284 



Potato Disease. 



[AUG., 



attack clover ; but flies from the " flax-seeds " in the stubble 

 may pass in a favourable season the following year to other 

 wheat plants ; and, in order to prevent such possible spread, 

 the cereal crop might be sown without " seeds," so that the stubble 

 could be ploughed in as burnt. 



In the case of infestation at the present time, the winter wheat 

 should be put in as late as possible, so as to avoid a possible 

 attack by flies that might issue this autumn. 



Potato disease* [PhytopJithora infestans) is practically wholly 

 propagated and carried on from season to season in the sets 

 themselves ; it is therefore of the first 



Potato Disease, importance that seed should not be saved 

 from diseased fields, and that it should be 

 stored under the most favourable conditions. In the ordinary 

 way seed potatoes should be carefully picked over and all 

 that show the least sign of taint rejected ; they should be 

 allowed to get thoroughly dry before clamping and should be 

 stored separately. Any diseased haulm should be removed and 

 burnt before the potatoes are lifted. 



It is observed that varieties of potato that have been long in 

 cultivation contract the disease more easily than many of the 

 newer sorts. Farmers, therefore, find that it is advantageous 

 occasionally to obtain a new or more resistant variety. 

 Experienced potato growers usually change their " seed " rather 

 frequently, and, as a rule, it is found that the best results follow 

 a change of seed from a poor to a good district. 



Very frequently, only a single plant in a patch of potatoes 

 is at first affected by the disease, and its prompt removal and 

 the burning of the diseased parts may prevent an epidemic. 



The rows of potatoes should be well " earthed " or " banked " 

 up, as the thicker the layer of soil the less chance is there of 

 the spores of the fungus reaching the young tubers. A mixture 

 of equal parts of powdered quicklime and sulphur sprinkled 

 on the surface of the soil destroys all spores that come in 



* A description of this diseo.se is given in Leaflet No. 23. 



