196 



THE CANADIAN HORTICULTURIST 



August, 1907 



spores were found in process of germina- 

 tion, i.e., zoospore formation (swim- 

 ming spores); moreover, the fungus 

 threads or mycelium were found rami- 

 fying through the interstices of the soil 

 for one-fourth to one-half of an inch 

 from the surface of such decaying tubers 

 and there sporulating abundantly." 

 These facts would seem to prove con- 

 clusively that the spread of the fungus 

 from tuber to tuber actually occurs. 



GENERAL RESULTS OBTAINED 



Summarizing the results obtained, 

 both by Professors Massee and Jones, 

 we note that there are several ways 

 whereby this phytophthora blight is 

 disseminated. 



(1) Infection of tubers by means of 

 spores, the latter being conveyed by 

 rains and so forth to the tubers. 



(2) Infection of tubers by spores from 

 adjacent decaying tubers, particularly 

 in moist soil. 



(3) Infection of tubers of same plant, 

 by mycelium extending from diseased 

 tubers through the stem into adjacent 

 tubers. 



(4) Infection of the plant by mycel- 

 ium, through planting diseased sets, in 

 which case the fungus threads develop 

 with the plant, sporulating on the leaves 

 and under favorable conditions the 

 •tubers. 



(5) Infection of host plant, by means 

 of spores, blown from neighboring dis- 

 eased plants, obtaining entrance directly 

 or through the leaf stoma. 



Considering these various ways of 

 infection, it is clear that the long-prac- 

 tised method of spraying with Bordeaux 

 mixture should be persistently continued 

 so that the blight may be controlled in 

 its preliminary stages and the fungus 

 spores either destroyed or kept well in 

 control. If these spores infect the 

 tubers and the infected sets are planted 

 the following spring, the fungus would 

 develop with the plant, maturing even 

 more rapidly and producing sufficient 

 spores to infect the whole neighborhood. 



THE POTATO SCAB 



The term scab refers to the irregular 

 rough areas on the tubers, and is caused 

 by the fungus Oospora scabies. This 

 fungus was widespread throughout the 

 State of Maine during 1905-6, but is 

 successfully controlled by treating the 

 tubers before planting with either cor- 

 rosive subHmate or formalin.* As this 

 precaution is commonly in vogue there 

 is no good reason why this disease 

 should prove destructive. Quebec was 

 comparatively free from this fungus. 



THE FUNGUS WET ROT 



There are several forms of wet rot, 

 some being due to fungi, and others to 



*Two ounces corrosive sublimate dissolved in two gal- 

 lons hot water; then make up to fourteen gallons. Leave 

 seed iwtatoes for one and a half hours. Allow potatoes 

 to dry before cutting or planting. Half pint of for- 

 malin to fifteen gallons water, soak potatoes two 

 hr»urs, then dry and cut. 



bacteria. Of the parasitic fungus forms, 

 the one which seems to have caused the 

 most recent damage is Rhizoctonia solani. 



This fungus is found parasitic upon 

 the potato tubers and occasionally gives 

 rise to a' series of adventitious tubers 

 upon the stem. It may attack the 

 plant at or beneath the surface of the 

 ground, and by girdling the stem, pre- 

 vent the development of tubers. In 

 severe cases a wet rot occurs, resulting 

 in the death of the plant ; but, in milder 

 forms, it simplv girdles the stem. 



Dr. Nelson (Bulletin No. 71, of the 

 Wyoming Experiment Station) informs 

 us that this disease was particularly 



Rhizoctonia 



Showing the result of sowing infected seed potatoes. 

 (From Bulletin 70, Colorado Experiment Station.) 



destructive in the middle west and in 

 the Rocky Mountain states during the 

 past few years, and as reports of its 

 occurrence have been received from. 

 Ontario (Huron County) and New 

 Brunswick, it is quite possible that it 

 may be far more widely prevalent than 

 heretofore supposed. 



Prof. F. M. Rolfe, of the Colorado 

 Experiment Station, after exhaustive 

 investigation, observes that there are 

 three characteristic stages of the disease. 

 These he designates : The Rhizoctonia 

 stage where only the fungus threads are 

 present; The Coriicium stage, where 

 minute spores borne upon short lateral 

 threads appear, and The Sclerotiuni 

 stage, where compact masses of fungus 

 threads are observed on tubers and 

 stem. This is the hybernating stage of 

 the fungus over unfavorable weather 

 conditions and it is in this form that 

 the disease is carried over winter, the 



sclerotia germinating following spriii. 

 It seems probable that this disease, 

 in affecting an entrance to, and injuring 

 the potato tuber, prepares a condition 

 suitable to the growth of bacteria which 

 enters the tuber and gives rise to a 

 bacterial wet rot. No specific instance- 

 can be given to prove, in this case, that 

 there is any special symbiotic relation- 

 ship between the fungi and bacteria ; at 

 the same time, it would appear that tli 

 tubers, ramified with fungus thread 

 are more susceptible to bacteria. For 

 this additional reason, we urge that 

 spraying be resorted to early in the 

 season, in order to control these fungus 

 diseases and help to minimize the con- 

 ditions favorable to bacteria. 



( To be continued ) 



Tomato GroAving in Alberta 



That tomatoes can be grown suc- 

 ces fully in Alberta is evidenced by 

 the accompanying illustration. Mr. W. 

 P. Reeves, of Edmonton, an enthusi- 

 astic horticulturist who has been in 

 Canada only two years, and who made 

 a hobby of general gardening in the 

 west of England for many years, has 

 met with much success in this Une at his 

 new home. Mr. Reeves does not pro- 

 fess to be a professional gardener, but 

 his first attempt at growing tomatoes 

 in this country created considerable 

 notice on the part of professional gar- 

 deners in the west. Owing to his ex- 

 periencing different conditions of cli- 

 mate than accustomed to in the old 

 country, his efforts have not yet 

 reached the perfection that he hopes 

 to attain. To The Canadian Hor- 

 ticulturist, Mr. Reeves recently wrote : 



"The plants shown in the photo- 

 graph were obtained from both English 

 and Canadian seeds. They were raised 

 in an open hotbed, but I intend start- 

 ing them, in future, as they should be, 

 in a frame. The seed should be sown 

 in the latter part of March, and the 

 plants transplanted to the open in 

 May, when they should reach 8 or 9 

 inches in height and be in the first 

 bloom. The custom, as far as I have 

 seen in this country, is to allow the 

 side-shoots and undergrowth to grow. 

 These should be trimmed to the main 

 stem in order to allow more nourish- 

 ment to be thrown to the fruiting 

 spikes. The plants should be weU 

 watered. The soil here is a black loam 

 with a sandy sub-soil. The latter is 

 not as advantageous as a heavier sub- 

 soil, as it requires more fertilizing." 



Bandaging Trees. — I am a thorough 

 believer in bandaging trees to prevent 

 the onslaught of insects. The large num- 

 ber of insects I have found in the bands 

 around my trees are all the proof I re- 

 quire of the advisability of bandaging. 

 — Adolphus Pettit, Grimsby, Ont. 



