1919] DISEASES OF PLANTS. 247 



of disease are recognized, the most eomniou one being tliat usually described 

 and figured as due to Vermicularia. This is characterized by the occurrence on 

 the dry outer scales of the bulbs of circular black spots 15 to 25 mm. in diameter. 

 The second type of the disease is said to occur on the dry outer scales, but it 

 is usually limited to the upper part of the bulb. It is distinguished from the 

 first type by the invasion of the fungus starting at the top of the bulb and usu- 

 ally stopping with the drying of the scales before the equatorial region is 

 reached. It is thought that this type pi-obably results from infection through 

 wounds caused in removing the tops. The third type of the disease is manifest 

 in the bulb scales while still succulent and juicy. The chief manifestation is 

 said to be the formation of tubercles or warty growths. This form of the dis- 

 ease often remains progressive until the scales dry and inhibit further progress. 



A study was made of the various phases of the fungus, and it has been deter- 

 mined that the conidial form belongs to the genus Volutella. The name V. cir- 

 cinann is given it. The perithecial stage has been determined, and is described 

 as CleiHtothecoitsis ciroinans n. g. and sp. 



It has been ascertained from observations that moisture favors the develop- 

 ment of the fungus, and it is suggested that onion sets be dried as rapidly and 

 thoroughly as possible after they have been harvested. Artificial drying in rooms 

 properly equipped for the purpose is considered the most promising method for 

 checking the progress of this disease and reducing losses from rot 



Potato insect and disease control, W. H. Rankin {Rpt. N. Y. State Food 

 Sup. Com., 1917, pp. 30-36). — An account is given of preliminary work and com- 

 nmnity, individual, and demonstration spraying, with results therefrom. 



Leaf roll and mosaic of potatoes, I. H. Vogel {Proc. N. T. State Potato 

 Assoc, 1918, pp. 21-24). — Lesif roll was somewhat generally distributed during 

 the previous season, the number pf infected plants found in liills inspected 

 ranging from to 80 per cent, with an average of about 25 per cent. It 

 seems to occur in all varieties, some developing the disease apparently as a 

 response to the influence of unfavorable environment. Certain climatic con- 

 ditions are important predisposing causes, among which warmth and dryness 

 are prominent. 



Mosaic was quite generally distributed in 1918, the degree of infection also 

 ranging between and 80 per cent with a corresponding i'e<iuction in yield. 

 Data which are mentioned are said to indicate that the percentage of mosaic 

 infection from the same strain is about the same in Northern as in Southern 

 States. Experiments are in progress bearing upon the possible agency of 

 insects in the spread of the disease. 



The most rapid progress in the elimination of either disease Is said to be 

 attained by employing a seed plat as a source of seed for field planting. 

 Tlie proper management of the seed plat is indicated. 



A new method of treating seed potatoes for scab {Iowa St a. Rpt. 1918, p. 

 27). — A method of treating seed potatoes with formaldehyde is described In 

 which the potatoes are soaked from 3 to 5 minutes in a solution composed of 

 2 pints formaldehyde in 30 gal. water, the solution being held at 122° F. 



In order to facilitate handling in large quantities, a machine has been de- 

 vised by which the potatoes are drawn through the hot sohition on an endless 

 chain. This machine has proved efficient for treating 100 bu. an hour. 



Potato spraying profitable (loivn, Sta. Rpt. 1918, p. 36). — As a result of 

 spraying experiments covering a period of five years, spraying with Bordeaux 

 mixture is recommended. Five applications are said to have given an in- 

 crease in yield of 17 per cent, three applications proved not to be sufllcient, 

 and seven represented a diminishing net return. 



