670 Cucumber and Melon Disease. [nov., 



The illustration shows a stem of a potato plant bearing 

 leaves which have been entirely distorted by the fungus. 

 Another case has been found where an underground branch 

 of a potato plant bore a healthy tuber and at the end of the 

 shoot a leaf as badly distorted as the leaf shown in the figure. 

 The appearance of the fungus on the part of the plant above 

 ground has been of great assistance in the detection of 

 disease. 



During the present year examples of a disease known as 

 Colletotrichum oligochaetum, Cavari, which attacks melons, 



cucumbers, and other cucurbitaceous 

 A Cucumber and plants, have been sent to Kew for inves- 

 Melon Disease tigation from various districts in Eng- 

 New to Britain. land> The disease is prevalent in 



France and Italy. Every part of the 

 plant is liable to attack, and seedlings are often killed in large 

 numbers, owing to the seed-leaves or cotyledons and stem 

 being destroyed. When the soil becomes infected the young 

 plantlets are frequently destroyed before they appear above 

 ground, but older plants do not succumb so quickly. On the 

 stem the spots are elongated, one to two inches in length, and 

 of a pale yellowish-green colour. On the lateral branches the 

 spots are similar to those on the stem, but smaller, and the 

 entire shoot soon turns yellow and dies off, showing a soft, 

 watery consistency. On the leaves the spots are more or less j 

 circular in outline, rarely more than half an inch across, at 1 

 first yellowish-green, becoming yellowish-brown, and darker 

 towards the edge. The diseased tissue becomes dry and 

 cracked within a few days after infection, but the dead portion 

 never falls away entirely, and does not leave a clear-cut margin 

 to the hole, as is the case when a leaf is attacked by Homo- j 

 dendron hordei. When the fruit is attacked, deep sunken 

 patches two to four inches long are formed near the tip. The 

 entire fruit soon after being affected changes to a pale yellow 

 colour and dies. Very young fruit dies within two or three j 

 days after infection and before sunken patches have time to 

 appear. In every instance minute pustules or warts of aj 

 pinkish colour at first, afterwards yellowish-brown, appear on 

 the diseased patches. These represent the fruit of the fungus, 



