Tomatoes Under Glass

Press, Volume CIX, Issue 32145, 14 November 1969, Page 6

Tomatoes Under Glass

The growing of vegetable crops under glass has many advantages although it is usually confined to rather few amongst home gardeners. One of the most popular

crops grown are tomatoes, which are subject to many upsets. One of the most common mistakes made is to water too often after they have been put in. After the initial watering has been made after planting no further water should be given in the vicinity of the roots until the first truss of fruit has set From then on water becomes a necessity. Damping down before this stage may, however, be required, particularly on hot and humid days. The drop of flowers from plants often causes puzzlement and worry. This is most often traceable to insufficient air moisture. Such a problem is particularly accentuated when the air is both very dry and warm. Cold conditions can cause similar symptoms. Pollination is effected by the transfer of pollen from the stamens to the pistil of the same flower. The optimum condition., for this occur in the presence of sunshine and moist air. A good procedure on fine days is to damp down house and plants first thing in the morning and then to leave the vents open for the day. In unfavourable weather it pays to go round and shake the individual plants. Sometimes the setting of fruit is poor or non-existent for other reasons; for instance excessive use of nitrogenous fertilisers can hinder fruiting. Mosaic infection can produce deformed sterile flowers which are unable to set fruit. There are occasional occurrences of inherited defects. Partial or complete unfruitfulness can occur in small plants—the shortness being due to the short internodes (the stem between successive leaves being shorter than in normal plants). Again there is the converse case of the giant plant which produces abnormally vigorous growth and practically sterile flowers and can be regarded as a rogue plant. Such a plant may as well be pulled up. Most growers will be familiar with a number of other oddities. Quite a common one results in a rolling up of the leaves. The upper surfaces become completely over-arched by upcurled mar-

gins which may meet above the mid-rib of the leaflet The leaf itself becomes very hard and stiff. There is considerable varietal and even plant differences in the degree of roll. This rolling is sometimes brought about by excessive hand defoliation which results in the remaining leaves receiving all the sap from which they become gorged. It can be most pronounced in dry, warm weather but does not affect the fruit yield. Heavy manuring leading to a high nutrient concentration and dark green foliage, which may have a violet tint reminiscent of spotted wilt infection, is more likely to induce this condition. .X The sight of fallen plants will not be.i unfamiliar to regular growers. On examination the stems will be found to be hollow, soft and placid yet not rotting, with the pith wholly or partly missing. The plant may remain green for a long time but no growth is made. This occurrence can be due to excessive water or nitrogen and is often caused by the affect of sudden change of conditions when planting out.