283 



the upper portions with the blossoming catkins, the han^est will be ver)^ light 

 and an immediate gathering is advisable. 



The disease may be confounded easily with the "copper rust," caused by 

 the weaver moth, but is distinguished by its location since the copper rust 

 colors the leaves on the upper part of the vines a reddish yellow and is 

 recognizable from its finely spun threads on the underside of the leaf, while 

 the summer rust causes a yellowing and drying of the leaves, beginning at 

 (he base of the vine. It is a sapping of the older organs by the younger 

 ones, which require the organic material there present for their further 

 development. 



The so-called "Pole Red" seems to correspond to the "blast" of grain 

 and to be the result of a sudden dry period when the catkins mature. 



In this and the related diseases of reddening the lack of atmospheric 

 moisture plays an especially decisive role, because watering only the soil 

 rarely proves a remedy. It is better, if possible, to water regularly in the 

 evening. But for larger areas in practical cultivation the necessary number 

 of laborers and the great quantities of water may rarely be had. Hence re- 

 sort must be had to preventative measures, in which either the excessive 

 evaporation is reduced by extensive shading,, or the saturation capacity of the 

 soil is increased by the supply of fertilizing salts (not animal manure). Fr. 

 Wagner^ cites an example for the later case. He found in his cultivation 

 that hop vines, without having been given nitrates, did not resist drought 

 and vegetable or animal parasites so well as those fertilized with chili salt- 

 petre and also their lower leaves turned yellow earlier. In the same way it 

 has often been observed in practical agriculture that fodder and sugar beets 

 withstand drought better when the soil has been fertilized with potassium 

 salts or nitrates, or even with abundant stable manure-. 



Similar discoloration resulting from a lack of moisture has been ob- 

 served in flax. This is described partly as the "Reds" {le rouge) and partly, — 

 when the points of the stems turn yellow prematurely, — as the "yeUozvs" 

 (le jaiine). 



"Leaf Scorch"— "Parching of Vines" — "Red Scorch." 



The above are collective names for a group of phenomena distinguished 

 with difficulty from one another, in which the leaves are colored red. As a 

 rule, the discoloration is followed by a partial or complete drying up of the 

 foliage, which begins to fall prematurely. Recently Muller-Thurgau^ has 

 determined a parasitic cause for a definite form of reddening* and takes 

 pains to emphasize the characteristics, apparent to the naked eye, distinguish 



1 Wag-ner, Fr., Salpeterdiingungsversuche des Deutschen Hopfenbau- Vereins 

 Wochenbl. d. Landw. Ver. in Bayern 1904, p. 182. 



- See, for example. Jahresb. d. Snnderpu«schu«ees f. Pflanzenschutz fiir das 

 Jahr. 1904. Arb. d. Deutsch. Landw.-Ges. 1905, p. 91. 



3 Mtiller-Thurgau, H., Der rote Brenner des Weinstocks. Centralbl. f. Bakt. II, 

 1903. Parts 1-4. 



4 Another form of Red Scorch connected with Botrytis vegetation is described 

 by Behrens (Untersuchungen tiber den Rotbrenner der Reben) in Ber. d. Grofsh. 

 Bad. Versuchsanstalt zu Augustenborg 1902, p. 43. 



