252 



THE CANADIAN HOETICDLTUKIST. 



PEAR BLIGHT. 



N. Y. Agricultural Experiment Station, 

 Geneva, N. Y., Aug. 24, 1885. 



The progress of the work at the 

 Station on pear bliglit this season has 

 been substantial and pi'actical. The 

 work last year established the infecti- 

 ous nature of thft disease. The large 

 number of artificial inoculations made 

 for this purpose wei-e quite free from 

 any danger of accidental contamination, 

 as there was no spontaneous occurrence 

 of the disoi'der in the orchard or the 

 immediate vicinity. This year the 

 disease has shown itself in force, over 

 one-third of the trees in the orchard 

 being attacked, as well as the trees in 

 the adjoining grounds, and the nursery 

 stock, hawthorn hedges, etc., of the 

 vicinity. This opportune visitation 

 has permitted a very thorough study of 

 the progress of the disease in its viru- 

 lent form. 



Last year's work, as well as that of 

 Professor Burrill in Illinois some time 

 since, indicated that the disease does 

 not as a rule spread from limb to limb, 

 and we have now discovered the reason 

 why it does not, and what is moi'e im- 

 portant, have found out the manner 

 and time of its real attack upon the 

 tree — when it first finds entrance into 

 the tissues and begins the work of des- 

 truction. 



While taking a stroll the last day of 

 June a solitary hawthorn shrub was 

 met, with the larger part of the leaves 

 brown and dead. Its odd appearance 

 attracted attention, and a close inspec- 

 tion indicated that it was suflfering 

 from blight, a conclusion fullj corrobo- 

 rated by a subsequent microscopic ex- 

 amination. In all cases the bliofhtine 

 had evidently begun at the ends of the 

 branches, and largely at the ends of the 

 short spurs along the sides of the limbs. 

 These spurs usually terminate in one or 

 more clusters of flowers in the haw- 

 thorn, wbich at that time had Ions 



passed, and on the uninjured parts had 

 matured into fruit fully two-thirds 

 grown. On the diseased spurs, how- 

 ever, the dead flowers had not precep- 

 tibly developed beyond the condition 

 at flowering. Here was surely a sig- 

 nificant fact. The blight must have 

 attacked these parts not later than the 

 period of flowering, which this year 

 was from the middle to the twentieth 

 of May. The germs found a favorable 

 place of entrance through the moist 

 surface inside the flower, and from that 

 point passed down the flower stalk into 

 the Vjranch, and so on, killing the tissues 

 as it progressed. In cases where it did 

 not find entrance in this way it had 

 attacked those shoots of the present 

 season which were making the most 

 vigorous growth, as the length of the 

 intei'nodes and the number of partially 

 grown leaves on the dying portion 

 readily showed. Subsequent inspection 

 of several untrimmed hawthorn hedges 

 near the Station confirmed all that has 

 been said above, both in regard co the 

 behavior and extent of the disease. 



The orchai'd was at once carefully 

 gone over, and evidences of blight were 

 found in no less than one-third of tlie 

 trees. The following varieties were 

 among the blighted ones .• Bartlett, 

 Buflfum, Doyenn^ Boussock, Flemish 

 Beauty. Mt. Yernori, Seckel, Sheldon 

 and White Doyenn^. In fact the 

 blight seemed no respecter of varieties 

 so far as our assortment was concerned, 

 for all kinds on one side of the orchard 

 were touched, while almost every tree 

 on the opposite side i-emained free. It 

 was found that in many instances the 

 entry had been made through the 

 flowers as in the hawthorn, but more 

 often through the growing tip of a 

 branch. An armful of blighted branches 

 from Kiefler pears, which are not found 

 in oiir orchard, were brought me on 

 July 24 as badly blighted as one often 

 sees. 



