15 



next to Marie Louise in qualit}" of flowers, lacking onl}' the deep rich 

 color of the latter. The single varieties are as a rule more resistant 

 than the double, though occasionally they are seriousl}" afi'ected. 

 (Plate VII.) 



PREVENTIVE MEASURES. 



So far as we are aware there is at present no effective remedy for 

 this disease when it has gained a foothold. The principal fungicides 

 in common use for the prevention and check of plant diseases have 

 frequently been tried for this trouble, but with varying results. The 

 experiments of the Division in spraying violets with some of the 

 more important of these, among them Bordeaux mixture and ammoni- 

 acal solution of copper carbonate, seem to show that they possess little 

 or no value in preventing the disease, while on the other hand they 

 render the foliage worthless for bunching with the flowers, and thus 

 occasion considerable loss and inconvenience. From the writer's 

 experience and that of many others it would seem that the solution 

 of this problem of controlling the disease lies in preventing it by 

 giving careful attention to the production of vigorous, healthy, plant 

 growth rather than in attempting to check the trouble after it has 

 once gained a foothold. 



The successful growing of violets free from disease and the pro- 

 duction of flowers of the best quality are governed by a number of 

 factors which must be kept in mind. The principal rules which should 

 govern the grower are the following: 



(1) Study carefully the behavior of the plants under the varying 

 conditions surrounding them. Endeavor by modifying these condi- 

 tions, when necessar}", to secure plants of ideal development. Set the 

 standard of excellence high and be satisfied with nothing short of its 

 attainment. 



(2) Grow the plants during the entire season where the}" can be 

 given the conditions necessary for making a vigorous, healthy growth, 

 and where they can be protected at all times from conditions likely to 

 induce disease. 



(3) Keep the houses or frames clean, sweet, and in perfect condition 

 for growing healthy plants, by repairing and painting them when nec- 

 essary, and by removing and destro3dng all rubbish likely to harbor 

 vermin or disease. 



(4) Propagate only from healthy, vigorous stock (;f known parent- 

 age at the season most favorable to the plants. 



(5) Select each spring none })ut perfectly healthy, vigorous plants 

 from the rooted cuttings for planting into the houses or frames. Old 

 plants are sometimes carried over, and occasionally yield a large crop 

 of flowers. They are not as reliable as the young plants, however, and 

 are much more liable to all kinds of disease. The best growei's rarely 

 use them if it is possible to secur(> strong, health}' young plants for 

 spring or early summer planting. 



