736 



The Weekly Florists^ Review* 



MARCH 31, 



pots, but do far better and are more 

 easy to manage planted on a bench in 

 a light, warm house. 



If after the end of March you need 

 the bench for some other crop you can 

 cut down the bouvardias to within a 

 few inches of the bench, lift them, 

 shaking off all the soil, and place them 

 close together in flats with three or 

 four inches of moist soil around them 

 and put under a bench where there is 

 not much drip, and they will do there 

 all right till planting out time. The 

 old plants will of course be much lar- 

 ger than those propagated the first 

 year. 



Red spider attacks them, and so do 

 mealy bug, but their presence is in- 

 excusable, for a proper use of the hose 

 will prevent both. Green fly will ap- 

 pear if fumigation is neglected, but be 

 careful to smoke lightly, particularly 

 when the plants are first housed, for 

 they burn readily. 



In lifting, I cannot say as you can 

 about carnations, "let all the soil tum- 

 ble off if it will, so long as I save ev- 

 ery fibre," for they do not lift so well, 

 or rather, do not recuperate so quickly. 

 Lift carefully with a good ball of earth 

 and for the first week shade and sy- 

 ringe frequently. 



GREENHOUSE PESTS, SAN JOSE 



SCALE AND LEGISLATION 



VERSUS INSECTS. 



[Read by Professor John B. Smith before tlie New 

 York Florists' Club.] 



The topics are wide, and either would 

 furnfsh a text tor a sermon it treated at 

 large; but I will content myself with 

 making suggestions rather than exhaus- 

 tive and exhausting descriptions. 



All rational methods for the destruc- 

 tion of insects, indoors or in the fields, 

 must be based upon a knowledge of the 

 character ot the insect to be dealt with, 

 of its life history and of the way in 

 which the destructive agent Is expected 

 to work. 



In the greenhouse where leaves and 

 flowers are the desired products, many 

 methods that are available in the field, 

 become useless. The plants are more 

 delicate, the foliage Is more tender and 

 the flowers must be guarded from any- 

 thing that will tend to discolor or in any 

 way Injure their perfection. 



We must attempt to arrange our prac- 

 tice so as to destroy the insects without 

 harming our plants, and the selection of 

 a proper agent Is sometimes difficult. 

 First, It is important to know how we 

 kill insects. Of course In those cases 

 where the creatures eat the leaf-tissue 

 and we use arsenicals. the matter is sim- 

 ple. The poison acts through the stom- 

 ach exactly as if some higher animal 

 were the victim. But stomach poisons, 

 especially arsenicals, are rarely desirable 

 in a greenhouse, and the insects against 

 which they are necessary are not among 

 those that are most destructive. 



Most of the greenhouse pests are suck- 

 ers and creatures that live on the plant 

 Juices and merely puncture the outer tis- 

 sue to get at the liquid within. Crea- 

 tures like that cannot be reached by 

 stomach poisons until we learn how to 

 poison the plant circulation itself. 



Of course the damage caused is in direct 

 proportion to the number of insects pres- 

 ent. A single plant louse, for instance, 

 can do little harm; on a carnation leaf, 

 for example— it makes a puncture or 

 two. exhausts a few cells and dies. The 

 amount of sap taken is insignificant, 

 and not in the least a drawback to the 

 plant. Locally we see a minute yellow 

 spot, and if the leaf be held up toward 



the light and examined with a glass, a 

 thin spot of exhausted plant cells is seen. 

 AVith a higher magnitication we may see 

 tlie minute puncture itself. But this is 

 not all. unfortunately. Bacteria and 

 other disease germs are constantly pres- 

 ent in the air and on the plant surface; 

 so long as this surface remains luibroken 

 they are harmless; but so minute are 

 they, that even the slightest wound gives 

 them entrance and the puncture made by 

 a plant louse Is more than sufficient. The 

 exhausted and partly decaying cells in- 

 jured by the insects form an excellent 

 culture medium for the micro-organism 

 and soon the minute spot begins to grow. 

 Then we find a bacteriosis of carnations 

 fully established and now a germ disease 

 instead of an insect must be fought. 



1 do not mean to assert that all cases 

 of bacteriosis are started in this way, 

 for any skin wound will serve equally 

 well; but it cannot be doubted that in a 

 large percentage of cases the origin of 

 the disease Is from an insect puncture. 

 As the insects increase in number, their 

 injury becomes more severe. Yellow 

 spots multiply and the plant begins to 

 feel not only the loss of sap, but the fail- 

 ure of the leaves to exercise their proper 

 function. The disease centers are equally 

 multiplied and the plant becomes physic- 

 ally unfit to perform its work of pro- 

 ducing perfect flowers in satisfactory 

 quantity. 



We get then one very important sug- 

 gestion here — keep plants as sound as 

 possible and deal with insects at once, 

 when they are few in number, not when 

 they have become so numerous that the 

 plants are practically unable to recover. 

 We must always remember that plants 

 are living beings and responsive to both 

 good and bad treatment. They are as 

 variable in their resisting powers to out- 

 side influence as are the members ot the 

 animal kingdom, and the one in the best 

 physical health in either case, stands the 

 best chance ot altogether avoiding In- 

 jury. 



To understand just how contact 

 poisons work on insects we must con- 

 sider for an instant the general anato- 

 my, and particularly their mode of 

 breathing. Insects have no closed sys- 

 tem of blood circulation such as we find 

 in higher animals. There is only one 

 long tube more or less divided into cham- 

 bers and this acts as a pump, forcing the 

 blood Into the head cavity and from 

 there it makes its way through the body 

 among the muscles and viscera until it 

 finds its way back into the pump. 



Neither do insects have lungs and yet 

 they require air to purify the blood, tor 

 life is essentially the same in them as in 

 man. Therefore a modification m struc- 

 ture has occurred and the air is carried 

 in flexible tubes to all parts of the body. 

 These tubes go everywhere where the 

 blood goes and they open along the sides 

 of the body — never on the head. An in- 

 sect breathes, then, along the entire 

 length of each side and there may be as 

 many as 20 openings, although there are 

 usually less. Ordinarily contact poisons 

 act through these spiracles or breathing 

 pores, though sometimes, on soft-bodied 

 slugs, we can use caustics. In the green- 

 house, however, these caustics would be 

 almost as dangerous to the plants as to 

 the insects, hence the safer materials 

 which act through the spiracles must be 

 employed. 



These may be soaps of various kinds, 

 tobacco decoctions, oils, dry powders or 

 gases, and each of these acts in a differ- 

 ent way. 



C>ne of the simplest of the remedies 

 usually employed is sulphur, either dry 

 or in the shape of sulphur water. In 

 either case the result is due to the decom- 

 position of the sulphur producing a va- 

 por which is deadly to insect life. 

 Against creatures like the red mite or 

 spider so often found on violets and 

 other plants, dry sulphur spread on the 

 soil and allowed to decompose slowly 

 by the warmth and moisture often acts 

 like a charm. Sulphur, indeed. Is almost 

 a specific against mites or similar minute 

 spider-like creatures. The gases given 

 off by its decomposition seem to be dead- 

 ly to them. To the plants it is harmless 



unless used in unreasonable quantity. 

 Exactly where the reasonable line ends 

 is a question which the experience of the 

 gardener must ascertain for each line of 

 plants; but ordinarily there is no risk in 

 sowing the sulphur so as to yellow tho 

 soil very perceptibly. 



The sulphur acts only when the insects 

 are In the active stage, and does not in- 

 jure the eggs, hence infestation may con- 

 tinue for some time after the sulphur is 

 applied, and so long as any unhatched 

 eggs remain. 



Against plant-lice sulphur is of little 

 use as compared with tobacco. Tobacco 

 in all forms is a good thing. It is a fer- 

 tilizer, the nicotine as it is sradually ex- 

 tracted by the moisture of the soil kills 

 almost all insect life contained in it, and 

 when vaporized it is death to plant lice. 

 The mere smell of the tobacco while ap- 

 parently unpleasant to many nsects is 

 not poisonous to them. But an extract 

 in water so applied that the insects be- 

 came covered, is rapidl.v fatal. So to- 

 bacco smoke when breathed by insects Is 

 fatal to many, while it stupefies a yet 

 greater number. I need not speak on 

 this point to practical florists, all ot 

 whom have probably had experience in 

 this direction. A very good way to use 

 tobacco where pipes are sufficiently hot 

 is to smear them with a tobacco extract 

 and moisten from time to time until it 

 has all evaporated. This will penetrate 

 everywhere and will settle on everything 

 in almost invisible globules, killing all 

 the aphides that come under its influence. 



This leads naturally to another very 

 Important point that must be considered 

 and whose neglect accounts for many 

 failures. Most insects have the bodies 

 either pubescent, very polished, or pow- 

 dery or somewhat waxy on the surface, 

 so that they shed water quite readily 

 and anv application of a coarse spray 

 simply rolls off without effect. So also 

 the spiracles or breathing pores are fur- 

 nished with protecting screens ot hair or 

 bristles which serve to keep out foreign 

 material. A large drop of water or wa- 

 tery decoction has not the least chance 

 of penetrating through this protection 

 and the application is useless as an in- 

 secticide. Use the same mixture with an 

 atomizer and the result will be quite 

 different. The minute globules adhere 

 readily to the insect because they are 

 not heavy enough to roll off; they pene- 

 trate between the protecting screen or 

 under it, and enter the body with the in- 

 breathing. Therefore when tobacco or 

 anv other watery mixture is to be ap- 

 plied it should be put on in as fine a spray 

 as can be secured. 



For cleaning house plants of all save 

 scale Insects, a tobacco soap suds put on 

 with an atomizer, is almost perfect. 

 This brings me to soaps as insecticides 

 and they act in a somewhat different 

 way. When put on very strong they are 

 ot course very caustic and as dangerous 

 to plants as to insects. Put on at a 

 strength safe to the plants they clog the 

 spiracles and thus choke the insects to 

 death. 



Some of you in days gone by may have 

 made soap bubbles, and if you did not 

 vou have probably seen others make 

 them. This is a good example ot the 

 tenacity ot a soap film, and it such a one 

 forms over the spiracles of an insect the 

 creature simply chokes to death. That 

 explains how soaps art and the one that 

 forms the stickiest film is the best. Tar 

 soaps, or fir-tree oil soaps are particu- 

 larly good for that reason, and fish oil 

 soaps come next. You can readily test 

 the difference between these and the 

 common hard soap suds if you make a 

 solution of equal strength. The common 

 soap suds will feel clean and smooth and 

 crisp to the hand, while the others will 

 feel more or less slimy. These soapy 

 mixtures should also be put on in a fine 

 spray and from what I have said you 

 will realize that thoroughness is essen- 

 tial, for no Insect not actually hit by an 

 application will be in the least affected 

 by it. Soap suds have an advantage 

 over mere watery mixtures, because they 

 adhere better. The insect surface that 

 will shed a droplet of water will retain 

 and become covered by one ot soap-suds 



