225 



or bacteria, can only destroy the seedlings where they have some predis- 

 position to take up such organisms. This predisposition is the product of 

 the soil in which they are grown under definite atmospheric conditions. 



Therefore, the soil condition is always the first cause afifecting the as- 

 similatory process and inducing rootblight. The question wdiether this affec- 

 tion always takes place with an excess of free oxalic acid and whether the 

 abundance of the acid acting poisonously is due to the formation of more 

 acid by the plant body or that less acid is oxidized because of a scarcity of 

 oxygen, may be left for later investigation. It is enough for our purpose to 

 know that the disease is a result of a binding consistency of the soil under 

 unfavorable atmospheric conditions, i. e. cold, wet weather. 



We will now return to the statements of practical workers, who, from 

 the beginning, have insisted that the cause of rootblight lies in the condition 

 of the soil. 



When citing these expressions, we come to the self-evident regulations 

 for fighting it. Briem reports a case from the years 1904-1905^. On a newly 

 broken field near Prague in 1904, with cold, wet weather, and a consequent 

 slow growth, beets were extensively root hlighted although until that time 

 the phenomenon had been rare. Also, the beets did not revive completely 

 until later. The same field in the following year, after a rich fertilizing with 

 potassium, nitrates and phosphates, was again planted with commercial beets. 

 As a result of the very wet, cold weather, the seed sprouted only at the end 

 of two weeks (on the 24th. of April). It was feaned that, with the weakened 

 growth resulting from the cold nights, rootblight would again set in. Fort- 

 unately this did not happen and the warm days, coming at the beginning of 

 May, soon caused the rapid, vigorous unfolding of the first pair of leaves. 

 However, when, on the 20th of May, a violent rain had beaten the field 

 down unusually hard so that water could only soak in very slowly, manv 

 seedlings showed the beginning of rootblight after five days. This example 

 of the result of a sudden exclusion of the air from soil, beaten hard by rain, 

 shows therefore that it is primarily advisable to; keep the upper surface of 

 the soil constantly open by cultivation. Secondarily, even if the soil contains 

 lime, a further supply of quick lime must be given. The effect of the lirne 

 must not always be considered as a nutritive means, but as a mechanical one 

 for improving the soil since it increases its friability. Superphosphate has 

 given good results-. In fields liable to these conditions, increased attention 

 should be given to the use of as vigorous seed as possible. 



If one wishes to sterilize the seed which, according to our theory, is of 

 very little advantage'', a carbolic acid solution should be used. For the 

 sterilization of one hundred and twelve pounds of beet seeds 1.5 k. carbolic 



1 Briem, H., Wurzelbrandentdeckung und kein Ende. Blatter f. Zuckerrlibenbau 

 V. .June 15, 1905. 



^ Zeitschr. f. Pflanzenkrankh., 1896. p. 54 and p. 340. Landwirt, 1896, Nos. 15, 17, 

 21. Jahresber. d. Sonderausschusses f. Pflanzenschutz, 1902. 



3 Hiltner in Mitteil. d. pflanzenphysiolog. Versuchsstat. Tharand. Sachs, landw. 

 Zeit. 1904, Nos. 16-18. • 



