PioTHYBRiDGE — Observations on Phytophthora eri/throseptica. 193 



and tlie fungus lias now been found in suoli plants in the underground 

 portions of the stalks, in the rhizomes and in tlie roots, always bearing 

 sexual organs in abundance, and sometimes a few oonidia. 



As stated above, affected plants show symptoms of the disease in their 

 overground stalks and foliage, as well as in their underground portions. 

 These symptoms only become apparent, however, somewhat late in the 

 season, so far at any rate as present observations show. They are as 

 follows : — 



From about the middle of August onwards' the foliage of affected 

 plants is characterized by its pale green or almost yellow colour; while the 

 margins of the leaflets are often rolled upwards and inwards, being brown, 

 dry, and crisp. Scattered over the leaflets are larger or smaller brown and 

 dead areas of tissue, which are either isolated or more or less continuous with 

 the brown marginal portions. Frequently all the stalks of a plant are 

 similarly affected ; but oases have been observed where some of the stalks 

 were diseased, while others remained healthy. 



Very often close to the ground-level there is a conspicuous crop of aerial 

 tubers, showing that the portion of that stalk below ground is injured or 

 destroyed. If the affected stalks be cut across with a sharp knife, the three 

 principal vascular bundles are sometimes seem to be somewhat browned, 

 rarely strongly so. On pulling up such stalks, the underground portions are 

 found to be rotten. The epidermal and cortical tissues are decayed, usually 

 without strong blackening, and frequently the wood is exposed. The pith is 

 destroyed, and a cavity is formed lined with cellular debris in which the sexual 

 organs are invariably found, sometimes in extraordinary abundance. This 

 rotting of the tissues at the base of the stalks does not as a rule proceed up 

 the stalk beyond about the ground-level. The mycelium of the fungus 

 has also been found in the wood- vessels ; and its presence there probably 

 accounts for some of the symptoms noticeable in the foliage. 



Some of the roots and the rhizomes may be partially decayed, and if so 

 the fungus with its reproductive organs is found in these also. Some of the 

 tubers, both amongst those at or above the surface of the soil, as well as the 

 deeper lying ones, are also usually affected ; but a few cases have been 

 observed in which the tubers up to the time of digging were free from the 

 fungus, although it was present in the stalks, and in some cases in the 

 rhizomes bearing tubers not yet attacked. 



' "Where such diseases as the blight and the Sclerotium disease are not so prevalent as they are 

 at Clifden, it might be possible to recognize the symptoms on a cursory glance somewhat earliei-. 

 Further, it is possible that the fungus may, by attacking the young sprouts, be the means of causing 

 " misses," 



