54:? 

 T.oih;ini; of thk Stalk. 



The frost injuries ahoxe described in stalks show different secondary 

 phenomena, according to the phice where the frost acted most intensively. 

 The most common case is where, with late frost, the base of the stalk is 

 attacked. Usually these injuries occur in deiinite centres in the fields be- 

 cause the cold air accumulates in low-lyinj:; hollows. Here also most of the 

 moisture from atmospheric precipitations collects so that parasitic infection 

 is added to the frost disturltances. The base of the stalk begins to molder 

 and the stalk itself falls o\er. Many of the cases of lodging of the stalks, 

 ascribed to Leptospliaeria and ( )plii()b()Ius, are found to be combination 

 l)henomena of which frost is the primary cause. 



There are, however, other cases, in which the stalks do not bri'ak at the 

 l)ase but at different heights. The i)henomcnon does not always occur in 

 definite centres in the field but may also be found in bands and manifesting 

 itself in such a way that healthy and diseased stalks stand side by side. 

 .Such cases not infrequently cause disputes since they bear a great resem- 

 blance to injuries due io hail. Rei)aration is refused by the Hail Insurance 

 Companies since it is not possible to prove where the hailstones have hit. 



In the basal lodging of the stalk, its ground tissue is found to l)e brown 

 and the shoot almost entirely dead. It is often, indeed, soft and always 

 infested by fungi ; also bacteria, mites and anguilla in continued dampness. 

 When the break occurs higher in the stalk, the ground tissue seems firm 

 and green and the shoots die only in places, often without infection by fungi. 

 Most frecjuently the broken place in the stalk is found at the second or third 

 internode above the surface of the soil and is characterized sometimes as a 

 one-sided, sometimes as a circular brown zone, the coloration of which in- 

 creases in intensity towards the next higher node. Accordingly the i)art of 

 a stalk, lying close below a node seems to be the most susceptible place. 

 Nevertheless, the node adjoining the upper side of the deep brown tissue 

 can fre(|uently lead to a secondary upbending of the fallen stalk so that it 

 finally stands upright again beyond the bent place. T^ut the heads of such 

 plants are weak and imperfect; the roots ap[)ear healthy, the brown part 

 almost alwa}s without any fungous growth. 



Tni". Condition ok .Sti:kii.k IIi:ai)s. 



A disease which apparently has the least connection with frost injuries 

 is the condition of sterile heads, as met with in Fig. 114, A and B. As yet 

 I have found the phenomenon only in rye and will describe only a special 

 case which I had opportunity to observe in June. 1900'. Here the stalks 

 were mostly of a normal size and vigorous growth, but the uppermost mem- 

 ber, or the one next below it, had pale yellow spots. Later these became 

 straw-colored to a brownish-yellow, often with darker edges, which en- 



1 Soiauer, I». tJbei- Frostbe.schadungen nm Gctreidc uiul lUimit in Veibinduiiy 

 stehende Filzkrankheiten. Landw. Jahrbiicher 1903, p. 1. 



