DISEASES AND INSECT INJUEIES. 387 



in the price has so raised the value of the produce per acre, 

 as to equal in many cases the value of the fee simple 

 of the ground; and instances have already been given 

 (page 360) where the produce of a district, relative to the 

 aggregate growth of the country, exhibited equal flue- 

 tuations. 1 



Both the diseases and the insect injuries to which hops 

 are subject, have, as might have been expected from the 

 importance of the interests at stake, received considerable 

 attention at the hands of scientific as well as of practical 

 men. The "mould" or "mildew" is that which has excited 

 most attention. This is a disease of a parasitical fungoid 

 character, greatly resembling those other forms already 

 described as affecting, under certain conditions, most of our 

 regular crops. Mildew is always more prevalent in wet 

 seasons, of low mean temperature, and in damp grounds, 

 than under different physical conditions of climate and soil. 

 Some varieties are considered to be more subject to it than 

 others the Goldings, for instance, than the Grapes. Of 

 all the risks the hops have to encounter in their growth, 

 this is always looked upon as the greatest, for it steadily 

 progresses in its attack with more or less vigour, as the 

 season continues favourable to it or otherwise, until har- 

 vest time. 2 When it shows itself to any considerable 



1 In 1801 the duty paid amounted to 241,227, and in 1802 it was only 

 15,463. The years 1812, 1816, 1823, 1825, 1829, and 1840, were also 

 extremely bad years, the average produce per acre having been only 



cwt. qrs. Ibs. 



1812 1 2 15 per acre. 



1816 2 19J 



1823 1 1 5 



cwt. qrs. Ibs. 



1825 1 8-1 per acre. 



1829 1 1 25 



1840 128 



2 In a paper on this subject, read at the Meteorological Society (1854), the 

 author traces a direct connection between the temperature and moisture of the 

 season and the hop produce. In comparing the temperature of the twenty-two 

 years of smallest produce with that of the twenty-two years of largest yield, 

 the author found that in the former series the average amount of duty was 

 55,728, and the mean temperature of the summer quarter 0'9 9 below the 

 average; whereas in the latter, with an excess of temperature of 1*5. the 

 average amount of duty each year was 211,909. 



