DISEASES OF PLANTS. 147 



various varieties were investigated. While nil varieties have produced 

 them at times, with some varieties they appear more commonly than 

 with others. The production of hollow stalks is thought to be an 

 hereditary trait, and conditions of soil may also have something to do 

 with their occurrence. 



The treatment of plant diseases in 1896, F. D. Chester {Dela- 

 ware Sta. Bui. Vi, jip. 22, lias. •/).— During the year experiments were 

 conducted for the treatment of potato rot, apple scab, potato scab, and 

 black rot of the sweet potato. 



In continuation of the experiments reported in Bulletin 29 of the 

 station (E. S. R., 7, p. 785) the author sprayed Hale Early and Early 

 Elvers peach trees for the prevention of rot. ( .>7 trees of liale Early and 

 32 of Early Rivers being treated. The experiments show that spraying 

 will increase the amount of sound fruit from threefold to fourfold, and 

 that while the previous year spraying alter the fruit reached the size of 

 large peas did not diminish the amount of rot, the contrary effect was 

 observed this season. Spraying trees 10 days or 2 weeks after the 

 beginning of coloring did not effect the diminution of the rot. 



The recommendations of the author for the treatment of peach 

 orchards are (1) to spray heavily with Bordeaux mixture just before 

 the blossoms open; (2) when the fruit has set give second spraying, 

 adding 3 oz. of Paris green to a barrel of the Bordeaux mixture; and 

 (3) when the fruit begins to color spray with copper acetate solution 

 (S oz. to a barrel of water), and repeat in from 1 to 2 weeks if conditions 

 are favorable to the development of the rot. 



The principal sources of infection are pointed out. and especial atten- 

 tion is called to the necessity of removing and destroying decayed 

 fruits. Besides spreading the peach and plum rot, if the fruit is allowed 

 to remain for a long time upon the tree the fungus will make its way 

 into the twigs and kill the wood at the point of attachment. 



Experiments for the prevention of apple scab were conducted with 

 Strawberry and Wmesap apples, in continuation of those reported in 

 Bulletin 21) of the station, and it is shown that 4 applications of Bor- 

 deaux mixture did not decrease the amount of scab sufficiently to war- 

 rant the extra expense, and that 3 applications increased the yield of 

 hrst-class fruit more than 5 times that of trees not sprayed. 



The treatment of seed potatoes with sulphur as a preventive of scab 

 was tested on 8 plats of potatoes. The land was presumably free from 

 scab, there being no record of potatoes ever having been grown ou the 

 land. Before planting, the cut tubers were dipped in water, immedi 

 ately drained, and the pieces, while still wet, rolled in sulphur. The 

 results obtained seemed to warrant the statement that rolling the seed 

 potatoes in sulphur previous to planting will diminish the amount of 

 scab in the resulting crop when grown upon land apparently free from 

 scab. 



The use of sulphur as a pieventive for black rot of sweet potatoes 



