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SUMMARY
Spore germination of Chrysomyxa piperiana (I, II, IV), C. ledi var. rhododendri (II), C. ledi var. glandulosi (II, IV), C. ledicola (I, II, IV) and C. roanensis (II) was highest on water agars; Noble and Purified agars were better than Bacto agar for uredospores and aeciospores and Bacto agar better for basidiospores.
Uredospore germination from most collections of C. ledicola and C. ledi vars. rhododendri and glandulosi was high (50-90%) on water agar. The addition of chelating compounds such as EDTA, citric acid, and L-cysteine at 100,000 ppm was required for comparable uredospore germination of C. piperiana and C. roanensis. These chelators also increased germination of poor germinating collections of the other species. The cardinal temperatures for uredospore germination varied for different collections and species but the optima were usually between 15 and 20 C. The minima were near 1 and the maxima between 30 and 35 C for most species. Light intensities of 30–100 ft-c usually gave more germination than higher intensities or no light. Uredospores air dried in the laboratory for 4 hr and flame-sealed in vials, survived longer than nondried spores.
Air dried uredospores stored at –76 C retained viability for from 636 days (C. ledi var. rhododendri) to 832 days (C. lodicola and C. piperiana). Germination of uredospores stored at –62 to –76 C was increased by a short heat-shock (e.g., 5 min at 40 C) immediately after removal from refrigeration.
Telia matured more rapidly at constant 20 C than at higher, lower, or fluctuating temperatures. Discharge of basidiospores was heaviest at 15–20 C and was inhibited at 25 C and above.
Basidiospore germination was better in the dark than in light. Optima for germination were 10–15 C for C. piperiana, 15 C for C. ledicola. and 20 C for C. ledi var. glandulosi. Basidiospores of C. piperiana survived only 5 hr at 5–10 C and 99–100% RH.
Aecia of C. piperiana matured most rapidly at 20 C. Aecia produced at 10 or 15 C were larger than those produced at 20 or 25 C. Light increased germination of C. ledicola aeciospores. The optimum range for aeciospore germination was 25–30 C, the minimum 5–10 C and the maximum, 30–35 C. Aeciospores of C. ledicola germinated (30%) after 528 days storage at –76 C, C. piperiana (0.2%) after 829 days.