io6 FUNGOID DISEASES 



Preventive Measures. — 



1 . Remove all tops and refuse. 



2. Grow mano^els on other P^round. 



3. Spraying with Bordeaux Mixture is recom- 

 mended, but it is of doubtful value. 



V. Beetroot and Mangel Rot [^Phonia Betce, 

 Frank). Fungi Iniperfecti ; Order: Sph.^ropsi- 



DALES. 



Symptoms. — Seen in dry summers during July 

 and August and sometimes later. The young inner 

 leaves become blackened ; in bad cases the whole 

 of the leaves suffer, the attack spreading from the 

 inner leaves outward. Later the mano^el itself falls 

 a prey to the fungus (this constitutes the dry rot) ; 

 first the epidermis is discoloured, and later the inner 

 tissue becomes brown and dry. 



Cause. — The fungus Phoma BetcB with its thickish, 

 septate, colourless hyphae is present in the tissues 

 causing disease, Picnidia (small cases containing 

 spores) are seen in the diseased tissue as minute black 

 points. They liberate the spores from a small 

 opening. They may remain in the ground a long 

 time and still be capable of germination when 

 favourable conditions occur. 



This fungus is often accompanied by Fusarium 

 beticola, which has crescent shaped spores. 



VI. Violet Root Rot {Rkizocto7iia vio/acea). 

 Fjingi Imperfecti. 



Mangels and beet suffer, though not seriously. 



