82 EEPOllT OF THE COMMISSIONER OF AGlilCULTUliE. 



application of some fungicide might prove, beneficial. Experiments 

 alone will prove the usefaliies.s of this. 



The leaf-spot disease of the pear, or "loaf brownuess," as it has been 

 termed, is a common' disease here, and has l)eeu reported as being very 

 destructive in some parts of Europe, The fungus causing it is Mor- 

 tkiera mcspilL It attacks the leaves and young shoots, and the writer 

 has observed it on the ri])e IVuits, spotting them badly. 



As a measure against the si)reiid and api)earaiice ot tlie <lisease, I he 

 exi>criment miglit be made of raking together and burning the leaves 

 uliieh liave fallen !Vom the diseased plants, and in the si)ring severely 

 ]utiiie the naked branches provided with diseased spots, burning (liese 

 cuMiiigs also.* 



The white rust of the strawberry, a \vide-si)read and well-known 

 <lisease, has caused serious loss to the growers of this fruit in several 

 parts of tlie country. Mr. T. S. V^ari read a psiper on this and other 

 diseases of strawberries before the annuid meeting of the ^Mississippi 

 Valley IJorticultural JSuciety, at New Orleans, January 10, ISSo, and 

 i'lof. William Trelease has given a very full account of the disease with 

 Ihe bibliography, &c., in the second annual report of the agricultural 

 e.Nperinient station of Wisconsin, pp. 47-58. 



Piofessor Trelease says that, so far as can be made out, the disease is 

 favored by hot, wet weather in early n)idsummor. It generally appears 

 in its worst form somi after the berries are ])icked, and is often espe- 

 cially noticeable when a wet spell is followed by drought. Whatever 

 tends to lower the vitality of the plant is believed by some to promote 

 the seveiity of the disease. The disease is caused by a fungus [Ramu- 

 laria tulasuci), whose vegetative ])ortion grows within tlie tissues of the 

 leaf, producing pale or whitish spots, suir(niuded by a dark-red or 

 brownish border. The spots have usually a roundish outline, and their 

 number varies with the extent of the disease. The summer spores or 

 conidia are develoi)ed on the white spots, imparting to them a frosted 

 appearance when viewed with a simple lens. These conidia are borne 

 upon short brauch.es of the mycelium that project through the stomata 

 of the leal', and being exceedingly small and light, are easily transported 

 by the wind or other agencies from place to place, thus distributing the 

 disease. A winter state of this fungus is described and figured by 

 Professor Trelease in the paper above referred to. It appears as small, 

 black, Qix<:; shaped bodies that protrude from both surfaces of the leii ves. 

 These bodies are obviously compact outgrowths from the mycelium 

 and correspond to the sclerotia, in which many other fungi, e. /;., the 

 ergot of the rye and other grasses, pass the winter. By cultiviitiou 

 these sclerotia are made to produce spores exactly like the summer 

 siioi'es. In suggesting remedies for this disease of the strawberry. Pro- 

 fessor Trelease states that it is advisable to select for the i)lanting those 

 A'iirieties which have proved best able to resist its attacks, and espe- 

 cially to reject those which are notorious for spotting badly. Borne 

 :idv;>iitage may be hoped from a free use of lime, wood ashes, fiowers 

 of sulphur, &c., when the disease first appears, as a great number of 

 lie conidia may thus be destroyed and its progress possibly checked. 

 When the plants are badly infested, the Avisest course seems to be to 

 eompletely destroy them by fire, after the berries are gathered, and 

 reset the ground with fresh and healthy plants. 



There are few plant diseases that have caused more serious loss tu the 



* See Jacob Eriksson, " Contribution to the kuowledgo of the diseasos of our culti- 

 vated plants," p. 78. [lu Swedish.] 



