»r-.^ ■,vr.'- • ' 



,...,p.,..,.or-j-^-.- i;f Jfe ;•.'., ir'f 



March 16, 1922 



The Florists^ Review 



31 



_rgSesaSBS25HSHSHSHSH5iSHSHS2SZ5HS2SHSHSasaSE5HS2SasaSHSHSH5aS?SasaSHSESasaSHSap 



SCIENTIFIC INFORMATION 



i-2SH5ESHSHSaSH5B52SE5HSHSHSHSES2SHSZS2S2S2SSSHSHSHSSSH5HSSSESaSHS25ZSZ5E5HSZ5H' 



\ 



WHAT FLOEISTS SHOULD KNOW. 



Controlling Soil Diseases. 



In attempting to discuss a big arfd 

 more or less indefinite subject such as 

 the title of my paper suggests, I do not 

 wish to have you think that the writer 

 knows more about the practice of grow- 

 ing greenhouse crops than do his listen- 

 ers. The writer is fully aware that 

 growing plants for the production of 

 flowers of high quality is an art based, 

 in a large measure, upon experience. 



But aside from the knowledge ac- 

 quired by experience, there is a mass of 

 knowledge, more or less systematized, 

 which haa been acquired by careful and 

 painstaking experiments. Scientific 

 facts, however, are not always easy of 

 application and often, unfortunately, it 

 is difiicult to harmonize them with our 

 experiences. 



One of the important problems of the 

 florist at the present time is the control 

 of soil diseases. By soil diseases I mean 

 nof a lack of fertility of soil, due to an 

 insufiSciency of plant nutrients, but 

 diseases caused by fungi which inhabit 

 the soil. The aster is killed by a wilt, 

 the sweet pea by a root rot, the carna- 

 tion by stem rot, the violet by a root 

 rot, the cyclamen by a rot at the base 

 of the leaves. 



Futility of Sterilizing Soil. 



We have not yet learned how to con- 

 trol these diseases in every case. The 

 fact that the causal fungi live in the 

 soil and attack the plant at the root or 

 at the base of the stem, makes the com- 

 mon practices of spraying and fumi- 

 gating useless. Soil sterilization by 

 means of heat is not always practical 

 and, in the case of some diseases, it is 

 also ineffective. Stem rot of carnations 

 is most destructive early in fall, during 

 August, September and October; the 

 root rot of the sweet pea is noticeably 

 destructive if the crop is planted early. 

 In a similar way with other crops, the 

 temi)erature of soil and air is a de- 

 termining factor. We may conclude 

 from this that a metliod of control of 

 such diseases lies in the time of plant- 

 ing the crops. Soil sterilization by 

 means of heat is not always practical 

 and, in the case of some of these 

 diseases, not effective. 



Formalin has been tried extensive- 

 ly by several experiment stations for 

 the control of root rot and damping off 

 of seedlings, and is definitely recom- 

 mended. Sodium cyanide in solution 

 has been recommended for the control 

 of eelworm, with the suggestion that 

 this substance may prove efficient 

 against soil fungous diseases as well. 

 Acid phosphate has been found useful 

 in the control of the root rot of some 

 ■plants. Bleaching powder gave good 

 results in England in some experi- 

 mental plots of vegetable crops. 



We must realize, however, that soil 

 disinfectants, although they have prov- 



Address on "What the Florist Should Know." 

 presented by Dr. P. A. L«henbauer, plant 

 physiologist of the department of horticulture. 

 University of Illinois, at the annual meeting of 

 the Illinois Stiue Florists' Association, at Ur- 

 t)ana, March 15. 



Dr. P. A. Lehenbauer. 



en successful in particular cases, have 

 certain limitations and shortcomings. 

 Fungi often are in a stage in which 

 they are resistant and, like seeds of 

 higher plants, may be subjected to 

 drying, freezing, high degrees of tem- 

 perature, and poisons without being 

 killed. A fungus is killed readily, how- 

 ever, when in the growing stage. It is 

 imperative, therefore, that when a dis- 

 infectant is applied to a soil, condi- 

 tions have been favorable for the 

 growth of the fungus. Such conditions 

 imply a favorable temperature and ade- 

 quate moisture. But it is more impor- 

 t;int to keep in mind that any addi- 

 tions of soil, manures or other organic 

 matter will inoculate the treated soil 

 with the fungus and thus influence the 

 effectiveness of the disinfectant. The 

 soil in the bench may be disinfected 

 and the parasitic fungus thus de- 

 stroyed, but when seedling plants are 

 set into this soil, the fungus may read- 

 ily be reintroduced by means of the 

 soil clinging to the roots of the pl-ants. 

 Adding natural manures to the soil 

 after disinfection may bring about sim- 

 ilar results. 



Analyzing rertllizers. 



From the standpoint of fertility there 

 are three essential food elements with 

 which the grower is concerned; namely, 

 nitrogen, potassium and phosphorus. As 

 to the form in which fertilizers occur, 

 we may classify them in a general way 

 into two groups: Those which are read- 

 ily available to the plant, and those 

 which become available only slowly. 

 The florist expects a relatively rapid 

 growth of his plants and, in order to 

 obtain this, a fertilizer which is read- 

 ily available is desirable. It is for this 

 reason that we recommend such fer- 

 tilizers as sodium nitrate, dried blood, 

 acid phosphate and treated bone. Solu- 

 ble nitrogen compounds are more or 



less pronounced in their effects on 

 plants by the resulting type of growth. 

 The effects of phosphorus and potas- 

 sium compounds are less evident, but, 

 on the other hand, overfeeding with 

 them is also less likely. 



The application of proper fertilizers 

 to soils does not necessarily insure the 

 best growth of plants; the use of phos- 

 phorus, and potassium and nitrogen 

 will not result in high-grade plants if 

 other conditions are unfavorable to 

 growth. Tlie plant has certain soil re- 

 (juirements, aside from those of chem- 

 ical composition of soil. The physical 

 state of the soil is no less important. 

 Therefore, growth of the root system 

 requires conditions within the soil 

 which i)erniit a ready diffusion of air 

 in order that the cells of the roots may 

 be supplied with oxygen and, at the 

 same time, conditions which permit 

 them to dispose of the useless waste 

 products. In addition, a circulation of 

 air in the soil is essential for the va- 

 rious chemical processes which are go- 

 ing on in our soils, whereby the soil 

 materials are made soluble and changed 

 into forms usable by the plant. 



Tliese physical conditions of the soil 

 often are the limiting conditions of 

 growth; that is, they are the factors 

 which determine the amount and qual- 

 ity of growth rather than the quanti- 

 ties of fertilizers present in the soil. As 

 I have pointed out to you on previous 

 occasions, these physical conditions of 

 the soil may be provided in our green- 

 house soils by means of organic matter, 

 such as manures, and by regulating the 

 moisture conditions of the soil. Natural 

 manures supply food materials to the 

 j)lant, but in addition they furnish, 

 what is equally important, a favor- 

 able environment for the roots of the 

 jilants. The organic matter of soils, 

 which may bo provided by means of 

 manures, furnishes not only food ma- 

 terials for both plants and bacteria, but 

 by means of it the soil is provided with 

 pro})er conditions of air and moisture 

 for the growth of the roots. If the soil 

 is heavy and comi)act, it is made more 

 oi)en and porous, so that water and air 

 penetrate more freelj'; if the soil is 

 light and sandy, it is made more com- 

 pact. 



Regulating Growing Conditions. 



The florist grows his plants under 

 intensified conditions; that is, under 

 conditions stimulating rapid growth. 

 The factors involved in this forcing 

 process are a relatively high tempera- 

 ture, increased moisture and an abun- 

 dant food supply. Under these intensi- 

 fied conditions, the plant reaches a high 

 state of perfection. So long as the ex- 

 ternal conditions, as well as the inter- 

 nal conditions of the plant, remain uni- 

 form the plant responds ideally, but 

 with each and every change in the 

 growing factors there occurs a critical 

 period in which its health, if not its 

 very life, hangs in the balance. In its 

 natural state the plant is adjusted to 

 the variable and even severe changes 

 and it responds readily without effect. 

 But in our greenhouses, where condi- 

 tions of intensive culture prevail, at 



