91 



Early Rlight. or Potato Leaf-Curl {Maerdsporiiini solniii). 



This is caused by a fimgiis wliich attiU'ks tlie foliasio. It first appears 

 (111 the older leaves in the form of small brown or grayish-brown spots, which 

 gradually spread and join, so that soon a considerable area is involved, the 

 affected parts becoming curled, hard and brittle, while the remainder 

 frequently assumes an unhealthy yellowish colour. On the ai)pearance of the 

 disease the tubers cease to grow. T'sually in about three weelcs mo.st of the 

 leaves are dead: the stems remain green for some time longer, and then 

 gra(hially perish. The tubers, being tindeveloped and unripe, turn soft and 

 will nnt keep. It has been proved by extensive experiments, both in Kuroiie 

 and America, that spraying with Bordeaux mixture will not only jirevent or 

 keep down fungous disea.ses. but will so increase the yield as to more than ]>ay 

 the extra exjieuse incurred. Great care must, however. lie taken in mixing 

 and api)lying fungicides and insecticides. 



The Macrdniinrhiiii must iidt be mistaken for the extremely destructive 

 "potato-rot." so much dri'adeil in nider countries. There is no doulit that it 

 has been so mistaken, both in England and America, and this mistak<' has 

 given rise to reports that "potato-rot" [Plnitoiihtliurn infcxtunx) had broken 

 out in various localities, when it was onl.v Miicrosi)orium, which, serious as it 

 may be. is not nearly so bad as Phijtoplitliorn. 



Trcutiiiciit. 



As the spores of the potato leaf-curl live through the winter on the dead 

 haulms and leaves of affected plants, it naturally follows that to prevent a 

 recurrence of the disease it is essential to carefully burn all tojis. etc.. that 

 have in the previous season shown the least signs of infection. This burning 

 should be done as soon after the potat<jes are harvested as piossible. as delays 

 are always dangerous. 



I'OTATO Bacteriosis (Bticilliis sol a II (Wear Kill). 



The first sign of disease is disclosed by the yellow colouration and jiretna- 

 tnre wilting of the foliage. Sometimes only a few isolated jilants are 

 attacked, at other times whole rows ma.v become dise.Mse<l. At a later stage 

 the veins of the leaves take on a darker hue than the rest of the foliage, which 

 then rapidl.v di.scolours and dies. 



If a diseased haulm is cut across it will be seen that the woody cylinder 

 shows a brown discolouration, and the vessels are filled with bacteria, which 

 gradually ooze out from the cut surface in dirty-cobmred drojis. lu cases of 

 severe attack tlu' tubers become affected early and rapidly rot. 



Picrciitirc Mriiiis. 



It has been definitely proved that this disease is transmitted from held to 

 field through the agency of leaf-eating insects ; in the United States the 

 Colorado beetle being espeeiall.v active in .siireading this bacterial blight. In 

 consequence of this, it follows that in districts where bacteriosis is known to 

 exist all leaf-eating insects should be kept in cheek. For this purpose the 

 addition of 4 oz. of Paris green to every 40 gallons of Bordeaux mixture will 

 be found an excellent check. 



