Nothing says ‘summer’ quite like sun ripened tomatoes on the vine

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Tomato 'Heir Rainbow Blend' Picture courtesy Ball StraathofTomato 'Heir Rainbow Blend' Picture courtesy Ball StraathofLearn how to grow great tasting tomatoes with good yields, and how to prevent pests and diseases of tomato crops.

Tomato' Sweet n Neat' Scarlet. Picture courtesy Ball StraathofTomato' Sweet n Neat' Scarlet. Picture courtesy Ball StraathofWhether you want to grow tomatoes on a larger scale or simply need a few varieties in your back yard garden, everyone wants to grow tomatoes like a pro, and once you’ve tasted home grown tomatoes, there’s no going back to store bought ones.

Overall, tomatoes are a pretty easy crop to grow, but there are some things you can do to ensure good crop health and strong production, and one of the keys to success includes managing your plants' environment and treating pests and diseases quickly.

Tomatoes are indigenous to western and central South America where they were first cultivated by the Indians of Peru and Mexico. European explorers took seeds to Europe and in the early 16th century the Italians starting cultivating them. And today gardeners are spoilt for choice, and extensive crossbreeding has resulted in hundreds of varieties that differ widely in size, shape, colour, growth habit and resistance to disease. 

The commonly grown varieties can be divided into two types, determinate (short) and indeterminate (tall) varieties.

Determinate tomatoes grow about 1 to 1.2m tall and both the top shoot as well as the side shoots form flowers and fruits.

Indeterminate tomatoes will keep on growing until the top growing tip is pinched out as well as the side shoots. Indeterminate tomatoes must be tied up onto stakes about 2.5m high and are usually pruned to have only one or two main stems, and all the side growth is removed.

The miniature and dwarf varieties will grow easily in containers and hanging baskets, making growing tomatoes in any available space at home really worthwhile.

Tomato 'Tumbler' Picture courtesy Ball StraathofTomato 'Tumbler' Picture courtesy Ball StraathofHealth Benefits:

A diet rich in organic fruits and vegetables will provide your body with essential nutrients, vitamins and phytochemicals. Phytochemicals are non-nutritive plant chemicals that are not required by the human body for sustaining life, but have disease preventive properties. It is well-known that plants produce these chemicals to protect themselves, but new research demonstrates that they can also protect humans against diseases.

There are more than a thousand known phytochemicals, with one of the most well-known being lycopene - a chemical in the carotenoid family that gives tomatoes their distinctive colour, and is linked to many of their health benefits.  Lycopene is a powerful antioxidant that helps protect cells from damage and for this reason ongoing research is being done on the role lycopene may have in preventing cancer.

Lycopene is found in watermelons, pink grapefruits, apricots, and pink guavas. It is found in particularly high amounts in tomatoes and tomato products, and processing raw tomatoes using heat, like in the making of tomato juice, tomato paste or ketchup, actually changes the lycopene in the raw product into a form that is easier for the body to use.

Lycopene is available in supplements and is about as easy for the body to use as lycopene found in food. People take lycopene for preventing heart disease, “hardening of the arteries” (atherosclerosis); and for cancer of the prostate, breast, lung, bladder, ovaries, colon, and pancreas. Lycopene is also used for treating human papilloma virus (HPV) infection, which is a major cause of uterine cancer. Some people also recommend the use lycopene for cataracts and asthma.

Tomato 'Cherry Yellow Pear' Picture courtesy Ball StraathofTomato 'Cherry Yellow Pear' Picture courtesy Ball StraathofOrganically home grown tomatoes that are allowed to ripen on the bushes are the best to use medicinally.

In the Kitchen:

Commercially grown tomatoes are picked when they are still green, before their flavour has fully developed, making home grown, sun ripened tomatoes the most delicious to use in the kitchen. Pick them as required and if you do have to store them, try to keep them at room temperature as refrigeration makes them bland and mealy. And if you have too many to eat fresh turn them into delicious chutneys or tomato sauces for winter use.

There are thousands of mouth-watering recipes online, so take a culinary tour around the world for inspiration on how to use tomatoes.

From simple and easy to make recipes like: Pasta Salad with Spring Vegetables and Tomatoes, Stuffed Tomatoes with garlic, pistachios, and stretchy molten-mozzarella, Summer Gazpacho, the ultimate Caprese Salad, to Grilled Cheese Sandwiches or Grilled Tomato Salsa, tomatoes can be so versatile and simple to prepare.

And if you are a bit more adventurous why not try recipes like: Chile-Lime Clams with Tomatoes and Grilled Bread, Chorizo Tomato and Chickpeas with Yogurt, Tomato and Parmesan Risotto, or Tomatoes with Fig and Prosciutto. You are sure to find recipes which suit your family’s tastes and budget.

 Tomato 'Black Prince' Picture courtesy Ball StraathofTomato 'Black Prince' Picture courtesy Ball StraathofCompanion Planting:

While scientists refer to the idea of companion planting as "pseudoscientific," as it hasn't been scientifically validated, many experienced gardeners vouch for their carefully compiled lists of companions, which were noted through experimentation and observation with pairing plants. Simply put, companion planting refers to the practice of planting different crops in close proximity to each other to enhance nutrient uptake, provide pest control, encourage pollination, and increase crop production.

Some companion plants reportedly help boost the health and vigour of tomato plants, some improve the flavour, and others allegedly repel and insect pests and diseases. Luckily, many popular garden vegetables which you are probably going to grow anyway, make good companions for tomatoes, so why not experiment on your own and use some of them as companion plants for your tomatoes?

Basil and tomatoes taste wonderful together and if planted together also look lovely. Basil repels insects, improves growth, and enhances flavour. It is even known to repel mosquitoes and flies, including fruit flies.

Borage with its large hairy leaves and beautiful blue flowers improves the growth and flavour of tomatoes and also repels tomato hornworms.

Garlic repels red spider mites, and organic gardeners use garlic sprays help control late blight.

Lettuce appreciates some shade in hot weather and benefits by being planted in the shade of taller tomato plants, where it will also provide living mulch, helping to keep the soil cool and moist.

Tomato 'Heinz' Picture courtesy Ball StraathofTomato 'Heinz' Picture courtesy Ball StraathofMarigolds will not only beautify the vegetable garden with their vibrantly coloured flowers but are also known to reduce root-knot nematodes in soil.

Nasturtiums also look lovely planted with tomatoes, and serve as what is called a “bait trap” crop for aphids, because aphids love nasturtiums and will infest the nasturtiums before going for your tomatoes. Once they are infested they can easily be pulled up and disposed of, and seeds can be re-sown.

If you have asparagus in your garden, plant your tomatoes in rows between the asparagus. The asparagines in asparagus will protect the tomatoes from insects, whilst the solanine in tomatoes will help the asparagus plants by repelling nematodes.

Bad companions for tomatoes include all members of the cabbage family, corn, dill and fennel. And, because tomatoes, eggplants, peppers and potatoes all belong to the nightshade family, and are all susceptible to early and late blight, which can build up in the soil and get worse each year, avoid planting them near each other and practice crop rotation.

Cultivation and Harvesting:

Tomatoes are warm season plants which require full sun, and cannot take frost or cold weather.

In cold winter regions sow seeds indoors to plant out in spring, or once the weather warms up – planting can continue until November.  In cool winter regions seed can be sown to plant out in September and planting can continue until November or December.  In very hot or humid subtropical regions sow in late summer (February) and planting can continue through autumn to July.

Tomato 'Oxheart' Picture courtesy Ball StraathofTomato 'Oxheart' Picture courtesy Ball StraathofOne of the best things about growing your own tomatoes, especially if you grow from seed, is that you have a much wider selection available to you, including some very tasty heirloom varieties.

Unlike other fruit and vegetables, tomatoes do best if transplanted several times into pots, before being planted into the garden. Each time you transplant them bury the bare stem deeper, right  up to the first two leaves, and this transplanting can be repeated 2 or 3 times. Transplant the seedlings into the garden when they are about 25cm tall, spacing your plants according to the recommendations for that specific variety. Overcrowding is not recommended as this makes them more susceptible to diseases.

Dig large, individual holes for each plant, 45cm square and deep, and because tomatoes grow very quickly and are greedy plants, add lots of compost and mature manure to the soil together with organic 2:3:2 fertilisers, and a generous dressing of bone meal or rock phosphate to boost fruit production.  The ideal pH for tomatoes is 5.5 to 6.5.

Water the holes well and allow the soil to settle before planting. Water regularly and deeply during hot, dry weather, and especially when they are setting flowers. Do not overwater after the fruit has formed as this can cause the fruit to crack.

Tomatoes are susceptible to various wilts and diseases, many of which are caused by fungi in the soil. Mulching with straw or bark chips can help prevent their spread, and mulching will also keep the soil moist and smother weeds.

A three to four year-rotation programme with non-related crops is recommended to reduce the build-up of soil-borne pests and diseases. If you don’t have space for crop rotation, or if your soil is contaminated, plant them into large grow bags or containers which can be sterilised and filled with fresh soil each season.  And because overhead watering can lead to diseases it is recommended that you water at root level. This makes drip irrigation perfect for growing tomatoes.

Tomato 'Jubilee' Picture courtesy Ball StraathofTomato 'Jubilee' Picture courtesy Ball StraathofTomatoes do not have to be staked, but in the home garden all types will produce larger and healthier crops if staked. Remember to bury your stakes before planting to avoid damage to the roots later.

Tomatoes can be tied to a single stake or a triangle of stakes. Sturdy wire, chicken wire or plastic mesh can also be used to make a cage around the plants, and works very well, but ensure that the mesh is large enough for you to fit your hand through to pick the fruits easily.

Plants left to ramble without trimming take up far more room and are more prone to diseases because this reduces air flow around the leaves of the plants. While pruning limits the growth of the plant, it actually encourages more fruit. Basic pruning to remove all the lower branches will prevent   the soil from splashing onto the plant, and therefore reduces the spread of diseases.

Indeterminate tomatoes will continue growing until the tip of the main stem is pruned out, and they also benefit from additional pruning, especially if grown in small gardens. Train them to grow upright with a single stem or only two or three main stems by snapping off the suckers before they have a chance to develop. Suckers are the stems which grow out at an angle between the main stem and the leaf stem.

Tomato plants have a moderately high requirement of nitrogen which promotes better growth and better flower and fruit set. They also require high levels of potassium which results in improved colour, taste, firmness, sugars, acids and solids of the fruit. Phosphorus promotes root development, early flowering and fruit set, and ensures more vigorous growth.

Tomatoes also require micronutrients, and deficiencies of magnesium, calcium and molybdenum are common in acid soils. Boron and copper deficiencies are not often found in tomatoes, but if boron deficiencies do occur, it results in fruit cracking, pitted and corky areas, deformed shapes and uneven fruit ripening. Iron can also possibly be deficient on calcareous, alkaline soils or after heavy lime applications. Manganese deficiencies are mainly found in calcareous soils. Trelmix is a great product to use and covers all deficiencies.

Tomato 'Roma' Picture courtesy Ball StraathofTomato 'Roma' Picture courtesy Ball StraathofTo keep it simple, feed your young plants with a high nitrogen fertiliser for the first 18 weeks of growth, and foliar feeding regularly during the season with a seaweed product will encourage strong growth and help prevent diseases. Midway through the growing season, top dress the plants with several inches of well-aged manure, and once they start flowering and fruiting, feed every 4 weeks with a specialist tomato food, or fertilisers for fruit and flowers, like organic 3:1:5. Tomato crops respond extremely well to organic fertilisers.

Once your fruits star to ripen, you can protect them from bird and insect attacks by tying specialist protective bags over the fruits.  These are available from garden centres and can be re-used, making them economical and worthwhile. A clever and very economical way to do this is to purchase those little draw-string gift bags from gift stores to use.

Once your tomatoes turn red or their expected colour, remove them from the vine and enjoy. Generally tomatoes can be harvested from 9 to 13 weeks, and for successive crops, plant out every 4 to 6 weeks, depending on the variety grown. Don't rip or tear the stems when picking as this stresses the plant and opens the path for disease and insect damage. Most tomatoes will have a little knob in their stems, just above the tomato, where the stem will snap easily in two, releasing the tomato from the plant.

Pests  & Diseases:

Although the lists of pest and diseases below may seem daunting, do not let this dissuade you from growing tomatoes at home, as most of them can be avoided by practising correct growing methods and by purchasing disease free seeds or seedlings. And, it is highly unlikely that you will experience all of them in the home garden. When purchasing your seeds or plants, speak to knowledgeable staff at your garden centre about the most effective sprays to use on pests and diseases of tomatoes in your specific growing region. Often only one or two products are required to cover most of the problems you may encounter. Budget and purchase these at the same time as your plants, so you can practice preventative spraying, and have them handy to spray immediately any problem arises. 

Tomato 'Sunrise Sauce' Picture courtesy Ball StraathofTomato 'Sunrise Sauce' Picture courtesy Ball StraathofWhen you are growing tomatoes that are not stressed, pest and disease problems are small, and they say that “prevention is better than cure” and this is especially true when it comes to growing tomatoes.

Tomato Pests:

The most common tomato pests in South Africa are root-knot nematode, cutworm, bollworm, army worm, leaf miner, thrips, red spider mite, and aphids.

Cutworms are the greyish, hairless caterpillar (larva) produced by moths such as Agrotis segetum which live in the soil, and are troublesome in the seedbed and a threat to newly transplanted tomatoes. At night, the caterpillar bites through the seedling just above the ground, severing it from its roots – hence the name ‘cutworm’. Cutworms can usually be found near a damaged plant by digging about 2 to 5cm below the soil surface. Cutworm baits can be applied a few weeks before planting or sowing, but one of the best ways to reduce their numbers is to keep the beds free of weeds before planting. Start your weed control at least six weeks before sowing or transplanting.

Other caterpillars that feed on tomato plants are loopers, semi-loopers, bollworms, and lesser armyworm. Fortunately, many insecticides are registered to combat these pests, and in the home garden, if only a few caterpillars are present, they can be removed by hand.

Tomato rust mite is a tiny pest, only 0.2mm long, which feeds on both the stems and leaves. The first sign of damage is that the lower leaves curl up and infected leaves appear bronzed, later withering and dying.

Red spider mites are less than 1mm in length, and this tiny, red-brown pest penetrates plant cells and sucks up the chlorophyll in the leaves. The mites generally remain on the underside of the leaves but in a severe infestation may appear over the entire plant. Fine webbing may also be visible between leaves and the leaves may turn light yellow. Infected plants sometimes die and those that survive produce little fruit. These mites prefer dry, hot conditions. Various insecticides are registered for control of mites on tomatoes.

Tomato 'Pineapple' Picture courtesy Ball StraathofTomato 'Pineapple' Picture courtesy Ball StraathofWhiteflies are small, white sucking insects, and the wings and bodies of the adults are covered with a fine white powder, and can often be seen flying around the plant when the leaves are disturbed. This pest gathers in large numbers under the leaves, sucking the sap. Whiteflies can also introduce harmful viruses and must be controlled.  They can be controlled with various insecticides.

Liriomyza leaf miner is the larva of a 2mm fly that has a bold yellow dot between its wings. The female lays its eggs in a small puncture mark on the leaf, and the larva creates long, thin tunnels while feeding inside the leaves. Heavy infestation damages the foliage to such an extent it reduces fruit set and results in sunburn to ripening fruit.

Aphids are 1.5 to 2.5mm long insects ranging in colour from green to black. They prefer to hide under the leaves or congregate near the growth points of a host plant. They suck up the plant sap, and can cause even more damage by transmitting plant viruses. Many sprays are available to control them.

Bollworm is the offspring of a night-flying moth that is dull yellow to brown in colour. Fully-grown larvae are about 30 to 40mm long. Young caterpillars are hairy and their colours vary from black to brown-beige. They feed on flowers, leaves and the fruit of tomatoes. Later, they may feed inside a hollowed-out fruit. Many insecticides are registered against bollworm on tomatoes.

Potato tuber moth larva is a tiny, light-coloured caterpillar which bores into unripe and ripe tomatoes, starting where the stem is attached to the fruit, causing the fruit to rot. A tiny black ring usually indicates the entry point. Several insecticides can control tuber moth larvae in tomatoes.

Nematodes are microscopic worms which cause large lumps or galls to grow on a plant’s roots, resulting in low yields, stunted plants, and wilting of the top growth. The best management is to use newer, nematode-tolerant cultivars, and to rotate tomatoes with other crops.

Tomato 'Tumbling Tom' Yellow Picture courtesy Ball StraathofTomato 'Tumbling Tom' Yellow Picture courtesy Ball StraathofTomato Diseases:

There are few things more heart-breaking for the tomato lover than having your plants hit with diseases, because although sometimes the problem can easily be remedied, more often than not they can lead to the death of your plants.  Common tomato diseases like blight, target spot, blossom end rot, mosaic virus, and verticillium wilt, can ruin your crop if you don't act on them quickly. A regular preventative spraying programme against fungal diseases, is recommended for growing tomatoes.  A three to four year-rotation programme with non-related crops is recommended to reduce the build-up of soil-borne pests and disease

Bacterial canker is spread through infected seed and seedlings, and can be devastating.  Plants show progressive wilting and the older leaves die, but remain attached to the plant. The leaf edges and internal stem tissues turn brown. To control this, plant disease-free seedlings and use resistant cultivars. Strict sanitation practises and crop rotation go a long way in helping to protect crops.

Bacterial wilt (Ralstonia solanacearum) can be a serious problem in warm subtropical areas such as Mpumalanga and KwaZulu-Natal. Young leaves wilt, after which the plant dies, and there is no browning or yellowing of leaves or stems. If the lower stem of a badly wilted plant is cut off and placed in water, a milky stream of bacteria flowing out of the cut end is often visible within minutes. The internal tissues show a slight browning when the stem is cut open lengthways. Bacterial wilt attacks a wide range of plants and is spread by infected seedlings, infected ground water and infected soil. To control this, plant disease-free seedlings and select resistant cultivars. Strict sanitation practices, together with crop rotation, controlling weed growth and nematodes, and avoiding over watering will help minimise this disease.

Tomato 'Little Napoli' Picture courtesy Ball StraathofTomato 'Little Napoli' Picture courtesy Ball StraathofBacterial speck and black stem are both caused by Pseudomonas syringae. Bacterial speck occurs as small brown spots on leaves, stems and fruit. Infected fruit is downgraded, and nursery plants can often introduce an infection. Black stem causes a blackening of stems and leaf stalks, and often strikes tomatoes under cover. To help control these, plant disease-free seedlings, apply chemical controls, and practice crop rotation and strict sanitation. Avoid over-irrigating, and reduce humidity in the greenhouse or tunnel.

Early blight (Alternaria solani) is a widespread fungal disease which occurs in humid, moderately hot areas, or semi-arid areas that regularly experience dew. The pathogen attacks leaves, stems and fruit. Lesions start as small, brown spots on older leaves and stems, and grow rapidly into large, brown-black spots with concentric rings. The fruit is attacked at the stem end, where water accumulates, leading to leaf and fruit drop. To control this chemical controls can be applied, and by ensuring that you have a well-balanced fertilisation programme. Plant resistant cultivars, avoid overhead irrigation, eradicate weeds and practice good crop sanitation.

Late blight can be highly destructive under prolonged wet, cool conditions. Leaves initially show light-green blighted areas, which quickly turn black, with a whitish-grey fungal growth under the lesions when conditions are very humid. Stems show extensive black lesions. Leaves and stems die quickly as the disease spreads. Infected fruit shows diffuse blackening with a greasy appearance, and deteriorates rapidly. Late blight can cause total crop loss within a week. To control this apply chemical controls, do not use overhead irrigation, and practise crop sanitation.

Tomato 'Little Sicily' Picture courtesy Ball StraathofTomato 'Little Sicily' Picture courtesy Ball StraathofPowdery mildew is a serious problem in hotter areas, such as Mpumalanga and Limpopo. Initially, pale green or yellow spots occur on the upper leaf surface. Later, spots enlarge and develop into large, brown necrotic (having dead cells) lesions. Badly infected leaves die, but seldom drop, and fruit gets sunburnt. In this case plants grown under drip irrigation are more susceptible than those under overhead irrigation. Control by applying chemical controls, keep the beds free of weeds, and practice crop rotation.

Blossom end rot disease causes hard brown spots to occur on the tomato’s blossom end. To control this, mulch and irrigate regularly. Apply calcium fertilisation (calcium nitrate, gypsum and lime) and avoid high nitrogen fertilisation.

Problems:

Catface causes the fruit to be malformed and misshapen. It is caused by poor pollination due to sudden cold weather, incorrect fertilisation or overhead irrigation.

Blossom drop is caused by low temperatures in spring or very high temperatures in summer.