568 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Hibernating Mycelium in Tomato Seed.* — I. Massee has examined 

 seed produced by tomato plants suffering from " black-rot " (Macro- 

 sporium Solani). Such seeds often show black spots on the surface. 

 Microtome sections of such spotted seed proved the presence of mycelium 

 in varying quantities. In a healthy tomato seed the testa is in close 

 contact with the endosperm, but in an infected seed a thick weft of 

 closely compacted hyphre is present between the testa and the endo- 

 sperm. From this peripheral weft of mycelium hyphae pass into the 

 endosperm and also into the embryo. These hyphaa are inter- and 

 intra-cellular. On the germination of infected seed either the embryo 

 is killed almost at once by the mycelium, when present in considerable 

 quantity, or the mycelium grows along with the seedling. 



Saprophytic Fungus becoming Parasitic.f-G. Massee records the 

 fact that a batch of GUrodmdron fallax became studded on the lower 

 surface of the leaves with peltate glands which exuded a liquid drop 

 with a sweet taste. The ubiquitous floating species Cladosporium 

 epiphyllum found these sugary drops a congenial pabulum, and each 

 gland was soon tipped with a fruiting tuft of Cladosporium. At first 

 the Cladosporium was strictly confined to the glands and depended on 

 the secretion for its support, but it gradually passed from the saprophytic 

 condition and entered that of a facultative parasite, passing beyond the 

 range of the gland and attacking the surrounding living tissue of 

 the leaf, forming conspicuous brown, dead patches on the upper surface. 

 Three weeks after the disease first appeared, the spores of the fungus 

 were capable of infecting any portion of the leaf, quite apart from 

 receiving an initial start on the sugary excretion from a gland. It is 

 also pointed out how mechanical injuries, which are often self-inflicted, 

 may form the centre of an attack by microfungi. 



Plant Diseases. :f — G. H. Pethybridge gives an account of his 

 investigations on potato diseases. Experiments were conducted on 

 Phytophthora infestans in continuation of those of 1913, to ascertain 

 which is the best time to spray, the best method of application of the 

 spray, the strength of the mixture, and the efficiency of certain pro- 

 prietary spraying materials. In the case of Sclerotinia sclerotiorum, 

 which, next to the blight, is apparently the most serious potato disease 

 in the west of Ireland, since all experiments in spraying have resulted 

 in failure to control it, attention is being devoted chiefly to investigating 

 the relation between the virulence of the attack and the date of planting. 

 It has been clearly established that the later the potatoes are planted 

 the less is the number of plants which become attacked. Notes are 

 also given on Bacillus melanoyenes, Sponyospora subterranea, and Phytoph- 

 thora erythroseptica. 



The same writer § has also investigated the possibility of the spread 

 of celery leaf -spot disease (Septoria Petroselini var. Apii) by the use of 



* Kew Bull., No 4 (1914) pp. 145-6 (1 pi.). 



t Kew Bull., No. 5 (1914) pp. 190-1. 



% Dept. Agric. and Tech. Instr. Ireland Journ., xiv. (1914) 24 pp. (3 pis.). 



§ Dept. Agric. and Tech. Instr. Ireland Journ., xiv. (1914) 9 pp. (1 pi.). 



