The Lusk Herald

Pear Blight.

The last report of the Kansas State Board of Agriculture contains a paper on "Pear Blight," from which we select some views regarding the dreaded disease. In the past it has been attributed to insects; to an unknown fungus; to freezing of the sap; to a deficiency of some element in the soil necessary to the growth in the tree; to excess of fertilizers; to constitutional weakness of the trees themselves; to meteorological causes, etc., all of which failed of verification by a review of facts. More recently Prof. Burrell, of Illinois, claimed to have discovered the cause of the disease in bacteria that are invariably present in connection with the disease. He also established the fact that the disease is infectious and can be communicated from one tree to another by means of inoculation, and from the pear to the apple and quince. Last season Prof. Arthur, of the New York Experiment Station, pursued investigations upon the subject which seemed to confirm Prof. Burrell's views. In the experiments it was found that a fluid bearing the bacteria could be filtered of them only by passing it through porous earthenware. That an inoculation by the fluid thus filtered would produce no disease, while inoculation with a fluid in which they were contained invariably produced the disease in a virulent form.

In this way it is scientifically proven that the bacteria are the cause of the disease, and that it is no longer allowable to speak of the bacterial theory of pear blight.

Prof. Burrell has given to this minute organism a specific name—micrococcus amylivorus, or starch-devouring micrococcus.

The investigations of Prof. Arthur lead to the belief that the disease germs enter the tree in the spring through the soft glandular surfaces within the flower or the tender surface of the expanding buds, from the air. It was also found that in July and August great numbers of bacteria were dislodging from the tender limbs, but so agglutinized that the air could not dislodge them; rains, however, would wash them from the tree to the ground, where they would find a congenial nidus in which to remain until finally caught up into the air to be carried and lodged for the work of destruction. Insects might also be the means of carrying the virus from one tree to another. The pruning-knife applied below any diseased portion seems to be the only remedy that is recommended with much confidence. With proper care and attention it is believed that by this means the progress of the disease may be very much arrested.—Farm, Field, and Stockman.