Letters on the Diseases of Flants. 



21 



3. Whitewash is a good substance to apply as a destroyer of the spores or 

 other propagating agents of the fungus. Bear in mind that a thin white- 

 wash can be very economically applied with a spray-pump and a coarse Nixon 



Fig. 21. — Showing young 

 fruit-tree whose trunk is 

 protected from the full 

 force of the sun's rays by 

 means of a cylinder of very 

 thin veneer sawn from 

 bark or other material. 



Fig. 22. — Limb of a tree showing 

 proper and improper pruning. 

 The vipper branch has been 

 sawn off too far from the main 

 limb. The lower branch, 

 having been sawn off close 

 to the main limb, will heal over 

 more successfully, and give 

 canker fimgi much less oppor- 

 tunity to gain entrance and 

 do damage. 



nozzle. One advantage of this method of applying the wash is that the 

 smallest twigs can be whitewashed, a thing not feasible with a brush. 



4. A winter spraying with the strongest Bordeaux mixture will do good. 

 The great advantage of a winter spraying is that the solutions may be used 

 much stronger than w^hen the tree is in leaf. Solutions that would injure 

 the foliage may be applied in winter to the bark and buds with impunity. 



How simple and reasonable all these remedies seem when once the nature 

 of the disease is understood ! 



IV. Diseases op the Potato. 

 1. Wet Rot. 



"While the name loet rot is very descriptive of this disease, the name stinTcing 

 rot would be still more appropriate. The disease attacks potatoes in the 

 ground as well as in store, and reduces the tubers to disgustingly stinking, 

 almost liquid masses of mattery-looking rot. Often the whole potato is 

 found so rotton that the slightest attempt to move it causes it to collapse 

 into a semi-liquid mass. Again, only part of the potato will show the liquid 

 rot, the remainder having not yet succumbed. In the earliest stages, while 

 the potato is still hard, the rot may be detected by a dark band which can be 

 seen somewhat below the skin when the potato is cut in two. 



Though it seems fairly certain that the disease is caused by a microbe, it 

 is as yet uncertain what is the exact relation of the microbe to the potato 

 plant. The disease never occurs without the presence of the microbe, and 

 the disease may be transferred from one potato to another with great ease, 

 merely by inoculation with some of the putrescent rot. The microbe has 

 been isolated and cultivated and described. The difficulty arises when we 

 come to consider the relations of the microbe to the stalk of the potato. 

 A disease-producing microbe occurs in the stalk, more particularly in 

 connection with the fibrovascular bundles, it is said, and the question that 

 naturally presents itself is this, " Are these microbes in the stalks identical 

 with, or in any way related to, those in the tubers ?" and this question has 

 yet to be definitely settled. Fortunately for growers these questions do not 

 stand in the way of suggesting very definite and effective remedies. 



