Agricultural Research in New Hampshire 25 



The season was characterized by a severe outbreak of aphids; in 

 spite of having an ample supply of DDT dust to apply, considerable leaf 

 roll was spread into the one and one-half acre block late in the season. 

 Winter greenhouse trials on the tubers from which the vines were killed 

 early showed six per cent leaf roll, which was too heavy an infection for 

 use as foundation stock. Since the variety shows some net necrosis and 

 since, from this first year's test, the variety appears to be leaf roll suscep- 

 tible, there is some question as to whether or not work should be con- 

 tinued with the Mohawk. A half-acre block is being tuber-united this 

 year and the vines will all be killed early, in the hope that leaf roll can be 

 controlled. 



Tuber unit work has been started with two other varieties new to 

 New Hampshire; Pawnee, a promising mid-season variety, and Ontario, 

 a scab-resistant variety. These are being grown at Durham, in sufficient 

 volume to multiply into large blocks in the Colebrook area in 1947. 



In addition to the tuber unit work, 18 varieties of potatoes were 

 grown in 1945 in properly replicated plots in Madbury. A tabulated 

 summary has been made of yields of No. Is and No. 2s together with a 

 count of the number of rotten tubers. Many of these were too badly 

 decayed to weigh; therefore, the weight was not tabulated. 



There was much variation in total yield as well as in the yield of 

 No. 2 potatoes. Mohawk and Pawnee ranked third and fourth with re- 

 spect to yield. Mohawk showed a very low weight of No. 2 potatoes and 

 Pawnee exhibited no rot. The Ontario was not included in the 1945 tests. 



Some of the less promising varieties have been dropped in 1946; but 

 new ones have been added so that there are 28 varieties growing in the 

 current season's tests. Eight of these are new strains that have been pro- 

 duced by plant breeders and are supposed to be resistant either to leaf roll 

 or late blight. 



In addition to the yield and other data, all the varieties were tested 

 for "quality" by the specific gravity method. 



P. T. Blood, M. C. Richards, L. T. Kardos, 

 L. J. Higgins, F. S. Prince 



Proper Construction of Farm and Commercial Potato Storage 



Preliminary results, in 1945, indicated that carbon dioxide could be 

 used to retard the sprouting of potatoes at normal storage temperatures 

 as the latter increased to a value of 62 °F in July. 



The gaseous storage of potatoes was studied further and compared 

 with a hormone type of sprout retardant. Carbon dioxide and oxygen 

 concentrations were varied and the tubers were held at a constant tem- 

 perature, approximately 53°F. The gaseous concentrations were within 

 the range of from less than one per cent to slightly more than 10 per cent 

 C0 2 with the latter supplied in part or wholly by the respiration of the 

 tubers. The hormone used was the methyl ester of alpha naphthalene 

 acetic acid, and was applied in the form of a dust with 0.45 and 0.90 grams 

 of ester per bushel of tubers. Katahdin tubers, free from cuts and bruises, 

 were used and the duration of the trial was from March 18 to May 6. At 

 the close of the experiment, the loss in weight of the tubers, degree of 



