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Tricks to getting tomatoes to crop well

Tomatoes would have to be the most popular homegrown vegetable in Australia. We are all hanging out for sweet, tasty fruit (botanically they are a fruit) after going through winter with mostly tasteless, hard semi-ripe tomatoes.

Many of the modern supermarket hybrid tomatoes we have endured over the years were bred specifically to be harvested by machine, picked green and later gassed to ripen, have tough skins to reduce bruising in transporting and are disease resistant. Flavour was never a factor. Thankfully, we are seeing a bit more variety on the supermarket shelf these days.

There are many greenhouse-grown tomatoes available but, as everyone knows, the best tomatoes are home-grown, mainly because they stay on the bush until they are perfectly ripe and the fruit has developed all the sugars.

There are so many varieties available now in both seed and seedlings. The heirlooms are my favourite, full of flavour and producing a crop for many months.

Tomatoes are a hot-climate plant from South America and need a long growing season of four months above 20C (not a problem here in the west). They will struggle in temperatures above 38C; it affects the pollen and flowering and fruit, which can get sunburnt or split.

There are, however, a few tricks to know about getting tomatoes to crop well.

When you buy your seedlings, leave them hanging around the veranda for a week before planting out. Only water them twice, make sure they get root-bound and wait for them to flower before planting them out into the vegie patch. I guarantee you will have the best crop of tomatoes. This harsh early start to life sends a message to the plant to leap into flowering as soon as possible as a survival mechanism to ensure seed set for the next generation.

Tomatoes that are put into really rich soil before they flower will immediately think they can live off the fat of the land. They will put all their energy into growing lots of beautiful long stems, thick with lush leaves, and will forget to fruit. This is the main reason for delayed fruiting.

Once your seedlings have set flower you will need to start the feeding regime. Tomatoes are gross feeders, so make sure you have lots of good organic matter in the soil – compost, poo and, if you can get them, some worm castings.

Use a fruit-and-vegetable fertiliser and rock dust. Tomatoes will absorb all those important minerals that we then eat.

One week after planting out, apply liquid fertiliser to the foliage and soil. Always apply a mulch around your bushes, either pea straw, lupin or lucerne.

One of the most important contributors to the quality of tomatoes is consistent watering. If bushes are watered irregularly fruit production will be poor and nutrients will not be transported to the whole bush.

Blossom-end rot, fruit fall, woody fruit, weak stem tissue are all related to inconsistency of watering.

Sabrina’s favorite tomato varieties

Cherry tomatoes

  • Tumbler: Large cherry-sized fruit, great for pots, small grower
  • Sweet Cherry Gold: Low-acid, sweet, orange cherry-sized fruit, needing a short stake
  • Peruvian Red Cherry: A beautifully sweet little cherry to eat off the bush, great for salads
  • Sweetie: A vigorous staking vine producing large long bunches of grape-like, bright-red cherry fruit, 12-20 per cluster
  • Black Cherry: Purple-black fruit that is exceptionally sweet and disease resistant

Salad tomatoes

  • Tommy Toe: Winner of the Diggers taste test, this heirloom variety is a prolific producer of medium-sized, juicy red fruit on trusses
  • Green Zebra: Firm green-and-yellow striped fruit that seem to confuse pests who leave it alone. When you see the yellow stripes, it’s ripe.
  • Tigerella: Produces huge yields with sweet, red-striped fruit
  • Black Russian: A heritage tomato with large, sweet, firm, charcoal-coloured fruit, needing a tall stake
  • Stupice: A Czechoslovakian variety with juicy and tasty small/medium 50mm flattened fruit with a glossy red colour. A compact, productive vine with potato-like foliage.

Large slicing tomatoes

  • Bragger: Large, flat, fruit; disease- resistant and a tall grower
  • Black Krim: A large beef heart tomato with maroon/purple flesh
  • Purple Calabash: The ugliest and tastiest tomato, with large, pumpkin-shaped, ruffled brown/purple fruit. Great in heat extremes.
  • Top Dog: A large, sweet, disease-resistant tomato with sweet fruit, needing a tall stake
  • Beefsteak: Large, round, juicy sweet fruit, and a tall grower
  • Royal Flush: Gourmet sweet fruit needing a tall trellis
  • Moneymaker: A heritage tomato with firm, sweet and very productive fruit, needing a tall stake
  • Improved Grosse Lisse: Very large, fleshy, sweet fruit needing a tall stake

Tomato troubleshooting

The most important factors in controlling pests and diseases in tomatoes are to practise crop rotation, space the plants so they receive adequate sunlight and airflow, and encourage beneficial insects. Do not plant tomatoes in an area that has grown potatoes, eggplant or capsicum and rotate your tomato crop every four years. Our summers get very hot, so do not prune your tomato bushes or the fruit will get sunburnt in the peak of the heat. The only exception to this is to remove all the lower leaves that are near the ground so that disease doesn’t spread up the plant from water splash.

Here’s how to identify and treat some of the most common tomato pests and diseases.

Tomato russet mite
Lower leaves will become bronzed, droop and have a papery look and the trunk become corky. The best and safest control measure is to cover the bush with dusting sulphur (not in temperatures above 35C), diatomaceous earth, or Yates Tomato Dust. Mites move from the ground up so early treatment is necessary before they get to the fruit and cause fruit drop.

Looper caterpillars
Spray with Dipel, Success or derris dust. Hand-picking also helps control caterpillars. They burrow into the fruit as well as the foliage.

Root-knot nematode
With root-knot nematode, plants wilt on hot days, leaves look pale and the plant is slow to grow or stunted, and eventually dies.The roots will have lumpy nodules where in microscopic insect lives and feeds. Remove affected plants and burn. Nematodes love poor, sandy soils and one of the best methods of control is to build the soil up with lots of organic matter, including worm castings. Other methods of control are solarisation, planting out the marigold Tagetes minuta (stinking Roger) or bio-mustard, and drenching soil with beneficial soil microbes.

Bacterial canker
Bacterial canker causes curling and drying-out of leaf tissue, eventually affecting the whole leaf. It will start at the older leaves first and travel up the stem. If you look inside the stem it will have a brown stripe travelling all the way through the tissue. The fruit will have circular raised spots with a halo. Destroy plants and do not plant tomatoes in the patch for a year.

Fusarium wilt
Fusarium is a fungus that enters plants through the root system either via the soil or in infected seed. The plant will look yellow and wilting starts from the bottom upwards. Plants will be stunted and eventually die. Destroy plants and do not put tomatoes in that patch for four years.

Blossom-end rot
Not a disease but a deficiency, blossom-end rot is caused by moisture stress and low calcium levels. Fruit will have a circular brown soft mark at the bottom of the tomato. Add lots of organic matter to the soil, worm castings and water regularly.

Tomato tips

  • Push mulch up to the main trunk as plants grow. They will send out supplementary feeder roots that will add to the amount of fruit produced.
  • If you don’t have the space for crop rotation, tomatoes grow extremely well in pots. They will need regular liquid fertilising but the effort will be very rewarding.
  • Great companion plants for tomatoes are marigolds, calendula, thyme and basil to attract beneficial insects and help control pests.
  • The best tomato for drying is Principe Borghese, an Italian variety that produces masses of meaty fruit.

Season Summer
Subject bacterial canker, blossom-end rot, caterpillars, fusarium wilt, nematode, tomato