﻿STKAWBEERY EOOTWORM ON" GKEENHOUSE ROSES 39 



under observation succumbed shortly thereafter, thus corroborating 

 the earlier results. Other extensive tests were tried on a total of 

 about 20,000 bushes with the same degree of effectiveness. 



This treatment therefore finds convenient application, especially 

 when the new growth has started after the resting period, and in the 

 fall when it would be inadvisable to employ other remedies, such as 

 fumigation or spraying. Furthermore, every adult killed then would 

 mean so many less the following spring. 



SCRAPING THE SOIL OF BEDS 



It is a cultural practice among rose growers to scrape off 1 or 2 

 inches of the loose, dry surface soil from the beds during the drying- 

 off period immediately after the plants have been cut back. The soil 

 is then thoroughly soaked with water, bone meal is applied as a fer- 

 tilizer, and a mixture of well-rotted manure and composted soil is 

 used to replace the removed layer. Certain modifications of this 

 method, such as making deep furrows between crossrows of plants 

 and filling them with manure, are also used. 



Examination of the material removed from infested beds disclosed 

 30 adults in the soil surrounding 6 plants, and in another place 14 

 were found near 3 plants. Their prevalence at this time suggests a 

 practical means of destroying many beetles by shaking the plants 

 and by removing the soil from the house and treating it as soon as 

 the plants have been cut back. Unless this is done at once, however, 

 the beetles will severely injure the plants by devouring the buds and 

 girdling the stems. 



CLEAN CULTURE 



In a certain establishment already discussed under hand picking 

 it was customary to keep the beds immaculately clean and to apply 

 liquid manure instead of a mulch to the soil. At all times the beds 

 were kept free from dead leaves and debris by the workmen, who 

 removed them at frequent intervals and burned them. These beds 

 had the appearance or having been swept with a broom. Undoubt- 

 edly this practice contributed much toward reducing the infestation, 

 not only by removing many beetles and preventing the remainder 

 from hiding in the dead leaves over winter but also by decreasing 

 proportionately the amount of egg deposition in the spring. More- 

 over, it prevented many newly hatched larvae from reaching the soil. 

 From February until September the leaves should be removed every 

 10 days in order to destroy the eggs in them. In heavy infestations 

 it is desirable to fertilize the beds with liquid manure instead of 

 mulching. 



SOIL TREATMENT 



Since the larva and pupa stages, requiring about six to eight weeks 

 for their development, are spent in the soil, they appeared to furnish 

 a period when the insects would be susceptible to control by means of 

 soil treatments. During the first season efforts were therefore di- 

 rected primarily toward finding some soil application, either an 

 insecticide or a fertilizer, which would operate against these stages 

 and hence prevent the emergence of the adults. With this object in 



