Journal of the American Society for Horticultural Science (1996) 121, 948-953

I.E. Yates, K.M.T. Cason and Darrell Sparks (1996)
Pecan scab fungus lacks substrate specificity for early infection stages
Journal of the American Society for Horticultural Science 121 (5), 948-953
Abstract: Leaves and callus of pecan [Carya illinoinensis (Wangenh.) K. Koch], and glass, dialysis membrane, and agar were examined for capacity to support two of the earliest infection stages-conidium (spore) germination and appressorium formation-of Cladosporium caryigenum (Ellis and Langl.) Gottwald, the fungus causing pecan scab. Light and temperature effects on formation of germ tubes and appressoria were examined for conidia suspended in distilled-deionized water. Conidia formed germ tubes on all substrates and in distilled-deionized water; hence, conidia possessed endogenous materials required for germination and are independent of specific topographic or chemical stimuli. All substrates, except 2% water agar and water, sustained appressoria development, thus implicating regulation by surface hardness. More appressoria formed on leaf discs than on other substrates. Additionally, conidia formed appressoria with short germ tubes when near a leaf structural feature, such as stomatal guard cells. Thus, the pecan scab fungal isolate used in these experiments appeared to lack substrate specificity for forming germ tubes, but not appressoria, during the prepenetration stages of development. Conidium germination was maximized at about 25 °C and germination did not respond to light.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Ida E. Yates

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Venturia effusa	Pecan/hickory (Carya)