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November 2017 WINES&VINES 93 WINE EAST WINEMAKING Background on Pestalotiopsis The genus Pestalotiopsis consists of 205 de- scribed species. These species are differenti- ated based on conidial characteristics including size, septation, pigmentation and the presence or absence of apical appendages. The five- celled conidia have distinctive basal append- ages that make them appear like microscopic insects. Pestalotiopsis is a complex genus and can be difficult to classify to the species level because characteristics such as growth rate, conidial morphology and fruiting structure tend to vary within species. Pestalotiopsis species are considered to be weak pathogens, phytopathogens, saprophytes or endophytic symbionts. As a plant pathogen, Pestalotiopsis is thought to be opportunistic and can affect plants under stress. Many of the Pestalotiopsis species reported to be plant dis- ease pathogens are not host specific, and this lack of host specificity has resulted in confusion in identifying and classifying species. The range of symptoms that have been as- sociated with Pestalotiopsis among grape species and within interspecific grape cultivars makes it difficult to diagnose the pathogen within a field setting. Volenberg and Morton have devel- oped techniques to culture Pestalotiopsis both in-vivo and in-vitro for identification. Symptom- atic grapevine tissue was collected and trans- ported to laboratories located in Columbia, Mo., or Charlottesville, Va. They also took photo- graphs to document the symptomology viewed in the field and in the laboratories. In-vivo symptomatic tissue incubation Samples were initially inspected for fungal fruiting structures, prior to moist incubation. Berry or plant tissue with the symptomology of Pestalotiopsis was moist incubated in sealed containers at 21° to 24° C, with the samples elevated above moist paper towels. The sam- ples were under a 12-hour photoperiod sup- plied by fluorescent lights. Conidiophores arising from the tissues were gently crushed in sterile water, and conidia were viewed with optical microscopy. Black pycnidia producing black cirrhi (a mu- cus-bound ribbon-like mass of spores that exudes from a fungus) were observed on symptomatic leaf, petiole, pedicel and rachis tissue after 24 to Symptoms of Pestalotiopsis include leaf discoloration (seen above left on a Chambourcin vine in Missouri) and leaf splotch (pictured at right on a Norton leaf in Missouri). DEAN VOLENBERG PAT WOHLER