1920.] 



Plant Breeding at Aberystwyth. 



GST 



noteworthy fact has been the very poor results obtained from 

 Italian seed, due chiefly perhaps to the incidence of a disease 

 (due to fungus Gloeosporium sp.). This disease was first noticed 

 on the Italian beds, and the greatest damage was caused to the 

 clovers from this source. 



The disease in question is under further investigation. The 

 following brief notes are supplied by Miss K. Sampson, M.Sc, 

 w T ho has kept records of the incidence of disease on the various 

 plots: — 



The Gloeosporium disease of red clover is recognised by the 

 characteristic discoloured areas on the leaf-stalks and flowering 

 stems. They may be J to 1J in. long, and nearly girdle the 

 stem or petiole. The margin of each diseased area is black, and 

 the centre is brown and dry or contains a central cavity extending 

 to the hollow of the stem. As the stem is often completely 

 girdled by diseased tissue and breaks at the diseased patch, 

 dead and shrivelled leaves and stems are a conspicuous feature 

 of a clover bed attacked by this disease. (See Plate VU.) 



The fungus Gloeosporium sp. is spread by microscopic 

 spores produced in minute colourless pustules which can be 

 seen when the diseased areas on stems and petioles are 

 examined under a strong lens. Every diseased patch is thus 

 a centre from which the fungus may spread to new leaves and 

 stems. It is significant of the serious extent to which the 

 disease may spread that two beds of red clover from Italian 

 seed examined in July, when neighbouring beds were in full 

 flower, showed only one flowering stem in each bed, all others 

 having been destroyed by the attacks of this fungus. 



The Gloeosporium disease was first noticed on the red 

 clover plots at the end of April, 1920, and observations were 

 made during May, June and July. Although the disease was 

 widely distributed among the beds there w r as a marked differ- 

 ence in the extent of the damage suffered by clovers of 

 different origin. As has been indicated above, the beds from 

 Italian seed were most severely attacked, and in two instances 

 practically destroyed. By the middle of July serious damage 

 had been done on beds of English, Brittany, Canadian and 

 Wisconsin clover, and the attack was only slightly less severe 

 on beds of Chilian red clover. The most striking- feature 

 arising out of the observations was the relative freedom from 

 disease of late flowering red. Throughout the season this 

 variety presented, in the green healthy appearance of the 



