Accumulated temperatures in some pest habitats in 1976-78.
1981
Baker C.R.B.
Temperatures were measured at eight points in the soil and in a Stevenson screen on a 6 x16m experimental plot at Harpenden, southeastern England. Accumulated temperatures of 430 day-degrees C above 5 deg C were reached earliest at depths of 5 cm beneath flat bare soil and under the south slope of a small grass-covered mound. Temperatures were also accumulated to 150 day-degrees C above 10 deg C for the same sites and compared with those from four sites on the bark of a small apple tree on the same plot. The 150 day-degrees was reached very much earlier on the south-facing bark than at any other sitereflecting the large daily fluctuation in temperature on the bark, where maximum exceeded 40 deg C on occasions. The significance of these results in relation to insect emergence is discussed.
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