16 



The Florists^ Review 



Mat 6. 1920 



ought to be kicked out of the florists' 

 association. This so nettled Mr. Curran 

 that he said he used wood ^shes every 

 ten days and tobacco dust every ten 

 days on the soil during the spring; 

 that is, one every five days. Mr. Cham- 

 bers said other growers were trying 

 wood ashes and that he was trying the 

 two in the way named. 



The idea is that the lye in the wood 

 ashes destroys the larv» of the rose 

 beetle, as the lye is extremely strong. 

 The tobacco dust is used to prevent in- 

 jury to the roots of the plants. A good 

 watering between each application is 

 important. Of course, wood ashes can 

 only be used in moderation. 



DESCRIPTION OF BOSE BEETU:. 



From Entomologist's View. 



Mindful as always of the commercial 

 interests as well as the amateur inter- 

 ests more largely represented in the 

 American Eose Society, the editor of 

 the 1920 American Eose Annual, just 

 off the press, has included in the volume 

 short articles on the new pest of green- 

 house roses, by two government special- 

 ists, C. A. Weigel and J. G. Sanders. 

 That of the former is particularly of 

 value, since Mr, Weigel, who belongs to 

 the bureau of entomology of the Depart- 

 ment of Agriculture at Washington, de- 

 scribes the nature of the injury and the 

 appearance and habits of the beetle so 

 that it may be recognized. In the Eose 

 Annual article, he states: 



"The strawberry root-worm or leaf- 

 beetle, Paria canella, Fab., has been long 

 recognized as a serious enemy of straw- 

 berries and raspberries, and occasionally 

 of the apple, crab-apple, juniper and 

 several other plants. 



"Since the reports were received of 

 its injury to roses in greenhouses a 

 careful survey has been inaugurated in 

 order to establish its exact status under 

 greenhouse conditions. As a result, we 

 have recently secured positive evidence 



Fig. J. 



Rose foliage Infested with strawberry root 

 worm. 



that this insect is now of prime impor- 

 tance to many of the commercial rose 

 growers of the United States. At pres- 

 ent it is causing much anxiety in several 

 of the largest rose growing establish- 

 ments, and in some cases has practically 

 ruined their entire stock. While one or 

 two florists report that they have had 

 experience with this pest for several 

 years, the authentic records indicate 



that it has been exeeptionally injurious 

 during the last two seasons only. 



How Damage Is Done. 



' ' The damage to rose foliage is caused 

 mainly by the full-grown beetle and 

 does not differ materially from the in- 

 jury done to the strawberry. The entire 

 foliage is badly perforated and ragged, 

 presenting a shot-hole appearance (Fig. 

 1), as a result of their voracious feeding. 

 These more or less rounded holes, which 

 vary in size and shape, are so close to- 

 gether that the plants look as though 

 loads of shots had been fired into the 

 foliagS at short range. 



"The beetles show a marked prefer- 

 ence for the new and young shoots, 

 which they badly scar by their peculiar 

 manner of feeding, giving them an un- 

 sightly appearance. Ultimately, the en- 

 tire growth is badly stunted from the 

 gradual killing of the affected parts, 

 thereby reducing the commercial value 

 of the plants. 



Appearance of Beetle. 



"The full-grown, adult beetle (Fig. 2) 

 is about one-eighth inch long and oval in 

 shape. It is quite variable in color, so 

 that several colored varieties are known, 

 ranging from wholly black to yellowish 

 brown, but ordinarily it has four spots 

 on the wing covers. The common variety 

 is brown in general color, with black 

 markings. The entire insect is highly 

 polished, and the wing-covers are orna- 

 mented with longitudinal rows of minute 

 pits. 



"The larva (Fig. 2.), or grub, is about 

 the same size, and when full-grown it 

 resembles a white grub, the same as is 

 found under sod, except in size. It is 

 found close to the surface of the 

 ground, feeding on the roots of the rose 

 plants. 



"When the larva is full grown, trans- 

 formation takes place within a smooth- 

 walled cell which is constructed in the 

 soil for that purpose. Finally, it emerges 

 as the full-grown beetle, the female of 

 which lays the eggs for the future gen- 

 eration. As far as is now known, the 

 adults hibernate under mulch or other 

 convenient shelter during the winter 

 months. It has been noticed by the 

 florists who have reported damage that 

 the beetles put in their first appearance 

 about the latter part of May, or early 

 in June, and reach their maximum num- 

 bers during July. Their feeding may 

 continue throughout the month of 

 August or even later. There may be 

 several broods annually under glass. 



"The beetles are rarely seen and have 

 never been observed feeding during the 

 brighter hours of the day. Occasionally 

 they may be collected in dead or dried 

 and curled-up leaves, or under debris 

 among «the surface soil. Beginning at 

 dusk and extending to the early morn- 

 ing hours, they may readily be observed 

 feeding on the plants. On being dis- 

 turbed they play 'possum.' 



Control Methods. 



"In the preliminary control experi- 

 ments conducted by the writer, with the 

 assistance of E. L. Chambers, of the 

 federal bureau of entomology, it was 

 found that the arsenicals or stomach 

 poisons, which are ordinarily employed 

 to control leaf -eating insects of this 

 type, were quite ineffective. 



"The best results thus far obtained 

 were by the use of hydrocyanic acid gas 

 against the adult beetles. Until further 



progress has been made in the life his- 

 tory studies and habits of this new rose 

 pest in greenhouses, it is recommended 

 to fumigate at night only with the above 

 gas, using two ounces of sodium cyanide 

 for every thousand cubic feet of space 

 which is to be fumigated and giving ex- 

 posure of two hours. The destruction 

 of the adults at this time should fore- 

 stall a recurrence the following spring 

 and summer^ since a large percentage of 

 the females are killed many months 

 prior to the normal time of egg-laying. 

 Incidentally, as the insects oftcur in their 

 maximum numbers during June and 

 July, the above treatments fit in con- 

 veniently in normal cultural methods. 



"Growers are also advised not to 

 bring sod or soil into their houses in 

 which strawberries or raspberries, either 



On left, larva or grub, and on right, mature 

 beetle of the strawberry root-worm (Paria can- 

 ella Fab.) The figures are much enlarged; the 

 beetle Is about one-eightb Inch In length. The 

 grub feeds on the roots of roses in greenhouses 

 and the beetle on their leaves. 



wild or cultivated, have been growing, 

 because the larva or ^ grub stage occurs 

 in the soil, and such soiKis likely to be 

 the source of an infestation in the 

 greenhouses. 



"The bureau of entomology is now 

 actively engaged in a thorough study of 

 the life history, the habits and the best 

 means of controlling this new rose pest. 

 It is therefore requested that all speci- 

 mens of a suspicious nature, or which 

 may conform with the above description, 

 be immediately mailed to the writer for 

 examination, addressed to C. A. Weigel, 

 Bureau of Entomology, United States 

 Department of Agriculture, Washington, 

 D. C." 



SAVES FBICE OF BULBS. 



"We have learned to grow Paper 

 Whites without buying new bulbs every 

 year as we used to do," state L. M. 

 Smith & Co., Laurel, Del. "We plant 

 our Paper Whites close together in flats 

 four inches deep, in good, rich garden 

 soil — no fresh manure — and place them 

 outside until the weather feels almost 

 cool enough for frost, keeping them 

 weU watered all the time. Then we 

 bring them into the greenhouse and 

 place the flats under the sunny side of 

 the benches. When the plants bloom, 

 we cut only the flower stems, no foliage. 

 We allo>v that to remain until it dies 

 down and gradually dry off the plants. 

 After the foliage is dead, we place the 

 flats in a cool, dry place until Sep- 

 tember 1, then shake them out and re- 

 pot them in new soil and new flats. 

 In this way one can save the bulbs 

 from year to year. The same treatment 

 may be used for freesias. " 



