VEGETABLE GROWING IX XEW SOUTH WALES. 



some what velvety in texture. Later the whole blossom-half of the fruit may 

 be involved. The affected tissue collapses and becomes firm and leathery. 

 This collapsing of the diseased tissue, together with the continued 

 development of other parts of the fruit, may produce a definite depression 

 on the blossom end of the fruit, or often it results in .only a flattening of the 

 surface. 



The first effects of the disease are not always superficial. In fruit that, 

 appears normal from an external view the interior tissue may have collapsed 

 and be blackened in the parts nearest the blossom. The velvety appearance 

 that develops on the surface later is due to a growth of a fungus which is 

 not, of itself, capable of producing the rot, and is apparently a secondary 

 infection. The disease is not due primarily to bacteria or fungi, but to 

 various physiological conditions, and is not infectious. 



Experiments indicate that water supply is of the greatest importance in 

 the production and thi control of blac^ spot. The disease has been produced 

 on vigorous plants by a sudden decrease in the available water supply. 

 Excessive water supply has also produced the disease more readily and 

 uniformly than a scant or intermittent one. Plants receiving a moderate 

 and regular supply of water develop less rotten fruit than either lightly or 

 heavily watered ones. Too much exposure to the sun also tends to an 

 increase of the disease, so that methods of growth that allow for the foliage 

 shading the fruit, assist in checking the appearance of rot. 



The effects' of fertilisers on the production of the disease vary with the 

 nature of the soil and the amount of water supplied. Experiments by 

 Brooks in Xew Hampshire, U.S.A., gave the folio wing general conclusions : 

 " Lime is of value in reducing the disease, especially if the plants are well 

 watered, but under drought conditions it has little tendency to decrease the 

 disease : potash has no tendency to increase the disease, but nitrogenous 

 fertilisers favour its development. Heavy applications of stable manure 

 increase the disease out of proportion to the increased vigour of the plants." 



As the disease is not primarily due to fungi or bacteria, spraying will not 

 control it. 



Brown Fleck of Potato. 



This is a fairly common condition. Tubers that to all external appear- 

 ances are healthy and sound, when cut open show rusty markings of various 

 sizes and shapes. These discoloured areas consist of dead tissue, and must 

 not be confounded with blight. In the latter case, the diseased parts are, 

 at least at first, immediately beneath the skin, whereas in brown fleck the 

 markings are more internal, scattered, and usually not in contact with the 

 skin. No si^ns of disease are to be found on the stem or leaf parts of the 

 plants which produce such tubers, and the cause of brown fleck is not 



