1909.] Notes on Insect and Fungus Pests. 



645 



At Shipston-on-Stour only four were reported as diseased. 

 Finally, in the case near Taunton, where Up-to-dates were 

 the sufferers, the few that were affected were principally in 

 one place under the shade of a wall and trees, where they did 

 not get much sun. 



It appears, therefore, that the conditions under which this 

 disease exists are various. Cases are reported as occurring 

 on light soil and heavy soil, while the disease is said to be 

 found intensively in patches, or scattered throughout the 

 crop. It is undoubtedly of *old standing, having been first 

 described by Berkeley over fifty years ago, and is asserted 

 to have caused serious damage at times. It is spread by 

 damp, but in spite of the rainy season this year, and the 

 search that has been made for diseased potatoes in connec- 

 tion with wart disease, comparatively few cases have been 

 brought to the notice of the Board, and in none of these 

 has the loss proved serious. Growers would, however, be 

 well advised to examine their crop carefully, and reject all 

 tubers found diseased, since, according to Prof. Johnson, 

 the continual planting of diseased sets has led to a great 

 development of the disease in Ireland, and may, of course, 

 do so elsewhere. 



Several other potato diseases have been brought to the 

 notice of the Board. These include Violet Root Rot 

 (Rhizoctonia violacea, Tul.), which also attacks other 

 plants. The tubers in these cases were generally quite 

 sound, but covered with little lumps that looked like clods 

 of dirt. These generally split off when pressed with the 

 finger-nail, leaving the skin apparently clean underneath. 

 These little lumps, however, were the sclerotia, or masses 

 of compact but dormant mycelium which are capable of 

 spreading the disease if the tuber is planted. The mycelium 

 in this case is only capable of entering the tuber through a 

 wound, but when once it is through the skin, the potato is 

 soon reduced to a pulp. For further information see 

 Leaflet 171. Cases were reported from Derbyshire and 

 Essex. 



Another disease, reported from the neighbourhood 

 of Birkenhead, was Hypochnus Solani, Pritt. et Delacr. 

 In this case the parasite attacks the haulm just above the 



