230 



Onion Mildew. 



[JULY, 



tinguishable from that of strong tobacco. It is much relished 

 by stock, and seems to have a feeding value equal, if not 

 superior, to that of mangolds. 



Another way of utilizing the crop has recently been brought 

 to the notice of the Board by Mr. George Allen, who says that 

 on his farm at Hook Norton the maize is planted in somewhat 

 wider rows than usual and sheep folded on it. The sheep are 

 turned into a portion at the end of August. They begin to eat 

 from the top and work downwards, cleaning it all up, and are 

 then moved on. 



This well-known disease occurs wherever the onion is 

 cultivated. The first sign of the disease is the appearance 

 of small, scattered yellowish patches on the 



Onion Mildew leaves. These patches gradually increase 



{Feronospora 



' schleideni) '^^^^ 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. The powder consists of the 

 spores of the fungus, the spores being produced in immense 

 numbers, and soon infesting neighbouring plants. If a diseased 

 leaf is examined with a good pocket-lens, the spores will 

 be seen to be produced on branched threads which emerge 

 through the stomata of the leaf, and form a miniature forest on 

 its surface. 



During the early stage of the disease the fungus exercises 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," 

 as shown in the accompanying figure. The presence of this 

 " neck " is a certain sign of the existence of the disease. As 

 the disease progresses all growth of the bulb is arrested, but the 

 bulb itself is not attacked ; hence, if the fungus appears when 

 the onions are fully grown, or nearly so, the crop is not destroyed. 

 On the other hand, when attacked during the early stage of 



