VEGETABLE GROWING IN NEW SOUTH WALES. 107 



Large, sunken, decayed spots appear, which become covered with small dark 

 spots, formed in concentric rings. Later, the spots become white to pinkish 

 as the spores are produced and forced out over the surface of the diseased 

 area. 



The fruit should be handled carefully to prevent any injury, as spores; 

 readily infect sound fruit if the skin be damaged. On no account should a 

 tomato showing signs of ripe rot be included in a case of sound fruit. 

 Rotation (see page 22) will act as a control, and diseased specimens should 

 be all absolutely destroyed. 



Rust of Beans and Peai. 



Several species of rust fuagi attack beans and peas throughout the world, 

 and one is common on our varieties of our garden beans. The fungus usually 

 appears late in the season and is destructive to the foliage, resulting in an 

 earlier and a reduced crop. At first, small and blister-like spots appear on 

 the leaves (usually on the under surface, though occasionally on the upper). 

 These rupture, and the spores produced give an iron-rust colour to the mass- 

 The fungus is harboured by the old leaves and vines ; hence, when this 

 disease appears in a crop it is advisable to burn all refuse and neither to- 

 throw any on the manure heap to be returned later to the field; nor to turn 

 any under the soil. Early spraying with weak Bordeaux mixture (see page 

 128) should be given. Later, when the pods are well developed the English 

 practice is to use permanganate of potash, about 1 oz. in 8 to 10 gallons of 

 water. The grower should always be on the look-out for seed from any. 

 resistant varieties. 



Another of these species of rust fungi has been recorded in New South 

 Wales on broad beans. It attacks pods, leaves, and stems, and in other 

 parts of the world occurs on garden peas. 



Scab of Potato. 



The confusion in the use of the word " scab " is so great that it would be 

 better to drop it altogether, but it is in such general use among growers that 

 this is rendered impossible. The best thing, therefore, appears to be"l;o 

 accept the term " scab " as meaning a roughening or abnormal growth of the 

 skin of the potato, with the proviso that the term conveys no suggestion as to- 

 how the abnormality is caused. 



The skin of a potato is really of the nature of cork ; it is only a thin- 

 layer, but so long as it is intact it is highly protective. When it suffers an 

 injury, the potato endeavours to repair it by producing an extra amount of 

 corky cell substance around t the seat of injury, and thus isolate it from 

 tfee healthy tissue. Tn this way a scab is produced, and scabbing may be 

 regarded as the manifestation of the efforts of the plant to, repair injury 



