1920.] 



Clover Stem-rot. 



1243 



texture of cheese. It is important to be able to recognise these 

 l)odies since they form one of the readiest methods of identifying 

 the exact nature of the disease. 



The sclerotia, \vhen buried in the soil, are capable of retaining 

 their vitality for a number of years. In any case they remain 

 dormant during the summer after their production, but may 

 germinate with the rains and cooler weather of late autumn 

 and give rise to bodies producing spores. In order to germinate 

 they have to be near the surface. Those that are deeply 

 buried remain dormant and germinate at irregular intervals^, 

 as they are successively brought to the surface in the ordinary 

 routine of farm cultivation. 



On germination the sclerotia give rise to small, brownish 

 pink, cup-shaped toadstools (apothecia) (see Figs. 2 and 3), 

 which contain in their upper portions vast numbers of spores. 

 In common with many fungi belonging to the same group,, 

 the apothecia when mature forcibly discharge their spores, 

 which on a warm, sunny day are visible as minute clouds. 



These spores alight on the foliage of the surrounding plants, 

 and readily germinate, thus giving rise to the mycelium which 

 produces the new infection. 



Relative Susceptibility of Legruminous Crops. — The fungus 5. 

 fri/olionim attacks many kinds of leguminous plants, though 

 with varying degrees of intensity. The following list is based 

 on observations carried out in Cambridgeshire* : — 



Common or Broad Red Clover. — Extremely susceptible. 

 Late-flowering Red Clover or Single-cut Cow-grass . — Very sus- 

 ceptible. 



Lifcerne. — Ver^' susceptible during the first year, less so later. 

 Sainfoin. — Susceptible, especially the first year, occasionally 

 severely attacked. 



Trefoil. — Not often severely attacked, 



Alsike or Swedish Clover. — Occasionally attacked, but not 

 severely. 



Dutch White Clover. — Occasionally attacked, but not severely. 

 It must be remembered that the above list refers exclu- 

 sively to the Stem-rot Disease. The names of the varieties 

 resistant to the Eelworm Disease will be found on p. 4 of 

 Leaflet No. 46. Of other plants the disease is known to attack 

 beans, but crops of peas and tares are apparently quite 

 immune. 



Distinction between Stem-rot and Eelworm Disease. — ^The leaves 

 and shoots of plants attacked by Stem- rot die off rapidly in 

 late autumn and winter and turn an olive-brown colour ; 



• For further details see paper by A. Amos, referred to on p. 1241. 



