VEGETABLE GROWING IN NEW SOUTH WALES. 91 



Fungus Diseases* 



G. P. DARNELL SMITH, D.Sc., F.I.C., F.C.S., Biologist. 

 Most diseases of plants are caused by low forms of vegetable life known as 

 fungi, which live upon and within the tissues of the higher plants. The 

 main difference, other than size, between the fungi and the higher plants, is 

 the lack of the green colouring matter so abundant in the higher order of 

 vegetation. The methods of development in the fungi are often different 

 from those of higher plants, and their microscopic\ size renders their study 

 more difficult. The parasitic fungi spend the winter months mostly within 

 the living- and dead vegetable tissues, and during the early spring days send 

 out small spores, which correspond to the seeds of the higher plants. These 

 spores are disseminated by the wind and other agents from plant to plant. 

 With favourable conditions as to moisture and warmth, the spores send out 

 small branches, which penetrate into the living tissues of the higher orders of 

 plants. By the application. of a fungicide to a plant, we destroy the spores 

 which have found lodgment upon it, and thus prevent the development of 

 additional spores, which would cause disease. Just as long as the tissues of 

 plants are covered with a thin, even coating of fuiigicide, very few fungi can 

 develop upon them. Thus, if a fungicide were applied at regular intervals 

 during the growing period, most of such plant diseases would be held in 

 check. To the vegetable grower, however, this is scarcely practicable, and 

 the application of the fungicide should begin immediately the disease has 

 advanced far enough to manifest itself to any extent. 



Anthracnose or Pod Spot of Beans. 



The disease known as anthracnose or pod spot is caused by a fungus and 

 occurs all over the world wherever beans are grown, often doing very serious 

 damage. It attacks pods, stems, and leaves, but the most conspicuous 

 injuries are the spots on the pods. The fungus penetrates the affected parts 

 to a considerable extent, and the seeds in the pods beneath the spots are 

 often spotted or discoloured, so that the fungus is readily distributed 

 by the use of infected seed. It appears upon the seedling leaves of 

 the young plants when badly infected seed is sown. The fungus spreads from 

 the seed leaves to the first-formed true leaves of the plant. The stems of 

 plants are often so badly diseased near the base that they may fall over 

 and die. The pods, when quite young and succulent, offer the best con- 

 ditions for the growth and development of the fungus, which develops best 

 with continued wet weather or with heavy dews. 



