VEGETABLE GROWING IN NEW SOUTH WALES. 



97 



In the tuber itself, infection first shows as a browning of the vascular 

 ring at the stem end, and on cutting across, tbe dirty greyish bacterial slime 



may ooze out. 



Infection may take place in two ways : (1) If slightly infected potatoes are 

 usec} for seed (the disease will not be noticed unless the tubers are cut), the 

 bacteria are able to spread to the growing plant ; (2) leaf-eating insects 

 feeding on diseased plants can transmit the disease from plant to plant. 

 Thus, the chief means of control are careful selection of seed, and spraying to 

 keep down insects. The disease has been very rare in New South Wales ; in 

 fact, its actual existence here is questioned. 



Brown Rot, or Bacterial Rot,. 



Club-root of Cabbage and Cauliflower. 



Plants affected with club-root are characterised by swellings of the roots, 

 sometimes to as large as two fists. Few or no lateral roots are formed. 

 The affected plants have a wilted appearance during the day, but recover at 

 night. Plants ,are generally attacked when young or in the seed-bed, and 

 when so affected have a stunted and sickly appearance and seldom grow to 

 maturity. The malformations may be confused with root-knots caused by 

 eelworms (or gallworms), but these as a rule are not so large as the malfor- 

 mations associated with club-root. 



The cause of the disease is a small parasite which lives within the cells of 

 the roots of certain plants, especially these belonging to the natural order, 

 Cruciferae. 



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