Life-history of Phragmidium rubi-idaei on red raspberry in the United Kingdom

Phragmidium rubi-idaei produced five spore stages on red raspberry and overwintered as teliospores adhering to canes. In the field spermagonia appeared in a single flush in early summer on leaves of the primocanes (first-year canes) and on leaves of the lateral shoots of fruiting canes, and were followed by aecia, uredinia and telia. Aecia and uredinia occasionally appeared on petioles and sepals and uredinia on drupelets of mature fruit. Lesions caused by aecia and uredinia on the bases of primocanes did not become cankerous in the following fruiting year. Necroses associated with large aecia produced a shot-hole effect and leaflets heavily affected by either aecia, uredinia or telia abscissed prematurely.
The sequence of spore stages on pot-grown plants inoculated with mature overwintered teliospores took 60 days to the reappearance of telia. The rate of development of uredinia and associated necroses was faster on younger than on older leaves but the cumulative spore yield was not significantly different.
Optimum temperature for germination of urediniospores in vitro (18.4–20.9°C) was higher than for mature teliospores (14.6–18.4°C). Light inhibited germination of both types of spores. Teliospore germination was inhibited by wavelengths of 590–750 nm, but this was partially reversible under other light conditions. A reversible inhibition of basidiospore formation was also observed under shorter wavelengths.