498 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



P. Kropoulos ■■■ has investigated seedling blight, with special reference 

 to Brassica plants. He finds a fungus which exactly corresponds with 

 Moniliopsis Aderholdii in the young plants. If these are attacked before 

 the first leaves are formed death ensues ; l3ut if the leaves have already 

 developed the plant may recover. 



A. A. L. Rutgers t has investigated a Feronospora disease of 

 maize, known in Java as " Omo Lyer." Plants attacked at an early 

 stage die off ; if the infection takes place at a late stage the leaves 

 become striped with yellow ; with some, ripe seeds may be produced. 

 The host-plants when young may be infected by conidia. 



A. J. Lobik| publishes a study of the effect of various diseases on 

 clover. He includes four parasites in his table of calculations : — 

 Phyllachora Trifolii, Erysiphe Polygo7ii, Glmosporum cauUvorwn, and 

 Uromyces Trifolii. Thus, according to approximate calculations, the 

 average crop of clover should be 36 cwt. per acre, but if attacked 

 by Gkeosporiimi it is only 21 •4 to 23 cwt. per acre. In the case of the 

 rust, Uromyces Trifolii, the production is higher than in healthy plants. 

 The attacked plants were actually taller, more bushy, and had more 

 abundant flower-heads. 



Rubber Diseases. — J. F. Dastur § reports on Phytophthora sp. as the 

 cause of Black-thread Disease of Hevea brasiliensis in Burma, which 

 causes a very great loss of rubber. The fungus grows mainly on the 

 fruit, but passes to the stem to the wounds left on tapping for rubber. 

 Light and air are essential agents in checking the disease. 



J. G. C. Vriensjl has described the action of Stilhella Hevese and of 

 Ustvlina zonata on rubber-trees. The mycelium of Stilhella spreads over 

 the young shoots and leaves, which soon lose their colour and die. 

 Ustulina attacks the wood through wounds probably caused by insects. 

 The destruction of infected material is recommended in both cases, and 

 care should be exercised not to leave dead wood about that would 

 harbour insects. 



Tuber-rot in Potatoes.lF — 0. A. Pratt finds that Fusarium radicicola 

 gives rise to two types of rot : — 1. Dry- or black-rot, characterized by the 

 blackening of the tissues, ensues when the fungus enters the tuber by the 

 stem-end or point of the branch where the swelling of the tuber Ijegins, 

 \)j the lenticals, and by the eyes. In these different infections the 

 fungus reaches somewhat different tissues, but in all cases the infected 

 tubers show a sunken brownish- black region. 2. Soft-rot, when the 



* Ceutralbl. Bakt., xlv. (1916) pp. 244-56. See also Bull. Agric. lutell. Eome, 

 vii. (1916) pp. 1855-6. 



t Med. Lab. Plantenz., No. 22 (1916) 30 pp. (7 pis.). See also Bull. Agric. Intell. 

 Rome, viii. (1917) pp. 305-6. 



X Bull. Phytop. Stat. Bot. Gard. Petrograd, 1915, pp. 115-30. See also Bull. 

 Agric. Intell. Rome, viii. (1917) pp. 307-8. 



§ Dept. Agric. Burma, Bull. No. 14 (1916) pp. 1-4 (1 pi.). See also Bull. Agric. 

 Intell. Rome, vii. (1916) pp. 1547-8. 



II Med. Adors. No. 5, Medan (1916) pp. 66-8. See also Bull. Agric. Intell. Rome, 

 vii. (1916) pp. 1712-13. 



^ Journ. Agric. Research, Washington, vi. (1916) pp. 297-309. See also Bull. 

 Agric. Intell. Rome, vii. (1916) pp. 1546-7. 



