1917] DISEASES OF PLANTS. 49 



Experiments were conducted to determine the probability of the establishment 

 of this disease in Connecticut, and tubers were planted ia clran soil after being 

 treated with formalin alone or with formalin and dusted with sulphur. No 

 powdery scab ar)peared, and another experiment was undertaken on the sup- 

 position that the soil might have l)ecome infected. Badly scabbed potatoes 

 were received and planted in a new plat, and potatoes treated as above were 

 planted in the places occupied by the potatoes in the previous experiments. The 

 potatoes when dug showed no powdery scab, even under microscopic examina- 

 tion. The author concludes that this disease is not likely to prove a serious one 

 in Connecticut. 



Seed and soil disinfectants for the Rhizoctonia disease of potatoes, W. J. 

 Morse and M. Shapovalov {Abs. in Phytopaihologif, 6 (1916), No. 1, pp. 118, 

 119). — Seed tuber treatment for the control of Khizoctonia disease of potatoes 

 was found more successful with corrosive sublimate than with formaldehyde. 

 The application of sulphur in the soil at the rate of 500 lbs. per acre increased 

 the diseased plants from 20 to 30 per cent. 



Potato spraying experiments, third report, G. P. Clinton {Connecticut State 

 f^ta. Rpt. 1915, pt. 6, pp. JflO-.'fSl). — In continuation of a previous report (E. S. 

 K., 25, p. 545), the author gives the results of spraying experiments which 

 have covered a period of 14 years. These experiments were undertaken to 

 determine the value of Bordeaux mixture as a fungicide, to compare the effect 

 of ridged and level culture in preventing rot of tubers, and the value of other 

 fungicides as compared with Bordeaux mixture. 



Homemade 4 : 4 : 50 Bordeaux mixture gave an average increase of 38 bu. 

 per acre during the 13 years the tests were carried on. Not only did the Bor- 

 deaux mixture control blight, but in dry years lessened injury from tip burn 

 and had also possibly a stimulating effect as shown by an average increase 

 of 29 bu. per acre during blight-free years. In all but 4 of 22 tests, the extra 

 cost of spraying was more than covered by the net gain. 



In the experiments with ridged v. level culture, it was found that ridging and 

 deeper planting tend to lessen rot and blight of potatoes in bad seasons, and 

 in addition, the ridging permits better spraying and easier access to the plants. 

 The total yields of ridge<l potatoes were as high as those from level culture, 

 the yields of first quality potatoes were greater, and the tubers were less sub- 

 ject to sunburn. 



In the comparative test of fungicides, none was found to equal homemade 

 Bordeaux mixture. 



A new species of Melanconium parasitic on the tomato, W. II. Tisdale 

 {Abs. in Phytopatholoyy, 6 {1916), No. 1, p. 116). — On both green and ripe 

 tomatoes in the greenhouse at the Wisconsin Experiment Station, small, dark 

 brown or black spots, seldom more than J in. in diameter, have been observed. 

 From these a fungus was isolated and inoculations were made both through 

 wounds and by spraying unwounded fruit. The characters of the fungus are 

 said to correspond to those of the genus Melanconium, although no record of 

 the parasitism of this genus on the tomato has been found. 



Infection and resistance studies of Phytophthora infestans on the tomato, 

 I. E. Melhus {Abs. in Phytopathology, 6 {1916), No. 1, p. 107).— The author 

 reports tomato foliage as readily infected with P. infestans from the Irish 

 potato, but it has not been possible to infect the fruit except through the 

 peduncle, the calyx, or the epidermis when ruptured. The fungus is said to 

 spread more sparingly on the foliage of the tomato than on susceptible varieties 

 of potato. Variations in susceptibility of different varieties of tomato and po- 

 tato to attack by this fungus are reported. 



