343 GEEENHOUSE MANAGEMENT. 



carbonate of copper mixture, with fair results. But the 

 beginning of the trouble„is often below ground and quite 

 out of the reach of fungicides, as shown below. 



THE VIOLET EEL WOEMS (Root Galls). 



One of the serious pests of the violet is the eel worm 

 or nematode. These are microscopic worms that mul- 

 tiply in the substance of the violet roots, and cause 

 enlargements called .galls, that may be very numerous 

 and sometimes of considerable size. The worms enter 

 the tender roots from the soil and there increase rapidly. 

 Their presence seems to poison the tissue and induces an 

 abnormal growth, similar to that which takes place upon 

 many sorts of leaves when stung by gall flies and other 

 insects. Many plants have their roots affected in this 

 way, and the same species of nematode probably inhabits 

 scores of kinds of plants. 



So far as known, the gall trouble of roses is the 

 same as that of the violet, and if this be true, it follows 

 that the infection may pass from one kind of plant to 

 another. It would not be well to grow violets in soil 

 where roses had been galled, or vice versa. 



There is no remedy for a plant that is badly infested, 

 for nothing harmless to the plant can be used to kill the 

 worms. The main point is to keep the nematodes out 

 of the roots. The soil, therefore, should be free from 

 them, and this is a difficult matter. The soil could be 

 heated to a high temperature and the worms would be 

 killed. Freezing would accomplish the same end; but 

 either of these two extremes is not always possible. Lime 

 water is said to kill them. The less manure used, 

 the better, so far as the galls are concerned. Violets 

 could probably be grown profitably with no manure. 

 With the soil free from the worms, and the plants also, 

 there ought to be no trouble in having violets, exempt 

 from the nematodes. In setting out the plants, it is 

 well to look at the roots and reject all with galls. 



