1872 The Western Pomologist and Gardener. 107 



Pear Bliglit, --Criticisms on Dr. Stayman's Position. 



Br D. B. WiEn, Lacon, III. 



Ed. Pomologist and Gardener. — In thu January number of the Pomolooist, Dr. 

 Stayman complains of trouble in tracing pear blight to a fungoid cause. The Dr, 's 

 right in his firstly, secondly and thirdly, but certainly not in his fourthly, where he says 

 " They (fungi) will attack trees in a most destructive form on one piece of ground, and on 

 another piece of ground not one hundred yards distant, containing trees of the same kin^t 

 same age, and even of the same variety, they make no attack whatever, notrnthstandivg 

 all the trees are iurrounded by the same circumstances, in regard to heat and cold, wet and dry, 

 sunshine and shoxcer." This must have been written thoughtlessly, and I am certain the 

 Dr. does not believe it himself No two pieces of land, even only fifty yards apart, 

 were ever surrounded by the same circumstances in regard to any point named, and 

 believing as I do that blight in a pear tree may reasonably have its origin in the slightest 

 causes imaginable, lhe.se little points have their weight. 



That the most fatal blight irv the pear, and the one most common, or n other words 

 the one that destroys the bark and sap-wood is a fungus, is a fact as well proven as any fact 

 in science can well be. Farther, blight does attack pear trees in the driest of summers, as 

 is well proven by its development among my trees the last two exceeding dry sum- 

 mers, while in the exceeding wet summer of 1869, I saw no case of wood and bark blight 

 in that season in this neighborhood. It is certainly the most prevalent here in very dry, 

 hot Junes, if the trees are making a very thrifty growth at that time. And farther, it is 

 well proven that some fungi do from their own vital power alone attack and destroy 

 healthy, living tissue. Whether they do this by their own vital power, or by exlialing 

 noxious gasses, or by absorbing principles necessary for the health of their victims, 

 remains to be proven in any particular case; yet, it is the general rule that they usually 

 find nidi in disorganized tissue primarily, but tliis does not militate against their ability 

 to destroy healthy, living tissue in contact with a nidus. Now if these are facts, and I 

 believe them incontrovertable, it is easy to explain to the Dr. how blight can attack a 

 seemingly perfectly liealthy and vigorous tree, why it does not attack one of feebte growth 

 and why root pruning can and does check it, if it is properly done and at the right time, 

 and also why it is more to be feared in a dry time, if there is a thrifty growth of tree. 



Can any one find such a thing as a pear tree in the growing season in this little world 

 of ours, that has not diseased and disorganized tissue in contact with liealthy 1 Most 

 certainly he cannot. No pear tree ever did or ever can pass a summer without some 

 point being exposed to serve as a breeding place for a fungus, but that is no reason that tlie 

 fungus will propagate in it. Its proper seed or spore must first find a lodgment in il, 

 and the essential conditions must be right for that spore's germination, and it mu.st fiuti 

 in the nidus a sufficiency of proper food to support it. If all things arc right it generates 

 amazingly, and fills the whole tree with its disorganizing and deadly presence. I am 

 fully convinced that the most destructive form of pear blight, the one under considera- 

 tion, always has its birth-place in some point where living tissue of low vitality is 

 exposed, and such exposed part must generally be of some considerable size and remain 

 exposed for some considerable length of time, and be kept by the vigor of the tree (free 

 flow of sap) in a condition to act as a nidus and nourisher of the fungus. Now we come 

 to the point. But I will lead Dr. Staj'man up -to it carefully, so as not to startle him too 

 much. 



At what time of year do we find the most blight ? From the first of June to the 

 first of July. 



What are our pear trees doing during this month V They are depositing a new layer 

 of wood and bark on their branches and trunk. 



What aged trees are most generally attacked ? Those over four years, planted in 

 orchard. 



In what condition is the bark of such trees? The outer bark on the older portions 

 of the tree has become dead and hard, but still clings firmly to the inner live bark. 



