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Tomato Trouble-shooting

Aphids (Greenfly)

  • These little bugs must be the most pervasive garden insect pests of all. As soon as any new growth appears in spring, aphids seem to materialise out of nowhere.
  • They suck sap directly from the plant and, because they always attack the newest growth, this sucking can damage the most important growing parts.
  • Can be controlled with Yates ‘Mavrik’.


  • Like aphids, whiteflies suck the sap directly from the plant, so the damage caused is very similar to that of aphids.
  • If whitefly is found, and you brush past and disturb the foliage, a little cloud of white insects arise, but they usually fly back to that stressed plant and leave the healthy ones alone.
  • Best controlled with Yates Mavrik, sprayed every three days for two weeks to break the cycle, because the eggs hatch about every three days.


Spider Mites 

  • Like aphids and whiteflies, mites are sap suckers.
  • Symptoms are leaves which appear bronzed and may wither and die, and/or a fine webbing is produced, often on the underside of the leaves
  • Control with Yates ‘Mavrik’


  • This is a new insect pest is to attack tomatoes (and potatoes) in NZ.
  • The psyllid bug secretes a toxic saliva that can severely damage the plant.
  • First symptoms are a slight discoloration of the top leaves (ribbing and leave edges), then the entire plant top changes to a yellowish-green.
  • Use ‘Mavrik’ or ‘Confidor’ to control.

Late Blight

  • This is caused by an organism similar to a fungus.
  • Brown patches appear on the leaves and can spread very fast.
  • Thrives in a humid, moist environment.
  • Use Yates ‘Copper’, ‘Bravo’, ‘Greenguard’ or ‘Tomato Dust’ immediately.


Verticillian Wilt

  • This is caused by a fungus attacking the roots or the base of the stem, often in cooler weather.
  • The leaves begin to turn yellow and wilt and soon the whole plant begins to wilt.
  • Remove the whole plant immediately or else it will spread to your other plants.

Tomato fruit-worm 

  • At the caterpillar stage, they eat into the green or ripened fruit, leaving small tunnels and holes.
  • To help prevent the problem, do not plant sweet corn near your tomatoes, as this is the favourite food of their parent moths.
  • Treat with Yates ‘Tomato Dust’ or ‘Success’.

Blossom End Rot

  • This is a physiological disorder – i.e. a problem that is caused by the growing conditions; NOT by a pest or disease.
  • Dark brown hollow patches form on the bottom of the tomato.
  • This is often caused by irregular watering.
  • Once the problem develops, quick fixes are difficult. All you can really do is try to maintain regular watering as much as possible.


  • Again, this is NOT caused by a pest or disease.
  • While Blossom End Rot is something going wrong at the base of the fruit, Greenback is something going wrong at the stalk end.
  • The fruit won’t ripen fully and remains hard and green around the stem.
  • This can be the result of having been allowed to become dry then followed by a spell of too much water, or too much direct sunlight and high heat.

Fruit Split

  • This is also NOT caused by a pest or disease.
  • This can be difficult to prevent, as it is usually caused by fluctuating temperatures and/or water supply.
  • Avoid giving nearly ripe tomatoes a long soaking.


    · Need a free-draining soil

    · Require regular watering and feeding



    Tomatoes are warm season plants. From a spring planting they produce fruit continuously from December until the end of May. This succession can come from the ongoing care of tall varieties growing on stakes or supports or from the easy-care method of successive plantings of dwarf varieties every three to four weeks.


    Selecting the Site

    Tomatoes grow best in a warm, sunny position. They should not be grown in the same area of soil for 2 years in a row. It is best to move them to a new site each year and return to each site one year in four.


    The Soil

    Tomatoes grow in most soils, but the usual rules apply. They require good drainage, compost added to improve structure and the planting area raised in clay soils.


    The Plants

    Tomatoes can be grown from seed or purchased as plants.

    There are many varieties with fruit which varies in size, shape, taste, colour, acidity, as well as the growing habit of the plants. So if you are a tomato fanatic try the different varieties until you find your favourite, it can be fun.


    ‘Money Maker’ is the most popular of the tall staked varieties. It has medium, large, round, fleshy fruit of good flavour.

    Sweetie’ is a tall variety with bunches of small fruit which hang like grapes.

    Roma’ is the traditional egg shaped fleshy, non acidic tomato, popular for cooking and sauce making.

    ‘Tasty Tom’ is a disease resistant variety, with a full rich flavour, and is a very heavy cropper.


    When to Plant

    Being a warm weather crop, tomatoes don’t really start growing until temperatures are up to 20°C  with night time minimums above 10°C.

    Hence in most areas they can be planted from late September onwards. Successive plantings, about 6 weeks apart until early January, will ensure a good supply of tomatoes through until the end of May or sometimes later.


    How to Plant

    Plants are best planted out 50 to 60cm apart when 15 to 20cm high. Work into the soil before planting  with Tui general garden fertiliser or Dynamic Lifter, together with a dressing of Lime.

    Tall varieties will require stakes or support.



    Tomatoes will yield much more if they are well fed. Hence in addition to the fertiliser applied prior to planting, commence weekly liquid feeding with Nichols Super Crop Tomato Food once the first truss of fruit has formed.



    Tomatoes require lots of water regularly. They must not be allowed to dry out as this drastically reduces yield. Irregular watering leads to blossom end rot - a sunken black patch on the bottom of the fruit. Water daily in hot weather once fruit has developed.


    After Care

    Tomatoes need to be supported by tying to a stake or fence. Most gardeners use a stake and tie the two main tomato stems to the stake at 30cm intervals. The two main stems come from the central leader of the young plant plus the first lateral or side shoot. Once these two stems are established all other side shoots (laterals) should be pinched out to keep the plant tidy and manageable. Pinching out the new side shoots should be done twice a week as they can get out of hand very quickly.


    Pests and Diseases.

    Many problems with tomatoes are associated with temperature, watering and feeding.  The main pests and diseases are -

    Aphids  -  use Mavrik or Confidor

    White fly  -  use Mavrik and sticky traps

    Mites  -  use Mavrik

    Blight  -  use Copper, Bravo or Greenguard

    Psyllid  -  use Mavrik or Confidor

    Tomato fruit-worm  -  use Yates Tomato Dust

      or  Success