Plant Disease (1999) 83, 367-370

R.A. Schmidt and T. Miller (1999)
Influence of inoculum concentration on production of spermogonia and aecia on pine seedlings infected by basidiospores of Cronartium quercuum f. sp. fusiforme
Plant Disease 83 (4), 367-370
Abstract: Seedlings of slash pine and loblolly pine inoculated with four concentrations of basidiospores of Cronartium quercuum f. sp. fusiforme and exhibiting large galls (>=25 mm long) were observed for spermogonial and aecial sporulation. Basidiospores from a genetically heterogeneous source at 50, 100, 1,000 and 5,000 spores/5-µl droplet were applied to the severed, succulent terminal of 6-week-old seedlings. Incidence of sporulation showing (i) spermatia (pycniospores) only, (ii) aeciospores only, (iii) spermatia and aeciospores, and (iv) absence of sporulation was recorded for 3 years. On slash pine, the percentage of seedlings showing only spermatia varied significantly and inversely with inoculum concentration. In contrast, the percentage of seedlings showing only aeciospores or aeciospores and spermatia varied directly with inoculum concentration. Results on loblolly pine were similar. It is suggested that, at low inoculum concentrations, hyphal anastomoses are limited by fewer haploid mycelia in infected tissues or fewer mating types resulting from incompatible host-parasite interactions.
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Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cronartium quercuum	Pine (Pinus)	U.S.A. (SE)