DISEASES OF PLANTS. 247 



greatly, while, on tlir contriiry, those affected with Sphseropsis become greatly 

 reduced in size and exhihit an irrei^ular wriulvled surface. Experiments with 

 cultures and inoculations show I lie (litTci'cnce in tlie two diseases. 



The author helieves that a laclc of moisture is one of the imjjortant factors in 

 determining the development of the :Monilia. The precautions taken to prevent 

 the occurrence of scah and other fungus diseases hy spraying with liordeaux 

 mixtiu'e, removing nunnmy fruits, etc., are reconunended for the prevention of 

 this disease. 



A brief ])ii)liograpliy completes the account. 



Pear blight ( Ohlalioiiia St a. Rpt. 1900, p. J/S). — A summary is given of a 

 press bulletin ])revi(msly i.ssued by the station calling attention to pear l)light 

 and giving suggestions for its control. The varying susceptibility of different 

 varieties to blight is pointed out and the desirability of additional data in respect 

 to lial)ility to disease is iudcated. 



The ripe rot or mummy disease of guavas, .1. L. .Sheldon ( West Virffinia 

 Ntd. Jiiil. 1(1). p/t. 299-.31.'). j)J.s. .). fif/. 1). — The author reports having observed in 

 the greenhouses of this Deiiartment some disea.sed guavas, from which material 

 was collected for study on account of the similarity of the disea.se to the bitter 

 rot of apples. Supplemental material was obtained from Porto Rico and 

 Florida, and a study made of the fungus and its effect upon the fruit. 



The disease, whicli has been previously described as due to Glocosportioii 

 psidii (E. S. R., 16, p. 477), seems to be rather widely distributed, and the fungus 

 is known to occur in Porto Rico, Florida, California, Mexico, and Australia. 



When infested by the fungus brown spots appear on the ripening fruits, and 

 these spots gradually increase until the entire fruit becomes affected, the de- 

 cayed fruits finally falling off or remaining on the trees as mummies. 



A study of the fungus to determine its relationship with allied species led the 

 author to l)elieve that it should I)e associated with the genus (Tlomerella. 



The presence of copper in olive oil obtained from fruit sprayed with 

 Bordeaux mixture, X. Passerini {Atti R. Accad. Ecoti. A (jr. Gcorg. Firenzc, 

 5. ser., 3 {19(i6). Xo. 1, pp. 139-l.'fJf). — In the author's investigations olive 

 oil was found to contain traces of copi>er whether the trees had been sprayed 

 or not. The amount found in oil from olives grown on sprayed trees was not 

 appreciably greater than from olives grown on unsprayed trees. The quantity 

 present, which was less than 1 mg. per kilogram of oil, was so small as not to 

 be injurious when eaten. The quantities found ranged from traces to 0.40 mg. 

 per kilogram in oil from olives on untreated trees and from a mere trace to 

 0.47 mg. on treated ones. 



Combined treatment for powdery and downy mildew, L. IIugounenq 

 (Rev. Vit., 2.', {1906). Xo. 6>i.',-6J,6. pp. .',29 .'/.3.?).— In commenting upon the effi- 

 ciency of the treatment suggested for these diseases ( E. S. K., 17 p. 87(0. in 

 which the addition of an alkaline polysulphid to a neutral copper acetate solu- 

 tion was recommended, the author states that this fungicide proved very adhe- 

 sive and quite ellicient in combating both diseases. 



The addition of the polysulphid to the copper solution is said to result in the 

 formation of :i chocolate-colored precii)itate mixed with a small quantity of 

 sulphur. Wlieii sprayed upon foliage this copper n()lysul])hi(l iiecomes copper 

 sulphid through exposure to the air and later is further changed into copper 

 ^•ulphate and sulphur. 



Experiments in combating downy mildew of grapes, X. Passerini {Atti 

 R. Accad. Hcoii. A<ir. (icon/. Fiiriizc. ■',. .<ter.. 3 {19(i(>). Xo. 1, pp. l.'io-UfS). — 

 Experiments are reported which were carried on in IDOn relative to the effi- 

 ciency of copper sulphate neutralized with lime; copper sulphate and iron sul- 



