i6i 



setting of the bloom, and then receives a check from a long drought, the 

 grain is not set ; a greater or less extensive failure of the harvest takes place, 

 which we may call the blasting of the grain. Ritzema Bos'^ experiments 

 with "Maartegerst," or winter barley sown in March, are very interesting. 

 A sowing was made on a field where autumn sown winter barley was frozen 

 out. Only a few of the autumn sown plants came through the winter and 

 produced stalks during the summer so that the same field produced autumn 

 and March sown barley. The plants from the March seeding suffered dur- 

 ing the hot summer from blasting, while the plants of the autumn sowing, 

 scattered among them, bore a full harvest of grain. With us, besides grain, 

 peas suffer most. Naturally in other plants as well, a failure of the seed 

 harvest can take place, due to the blasting of the blossoming parts. 



Thread Formation in the Potato (Filositas). 



In this disease ("mules"- — of the French) the eyes are deformed; from 

 them grow slender, thread-like stems as thick as medium sized yarn. Not 

 infrequently the eyes of tubers comparatively rich in starch did not sprout 

 at all, or if they did, the sprouts were weak; they are unable to break 

 through even a shallow soil covering. The tubers decay usually with the 

 appearance of dry rot, yet the disease has occurred extensively only where 

 the soils, being easily heated, have to withstand long droughts. 



Fig. i6 shows the basal part of a cutting grown in a water culture 

 from a potato affected by Filositas ; the proportions of the stem, leaves and 

 tuber correspond to the natural size and it is seen that the stems actually 

 are only as thick as a strong thread of yarn. The stolons (st.) are also 

 more delicate and have formed tubercles (k), some of which have lengthen- 

 ed at the tip and grown out to green sprouts (b) or developed scale-like 

 green leaflets (d). 



The cutting here reproduced came from an experimental culture, the 

 results of which are given in precise figures in the second edition of this 

 manual and lead to the conclusion that in the thread disease of the potato 

 we have before us conditions of premature ripening which had become 

 hereditary. Reports from the localities where the disease has occurred, 

 especially from the Marchfeld near Vienna", of the cultural methods fol- 

 lowed there, substantiate this theory. The potatoes, which were of the 

 earliest varieties, were forced artificially and planted as soon after as possi- 

 ble. Sandy soils on the Marchfeld near Vienna, lime soil near Poitiers'', 

 had a small water capacity and heated rapidly, consequently with the in- 

 creasing summer temperature and the superficial position in the upper soil 

 layers the growth of the aerial axes stopped at once. Tubers are formed 

 about this time, but they do not mature, they are filled with starch so that 

 they can be marketed very earl)' and command high prices. 



] Zeitschr. f. Pflanzenkrankh, 1894. p. 94. 



•- Altvatter, Das Marchfeld und seine Bewasserung-. Oesterr. landw. Wochenbl. 

 1875. No. 51. 



3 Journal d' Agriculture pratique; cit. Biedermann's Centralbl. f. Agrikultur- 

 chemie, 1873, No. 10 und Annalen d. I^andwirtsch., 1873, Wochenbl., No. 16. 



