Letters on the Diseases of Flants. 



25 



Fig. 26. — Mycelium and conidia 

 from the edge of one of the 

 small diseased spots shown in 

 Fig-. 29, &c. Magnified about 

 350 times. a, b, mycelium; 

 c, c, hyphae bearing sporidia. 



a perpetration which I gladly abandoned in favour of the more euphonious 

 American term. Again, I note that the small diseased spots start at the 

 breathing pores, or stomata, of the orange, as shown in the woodcuts on 

 page 24, which have been very carefully prepared, and give an excellent 

 idea of the appearances, as seen with the 

 microscope. Moreover I find, on examination 

 of the edge of well-developed spots, a well- 

 developed but somewhat peculiar mycelium. 

 This is better pictured in Fig. 26 than in any 

 words of mine. Finally, I note that on the 

 leaves the spots due to this disease are more 

 elevated and blacker than on the fruit. 



I can have no doubt, and I think the 

 scientific reader who trusts to my accuracy 

 of observation will agree with me, that the 

 fungus mentioned and pictured above is the 

 cause of this disease. Experiments have 

 shown me that the mycelium of this fungus 

 ceases to grow after the application of even 

 weak Bordeaux mixture, and experiments in 

 the orchard, so far as they have proceeded, 

 confirm those made in the laboratory. Moreover, both these results are in 

 accord with those achieved in the orchards of Florida. 



This disease is known to our orchardists, in the county of Cumberland at 

 least, as Orauge Rust, and occasionally as Maori. I think both these names 

 should be abandoned in 

 favour of Melanose. The 

 disease is in no sense a 

 "rust," the name of "rust" 

 being one that should be 

 reserved for those diseases 

 caused by fungi related 

 to the well-known wheat- 

 rust. Maori is a name 

 already in use for a distinct 

 disease of the orange, con- 

 cerning which I will here 

 only remark, that it some- 

 times resembles Melanose 

 in a very marked degree, a 

 fact that is sometimes very 

 puzzling to orchardists, es- 

 pecially as the two diseases 

 often occur on the same 

 orange, as shown in one of 



my photographs on page pj^ 27.-Au orange affected with the disease known as Maori, 



26. showing the continuous nature of the brown colouration 



mi • 1 -Li. J.-L X characteristic of this disease. The colouration does not in this 



-L nere is no CipUOr tnat case extend over the whole orange, though such is frequently 



Melanose is doing much the case. 



damage among the orchards around Thornleigh and Parramatta. Last season 

 oranges spotted over with the disease were to be found in the Sydney market 

 literally by the ton. Even where the tree is not prevented by the disease from 

 bearing a crop of fruit, the surface of the fruit is so disfigured by the multi- 

 tude of small dark spots as to have its market value seriously diminished. In 



