12 MASS. EXPERIMENT STATION BULLETIN 436 



the stands of Katahdin, Earlaine, and Sebago, and worse effects on the stands of 

 Chippewa. 



None of the seed treatments seemed to increase the vigor of plants. Careful 

 examination ot growing plants and later inspection of mature tubers after digging, 

 showed no consistent differences in the amounts of rhizoctoniose on potatoes 

 grown from treated and untreated seed. No scab developed in any of the plots, 

 not even in the control grown from untreated seed. 



On the basis of experimental results obtained in 1945 as well as the two previous 

 seasons, disinfecting seed treatments are of doubtful value as control measures 

 for rhizoctoniose of potatoes in most potato land. Although no scab developed 

 even in the control plots, it is reasonable to believe that disinfecting seed treat- 

 ments would be of doubtful value in the control of scab also. 



Evaluation of New Lines of Irish Potatoes for Resistance to Scab and Rhizoc- 

 toniose. (C. V. Kightlinger and H. M. Yegian.) Newly developed lines of Irish 

 potatoes were tested for comparative resistance to scab and rhizoctoniose in 

 informal cooperation with the Division of Fruit and Vegetable Crops and Dis- 

 eases of the United States Department of Agriculture. 



Several of the new lines were apparently highly resistant to scab. A few of 

 the lines showed no traces of scab when the Green Mountain control scabbed so 

 badly that its tubers were utterly worthless. A few of the lines showed evidence 

 of having considerable resistance to rhizoctoniose. Other lines bore enough small 

 sclerotia on their tubers to interfere greatly in estimating the comparative scab 

 resistance of the lines. There were not enough plants to spare any for examina- 

 tion in the growing stage to ascertain their resistance to rhizoctoniose more com- 

 pletely. More information about the comparative resistance of these lines to 

 rhizoctoniose is needed. 



Potato Variety Trials. (Karol J. Kucinski, Ralph \V. Donaldson, Walter S. 

 Eisenmenger.) Because the 1945 growing season was abnormally wet, the 

 yields obtained in the potato variety test were much lower than in former years, 

 ranging from 273 bushels per acre for Sebago to 107 bushels for 47102 Teton. 



Based on yields of marketable size, the ranking of potato varieties in the 

 Experiment Station plots during the season of 1945 was Sebago, Cayuga, 055, 

 Red Warba, 627-103, Green Mountain, Mohawk, Chippewa, Pawnee, Katahdin, 

 46952, Cobbler, Houma, Russet Rural and 47102 Teton. 



Corn Improvement Program. ( Hrant M. Yegian.) Seventy-five varieties, 

 mostly hybrid seed corn supplied by state experiment stations and private seed 

 companies were tested for their general adaptability and yield. In the early 

 maturity group. Wis. 41 2A and Mass. 62 produced the highest yield of shelled 

 corn per acre (90 bushels). Wis. 643 was the highest producing full-season silage 

 corn. The very late maturing varieties produced somewhat more silage per 

 acre, but this consisted mostly of stalks and leaves. Therefore, the quality and 

 feeding value of the silage would not be as high, pound for pound, as that from 

 varieties which produce a higher proportion of ears which are in the dough or 

 pre-dent stage before the killing frost. With somewhat earlier maturity it is 

 possible to ensile before the usual mid-September frost or hurricanes which do 

 great damage to silage corn. The results of the 1945 field tests are published in 

 mimeographed form and are available upon request. 



Fifty-five single crosses involving all possible combinations of eleven inbred 

 lines in the early maturity group were tested. On the basis of this test, a few 

 of the promising predicted double crosses were made in the greenhouse during 

 the winter and these are being tested in the field during the 1946 season. The 

 double cross (CC4xCC8) x (Q83xA96) promises to be an especially good, earlj'- 

 maturing field corn. 



