1921.] Yield of Potatoes and Root Crops, 1920. 1077 



The Ministry desires to bring to the notice of fruit growers 



the serious nature of Silver Leaf Disease and the obligations 



placed upon them under the Silver Leaf 

 Silver Leaf Order ^ of mg 



of 1919. Silvery leaves on a plum tree generally 



indicate that the tree is suffering from Silver Leaf Disease. If 

 one or two branches only are affected, these should be removed 

 and burnt. The branches must be cut back to a point where 

 no dark stain in the wood can be found, and, if practicable, 

 close to the main branch or. stem. 



When affected branches die, the fungus spreads out through 

 the bark, and forms flat crusts or bracket-shaped bodies, on 

 which are produced innumerable spores which spread disease. 

 The annual loss to growers through the disease is already very 

 considerable. 



By the terms of the Silver Leaf Order of 1919, growers must 

 grub up and bum all dead plum trees, and cut away and burn 

 all dead wood from plum trees, before the 1st April of each year, 

 under penalty for neglect. 



Full particulars of the disease and suggested measures of 

 control were given in an article published in the issue of this 

 Journal for May, 1919, p. 162, and are also contained in Leaflet 

 No. 302. Copies of the latter may be obtained post free on 

 application to the Offices of the Ministry. Whitehall Place, 

 London, S.W.I. 



A preliminary statement has recently been issued by the 

 Ministry showing the estimated total produce and yield per 



Produce and Yield acre of the P otato and r00t " cro P s in 

 of Potato England and W ales in the year 1920, with 



-o 4. ^ „ comparisons for 1919, and the average yield 

 and Root Crops r , , imAim ° J 



durin 1920 ^ er acre n ^ ears 1910-1919. 



It is stated that potatoes were planted 

 late as a rule, owing to the unfavourable weather of April, and 

 the crop did not develop well on heavy land during the cold 

 sunless summer. The tubers are therefore small in many 

 districts and yields were reduced appreciably by disease in the 

 south-west. The yield per acre over the whole of England 

 and Wales is estimated at 5.8 tons, which is tw^o-fifths of a 

 ton below the average of the 10 years 1910-19, aod practically 

 the same as in 1919. Generally speaking crops were some- 

 what above average in the eastern half of the country but 



