EXPERIMENT STATION BULLETINS. 



455 



The above figures indicate, first, that the higher ground is warmest at all 

 times during frosty nights; second, that the soil gives off sufficient heat to ele- 

 vate the temperature immediately above it from one to three degrees; third, 

 that during continuous cold weather heat is rapidly driven off from the soil until 

 finally the coldest temperature is that immediately above ground. 



Of the blossoms and buds marked, none were damaged until June 12, when 

 all had developed into fruit from one-quarter to two-thirds full grown. Only two 

 failed to show any signs of damage on June 13, and these two subsequently 

 dried up. Though all were thus killed by the frost of June 12, the fact remains 

 neverthless, that thousands of others which had not been marked were not 

 affected by any frost, since the berries were ripe a week later. It is possible, 

 •even probable, that the more or less reclined position of the blossoms of certain 

 varieties, may in some measure contribute more or less to their immunity from 

 frosts. The observations of the past two seasons howeVer, would rather indicate 

 that such immunity is due to a specific cell structure, innate or acquired, and 

 ■known as hardiness. The fact that blossoms were not damaged previous to June 

 12 would also indicate that partly grown fruit is more tender than blossoms. 

 During the coming season, observations will be taken for the purpose of ascer- 

 taining the value of mulches as a protection against the latest frosts. 



When considering the yields in the following table, it should be remembered 

 that the plots are still in the extreme wet condition heretofore described. In 

 the following table the yield per acre is given for 1902, as well as 1903, in order 

 to compare the probable effect of frosts upon certain varieties. As shown in 

 Special Bulletin No. 20, the spring frosts in 1902 were fewer and probably less 

 damaging to early varieties, since the last frost occurred a week earlier and was 

 less severe. 



TABLE OF STRAWBERRIES (In matted rows 4 feet apart). 



Yield 

 of plot, 

 inqts. 



147 



21 



27 



9i 



40 



146J 

 19 



3i 

 129 



2i 



8J 

 7 



57 

 309J 



27 

 3 



Varieties. 



Bederwood . . , 

 Brandywine. 



Bryant 



Bubach 



Clyde 



Excelsior 



Gandy 



Glen Mary. . . 

 Haverland... 

 Marshall 



Mayflower... 



Michigan 



Parker Earle 



Sample 



Seaford 



Success 



Sex. 



Perfect. . . 

 Perfect. . . 

 Perfect . . . 

 Imperfect 

 Perfect.. . 



Perfect. . . 

 Perfect... 

 Perfect. . . 

 Imperfect, 

 Perfect. . . 



Perfect. . . 

 Perfect. . . 

 Perfect. . . 

 Imperfect 

 Imperfect 

 Perfect. . . 



Length 

 of row, 

 in feet. 



460 

 200 

 180 

 100 

 570 



1,.520 



135 



30 



460 



95 



135 

 760 

 5S0 

 1,140 

 180 

 380 



First 

 blossom. 



May 13. 



" 25. 



" 24 



" 23! 



" 17. 



" 12 



" 2l'. 



" 26. 



" 24. 



" 24. 



" 13. 



" 29. 



" 24. 



" 26. 



" 24. 



" 17. 



First 

 ripe 

 fruit. 



June 23. 

 July 9. 



" 6. 



" 3. 



" 2. 



.Tune 22. 

 July 8. 

 June 27. 

 " 25. 

 July 2. 



June 24. 



July 11. 



4. 



" 4. 

 June 27. 



" 26. 



July 24. 

 .\ug. 1 . 

 July 21. 



" 20. 



" 24. 



" 21. 

 Aug. 1 . 

 July 23. 



" 24. 



" 28. 



" 21 

 Aug. 1 . 

 July 24. 

 Aug. 1 . 

 July 24. 



Yield Yield 



Last per per 



ripe acre, in acre, in 



fruit quarts, quarts, 



1903. ! 1902. 



3,480 

 l,14.3i 

 l,633i 

 1,034* 

 764 1-5 



l,049i 

 l,532t 



933} 

 3,0.54 



2861 



6851 

 100} 

 1,070} 

 2,957} 

 1,633} 

 1,060} 



4,344i 

 l,279i 

 1,149} 

 1,0S9 

 1,299} 



l,117f 

 1,855} 



544} 

 2,4.50} 



1141 



484 



222^ 



l,107i 



2,641} 



544} 



1,046 



