lo Jan.. 19 fo.] Irhli Bliglit in Tomatoes. 49 



recorded in the Journal of iJie Board of Agricultnn-. England, that one 

 grower lost 50 tons of tomatoes grown in the open air in 1907, out of a 

 total of 70 tons, or 71 per cent., owing to the plants being attacked by 

 Phytopht/iora infestans. The same disease, causing considerable loss, is 

 also found in tomato plants in New Zealand, both when grown in the 

 open and under glass. The disease generally attacks tomatoes similarly 

 to potatoes, first appearing on the leaves, then passing to the stems and 

 linally causing the fruits to rot. From the succulent nature of the tomato, 

 it is a splendid breeding ground for the fungus, and if the diseased fruits 

 are allowed to lie on the ground and not destroyed, they produce spores 

 iri countless millions, readily carried by the wind to other tomato plants. 

 Some of the most luxuriant crops of spores reared in my laboratory, have 

 been developed from tomatoes. 



Inoculation Experiments. 

 It is important for the grower to know if the disease is communicalile 

 from tomatoes to potatoes, and vice versa, for he can thereby be on his 

 guard against spreading the disease from one crop to the other, by means 

 of the diseased fruit or the diseased tubers as the case may be. Healthv 

 tomatoes can be inoculated from diseased potatoes and healthy potatoes 

 from diseased tomatoes, as the following experiments will show: — 



1. A healthy green tomato had sporangia from a diseased potato 

 placed on its skin in a drop of water. In course of time, the surface 

 around this spot became discoloured and depressed, and the infected por- 

 tion was clearly marked off from the diseased by being paler at the junc- 

 tion. The tomato was cut through, showing the brown tissues beneath 

 the skin, and on being placed in a moist chamber developed the fructifica- 

 tion in 49 hours. The time which elapsed altogether from the inoculation 

 of the tomato to the production of the fructification of the fungus was 

 sixteen days. 



2. A clean tomato was placed in a ves.sel where a diseased tomato had 

 been freely shedding its spores, and from mere contact with the spores, the 

 healthy tomato was infected, so much so that in nine days the fructifica- 

 tion appeared on the surface of the skin, ready to be blown away and 

 carried to fresh plants. 



3. A healthy potato of the Southern Cross variety was infected at the 

 crown end with spores from a diseased tomato. In 6| days the fructifi- 

 cation appeared in various patches with a profuse development of 

 sporangia, and the voung green shoc-ts of the potato were literallv covered 

 at the base with the fructification of the fungus. 



It is a well established fact, therefore, that diseased potatoes and 

 tomatoes are mutually infective, and every care should be taken only to 

 have seed potatoes or tomato plants from clean districts. So far affected 

 tomatoes have only been found in imported material from New South 

 Wales, but wherever the Potato Blight occurs in Victoria, there is a danger 

 of tomatoes being affected if grown in the same districts. Eternal 



vigilance is the price we must pay for freedom from this, as well as 

 other pests, and now that we know how to control the disease bv spray- 

 ing and to destroy the spawn of the fungus in the seed potatoes by sterilis- 

 ing, if representatives from the different States were to meet and agree 

 upon a common course of action, based upon our knowledge of the cause 

 of the disease, it would be found that the difficulties are not so great as 

 they appear, and that the loesses caused by it could be reduced to a 

 minimum. 



