″ of the starts are visible. Water the tomato transplants well and mulch them with straw.

Use straw mulch on the tomato beds to help retain soil moisture. Water tomatoes deeply during dry spells. Water the base of the tomato plant, not the foliage. Watering the foliage when tomatoes are maturing can cause the fruits to crack.

Indeterminate tomatoes need support. Tomato fruits mature more evenly when the tomato plants are trellised. Place trellis or other supports for the tomatoes before they are transplanted into beds. Use siskal twine liberally to tie the tomato plant to the support. Don’t let the branches of the tomato plant bend or they might snap from the weight of the tomatoes. Tomato plants need to be reinforced throughout the growing season so check them often and add additional support as needed.

Most tomato plants will need pruning. Pruning reduces the amount of space tomato plants take up and will encourage higher yields of tomatoes. Pruning involves snapping off the branch that grows in the middle of two others – often referred to as a sucker. Snap the suckers off tomato plants as they appear. If the sucker has flowers on it – leave it. Leave a few suckers toward the top of the plant to protect the tomatoes from the sun with their leaves. But keep an eye on them and prune them as needed to keep them from growing new branches.

Unpruned tomato vines become unwieldy and tomato harvest will be less. Studies have shown that a pruned tomato plant will produce tomatoes up to 2 weeks earlier than unpruned. Tomatoes are heavy feeders. Occasionally fertilize tomatoes with fish emulsion.

Pest and Disease Control

Tomato diseases are rarely fatal if the proper management is employed. Diseases must be caught on early, before it spreads to all tomato plants and possibly other plants in the same family, such as potatoes, eggplants and peppers. Foliage diseases include early blight, gray leaf spot, late blight, septoria leaf spot, southern blight and verticillium wilt.

Early blight can affect the foliage, stems and fruit of tomatoes. This disease is characterized by dark spots with concentric rings developed on older leaves first. The surrounding leaf area may turn yellow. Affected leaves may die prematurely, exposing the fruits to sun blister. Early blight fungus is soil-borne. It can also come in on transplants. This disease may be controlled by removing affected plants and by thoroughly cleaning fall garden debris. Wet weather and stressed plants increase likelihood of attack. Copper and/or sulfur sprays can prevent further development of the fungus.

Gray leaf spot affects only the leaves of tomatoes, starting with the oldest leaves. This disease is characterized by small, dark spots that can be seen on both the top and bottom surfaces of the leaves. The spots grow large and turn grayish brown. The centers of the spots crack and fall out eventually. Surrounding leaf areas turn yellow and the leaves dry up and drop. Fruit production is inhibited. Warm, moist conditions worsen gray leaf spot problems. This disease may be controlled by removing all affected plants and garden debris. Selection of resistant varieties also helps.

Late blight affects both the leaves and fruit of tomatoes. This disease spreads rapidly. This disease is characterized by irregularly shaped gray spots on leaves. A ring of white mold can develop around the spots, especially in wet weather. The spots eventually turn dry and papery. Blackened areas may appear on the stems. The fruit also develop large, irregularly shaped, greasy gray spots. Cool, wet weather encourages the development of the fungus.

Septoria Leaf Spot is sometimes mistaken for Late Blight. With septoria leaf spot, the papery patches on the leaves develop tiny, dark specks inside them. Older leaves are affected first. This disease may be controlled by copper sprays that halt the spread of symptoms.

Southern Blight manifests as a white mold growing on the stem near the soil line. Dark, round spots will appear on the lower stem and both the outer and inner stem will become discolored. Southern Blight fungus girdles the tomato stem and prevents the plant from taking up water and nutrients. Young plants may collapse at the soil line. This disease may be controlled by crop rotation. Extra calcium and the use of fertilizers containing ammonium may offer some protection.

Verticillium Wilt sometimes causes leaves to turn yellow, dry up and never appear to wilt. Verticillium wilt is caused by a soil-borne fungus and may affect many different vegetables. The fungus can persist in the soil for many years, so crop rotation and selection of resistant varieties is crucial. This disease may be characterized by wilting during the hottest part of the day and recovering at night, yellowing and eventually browning between the leaf veins starting with the older, lower leaves and discoloration inside the stems. Verticillium Wilt inhibits the plants’ ability to take in water and nutrients and eventually kills the plant. Verticillium wilt is more pronounced in cool weather. This disease may be managed by removing affected plants and by choosing resistant varieties.

Harvesting and Storage

Tomatoes are mature when they reach their mature color. Keep a close eye on the unripe tomatoes once the first ripe tomato has been seen on a tomato plant. The rest will follow soon after.

Green tomatoes may be harvested when the tomatoes reach their mature size but haven’t changed color. Harvest tomatoes often and remove all over ripe tomatoes from the bed. Harvest by clipping the tomatoes from their vines.
If harvesting of immature tomatoes is inevitable, place unripened tomatoes on newspaper in a cool, dark room. The tomatoes will continue to mature.

Tomatoes are cleaned either by dipping the fruits in plain water or by wiping individual fruits by hands with a clean, soft cloth.

Ripe tomatoes stored at room temperature will last 4-7 days. For longer storage life, keep tomatoes at 620 to 68°F with a relative humidity of 90% to 95%. Use forced-air cooling for tomatoes going to market. Do not store tomatoes in a refrigerator as the cold will alter the tomato flavor. Tomatoes are very sensitive to ethylene gas so do not store tomatoes with vegetables and fruits that give off ethylene gas such as apples and pears.

There is still no Philippine national standard for sorting and grading for tomatoes. Sorting and grading practices vary in the different supply and demand areas. Classification is based on size and ripeness.

Packing materials that may be used include wooden crates (25-kg capacity); bamboo baskets (“kaing” -60-80 kg capacity and “bakag” – 20-25 kg capacity).

Where to get seedlings:

Seeds World
Tel: (02) 365-4292
Mobile: 0921-8034343, 0906-2905774, 0906-4914655, 0908-4204883, 0928-3152162
Email: [email protected]

Author: Carmela Abaygay, Marid Digest

Leave a Reply

Your email address will not be published. Required fields are marked *