178 AGRICULTURAL REPORT. 



possible that a part of tlio o-flfected braucli may bo left behind, since tto new affection 

 eometimes extends down the brauch several inches. Should any such part be loft 

 behind, it. would develop into a new excrescence. It would be iuterestinjr to know 

 whether these apparent extensions of the excrescences are the product of a new sow- 

 ing of the spores or are produced by an advance of the myceliniw ol' the old tumor 

 just above. It certainly looks, from the frequency of this occurrence, very much as 

 if the luycelinm, having fnllillcd its mission to the old excrescence in waiting for and 

 aiding in the full development of the perithecia, then leaves these to produce their 

 spores without further aid, and with an industry worthy of a better cause pushes its 

 way down the branch through the sofo tissues of the bark and exterior sap-wood to 

 lay the foundation of a new colony. 



'3d. The cutting may be dene at the proper time and done thoroughly, and yet the 

 trees may continue to be attacked by this wretched malady. An indolent neighbor 

 may neglect to prune his trees, and thereby raise successive crojjS of spores to be 

 wafted by the winds to the trees of his more careful and diligent townsmen. Or there 

 may be wild-cherry and plum trees in the neighboring copses or groves which are 

 perpetuating the fungus and sending out each spring a shower of spores to fall upon 

 the cultivated fruit-trees of the vicinity. 



Hence, if we would overcome this enemy, there must be a combined and unanimous 

 effort against him, and skirmishers must be sent ouib to dislodge him from the sur- 

 rounding hills, woods, and waste places. I sec no reason why united and well-directed 

 efforts in this direction may not rid us of this miserable pest. 



Having thus dwelt at some length on this subject, we will brieflj^ notice one or two 

 inferences which we find in the articles in the Practical Entomologist from which we 

 have quoted. We would not even notice these did we not believe them erroneous and 

 fraught with mischief. It is stated that " about the last of July or the first week in 

 August, there grows from each fungus on the surface of the black-knot a little cylin- 

 drical filament about one-eighth of an iuchloug, which no doubt bears the seed, or 

 spores, as they are technically termed, of the f'lrgrij, and that these filaments will 

 shortly afterward fall oft' and disappear, leaving behind them the hemispherical plates, 

 which alone had been hitherto noticed by botanists. * .♦ j discovered 



that the filaments not only cover the entire surface of the black-knot itself, except 

 where a few of them had fallen off, but that they were thinly studded over the twig 

 for an inch or two above and below the swollen black part." 



We do not pretend to say what these little filaments were, not having seen them, but 

 it is very evident, from the fact that thev extended on the twig an inch or two above 

 and below the swollen black jiart, that they had nothing whatever to do with the bear- 

 ing of the spores of this fundus, for its spores, we have seen, are produced in little 

 sacks within the so-called hemispherical plates, which do not extend beyond the swollen 

 part, and besides the spores are not mature until long after the assigned time of these 

 filaments. Once only have we observed anything to correspond somewhat with the 

 description of them. In the latter part of August we collected specimens of black-knot 

 on the wild-cherry, rninus PennsyJvanica, some of the perithecia of which had a little 

 cylindrical rostrum or beak growing from the apex. But all these perithecia, when cut 

 open, were found to be black inside and entirely barren, while those without filament or 

 beak even on the same excrescence were white inside, as in the normal condition, and con- 

 tained rudimentary sacks. We have also frequently seen perithecia without the beak 

 that were black inside. These were in every instance sterile. 



We quote once more, this time in reference to the second inference : " But from the 

 evidence which will bo adduced below, it appears to follow as a necessary consequence 

 that the black-knot on the cherry is caused by a distinct species of fungus from that 

 on the plum." Then the evidence is adduced, which consists in plum-trees sometimes 

 being attacked while cherry-trees in theii- vicinity escape, or the reverse. Then these 

 words follow: "The practical inference to be drawn from the above theory is that 

 plum-growers need not be alarmed when their neighbors' cherry-trees are swarming 

 with black-knot, and chei'ry-growers need not be alarmed when their neighbors' plnm- 

 trees are infested in the same manner ; for the disease can only spread from plum-tree 

 to plum-tree, and probably from the wild red-cherry on to our tame-cherry trees." 



We are not disposed to dispute the correctness of the observations from which this 

 inference was drawn, but we do believe the inference to be incorrect and calculated to 

 lull fruit-growers into a feeling of false security. We have carefully examined good 

 fruiting specimens of the black-knot fungus taken from the choke-chen-y tree, rrunun 

 Firginiana, the cultivated cherry-tree, Prunus Cerasus, and the cultivated pinra-tree, 

 Pninus domestka, and we are prepared to state that there is no essential difierence 

 between the black-knots of these trees. The spores in all are essentially alike and 

 mature at the same tinje. There is a slight difference in the general external appear- 

 ance of the black-knota of the different trees, but this is all, and no good botanist would 

 venture to consider such a difference to be alone of any specific value. We have time 

 and Jigain observed plum-trees and cherry-trees along the same fence and in the same 

 inclosuie alike infested by black-knot. We have seen plum-trees badly infested in 

 localities where the wild-plum tree does not occur at all. We therefore conclude that 



