HORTICULTURE 



Soil Sterilization 



\¥e are indebted to tlie Massachusetts Agricultural 

 College and the Hatch Experiment Station for many 

 things, their thorough investigation of soil sterilization 

 being by no means the least of them. Boston lettuce 

 growers are particularly indebted to Dr. Stone of the 

 station, for if some easy and sure means had not been 

 found for controlling certain lettuce diseases, this profit- 

 able crop would have been abandoned by necessity. And 

 sterilization, as a means of preventing these diseases of 

 lettuce, does not apply to conditions around one particu- 

 lar spot or to one special crop. It is insurance from 

 attacks of all fungi which propagate through the soil. 

 The timber rot of cucumbers, the drop and Ehizoctonia 

 of lettuce, damping-off fungi, several kinds of which 

 attack seedlings and cuttings, and the stem rots of carna- 

 tions and chrysanthemums cover a wide range of coun- 

 try so that sterilization should be of wide interest and 

 adoption wliere it has not already found a place. 



Sterilization consists merely in heating all soil used 

 to a high degree of temperature in order to kill all 

 fungus growths which may be existing in it. This is 

 accomplished by the use of live steam (or boiling water) 

 run through a frame work of two-inch pipe, perforated 

 with four rows of 1-4 in. holes. The pipes are placed 

 about a foot apart and one end enters a header while 

 the other is firmly plugged. The steam is forced under 

 heavy pressure into the header and from there is dis- 

 tributed to the various pipes from which it is fed into the 

 soil. This frame is placed on the bed or bench and 

 earth is then piled on it frdm the side, thus one applica- 

 tion treats soil equal to two times the area of the frame. 

 The best results seem to come from treating the earth to 

 a depth of one foot, heating to 180 degrees or more for 

 an hour or two, after which the soil is covered with 

 burlap and the heat retained as long as possible. One 

 treatment should suffice for three or four years providing 

 no new soil or organic matter is added. 



Where it is not possible to submit all the soil used to 

 the influence of steam, excellent results can be obtained 

 by sterilizing that in which the seeds are planted, and 

 the sand used in cutting beds. Many troubles can be 

 traced directly to the infection of the plant while in the 

 cutting bench, so if the cuttings are put in sterile soil, 

 these particular ills can be avoided. 



Sterilization also helps germination. Another great 

 benefit is the extermination of wire worms, grubs, and 

 the like, besides the destruction of nematodes or eel 

 worms (Heterodeia) which tax violets, roses, cyclamens, 

 melons, tomatoes, etc. Weed seeds are also destroyed. 



This form of prevention has been practiced success- 

 fully for several years in a commercial way and while 

 the initial cost appears to be large, one outfit will last 

 several years and will treat large quantities of soil. 



Calceolarias 



From what we have observed the past summer, it is 

 our belief that the vital question, viz., the care of the 

 young seedlings during the hot summer months in the 

 cultivation of hybrid calceolarias, has not been solved 

 by a good many gardeners. We have been growing 

 these plants for a number of years and so far have had 

 no failures to record, and we think this is principally 

 due to the fact that we have used sterilized soil entirely. 

 Of course, we do not say that sterilized soil is a panacea 

 for all the troubles that attack calceolarias, or that the 

 eternal vigilance must in any way be released, but we 

 are convinced that it prevents in a great degree that 

 persistent habit the seedlings have of suddenly vanish- 

 ing from view by damping off. 



It is needless to go into the small details at any great 

 length here concerning the sowing, pricking off, pot- 

 ting on as required, the use of tobacco stems between the 

 plants, having the plants placed well up to the glass, 

 etc., etc. We sow in the usual mixture of soil, leaf 

 mould, sand, and fine charcoal, placing the seed pan's 

 in a cool shady corner and as soon as the seedlings are 

 fit to handle they are pricked off, and then potted along 

 as they require it, always bearing in mind that it is bet- 

 ter to pot a little ahead of time than to allow the plants 

 to become the least pot-bound. Spraying overhead 

 which is so beneficial to most seedlings, only encour- 

 ages damping in this instance, so we only wet overhead 

 when doing the regular watering, and that should be 

 discontinued as soon as they are large enough to be 

 watered singly. Shading must be strictly attended to, 

 for a half hour of bright sunshine on a hot day is most 

 injurious. 



The opinion has been occasionally expressed that it 

 does not pay to grow calceolarias, but the private gar- 

 deners, especially those who have a conservatory to keep 

 looking bright, find that they are almost indispensable, 

 coming in at a season along with pelargoniums, when 

 the usual run of winter-flowering plants are getting 

 rather stale to look at. We would suggest for the com- 

 mercial florist to try a house of them, say, instead of 

 chrysanthemums. If well advertised, small plants to 

 grow on should find a ready market further south than 

 New England, where conditions are said to be wholly 

 unfavorable for the raising of them in summer. 



Of course, the first important thing is to procure a 

 good strain of seed. Unfortunately there are still poor 

 strains offered, for we have seen flowers that were not 

 worth house room, but we feel sure that when we gar- 

 deners create enough enthusiasm in and demand for 

 high-class flower seeds, the seedsmen will vie with each 

 other in supplying our demands, for we hope to see the 

 time when all our seedsmen will have houses of cycla- 

 mens, primulas, cinerarias, calceolarias, etc., devoted 

 solely for seed purposes. 



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