WHITE ROT IN GRAPE VINES. 563 



which can live as saprophyte and as parasite i.e. the Dematophora 

 necatrix, although various cryptogams occur. In Australia this 

 vine disease occurs very frequently, for vineyards are often planted 

 in ground but recently grubbed, and many root stumps big and 

 small are left in the ground. The Dematophora infecting these 

 stumps as saprophyte spreads to the vine ; or the soil itself, where 

 the forest was, is infected, and in either case the fungus finds the 

 vine a suitable host. It causes more damage in clay or other stiff 

 soils, but even in sandy soils the vine may be affected, although in 

 such cases the fungus principally responsible for it is the Demato- 

 phora glomerata. All vines are subject to such disease, which may 

 be slow in its spreading, but certain n its deadly effect. Usually 

 when the fungus finds suitable environment the vine is killed after 

 about three years. An impervious sub soil with no natural or 

 artificial drainage, apt therefore to get water-logged, is a factor 

 that much helps to render the disease more fatal. It spreads very 

 much like phylloxera, making round patches ever increasing in 

 diameter, and the appearance of those vines suffering from the 

 white rot is also very much like that of those suffering from 

 phylloxera . 



Some species of vines originally from North America, which 

 are resistant to phylloxera, are just as liable to " pourridie " as 

 the Vitis vinifera,and to the same extent are apt to suffer by it. 



The Vitis rupestris, for instance, is specially subject to it, as 

 have the roots a very narrow angle of geotropism, and there- 

 fore tend to reach the deeper layers of the soil. 



The vineyard at the State Viticultural Station near Howlong 

 in the Riverina was planted in 1899 and 1900, soon after the ground, 

 which was a travelling stock reserve, had been cleared of its green 

 timber. Two years after I first noticed the symptoms of " pour- 

 ridie " in the block of Rupestris Metallica ^where the ground, which 

 is very flat all through, takes a dip. It extended every succeeding 

 year, and the affected patch was conspicuous for the chlorosis of 

 the foliage, the terminal portions of the shoots being the first to 

 show the yellow tint, which gradually gained the whole branch. 

 Neither the leaves nor the branches attained their normal size. 

 An examination of the portion of the stem underground and of the 

 roots showed them to be affected with " pourridie," also an examina- 

 tion of the other blocks in the same vineyard proved that the fungus 

 had a hold, more or less, all through the plantation. The worse 

 affected after the Rupestris Metallica was the Riparia Grand Glabre, 

 then the Riparia Gloire de Montpellier, and both these sorts are in 

 a very light sand loam about two feet deep, resting on a stiff sub-soil 

 at a varying depth. The roots of the Riparise have a very wide 

 angle of geotropism, they run therefore closer to the surface, still 

 the degree of infection was only next to that on the Rupestris 

 Metallica. It is rather curious that the same Riparia Grand Glabre 

 planted just alongside, but in a fairly stiff clay, showed little signs 



