376 



SCIENCE 



[N. S. Vol. L. No. 1294 



to have the apples in as sterile a condition 

 as possible. The apples were washed thor- 

 oughly in tap water, allowed to remain in 

 merem'ic chloride (1: 1,000) for five minutes, 

 washed in water that had been boiled, then 

 rinsed in 95 per cent, alcohol. Two punctures 

 were made on each apple with a sterile plat- 

 inum needle. The inoculum of conidiospores 

 was applied to each puncture with a sterile 

 loop needle. The inoculated apples were 

 placed in a sterile granite pan and covered 

 over with a similar pan. The total diameter 

 in millimeters of the spots on the ten apples 

 was recorded. The five series of inoculations 

 were averaged and the results recorded in the 

 following table : 



Apples inoculated on May 10: May 13, 140 

 mm.; May 1.5, 414 mm.; May 17, 788 mm.; 

 May 19, 1,060 mm. ; May 21, 1,386 mm. 



POLYSCYTALUM ON GRAPEFEUIT 



Polyscytalum, has only been found on the 

 market three times and as yet is not a disease 

 of importance. 



The fungus was isolated from a slightly 

 sunken soft area one half an inch in diameter. 

 The spot was of a little lighter color than the 

 color of the fruit itself. The spot has the 

 appearance of a blister filled with water. In 

 tlie early stages of the disease the rot works 

 down to the pulp of the fruit in a perpen- 

 dicular manner. The affected tissue is very- 

 soft, more so than that attacked by Penicil- 

 Hum. When a spot has reached the diameter 

 of 20 or 25 millimeters the fungus begins to 

 attack the pulp of the fruit. An attacked 

 fruit soon becomes a soft mushy mass. 



Five series of inoculations were made using 

 four grapefruits in each series. The average 

 development of a spot is shown as follows : 

 fruit inoculated May 10, May 17, 55 mm.; 

 May 19, 49 mm.; May 21, 70 mm.; May 23, 

 91 mm. 



GRAPEFRUIT FUSARIUM 



Fusarium sp. was first found on a shipment 

 of Florida grapefruit. The fungus was found 

 enough on the Chicago market to classify it as 

 a disease of economic importance. 



The isolation was made from a tan to red- 



dish brown rough sunken area an inch in 

 diameter. The tissue underneath was dry, 

 corky, and of a tan color extending inward an 

 eighth of an inch. These rough sunken areas 

 often reach the size of two and a half by one 

 and a half inches. In the case of the larger 

 spots the ftmgus often develops down into the 

 pulp of the fruit causing a rot. A black and 

 pink development is made in the host tissue. 

 A very fijie white cottony growth often de- 

 velops in the pulp of the fruit and sometimes 

 on the siu-face of the brown rough area. 



Ten series of inoculations were made using 

 three grapefruit in each inoculation. The 

 average growth of a spot is shown as follows: 

 fruit inoculated April 24, May 1, 5 mm. in 

 diameter; May 19, 10 mm.; May 29, 17 mm.; 

 June 2, 20 mm. It is seen that a Fusarium 

 spot develops very slowly. However, in fifty 

 per cent, of the inoculations when a spot had 

 reached a diameter of twenty of twenty-five 

 millimeters a rot developed at the edge of the 

 sunken area. When Fusarium, acts in this 

 manner it is very serious, for a grapefruit 

 will be a worthless rotten mass within forty- 

 eig'ht hours after the rot has started. 



In order to discover what fruit diseases are 

 of economic importance one has to study them 

 from a market point of view as well as in the 

 field. Some diseases are field infections which 

 develop and spread under transit and storage 

 conditions. A more complete study of fruit 

 diseases as occuring on the market will reveal 

 many diseases as yet imknown to plant 

 pathologists. Harold E. Turley 



U. S. Department of Ageicultuee 



SCIENCE 



A Weekly Journal devoted to the Advancement of 

 Science, publishing the official notices and pro- 

 ceedings of the American Association for 

 the Advancement of Science 



Published every Friday by 



THE SCIENCE PRESS 



LANCASTER, PA. GARRISON. N. Y. 



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