130 



TEE GARDENER'S MONTHLY 



[Mat, 



might be grown in this way, and vrould not only 

 charm the eye during the flowering season, but 

 add their mite to more material pleasure, in a 

 way agreeable to most persons of taste, if not of 

 refinement. 



Mow lawns very early the first mowing, or at 

 every subsequent mowing the lawn will look 

 brown. A thin sprinkling of salt is good for the 

 lawn, just enough salt to see the grains on the 

 surface, about a quarter of an inch apart. An 

 overdose will destroy the grass. Frequent roll- 

 ing is one of the best ways to get a good close 

 Bod. When coarse weeds get in the lawn, hand 

 weeding is the best remedy. 



Tuberoses, Gladiolus, Tigridias, Dahlias, and 

 other bulbous things which cannot be put out 

 till the ground gets warm, ought not to be kept 

 out of the earth any longer than necessary. It 

 was once supposed they thrive best in poor soil 

 — an error; they love rich food. 



COMMUNICA 7 JONS. 



DISEASE IN VIOLET ROOTS. 



BY DR. S. W. UNDERHILL, CROTOX POINT, N. Y. 



In the March number, " J. McB.," of Boston, 

 Mass., inquires about a disease aflecting his Vio- 

 lets. 



I have been quite familiar with this disease for 

 four or five years past, and believe it exists to 

 some extent in nearly every greenhouse in the 

 country, generally in such a mild form as not to 

 be noticeable. 



Since discovering it, I have always carefully 

 examined all plants received, and in most cases, 

 have found it prevalent to some extent. Have 

 received plants affected by it from Boston, New 

 York, Philadelphia and Baltimore, besides other 

 places. I have frequently thought it very singu- 

 lar it had not been noticed by gardeners before. 

 A person not familiar with it, would not notice it, 

 except in bad cases. 



The violet is the only j^lant, I have observed, 

 it killed outriglit; but it will attack many kinds 

 of greenhouse and bedding plants, such as Verbe- 

 nas, Petunias, Torrea Asiatica, Tea rose, &c., but 

 these plants are not as seriously injured by it as 

 the violet. 



This disease is owing to the attacks of an ex- 

 ceedingly small insect, with the habits of the 

 Phylloxera, but not more than one third the size. 

 Although I was confident from the first it was 



caused by an insect, yet it was along time before 

 I was able to find one, for whenever I examined 

 the roots, there were none to be seen. After re- 

 peated examinations, I found one running across 

 the field of the microscope, and with considera- 

 ble difficulty kept it in view long enough to see 

 that it resembled the Phylloxera, much smaller, 

 with longer leg-s and slimmer body, and much 

 more rapid in its movements. I afterwards found 

 them feeding on the roots, but they will run away 

 as soon as disturbed. 



It appears to be difficult to destroy them by 

 applications to the soil, and I find the best way 

 to get rid of them is in being very careful in se- 

 lecting soil for potting, and to grow all stock 

 from seed or slips, and not from division of the 

 roots, and to keep the stock plants in a different 

 house from the slips or yovnig stock ; also, to de- 

 stroy all stock plants affected by them as soon as 

 they can be spared. 



I find it is not safe to use sail from the vicinity 

 of the greenhouse, where I have found them at- 

 tacking the tomato, several kinds of weeds, and" 

 even the tobacco plant; although I think any rich 

 soil taken from near the greenhouse, is as good 

 as soil taken from the field if properly treated 

 beforehand. Heaping it in the spring and cover- 

 ing with a sufficiently heavy coat of mulch, to 

 entirely prevent a growth of weeds through the 

 summer, will effectually destroy them by fall. 



Killing all plants by hoeing or storing the soil 

 dry under a shed during the summer and autumn 

 will also answer the purpose. 



I think, from my experience, the good quali- 

 ties of fresh soil from a pasture is very much 

 owing to the absence of these insects. Where 

 the soil is rich and the plants can get an abund- 

 ance of nutriment, the effects of these insects 

 are seldom noticed on the growth of the plants; 

 consequently it is best to supply all affected 

 plants ^vith plenty cf nourishment. By this 

 means most plants, except violets, can be grown 

 successfully, even where they are very numerous; 



If they are very abundant on the violet, they 

 will, in the autunm, eat the bark from the main 

 roots or body of the plant, and cause it to rot oflf 

 below the surface of the ground. 



This trait is similar to one of the Phylloxera, 

 the effects of which on the different varieties of 

 grape vines I have been studying for several years 

 past — probably being one of the first to notice 

 them in this country — having discovered them 

 with a microscope, on some diseased grape-vine 

 roots, in the autumn of 18G9. My observations 



