956 



Inspection of Potato Crops during 1920. 



[Jan., 



Up to the present the chief concern of the Inspectors has 

 been to see that " rogues " were absent, or, if present, were 

 removed before the crop is certified. Little more has been 

 done except to note the presence of diseases, but in the case 

 of inheritable diseases such as Leaf Curl, if the disease was 

 present to any extent, the Inspector has persuaded the grower 

 to dispose of the crop for ware purposes, and not to sell for 

 seed. Very few crops have been rejected on account of disease 

 alone. 



Diseases. — Blight. — Blight was the most prominent disease 

 found on inspected crops. It started early in some 

 parts of Lincolnshire, making proper inspection rather 

 difficult, and it was necessary for the Inspectors to con- 

 centrate on this area so as to finish their work before the 

 haulms had been destroyed. Elsewhere, although present, the 

 blight did not spread to the same extent, and the Inspectors were 

 able to finish their work before the haulms had died down. 



Leaf Curl. — This disease is responsible for very seriously 

 lowering the potato yield in many parts of the country, and as 

 it is perpetuated from season to season by means of the ' ' seed ' ' 

 it is extremely important to eliminate it as far as possible from 

 crops intended for " seed " and from the " seed " growing 

 areas. Leaf Curl has been much investigated of late and it has 

 been proved to be not only inheritable, but infectious (see Leaflet 

 No. 164). It is common all over England, but its attacks are 

 more severe in the south. During the inspection some bad 

 cases were noted, and, as already mentioned, the grower was 

 persuaded to use his crop for ware purposes. In other cases, 

 where it was less abundant, a selection from the best parts of 

 the field was advocated. In certain areas Cases were noted in 

 which curling of the foliage occurred which was not referable 

 to true Leaf Curl. The most striking were those where fields 

 had been partially or entirely flooded in spring, the plants on 

 the flooded areas showing a curling of the foliage which was 

 absent on the partially flooded areas. 



Mosaic. — The mottling due to Mosaic is seen very generally 

 and clearly in the varieties Golden Wonder, Langworthy, Burn- 

 house. Beauty and Tinwald Perfection, especially early in the 

 season and in the cooler districts. It is also known in many 

 other varieties, but to a lesser extent. Mosaic disease, which 

 is known to reduce the yield very seriously in many counties, 

 is receiving close attention by the Ministry's experts. 



