16 CIRCULAR NO. 121, BUREAU OF fLANT INDUSTRY. 



be removed while still green. Otherwise, it" the material is allowed 

 to remain upon the ground for two or three days some of it becomes 

 extremely brittle and breaks up easily on account of the rapid drying 

 which usually takes place. The methods of beet-top removal now in 

 practice in the Arkansas Valley are at fault not only from the stand- 

 point of the control of the leaf spot, but from an economic standpoint 

 as well. Even where the beet tops of several rows are thrown to- 

 gether, shocked, and later removed, the ground underneath these 

 shocks is certain to be infected. The resultant beet-top hay, how- 

 ever, is of good quality. This method of shocking holds the disease 

 in check much better than the very general practice of leaving all 

 material as it falls at harvest time. When the beet tops are left scat- 

 tered indiscriminately over the ground, the leaves become so brittle 

 that they break into small fragments, thus makhig it im})ossible to 

 remove them from the field. If such a field is pastured by sheep, 

 much of the diseased material is trampled into the ground and there 

 results a poor control of the disease, a great loss of nutritive material, 

 and a packing of the soil, all of which should be avoided. 



Even after all the beet tops are removed from the field there is still 

 danger that in feeding them in a dried condition some of the material 

 will become broken up and will not be eaten. These fragments 

 become mixed with the manure and are returned to the land. It has 

 been proved in recent experiments that these broken-leaf portions 

 contain the Cercospora fungus in a viable condition and consequently 

 are capable of producing infection. 



Thorough control of the leaf-spot fungus is assured if the green beet 

 tops are made into silage. In the fall of 1912 a small silo, holding 

 approximately 3 tons, was filled with green beet tops. A few layere 

 of strav/ were added to absorb the excess moisture and to prevent 

 extreme fermentation. I'ive pounds of salt were also added for each 

 ton of material. In recent tests that have been made of the silage 

 resulting therefrom, no fungus of any kind has been found to be alive. 

 Numerous cultures examined for living Cercospora spores gave nega- 

 tive results in all cases. A portion of the silage material was steril- 

 ized and then inoculated with a fresh culture of the leaf-spot fungus, 

 but no growth developed. This is in great contrast to the viability 

 of the fungus out of doors, where directly after harvest it still has 

 almost the same vitality and vigorous growth that it evinced several 

 months before. 



It is very probable that the silo is to be the real solution of the leaf- 

 spot problem. Some of the advantages from an economic standpoint 

 to be gained by the proper utilization of the beet tops are given by 

 L. wS. Ware in his book, "Cattle Feeding with Sugar Beets, Sugar, 

 Molasses, and Sugar Beet Residuum," Philadelphia, 1902, pp. 93-96. 



ICir. 121] 



