September 20, 1913 



HORTICULTURE 



401 



THE RELATION OF LIGHT TO 

 GREENHOUSE CULTURE. 



Bulletin 144 of the Massachusetts 

 Agricultural Experiment Station is a 

 very interesting 40-page pamphlet by 

 Dr. Gieorge E. Stone on "The Relation 

 of Light to Greenhouse Culture." The 

 "summary" on the concluding pages 

 of the bulletin is as follows: 



The experiments described in this bulle- 

 tin not only have a bearing on the physi- 

 ology of crops, but also on greenhouse 

 construction and management. 



Light has an important influence on the 

 configuration of plants. Since most of 

 the plant energy is derived from the air 

 through sunlight, the optimum light con- 

 ditions are important, and there is a 

 marked difference in plants as regards 

 their light requirements. 



During the short winter days many 

 greenhouse crops do not obtain sufficient 

 light, therefore any factor in greenhouse 

 construction which will increase the 

 amount of light is Important. 



Lack of light is responsilile for many 

 greenhouse diseases; on the other hand, 

 too intense light may prove harmful In 

 gome Instances. 



The old type of greenhouse was crude 

 In constructiou, especially as regards light. 

 The modern tendency is to build larger 

 houses, to use stronger material casting 

 less shade, and larger and better quality 

 glass. 



Large houses can be constructed rela- 

 tively more cheaply and managed more 

 easily because there is a less rapid change 

 of atmospheric condltious. etc.. which helps 

 to eliminate many greenhouse troubles. 



Morning light is more Intense than af- 

 ternoon light, our experiments showing a 

 difference of W^c, and ranging as high as 

 30% for some months. This difference Is 

 not constant from day to day, from month 

 to month or from year to year. 



The difTerence between morning and af- 

 ternoon light has a practical bearing on 

 the location of greenhouses as regards 

 points of compass. 



The location of a house as regards points 

 of the compass has a bearing on the prac- 

 tice of spraying plants, the yield of the 

 crop, and to a certain extent on fungous 

 Infection. 



To obtain the best results in a house 

 running east and west, the house should 

 be from 1.") to 30° north of east. This en- 

 ables the plant to take advantage of the 

 more intense morning light and the crop 

 can be syringed with less danger from in- 

 fection. 



The difference in morning and afternoon 

 light mav be shown by various chemical 

 methods, "as well as by the growth of trees, 

 and of crops of cucumbers in north and 

 south houses. Other things being equal, a 

 crop will show greater development on an 

 east than a west exposure. 



There is considerable difference in the 

 light transmitting properties of glass. 

 Second quality, double thick greenhouse 

 glass transmits 18% less than No. 1, double 

 thick, and the third quality double thick 

 transmits 33% less than first quality and 

 157o less than second quality. 



An irregular surface, bubliles. etc., in 

 glass act as lenses and affect the even 

 diffusion of light. 



New glass is slightly superior to used 

 glass. The deterioriation from dirt and 

 other factors is much less than 1% per an- 

 num. ^ ^ , 

 The more nearly the angle of the root 

 coincides with the right angle of the sun's 

 rays the more light is transmitted. 



Relatively steep roofs are superior to flat 

 roofs for' transmitting light. Records 

 made in Februarv show that a house with 

 a roof angle of 46° gave 18% more light 

 than one with a 32° angle roof. 



The reflection of light from surfaces 

 varies greatly. In our experiments we 

 found aluminum bronze to constitute the 

 best reflector of light. 



The practice of lapping glass causes 

 some loss of light, an avefage of 11% In 

 our tests. 



There appear to be no important dif- 

 ferences in the light in a greenhouse at 

 different distances from the glass, practi- 

 cally the same light being obtained at 5 

 feet PS at 3(1 feet. The light to be had 

 directly under the glass, however, varies in 

 Intensity owing to the irregularity of the 

 surface. 



The loss of light from glass may vary 



from 13 to 36%. or more, depending on the 

 quality and condition of the glass, and 

 many other factors. ^ . » ■„_ 



Double glazed houses are much inferior 

 to those glazed with a single layer of glass. 



ODONTIODA CHARLESWORTHII. 



This is one of the bi-generic hybrids 

 which created a decided sensation in 

 England when It first appeared about 

 five years ago. Its parents are Coch- 

 lioda Noezliana and Odontoglossum 

 Harryanum. The color of the flowers 

 is scarlet red. Hybridists have been 

 busy with this phenomenal flower, 

 crossing it back with one of its par- 

 ents, Odontoglossum Harryanum, hop- 

 ing to get more of the character of the 

 latter into the color of the progeny. 

 Odontioda Brewii is one of these cross- 

 es which has flowered within a tew 

 weeks for the first time, but, although 

 it shows some most extraordinary 



Odontiod.\ Chablesworthii. 



characteristics the solid unbroken col- 

 oring is again perpetuated, contrary 

 to all preconception of what might be 

 expected. 



THE GOLDEN ROD. 



This flower is fuller of the sun 



Than any our pale north can show; 

 It has the "heart of August won. 



And scatters wide the warmth and glow 

 Kindled at summer's midnoon blaze, 



Where gentians of September bloom. 

 Along October's leaf-strewn ways 



And through November's paths of gloom. 



Herald of autumn's reign, it sets 



Gay bonfires blazing round the fields; 

 Rich'autumn pays in gold his debts 



For tenancy that summer yields. 

 Beauty's slow harvest now comes on, 



And" promise with fulfillment won; 

 The heart's vast hope does but begin. 



Filled with ripe seeds of sweetness gone. 



Because its myriad glimmering plumes 



Like a great army's stir and wave; 

 Because its gold in billows blooms 



The poor man's barren walks to lave; 

 Because its sun-shaped blossoms show 



IIow souls receive the light of God, 

 And unto earth give back that glow, — 



I thank Him for the golden-rod. 



— Selected. 



THE MUSK PLANT ODOR. 



Editor Horticulture: 



Dear Sir: — I believe Mimulus mo- 

 schatus, in its natural location, is al- 

 ways found on the borders of shel- 

 tered brooks and edges of moist 

 ground. In a damp, close greenhouse 

 the plant has quite a strong odor like 

 musk. I have noticed when the ven- 

 tilators were raised, on a clear, bright 

 day, the odor, which is very volatile, 

 would disappear. When the plant is 

 near an open door, the odor is scarce- 

 ly perceptible. 



Frank Buffington. 



Fall River, Mass. 



Editor Horticulturf,: 



There can be but little doubt that 

 the musk plant, Mimulus moschatus, 

 has lost its scent in the majority of 

 instances, and it is only by careful 

 selection of the most odoriferous plants 

 that a desirable strain can be had. In 

 America, so far as my knowledge goes, 

 there is not a large sale for this plant 

 in which case there would not be 

 enough plants in one person's hands 

 to select from. Twenty-five years ago 

 I remember that a five or six-inch 

 plant was sufficient to scent a whole 

 room and nearly a decade later when 

 I assisted to grow them by the thou- 

 sands for the London market, we found 

 that we had to keep only the scented 

 ones for stock plants, and to propa- 

 gate from cuttings only, and not from 



seed. J i,, » 



In this country I have observed that 

 during the morhing early in the sum- 

 mer the plants give the strongest odor 

 and revel in a moist and shady pos- 

 ition but later when the weather gets 

 too hot one has to smell at least twice 

 to catch any odor at all. Harrison's 

 variety which I have not seen in this 

 country is much to be preferred as a 

 pot plant and is only to be obtained 

 from roots or cuttings. 



Vernon T. Sheevcood. 

 Charlestown, N. H. 



"CROWN GALL" ON MARGUERITES 



Editor HoRTicrLTUKE: 



I would be much obliged and inter- 

 ested if one of your readers could tell 

 me what to do in the case of plants 

 affected -with crown gall, or what is 

 called I believe in the absence of ac- 

 curate scientific information. Bacter- 

 ium tumifaciens? With me this gall 

 has affected marguerite Mrs. F. Sander 

 and Queen Alexandra at the point 

 where the plants were stopped, and 

 grows as large as a marble. I have 

 tried cutting well back and dusting 

 with sulphur but to no purpose: the 

 gall forms again on top of the cut. 

 Both pot and field-grown plants are 

 affected and the young iilants appeared 

 to be perfectly healthy in the first in- 

 stance. 



Yours very truly, 



Vernon T. Sherwood. 



\t the Syracuse (N. Y.) Fair, last 

 week the Julius Roehrs Company, of 

 Rutherford, N. J., showed a carload of 

 tropical plants, together with dwarf 

 evergreens and bay trees, which Su- 

 perintendent Vick termed the finest 

 display of the kind ever exhibited in 

 this section of the country. 



