Number of cotyledons affects susceptibility to fusiform rust within but not among families of slash and loblolly pine
Plant Disease Reporter 62(8): 731-734
Seedlings of slash [Pinus elliottii var. elliottii] and loblolly [P. taeda] pine families were tested for susceptibility to fusiform rust [Cronartium quercuum f. sp. fusiforme] by artificial inoculation in a greenhouse environment. The average number of cotyledons per seedling differed significantly among families, but their numbers were not correlated with familial susceptibility to the disease. Within each family, slash pine seedlings having 8 or more cotyledons and loblolly pine seedlings having 7 or more cotyledons were significantly more susceptible to fusiform rust than were seedlings possessing fewer cotyledons. Susceptibility to fusiform rust in slash and loblolly pine seedlings, therefore, increased as the number of cotyledons increased within, but not among, families. Hypocotyl length was not correlated with susceptibility to the disease.