Semi-Centennial Volume. 135 



a violet colored mass of mycelium will be found, after which the disease 

 has been named "violet root rot." 



Leaf-spot of Alfalfa. PlcoHphan'ulina hi'iosiana Pol. This is the dis- 

 ease reported by Melchers' in 1915. It occurred in small quantities the 

 past season. Causes greyish-brown, irregular spots on the foliage. 



Leaf-spot or Blotch of Alfalfa. Pyrenopeziza medicaghiis Fcl. This 

 leaf-spot was described by the writer in 1915-'16 as PhyUosiicta medica- 

 gi)ns.'- It proved very prevalent during those years and considerable loss 

 was sustained. It was not common, however, in 1917. This spot on al- 

 falfa foliage is best described by calling it a "blotch" disease, rather 

 that a leaf-spot. The affected leaves become more or less yellowish in 

 color and the fruiting bodies are easily detected in the yellowish areas. 

 No dead areas are caused, as is common in the leaf-spots, but the entire 

 foliage assumes a sickly, sulphur-yellowish color or tinge. In severe 

 cases the growth of affected plants is considerably impaired. 



Alfalfa Stem Disease. Phorna sp. This disease has been observed 

 since 1915, and indications are that it has been in the state a good many 

 years. The stems of the alfalfa plant show dark areas, which in severe 

 cases cause more or less drying of the stalks. 



VEGETABLE DISEASES. 



Black Scurf of Potato. Rhizoctonia solani Kiihn. This disease was 

 very severe in Kansas in 1917. Many fields contained from one to twenty- 

 five per cent. The infection is carried on the seed, which if not given a 

 seed treatment before planting will kill the young sprouts. 



Black Leg of Potato. Bacillus phytophthm-us Appel. This disease is 

 found in many fields in the state, but very frequently a Fusarium infec- 

 tion is associated with it. Young sprouts die at the base, where a soft 

 rot of the stems occurs. Infected seed is the source of the trouble. 



Tip Burn of Potato. Non-parasitic. This malady and sun scald are 

 two of the worst troubles affecting potatoes in Kansas. The lack of 

 soil moisture at the proper time, together with transpiration factors in 

 the plant, are apparently responsible for this injury. Potato vines may 

 burn entirely brown and dry before the crop is mature. Tip burn is gen- 

 erally confined to the margins of the leaves, which turn brown, dry, and 

 are materially injured. This is most common during the dry weather 

 in July. 



Sweet Potato Stem-rot. Fusarium batatis Wolb. and Fusarium hyper- 

 oxyspomm This disease, which may be caused by either of the Fusaria 

 species, is common in the state. Most sweet potato fields have more or less 

 of this disease in them. The foliage of the diseased plant turns yellowish 

 and wilts. Infection enters through the roots and blackens the vascular 

 system. The potatoes show the disease at the place of attachment. By 

 making cross sections of the roots, the blackened streaks of infection can 

 be seen. 



Sweet Potato Soil Rot or "Pox" Disease. Cytospora batata Elliot. 

 This disease was reported for the first time this season in the state. It 



' Melchers, L. E. A New Alfalfa Leaf-spot in America. Science, n. s., 42:536-537, 

 n»i5. 



= Melchers, L. E. Plant Diseases .Vffecting Alfalfa. Kpf. Kans. State Board nf Agri., 

 :f5:339-353. 



