Many Tomato Disorders Appear In A Poor Season

Press, Volume CIII, Issue 30395, 20 March 1964, Page 6

Many Tomato Disorders Appear In A Poor Season

In general it has been a most disappointing season for outdoor tomato growing. Severe frosts cut back most of the early planted crops, strong winds caused damage and generally unfavourable weather until a few weeks ago inhibited growth considerably. Even the sunny periods failed to induce much ripening of fruit.

However, just recently some crops here began to move a little and we may be able to salvage something yet To this and every encouragement should be given the plants and this includes removal of surplus leaves, particularly from the lower region of the stem, total weed supression and adequate moisture in the soil.

The prevailing unseasonal climate conditions greatly influence the tomato crop in another way in that they subject the fruit to physiological

disorders which are often a puzzle to many growers. A physiological disorder or disease, may be described simply, as a disturbance in normal plant growth due to agents other then pest or virus bacterial or fungal disease.

Cracks In Fruit Everyone has at some time or another found that much of their ripe or semi-ripe fruit has splits on the surface. These semi-concentric rings usually occur at the stalk end and these may extend into the flesh. They provide easy entry for disease organisms which can cause rapid break down and rotting under suitable conditions particularly on dwarf tomatoes. The cracks invariably appear during warm, wet periods or when rainfall follows a dry spell. The cracking is a result of sudden swelling of the flesh within, while the skin is unable to expand at

the same rate. Careful use of irrigation during these dry periods will help reduce cracking as will regular picking before the fruit is fully ripe during this time; ripening can be finished indoors.

This trouble is associated with fluctuating moisture availability during early fruit development When there is insufficient water available for maximum fruit expansion there is likely to be drainage of fluid from the blossom end of the fruit which results in collapse of the tissue in that region. The small dark green spot which becomes visible at or near the blossom end of the fruit soon becomes firm, leathery and brownish black as the fruit ages. This spot is likely to be attacked by fungus or bacteria and such attack can be aggravated by the excessive use of nitrogenous fertilisers as well as by deficiencies of lime or phosphate. This trouble is most common on early formed trusses and it is Important that tomato plants should always have enough water for full fruit development Sun Scald

It is considered good practise in tomato culture to remove leaves from the base of the plant upwards so as to encourage air circulation, to permit access of sun and in-

creased light to the fruit trusses thus hastening ripening.

If, however, too much foliage is removed and the fruit is suddenly exposed to direct sun during a hot sunny day, a condition known as sun scald is likely to occur. Green fruit is just as susceptable to this trouble as is that which is colouring. This trouble can be avoided by judicious defoliation—taking off a few leaves at regular intervals. Those gardeners who grow dwarf tomatoes and are in the habit of slashing the tops off will be particularly aware of this trouble. Phosphate deficiency This condition does occasionally occur but it is not so very common. Symptoms are that the leaves become dark bluish green with a purple tinge along the margin.

A deficiency of phosphorous will cause stunting so that the plants remain small and seem to make no extension growth while the older leaves may become highly coloured

and fall. This condition can be remedied by an application of superphosphate to the soil.