DISEASES NOT DUE TO PARASITES OR OF UXKXOWX . ORIGIN' I37I 



the point where the parenchyma has the most powerful reaction, namely in 

 the bark. The consequence is often wet rot and death of the base of the 

 stalk This is the case of what is called " I^ohkrankheit ", the causa of 

 which is too large a supply of water through the roots. 



Among the injuries caused to the leaves, the appearance of transparent 

 spots rapidly spreading is characteristic in some large-leaved plants. 



In an atmosphere of gas, transpiration falls off greatly for each gram of 

 fresh substance. If the plants have an abundant amount of water at the 

 time of reduction of the evaporation coefficient, a great acciimulation of 

 water takes place in the organs of transpiration. Under the influence of 

 this accumulation it is observed in rapidly gro\ving plants that the cells of 

 the separation layer become gradually less coherent, and the result is the 

 fall of the leaf (in Fuchsia, Begonia and Azalea). In Taxiis and other trees, 

 big lenticular swellings were observed on the roots in consequence of too large 

 a water supply. 



1028 - Studies on " Dorrfleckenkrankheit" (Dry spot Disease) in Oats (i). — schikorra 



\^'., in Centralblatt fiir Bakterioloi^ie, Parasitenkunde unci Infektionskrankheitcn, Vol. 45, 

 No. 18-25, PP- '578-586. Jena, June 19, 1916. 



For the last two years it has been observed in Germany that growing 

 trials of oats carried out in pots are liable to the appearance of a character- 

 istic disease often producing death of the leaves. In 1913-14 the disease 

 appeared to a limited extent only, not hindering the experiments, but such 

 was not the case this year, the oats becoming diseased both in pots and in 

 the open field ; therefore the causes of the disease had to be studied. 



It was found to be the disease called " Dorrfleckenkrankheit " of oats by 

 Clausex-Heide ; it is distinguished by the fact that the leaves of the oats, 

 after normal growth, show pale, greyish-yellow spots the tissues of which die, 

 and the leaves break. The disease is known in Upper Bavaria under the 

 name of " Haftersucht " and in vSweden under that of " Graufleckigkeit " 

 of oats. The cause, according to Nilssox-Ehle, Eriksson, Krause, etc. 

 is Scolecotrichum graminis, but recent experiments have shown that typi- 

 cal " Dorrfleckenkrankheit " is a disease of the soil, often promoted by also 

 manuring with artificial fertilisers. 



The writer made experiments on the outbreak of the disease by studying 

 the influence of manuring with artificial nitrogenous fertilisers : 5 experi- 

 mental pots each containing 6 kg. of clayey-sandy soil were given a basal 

 manure of 5.5 grms. of dipotassium phosphate, after which 0.5 gms. of nitro- 

 gen per pot was added. As nitrogenous manure there were used, by way 

 of comparison with each other, pure nitrate of soda, sulphate of ammonia, 

 urea, nitrate of urea, cyanamide, ammonium chloride, Rehmsdorf nitro- 

 genous manure (organic nitrogenous manure), ammonium bicarbonate, and 

 the double sulphate of ammonium and soda; 5 other pots received no 

 nitrogenous manure and served as controls. 



The observations made on the plants cultivated in these pots gave 



(i) See also B. June loi 1. No. 575 {Ed. 



