Relationships Between Hour-Degree F Soil Temperature Summations and Apple Maggot Adult Emergence1

Abstract

Hour-degree soil temperature summations above 42°F at Rhagoletis pomonella (Walsh) pupal depth were obtained from late April to completion of adult emergence in August1964-65, 1967-68. A good correlation between 1st adult emergence and temperature summations was shown by totals of 24,620 hour-degrees in 1964 and 23,706 hour-degrees in 1965. On the day of mean peak emergence (August 1) in 1964 the summation was 32,256 hour-degrees. In 1965, on the day of mean peak emergence (July 24), the temperature summation was 32,202 hour-degrees. with a second setting of the thermograph bulb in 1967, temperature summations at 1st adult emergence were 18,567 hour-degrees in 1967 and 20,699 hour-degrees in 1968. Temperature summations at day of mean peak emergence were 25,548 and 26,641 hour-degrees in 1967 and 1968, respectively. Daily temperature summations exceeded 500 in late July. These data indicate that the times of 1st emergence and mean peak of emergence of apple maggot may be closely determined for any1 site by summing soil temperatures at pupae depth following a preliminary season’s record of soil temperature summations and emergence data. There was no correlation between dates of bloom of McIntosh and temperature summations. Periods of adult emergence from carryover pupae from 8 ‘Lobo’, ‘Cortland’, and ‘McIntosh’ trees for two 5-year periods show that since 1963 there were 14 carryovers to the 2nd season, 11 carryovers to the 3rtl season, 6 carryovers to the 4th season, and 3 carryovers to the 5th season.