1921.] The Distribution of Wart Disease. 947 



that there was need for experimental work to find some means 

 of helping the farmer to combat this newly-added difficulty. 



In 1909 the Ministry (then the Board) of Agriculture asked 

 the Lancashire County Council, the Harper Adams Agricultural 

 College, and the Holmes Chapel Agricultural College to arrange 

 a series of trials of potatoes on infected land in their counties. 



Three sets of trials were arranged by the Lancashire County 

 €ouncil, and one each by the two Colleges. In Lancashire two 

 of the trials were on infected fields, viz., one near Ormskirk, and 

 one near Manchester, while the third trial was carried out in the 

 grounds of the Ormskirk Workhouse, which even then were badly 

 infected. In Shropshire a number of adjoining infected gardens 

 were selected, and in Cheshire one badly infected field. 



All the trials were instituted by the Ministry of Agriculture, 

 and were consequently carried out on similar lines. Their pur- 

 pose was to obtain information in two directions : — 



(a) The possibility of a remedy by sterilizing infected soil. 

 (h) The immunity of different kinds of potatoes. 



Negative results were obtained under (a), but the trials under 

 (h) showed that of the commoner varieties of potatoes then culti- 

 vated the majority were susceptible, but that a few, viz., Lang- 

 worthy, Golden Wonder, Abundance, Conquest and Snowdrop, 

 remained clean, even though grown in infected soil. 



In the following year, the immunity experiments were en- 

 larged, so as to include other varieties not previously tested. The 

 results obtained showed that those kinds previously tested (in 

 1909) had remained immune, and in addition Aberlady Early, 

 Favourite, Supreme, Crofter, Laird, Provost, and White City 

 were not infected. 



This establishment of the immunity of certain varieties of 

 potato from Wart Disease was of the greatest importance to the 

 potato-growing industry, and to the Ministry of Agriculture in 

 its attempt to control the disease. 



The county trials, having served a useful purpose, were dis- 

 continued, but Mr. Malthouse, of Harper Adams College, assisted 

 by Sir Beville Stanier and by a grant from the Ministry, insti- 

 tuted further trials between 1911 and 1914. 



The result of these trials was that the list of immune varieties 

 was extended by the addition in 1911 of the following varieties : — 



Crimson Kidney, Early Favourite, Empire, Goodfellow, Invincible, 

 Monarch, New Provider, Redskin Flourball, Snowball, Stour- 

 bridge Glory, Wordsley Pride, Improved Kidney, The Admiral, 

 Leinster Wonder (an Irish potato), and five French varieties. 



