BITTER PIT AND ITS CONTRIBUTING FACTORS. 



75 



Generally, with us the disease is worst when the weather is intermittent ; when there is a dry spell 

 followed by heavy showers, and it would be instructive to learn what rain occurred during the 

 ripening of the apple, and when it fell." 



The following interesting reply was forwarded by I). Elkins, The Gardens, Trewsbury, 

 Cirencester, Gloucestershire (29) : — " I note in your issue for 9th March, page 119, that your Colonial 

 correspondent, Mr. D. McAlpine, asks for any information concerning Bitter Pit in apples, and refers 

 to the fruit figured in The Garden, 2nd December, 1911. He desires to know the rainfall during the 

 maturing of the apples in the orchard where the fruit of Tower of Glammis was grown. As the apple 

 figured was grown in these gardens, I have pleasure in giving him the rainfall during the maturing 

 three months, viz., August, September, and October. We had a slight rainfall on the first five 

 days of August, amounting to only 0"65 ; then there was no rain till the 21st. From then till the 

 end of the month we had 0*72. In September, rain fell on ten days, with a total of 1*49. In 

 October, rain fell on seventeen days, the heaviest on the 21st, when 0*75 was registered. The 

 total for the month was 3*48. Our soil is a thin loam overlying the usual brashy limestone of the 

 Cotswolds, and we soon suffer from lack of moisture. I think the trouble was due to the excessively 

 hot summer, followed by the rains in the latter end of September and October, as the earlier 

 varieties, such as Mr. Gladstone, Beauty of Bath, Lady Sudeley, &c, were not affected. I did not 

 observe any spots until the October rains. We grow over 60 varieties of apples. The softer-fleshed 

 varieties were affected most." 



Clearly the conditions favouring the disease were a dry and hot spell followed by rain at a 

 time when the most rapid growth of the flesh normally took place. 



I am also indebted to "Scientist" (76), in The Garden, for a comparison of the temperature 

 and rainfall for the past four years during the critical months in the formation of the fruit, viz., 

 August and September, in an orchard with light and porous soil, where the disease manifested itself 

 for the first time in a noticeable manner. 



Table XIII. — Comparison of Temperature and Rainfall for Four Years during August 



and September principally. 





1908. 



1909. 

 Au 6 ust - ^ tember. 



1910. 



1911. 

 August. JXr. 



August. 



Sep- 

 tember. 



August. 



Sep- 

 tember. 



Mean temperature 



. . degrees 



59-9 



56-0 



61-5 54-5 



61-3 



55*7 



67*1 



59*1 



Mean soil temperature, 1 ft. 



y y 



61-8 



56-3 



62-3 56'6 



61*5 



57*1 



67*7 



60*3 



2 ft. 



■ • 



62-5 



57*6 



62-8 58*1 



60*9 



57*3 



66*6 



61*3 



M 1> » 4 ft. 



y y 



60-7 



57'4 



59-7 57*6 



59*5 



57*7 



64*2 



61*6 



Rainfall 



inches 



3-18 



1-29 



2*16 ! 3-42 



2*16 



0*60 



0*62 



1*01 



Number of days of rain 





14 



13 



13 20 



15 



4 



6 



9 



Total rain, May to September 





9-78 inches 



13 'f>4 inches 



8 '9 inches 



5 *73 inches 



If we confine our attention to 1911, the year in which Hitter Pit was most prevalent, and 

 principally the two critical months of August and September, we find — 



(1) That the rainfall was the least of any. 



(2) That the number of days in which it fell was the fewest. 



(3) That the total amount from May to September was also least. 



(4) That the mean temperature of the air was the highest of any. 



(5) That the mean soil temperatures, at 1, 2, and 4 feet respectively, were also the 



highest in every instance. 



