T48 ■/oiintal of Ai/ricnlture, \'irturia. | 10 Mauch, 1919. 



FriSUr.S IJisEXSKS and TIIKIK TuEATTklEKT. 



Spraying with fungicides for these lowly forms of phint life, which 

 parasitically attack the trees, the fruit, or both, is another phase of 

 orchard management which annually- demands timely and prompt 

 attention. It is safe to state that never during the history of commer- 

 cial fruit-groAving has the war against these diseases been more scien- 

 tifically and energetically waged than at the present time. It is plain, 

 nevertheless, that the unsatisfactory results, which, owing to the vary- 

 ing climatic and other conditions, sometimes follow even the most care- 

 ful spraying, denote that complete mastery over fungus diseases is 

 difficult to attain. lender ordinary soil conditions, these fungi vegetate 

 most luxni'iantly, and fructify most prolifically in the shelter of dense 

 foliage, if the leaves be somewhat moist and the weather moderately 

 warm. But sunlight and fresh air, ISTature's two great disinfectants, 

 when admitted by scientific pruning to all ])arts of the branch syst-ems 

 of the trees, assist materialh' in subduing fungi. Much difficulty is 

 experienced in dealing with fungi under the humid atmospheric condi- 

 tions which usually obtain on tiat, deep, rich, luoist siltations, and 

 especially when the orchards are situated in secluded valleys. 



As well as the special conditions favouring the develoi)nient of 

 fungi just mentioned, it may be further stated that certain diseases are 

 more prevalent in some districts than in others. Moist weather con- 

 ditions during the vegetative periods favour their development, and 

 some varieties of trees are more liable to infection than others. Al- 

 though spraying is general and thoroughly executed when the setting 

 of a medium to heavy fruit crop is anticipated, some growers do not 

 spray when the_ prospects of a light crop are apparent. In the interests 

 of fruit-growing generally, it may be mentioned that spasmodical spray- 

 ing efforts cannot be regarded as satisfactory, because, during the term 

 of the growers' inaction, the diseases are allowed to re-establish them- 

 selves. When the foliage is liable to be attacked as well as the fruit, 

 the former should be protected by spraying. Careful apple-growers 

 spray young trees such as Yates, which is subject to black s])ot, prior to 

 its arriving at the bearing age in order to maintain a maximum of 

 healthy leafage, which promotes vigorous growth. 



In writing up the subjects connected with fruit-growing, and parti- 

 cularly those relating to pests and diseases, it is difficult, owing to the 

 many indispensable technical terms involved, to treat these mattei's Avith 

 the degree of clarity and simplicity desired by the orchardists. Super- 

 visors, however, when visiting growers not versed in the official phrase- 

 ology of the departmental ])ublications, will endeavour to explain away 

 the apparent complexities and difficulties which confront orchardists. 

 Because a wet spring encourages the growth of fungi, when much dam- 

 age is done to fruit tre<'S, some growers argue that the injiiry is solely 

 due to rain, but only persons unacquainted with the parasitic nature 

 and development of the accompanying destructive agciit would enter- 

 tain such an erroneous idea. 



Bi.Ac'K SroT oi<' THE Appi.E (Venturia inaequalis). 

 The spores or seeds of this fungus, which, especially in wet seasons, 

 is a source of great anxiety to aj^ple-growers, were probably introduced 

 into Australia on the first imported trees. Speaking generally, the 



