DISEASES OF PLANTS. 449 



The influence of drought on vegetation (pp. 3G0-362). — The year 1897 is 

 said to have been remarkable for excessive rains in July and for 3 

 periods of drought during the growing season, the influence of which 

 on vegetables and ornamental plants is stated. 



Experiments with sir eel potatoes (pp. 362-372). — In continuation of 

 work reported on sweet-potato diseases (E. S. JJ., 9, p. 655), the effects 

 of sulphur and kaiuit were again tested, different plats receiving 800, 

 000, 400, 300, and 200 lbs. of the fertilizer. Two varieties of sweet 

 potatoes were used, Nansemond and Jersey lied. The results indicate 

 that sulphur is valuable as a remedy for the prevention of the soil rot, 

 and that it may be advantageously used in connection with kaiuit. 



Experiments in spraying for asparagus rust (pp. 372-370). — The exten- 

 sive experiments with fungicides showed that while they did not pre- 

 vent the disease they reduced it fully one-fourth. 



Experiments with pear blight (pp. 377-383). — The author reports upon 

 a series of experiments begun on an orchard placed at the disposal of the 

 station, the present report being confined to the effect of winter and 

 summer pruning. In general it may be stated that while the winter- 

 pruned trees were cut back the heaviest the pears were much larger 

 and yielded about as great a quantity as the summer-pruned ones, the 

 difference between the 2 forms being very slight. The experiments 

 testing the effect of cultivation and the use of fertilizers on the devel- 

 opment of blight are to be continued. 



Greenhouse experiments with violets (pp. 383-394). — The leading fungus 

 diseases of the violet are said to be the leaf spots {Cercospora violce), a 

 second form of leaf spot (I'hyllosticta violce), Ascochyta viola', Marsonia 

 viola', Glceosporium violce, an anthracnose due to an undescribed Colle- 

 totrichum, a mildew [Peronospora viola'), and Zygodesmus albidus. In 

 addition to these nematodes are one of the most serious troubles of 

 violets. During the winter of 1896-97, experiments were conducted in 

 the greenhouse in which the effect of depth of soil, fineness of mixture, 

 drainage, mulching, watering, subirrigation, fertilizers, manure, aera- 

 tion, spraying, and soil fungicides were tested. A depth of soil of 5 

 in. seemed to give best results. The coarsest soil, i. e., that which did 

 not go through a sieve with a half-inch mesh, gave best results. 

 Where sand was added in different quantities to fine soil but little 

 difference was noted. The experiment in soil drainage seemed to indi- 

 cate that the use of rock bottom for drainage is useless. Increasing 

 the amount of manure was followed by beneficial results. There was 

 no leaf spot or other foliage disease which seemed to interfere with the 

 growth of the plants, but attacks of nematodes were very apparent, 

 many of the plants being badly galled. 



Field experiments were conducted with violets in which soil treat- 

 ment with lime, sulphur, corrosive sublimate, and kainit were tested, 

 the intention being to note the results of this soil treatment on the 

 winter plants. All the treatments greatly reduced the formation of 

 nematode galls on the roots, and in many cases wholly prevented them. 



