128 GROW YOUR OWN VEGETABLES 



gradually increase in size and blend with each other, until 

 finally the entire leaf presents a sickly yellow appearance 

 and becomes thickly covered with a white powder. This 

 has the appearance of hoar-frost, but soon changes to a 

 dingy lilac colour. 



" During the early stage of the disease the fungus exer- 

 cises a very marked stimulating effect on the growth of the 

 onion. This is shown by the rapid increase in length of that 

 portion situated between the top of the bulb and the base of 

 the leaves. This abnormally elongated portion is spoken of 

 as the ' neck/ and the presence of this is a certain sign of 

 the existence of the disease. 



" All plants showing a trace of disease should be removed 

 or burned, and the healthy surrounding plants, or preferably 

 the entire crop, should be dredged with a mixture of powdered 

 quick-lime and sulphur in the proportion of one of lime and 

 two of sulphur. The dredging may be done by placing the 

 mixture in a muslin bag and shaking it over the plants or 

 by specially made bellows or other contrivances now on the 

 market. The work should be done when the plants are 

 covered with dew. 



" It is very important that, as far as practicable, every 

 trace of diseased onions should be collected and burned and 

 not thrown on to the manure heap or into the piggery. If 

 such are allowed to decay on the land, a recurrence of the 

 disease is almost certain, as a second form of fungus fruit is 

 produced in the decaying tissues of the leaves. This fruit 

 remains unchanged until the following season, or, if deeply 

 buried, may remain so for several years, and when again 

 brought to the surf ace in the ordinary routine of cultivation 

 germination takes place, and, if onions happen to form the 

 crop, infection follows." 



