408 WALNUT BACTERIOSIS. 



is only in the Cango Valley that there are any number of bearing 

 trees; a number of farms in this valley were visited, and the 

 trees examined during last November, they were all bearing 

 well, and in some instances promised a record crop ; no sign of 

 bacteriosis could be detected on the foliage or on the young nuts. 

 The average rainfall in the Oudtshoorn district is about lo 

 inches, and this falls mostly in winter, so that even if the disease 

 were introduced it is doubtful whether it would do much damage 

 there : bacteriosis only spreads rapidly where there is a good deal 

 of rain and mist during the spring and early summer while the 

 nuts are forming. 



A case of infection occurs at Napier, in the Bredasdorp dis- 

 trict, where the rainfall is i8 inches, but this only involved one 

 tree in a private garden. 



Bacteriosis occurs in several localities in the Eastern Pro- 

 vince ; but it appears sporadically, and possibly in most cases 

 only where it has been introduced with nursery stock. There 

 was no sign of the disease on trees in and around Grahamstown, 

 nor on a few which I examined in the Kowie Valley at Bedford; 

 but at Eastport. where there were a large number of trees 

 in full bearing, the disease was causing serious damage. The 

 season had been an exceptionally wet one, and driving mists had 

 been very frequent. As a result, all the nuts on the side exposed 

 to these misty rains were aflfected and a large percentage of those 

 on the more sheltered side. During the previous season (1916- 

 17) the disease was not so bad, and a good price was obtained for 

 the nuts, but, two or three years belfore, the nuts all became 

 spotted and dropped, just as they did last summer. It is evident, 

 therefore, that the amount of damage which the disease causes 

 is dependent largely on the weather conditions during the time 

 that the fruit is forming. Some of the trees at Eastport are of 

 French origin, and bear exceptionally large nuts, and many people 

 have been getting seed from these for planting. Although I have 

 not _seen any statements to the efifect that the disease can be 

 carried with the seed, and I have not carried out any tests, it 

 seems to me that there must be considerable risk of spreading the 

 infection in this way. 



At Alice there are a number of trees which are looking 

 decidedly unhealthy, the upper branches are dying back as a 

 result of unsuitable soil conditions, but I could see no sign of 

 bacteriosis there. At Toise River, from the reported condition 

 of the fruit, there is probably infection, but this has not been 

 definitely ascertained. 



Owing to exceptional rains last season, serious losses from 

 bacteriosis occurred at Clocolan, in the Orange Free State; the 

 disease has probably been in the trees for some years, but the 

 weather conditions have not before been so favourable for its 

 rapid development. The growing nuts all became spotted, and 

 in about three weeks three-quarters of the crop had fallen, the 

 walnut crop was a complete loss, and the nuts which did not drop 



