TOMATO DISEASES

Evening Post, Volume CXVII, Issue 111, 12 May 1934, Page 24

TOMATO DISEASES

SHARED WITH OTHER PLANTS

The second of tho Cawthron Institute bulletins deals with the virus diseases of the- tomato, giving details of the symptoms, efEect, transmission, and control of, the three diseases known as "mosaic," "streak," and "spotted wilt." v Dealing in general with such diseases, the bulletin remarks; that during the last ten years no problem in plant pathology has caused more concern than that connected with the ever-increasing loss—particularly in common crops such as tomatoes, potatoes, tobacco, sugar beet, and small fruit—resulting from the onset of virus diseases. As long as thirty years ago obscure diseases, for which no causal agent could be detect-^ ed, were noted in both America and Europe, while in recent years, in every part of the world, including the tropics, crop after crop has proved subject to virus attack which in certain eases has been sufficiently severe to spell disaster to tho agriculturist. The great need for research in this important field of plant pathology was fully recognised at the Imperial Agricultural Conference held in London in 1927, and as a result tho Empire Marketing Board, has accorded financial' support for fundamental work relating to the nature and control of these diseases to the Rothamsted and Cheshunt Experiment Stations, the Scottish Society for Research in' Plant Breeding, and tho University College, Dublin. On analogy with diseases caused by bacteria, the tendency at first had been to ascribe virus diseases to the action of an-organism, but although foreign organisms aro known to occur in certain virus-infected plants, the consensus of opinion at • present ascribes the cause of the diseases to the presence of an "infective principle" in the cellsap of the plant. In spito of our present inability to attach a label to this infective principle, we aro rapidly gaining information on the characteristics of individual viruses, and with more or less certainty are now able to distinguish between both the viruses in different plants and tho several viruses that may occur in a single plant.

Virus diseases are- known to attack every type of plant—cereals, fodder crops, fruits, flowers, and weeds. Even the weed viruses may be of importance if tho weed grows near a crop of related, economic plants, for if perennial it may maintain tho disease from one season's economic crop to tho nest. In New Zealand the virus diseases with which we are specially concerned include those of tomato, tobacco, potato, and small fruits. The tomato-tobacco-potato section forms a natural group of host plants, closely related botanically, which to some extent share their diseases in common, the sharing being more marked between tobacco and tomato than between potato and either of the other two.