CORNELL UNIVERSITY EXPERIMENT STATION BULLETINS. 329 



These fertilizers were applied May 14, 1891, and June 23, 1892. They 

 were sown upon the ground and found their way under the surface at the 

 regular hoeings. The soil upon which these cuttings were grown was a 

 poor and very hard gravel. This soil was selected because it had .received 

 no fertilizers in recent years and because the results of the different mate- 

 rials would be undisguised by the heavy growth which would be given by 

 a good soil. The early season of 1891 was very dry and many of the cut- 

 tings did not start. Later in the season the remaining plants made a fair 

 growth but no difference could be seen in the plots. It was evident that 

 the fertilizers had not yet reached the roots of the plants. But in 1892 

 the effect began to be marked early in summer, and it was evident that 

 plot No. 4 — nitrate of soda — would distance all the rest. Final observa- 

 tions were made October 19, when it was found that plot No. 4 was best 

 and No. 5 second. These plots gave easily fifty per cent, more growth than 

 any of the remaining eight. No. 2 — cotton-seed hull ashes— was the best 

 of the remaining plots, although its advantage was slight. Between the 

 other seven there were no obvious differences. 



Plot 4 — nitrate of soda — was conspicuously darker in foliage than any 

 other throughout the season. The vines matured well, although the yellow 

 leaves still hung to the plants in the middle of October. Plot No. 5 — sul- 

 phate of ammonia — was perhaps ten per cent, below No. 4 in amount of 

 growth, and the wood was not so well ripened as in the other. 



THE BLACK-KNOT OP THE PLUM AND CHERRY. 

 THE ISEW YORK LAW. 



The black-knot is a serious disease, attacking the branches and twigs of 

 "the plum, sour cherries, and sometimes sweet cherries. It is also common 

 upon wild choke-cherries from whence it spreads to the orchards. The 

 most prolific source of the disease, however, are the neglected hedge-rows 

 of plums and Morello cherries along road-sides and about old buildings. 

 Sometimes black-knot will be noticed sparingly in a community for 

 several years before it seriously attacks cultivated trees, and this fact has 

 caused people to become indifferent to it; but sooner or later it will spread 

 and become a most pernicious evil. Plum-growing is abandoned in some 

 parts of the Hudson river valley because of the incursions of black-knot, and 

 a similar fate is likely to overtake any community which neglects it. It is 

 the duty of every citizen to exert himself toward the extirpation of this 

 pest, and New York and Michigan now have laws to compel its removal. 



Black-knot is a fungous disease, and the only reliable treatment yet 

 known is to cut off the knots and burn them. This operation should be 

 done just as soon as the leaves fall, at the latest. Good plum-growers 

 inspect the trees once or twice during the summer if black-knot is feared. 

 Always burn the knots; if they are not destroyed the spores of the fungus 

 will still develop, even after the knot is cut from the tree. The old knots 

 often contain worms, but these only burrow in the spongy tissues; they do 

 not cause the disease. 



The following is the New York law. Every citizen should support it: 



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