Table 1. Development oi Schizothyriiim pomi thyriothecia collected in the 

 tleld and grown in controlled temperatures and liigh humidity chambers in 

 each of tlrree years. 



Year 



RH^ 



Temple 



Days elapsed DDq 



to mature spores to mature spores 



1995 



1996 



1997 



Mean 



high 



high 



99 



125±33 



^Relative humidity. In 1995 and 1996, thyriothecia were incubated in sealed 

 glass Petri dishes containing filter paper saturated with distilled water; in 1997 

 incubation was in a sealed glass Petri dish containing salt-amended agar that 

 maintained relafive humidity at pre-determined levels. 

 ''DDo are degree-days base Q°C accumulated over the incubation period. 

 "^A dash indicates failure to develop at that treatment. 



in borders near commercial 

 orchards over 3 years. They 

 developed in a consistent 

 pattern over the 3 observation 

 years and over the five 

 orchard sites (Figure 1). 

 Mature ascospores were first 

 observed when Mcintosh was 

 in pink or bloom, hi 1 997 and 

 1999, all thyriothecia had 

 matured 4 weeks after 

 Mcintosh petal fall, while in 

 1998, maturation ended 6 

 weeks after petal fall. When 

 thyriothecium maturation 

 stopped, Mcintosh fruit were 

 from 1 to 3 in diameter. Over 

 all orchards and dates, the 

 earliest date at which 

 thyriothecia reached 95% 

 maturation was June 8, while 

 the latest was June 19. 

 US. pomi spore development 

 follows apple development, 

 then like apples, the fungus 

 maturation process may be 



Table 2. Days from green tip to bloom, degree days base 0°C, and degree days base 0°C for periods at or above 95% 

 relafive humidity for orchard sites in Massachusetts, 1997, 1998 and 1999. 



■"Green tip, the phenological stage where 50% of 'Mcintosh' fi-uit buds have opened and show green tissue. 



''DDo are degree-days base 0°C accumulated over the specified period. 



■^ DDo;rh?95% are degree-days base 0°C that accumulate over the specified period when relative humidity is at or above 



95%. ' 



''a dash indicates that there was insufficient relative humidity data to calculate DDo;rh?95%. 



Fruit Notes, Volume 69, Summer, 2004 



