28 N. H. EXPERIMENT STATION [Bulletin 319 



supplementary spray did not better scab control, and that three cov- 

 er sprays did not give materially better control than two. 



Lime-sulphur solution is very commonly believed to "burn out" 

 scab. However, scab on foliag-e was not killed by spraying with 

 lime-sulphur as the organism sporulated freely around the edges of 

 the dead infected tissues. (Hatch F^ind) 



Ascospore Discharge Relation to the Apple Scab Spray Schedule 



Most standard spray schedules for apple scab base their time of 

 application on different stages of the development of the buds, foli- 

 age, and fruit of the host tree. i\Iore recently, there has been con- 

 siderable work done towards timing the application of the sprays by 

 the activities of the fungus. Records for the past eight years of ex- 

 perimental spraying at the New Hampshire station have been kept 

 by S. Dunn with a view to determining something about the effec- 

 tiveness of such methods and the relation of the development of the 

 fungus to some environmental factors. 



There is considerable variation in dift'erent seasons in the duration 

 of snow cover. Records were kept of the total number of days that 

 snow covered the ground in the experimental orchard, and subse- 

 quently the date on which ascospores were first shot was determined 

 by placing greased slides over scabby leaves on the ground. This 

 was preceded by frequent microscopic examinations of the contents 

 of the developing perithecia to forecast the maturit}- of the ascos- 

 pore. It was found that while the time of snow cover varies consid- 

 erably, the dates of spore shooting varied but slightly from year to 

 year except for 1939 and were not in accordance with the length of 

 snow cover. From this it is concluded that the duration of snow 

 cover has only slight influence on this function. Frequently the fun- 

 gus will vary considerably from year to year in its rapidity of devel- 

 opment, but it will usually finally mature its spores for shooting at 

 close to the same time each year. 



In only three of the eight years did the time of initial spore dis- 

 charge occur later than the regular date of application of the pre- 

 pink s]iray. Furthermore, in two of these years the spores were 

 shot very soon after, five days later in 1933 and six days later in 

 1935. This raises the question of economy of time in spraying. For 

 six of these seasons a plot of trees was given applications of the pre- 

 pink s]iray in accordance with the time spores were first shot. For 

 four years where the dates agreed, the spray on these plots was put 

 on at the regular time. In the other two just mentioned the time of 

 spraying was later but came before the pink spray, so that no time 

 was gained. It was necessary to put on the same number of sprays 

 for these plots as for the others. Only in the year 1939 could the 

 pre-pink spray have been omitted safely on the basis of such infor- 

 mation. (Hatch Fund) 



Seed Certification 



Seventy-one acres of Green Mountains were entered for certifica- 

 tion and the entire acreage passed. Three acres of Chippewa and \.S 



■.\cri-<. .pf Iri>^li r. ,1)1, lev \^ err ,-il<i, rntr-red and passed. 



(Misiccllancova Income) 



