April, 1935] Agricultural Research in N. H. 15 



Bitter-Pit in Apples 



The effect of hay mulch on the development of bitter-pit in apples was 

 studied during the year. The hay was placed round the trees at the approxi- 

 mate rate of 400 pounds per tree during July, so that the tree would become 

 adjusted to the change in environment brought about by the mulching when 

 the next growing season opened. 



The experiment on the effect of fertilizer on bitter-pit was brought to 

 a close during the year. No direct effect was obtained from any fertilizer 

 combination, either with or without the heavy application of lime. It was 

 observed, however, that the per cent of bitter-pit present was affected by the 

 yield; hence the fertilizer combinations most effective in increasing yield 

 did indirectly reduce the incidence of bitter-pit. Good results were obtained 

 from the use of a phosphatic manure alone, a nitrate alone, and a nitrate 

 combined with a phosphatic or potassic manure was more active than a 

 complete fertilizer. 



Continuing work on the development of bitter-pit in storage, confirma- 

 tion, in general, of results previously obtained has been established. It was 

 found that the date of harvest has some bearing upon the development of 

 bitter-pit in Baldwin apples. Apples harvested on October 7 showed a total 

 of 76.1% and no internal symptoms ; apples harvested on October 16 showed 

 a total of 53.9% and 9.2% internal symptoms only; fruit harvested on 

 October 23 showed a total of 43.9% and 16.0% internal symptoms only ; 

 and fruit harvested on October 30 gave no indication of bitter-pit. (0. But- 

 ler — Purnell Fund.) 



Potato Disease Experiments 



Mosaic potato plants grown at a mean temperature of 20° C outyielded 

 the plants grown at a mean temperature of 15 °C, results which confirm 

 data previously obtained. It was also found, again confirming previous ob- 

 servations, that unmistakable symptoms of mosaic do not appear at any 

 regular and set interval following the date of emergence. The earliest date 

 of appearance of symptoms was two days after emergence, the latest 12 

 days. To date mosaic plants have shown no tendency to run out, either when 

 grown continuously at a mean temperature of 20° C, or 15°C. or when after 

 growing one season at one temperature they are removed the next season to 

 the other. 



Leaf-roll plants show a marked tendency to become less productive from 

 year to year when grown continuously at a mean temperature of 20° C or 

 15°C. When, however, plants grown one year at either mean temperature 

 are removed the next to the other, unproductiveness is increased, and espe- 

 cially so in plants moved from the higher to the lower temperature. 



The behavior of the seed-piece of leaf-roll plants is aifected by the tem- 

 perature at which the plants are grown. In the case of plants grown at a 

 mean temperature of 20°C seed piece decay is the rule. The results secured 

 during and including all the series of plants grown were as follows : plants 

 grown at 15°C showed seed-piece decay of 7.7 per cent; plants grown at 

 20°C showed seed-piece decay of 50 per cent. 



The healthy plants grown have not shown, up to the present, any ten 

 dency to become less productive when grown continuously at either 20° C or 

 15°C, nor has removal from season to season from one mean temperature 

 to the other caused any ill effect. (O. Butler^Ptirnell Fund.) 



