September, 1907 



THE CANADIAN HORTICULTURIST 



219 



Potato Diseases 



Douglas "Weir. B.S.A., Macdonald College 



(Continued from last issue) 



ANOTHER wet rot which caused been less favorable 

 considerable loss in the province 

 of Quebec and was also reported 

 from other parts of Canada, is the Bac- 

 terial Rot, caused by Bacillus solanis- 

 aprus. 



Bacterial Rot 



Infected tubers in section. (From Abdruck aus dem 

 Centralblatt fur Bakterioloeie, Band XVII, 1905) 



According to Prof. F. C. Harrison, of 

 the Macdonald College, Ste. Anne de 

 Bellevue, (Abdruck aus dem Central- 

 blatt fur Bakteriologie, Band XVII, 

 1906), this rot was observed as being 

 destructive, in several districts, as far 

 back as 1904. Since then, it appears to 

 be increasing rather than decreasing, 

 and suspected specimens received from 

 the provinces of British Columbia, Mani- 

 toba, Ontario and New Brunswick, 

 proved, upon examination, to be due to 

 this organism. The leaves of the potato 

 plant, at first, become yellowish and 

 droop ; later, black areas appear on the 

 stems, extending until the leaves, or it 

 may be the whole plant, topples over 

 and dies. The tubers have a bruised 

 appearance and the flesh is soft ; finally 

 the soft areas become black and emit 

 an offensive odor. 



Insects disseminate the disease by 

 carrying the spores about on their 

 bodies, and flying from diseased plants to 

 healthy ones, they inoculate the latter 

 in eating the foliage. 



The remedial measures consist in col- 

 lecting and destroying infected tubers, 

 selecting healthy seed potatoes, storing 

 at a temperature below 45° F., and con- 

 trolling the fungus diseases of the potato. 



LOSSES AND REMEDIES 



When we endeavor to compute the 

 loss to the country caused by insects 

 and fungi in the potato field, we are 

 confronted with most astounding facts. 

 The actual marketable crop for Quebec 

 and Ontario in recent years amounts to 

 about 30,000,000 bushels per annum. 

 In 1901, a good year, the yield was 

 37,000,000 bushels; but later years have 



Dr. Fletcher, the 

 Dominion Entomologist, in his report 

 for 1904 (Experimental Farms 1904, 

 p. 223) says: "In Ontario there was a 

 large yield, but considerable rot ap- 

 peared, especially on heavy soil or on low 

 land ; the extent of the loss is variously 

 estimated at from twenty to fifty per 

 cent.," or in money to the extent of 

 something over seven millions of dollars. 



Professor Lochhead, of the Macdonald 

 College, conservatively estimates the 

 loss from the Colorado beetle alone at 

 ten per cent. An absolutely accurate 

 appraisement of loss is, of course, scarcely 

 possible. But it is no rash deduction, 

 that but for the scourges we have been 

 describing^, the crop of 30,000,000 to 

 37,000,000 bushels, might easily have 

 reached 70,000,000 bushels. 



Anyone can easily compute the actual 

 loss in dollars to the country, and form 

 a fair estimate of the probable loss from 

 vear to year resulting from the exist- 

 ence of these most virulent diseases in 

 so necessary an article of food. The 

 matter is clearlv one of vast economic 



and the necessity of conducting further 

 investigation by scientific methods, 

 have led the Department of Biology in 

 the Macdonald College to decide upon a 

 thorough examination of these causes 

 and remedies of potato infection. The 

 results of these special researches will 

 be duly published and circulated as 

 widely as possible. 



Fall W^orK with Potatoes 



W. A. Broughton, Sarnia, Ont. 



As soon as potatoes are matured, they 

 should be dug. Early varieties are 

 usually sold at once. I have used a 

 potato digger for eight years and could 

 not now do without one. The Hoover 

 digger is the best, as they can be used 

 while the vines are green and heavy. In 

 digging with this digger, 8 to 10 pickers 

 are required. From 1,000 to 1,500 

 bushels can be harvested in one day if 

 the crop is good. 



The pits should be made in rows, one 

 row for everv 20 to 25 rows of potatoes, 

 and about 60 or 70 feet apart in the 

 row, so that the picker will not have far 

 to carry the potatoes. The potatoes 

 should be sorted when picked, the un- 

 saleable ones being put into bags and 

 carted off the field to be fed to hogs or 

 otherwise disposed of. 



Bacterial Rot 



Showinff how the disease has completely severed the stem at point of inoculation, 

 aus dem Centralblatt fur BakterioloBie, Band XVII 1906) 



(From Abdruck 



importance and demands the most 

 earnest and intelligent action on the 

 part of all concerned ; upon the grower 

 the responsibility probffbly lies heaviest, 

 and upon him we would earnestly urge 

 the adoption of the following remedial 

 measures : 



(1) The selection of seed from fields 

 unaffected by diseases. 



(2) The collection and destruction by 

 fire of all infected tubers and plants. 



(3) Regular, thorough and early spray- 

 ing of the Bordeaux- Paris green mixtures. 



The importance of this whole subject 



Seed potatoes should be either pitted 

 or stored in a cool cellar. The pits 

 should be covered with straw with 

 about three inches of earth on top. 

 When wanted for market, the potatoes 

 should be filled into bags with a potato 

 scoop. If they are to be stored until 

 spring, they should be put in pits; but, 

 if they are wanted during winter, they 

 should be put in a cool, dark, frost- 

 proof cellar. 



Vegetable plants should grow quickly 

 and continuously. 



