48 SECOND REPORT ON ECONOMIC BIOLOGY. 



PREVENTIVE AND REMEDIAL MEASURES. 



Wherever the disease has occurred all haulms should be burned. 



Spraying with Bordeaux mixture as soon as the disease shows 

 itself will arrest it and reduce the injuries to a minimum. 



Tubers required for " sets " should be obtained from districts 

 and crops known to be free from the disease. 



CUCUMBER COLLAR ROT. 



Hypochnus cucumeris (Frank). 



Cucumber plants received from Hertfordshire last August were 

 found on examination to be attacked by this disease. The fungus 

 attacks the plants at the base of the stems, at the soil level. The 

 mycelium forms a grey mat-like covering over this area, and also 

 penetrates into the tissues, ultimately choking up the vessels. The 

 food and water supply thus become restricted and ultimately cut off, 

 and the plant then wilts and dies. 



The spores are frequently carried into houses with leaf -mould. 



Wherever the disease has occurred the soil should be treated 

 with ground unslaked lime, sometime before it is required for use. 



The disease may be checked by watering with a solution of 

 potassium sulphide, commencing with ij Ibs. of the solution to 100 

 gallons of water; repeat in a few days, using 2 Ibs. to 100 gallons, 

 and later 3 Ibs. to 100 gallons. 



Sulphate of potash has been used, but I have no information as 

 to the quantities or any practical experience with it. 



CUCUMBER LEAF BLOTCH. 



Hormodendron Jiordei, Bruhne. 



This disease is not to be confused with the well-known leaf blotch 

 of cucumbers and melons due to the fungus Cercospora mclonis (Cke.). 



It is first noticeable on the leaves as pale green spots, which 

 ultimately become perforations, so that the leaf has the appearance ol 

 having been eaten by the ground larvae of some insect or by slugs. 

 On the ragged edges of these perforations fruit bodies later appear 

 which infect other leaves and plants. When cultivated under glass 

 the disease soon assumes the proportions of an epidemic. 



