HAMPSHIRE COUNTY 



FARM BUREAU MONTHLrV 



Published by the Hampshire County Farm Bureau 



PRICES 50 CENTS PER YEAR; $1.00 PER YEAR INCLUDING MEMBERSHIP IN FARM BUREAU 



:ilO 



Vol. 1 



Northampton, Mass., June, 1916 



No. 10 



P POTATO DISEASES 



Extracts from paper read by Prof. 

 W. J. Morse, Plant Pathologist, 

 Maine Experiment Sta- 

 tion, Orono, Me. 



(Facts For Farmes M. A. C.) 



The fact is very evident that the 

 .seed tuber is an important agent in 

 the propagation and spread of potato 

 diseases. It is important and desir- 

 able that potato grovvfers should learn 

 to recognize as many of these dis- 

 eases as possible, but it is by no 

 means absolutely necessary. If only 

 healthy tubers from healthy plants 

 are used for seed purposes, and as an 

 extra precaution these tubers are dis- 

 infected before planting, much of the 

 danger of the propagation and spread 

 of destructive potato diseases will 

 be eliminated. 



Rough handling of seed should be 

 avoided as much as possible, as in- 

 juries and cracks give an opportuni- 

 ty for the fungi which causes stor- 

 age decay to gain entrance. Black- 

 hgart is caused by overheating the 

 cars in transit and is nothing that 

 can be communicated to other tub- 

 ers. 



Blacklea: ^^ ^ bacterial disease, is 

 carried only by the seed potatoes, and 

 does not live over winter In the 

 ground in Maine. It is, comparative- 

 ly, an easy disease to control. It 

 may be entirely eliminated by care- 

 fully sorting the seed and removing 

 all tubers which show any rot or 

 diseased areas or any which are ap- 

 parently cracked and jammed, and 

 then disinfecting the remainder 

 with corrosive sublimate or formal- 

 dehyde before planting. 



Potato scab lias been reported on 

 a few other vegetables and root 

 crops, but on none of these is it of 

 any importance except occasionally 

 on be&ts. This disease is of a para- 

 sitic nature and can occur only 

 where the parasite exists in the soil 

 or is introduced with the seed tubers. 

 Limited amounts of uncooked, scab- 

 by potato tubers may be few to cows 

 and the manure used with a fair de- 

 gree of safety, but the germs of this 

 disease readily pass, in a living con- 

 dition, through the digestive tract 

 of a horse. 



There is a fungus which has long 

 been known to students of pathology 

 as Rliizoctonia. One of the char- 

 acteristics of this disease is that the 

 tops may, as a rule, rook fairly 

 strong and healthy and give promise 

 of a good yield, but when dry wea- 

 ther conies on will ripen premature- 

 ly and the yi 'Id will be disappoint- 

 ing in quality and size. Corrosive 

 sublimate seems to be the most ef- 

 fective disinfecting agent for Rhizoc- 

 tonia, but seed should be selected 

 which is as free from the fungus as 

 possible. The land on which it oc- 

 curs in a destructive manner should 

 be given over to other crops as long 

 as possible, before again being 

 planted to potatoes. 



In the disease known as potato 

 wilt, the plants, after they reach 

 the size when the tubers begin to 

 set, may wilt and die more or less 

 suddenly. Sometimes the lower 

 leaves begin to die before there is 

 much evidence of wilt. Tubers with 

 discolored flesh should not be plant- 

 ed for they carry the fungus which 

 causes the disease, and the man who 

 discards all potatoes showing any 

 suspicious discoloration will insure 

 himself against the introduction of 

 wilt. 



Early blight is likely to attack 

 those plants which are weakened by 

 flea-beetle injury or dry weather. It 

 will be seen that early blight is 

 more of a leaf-spot disease and while 

 these spots may run together and 

 cause the death of the leaves, the in- 

 dividual spots are relatively small 

 in size, somewhat circular or angu- 

 lar, and always stop at a vein or 

 midrib. Early blight never causes 

 the decay of the tuber. 



Late' bliffllt produces large blotch- 

 es on the leaves and these do not stop 

 at veins or midrib, but when con- 

 ditions are right spread very rapidly 

 and kill the entire leaf. Epidemics 

 of rot follow severe outbreaks of 

 late blight on the foliage. Bordeaux 

 mixture is a preventive of late blight 

 and not a cure. After the spores 

 have once germinated, and the germ 

 tubes enter the leaves, spraying is 

 useless. 



Seed disinfection, sprays and 

 other preventive and remedial meas- 



ures are valuable and should not be 

 neglected, but they are not the main 

 line of defence against the enemy. 

 The fii-st and most important essen- 

 tial is healthy seed produced by 

 healthy plants. 



SPEAYING POTATOES 



With he exception of last year, 

 for the past five or six years we have 

 experienced very dry seasons with a 

 corresponding small amount of late 

 blight on the potatoes. With practi- 

 cally no trouble from blight, most of 

 the farmers have given up spraying 

 their vines with bordeaux mixtures. 

 Last season many lost heavily by 

 their vines blighting and as the re- 

 sult are turning their attention more 

 to spraying this year. 



Spraying with bordeaux is an in- 

 surance against blight. But even if 

 one was certain that his field would 

 not be struck, efficient spraying with 

 bordeaux should increase the crop to 

 more than offset the cost of spraying. 



At the Vermont Experiment Sta- 

 tion, experiments covering a period 

 of 21 years have been carried on with 

 remarkable results. 



During the last six years with 

 practically no blight present, the 

 average increase per acre of the 

 sprayed over the unsprayed fields 

 have been 67.5 bu. 



The following figures show clear* 

 ly the advantages of spraying even 

 during dry seasons. 



Green Mountain variety 

 Yield per 

 acre 





c4 



5, 



CO 



.'So!* 

 CS cS a 



Year ^ bu. bu. bu." p!, "g 



1906 Two 133 101 32 some 



1907 Pour 171 63 108 little 



1908 Four 156 65 91 none 



1909 Four 243 188 55 none 



1910 Five 240 202 38 none 



1911 Four 156 75 81 none 

 Average for 



last 6 years 183 116 67 

 Average for 

 21 years 263 159 104 



Continued on Page 2. 



