DISEASES OF MINOR FRUIT PLANTS 357 



The mycelium does not grow weU at high temperatures, and 

 it is quite likely that this character prevents the disease from 

 assuming importance in these islands. 



Control. 



The use of clean seed in clean soil is the best means of pre- 

 vention. Training the plants on stakes reduces infection and 

 enables spraying, when it becomes necessary, to have more 

 effect. Under favourable conditions the periodic use of Bordeaux 

 mixture has given good results, but these are in general uncertain, 

 and J. A. Stevenson reports that no benefits resulted from re- 

 peated applications in trials made in Porto Rico. 



Bacterial Wilt. 



During a visit of the writer to St. Vincent in 1917, some 

 attention was given to a wilt disease which was found to be 

 occurring extensively at the Experiment Station, Kingstown, in 

 beds of hybrid tomato plants (Ponderosa x Native) and in a 

 row of the variety Earliana from American seed. 



The symptoms of the affected plants, the appearance of the 

 associated bacterium under the microscope and on agar cultures, 

 and its virulence when inoculated into healthy plants, leave no 

 reason to doubt the identity of the disease with the wilt due to 

 Bacterium (Bacillus) solanacearum, E. F. Sm. 



This disease is very prevalent in the southern United States, 

 and makes the growing of tomatoes impossible over large tracts 

 of country. A closely similar, probably identical, affection has 

 been reported in many countries of the Old World. Several 

 other members of the natural order Solanaceje, especially egg- 

 plant, potato, and Datura spp. are liable to serious diseases 

 produced by the same organism. The whole series has been 

 grouped together under the name of Brown Rot of Solanaceae, 

 and very fully treated in Volume III of E. F. Smith's " Bacteria 

 in relation to Plant Diseases." 



So far as the records of the Imperial Department show, the 

 disease has only been previously reported in the Lesser Antilles 

 on one occasion, on tomatoes from Union, St. Lucia, in January, 

 1904. 



Symptoms. 



The outstanding character of the affection on tomatoes, as 

 seen in St. Vincent, is the wilting, usually sudden, of the whole 

 plant, which has just the appearance which would be produced 

 by severing the base of the stem from the roots. No preliminary 

 browning of leaves or stems was observed. When the bacterium 

 was artificially introduced into a single stem, wilting above the 

 point of inoculation took place in from two or three days to a 

 week, while downward infection proceeded only slowly. 



