Presentation Title

Potential Spread of the Fungal Pathogen Botryospharea dothidea from Chaparral Shrubs to Grape Vineyards in the Santa Monica Mountains

Faculty Mentor

Natalie M. Aguirre, Rodney L. Honeycutt, Stephen D. Davis

Start Date

18-11-2017 12:30 PM

End Date

18-11-2017 1:30 PM

Location

BSC-Ursa Minor 53

Session

Poster 2

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

We tested the hypothesis that an opportunistic endophytic fungus, Botryosphaeria dothidea, that frequently infects and causes dieback in species of chaparral shrubs in the Santa Monica Mountains during drought events, may spread to grape vineyards in the Santa Monica Mountains. Recently a dominant chaparral species in coastal exposures of the Santa Monica Mountains, Malosma laurina, has undergone extensive dieback in low elevation, dry sites, in response to historic drought in California, but less dieback in high elevation moist sites. M. laurina frequently grows adjacent grape vineyards. Thus we hypothesized that fungal isolates from a low elevation, dry vineyard would have higher incidence of B. dothidea, than a high elevation, moist vineyard. We tested this hypothesis by isolating the fungus from twelve samples at each location. Greater than 75% of the samples produced fungal growth on potato dextrose agar. We found two cultures from the low elevation vineyard and one from the high elevation vineyard, to have colony morphology similar to B. dothidea. We isolated DNA from each culture and used genetic markers of internal transcribed spacer (ITS), elongation factor 1α (EF1), and beta tubulin 2 (BT2) to identify the fungus. None of these three samples were B. dothidea. However all three samples are considered close relatives of B. dothidea and the sample at the low elevation dry site was Diplodia seriata, an anamorph of Botryosphaeria obtusa. We interpret this to mean that Botryosphaeria dothidea has not jumped from native chaparral species to grape vineyards, at least at the two sites examined in the Santa Monica Mountains. One possibility is that the standard irrigation of grape vineyards in the Santa Monica Mountains has maintained their ability to ward off Botryosphaeria infestation during historic drought in California whereas this has not been the case for non-irrigated Malosma laurina.

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Nov 18th, 12:30 PM Nov 18th, 1:30 PM

Potential Spread of the Fungal Pathogen Botryospharea dothidea from Chaparral Shrubs to Grape Vineyards in the Santa Monica Mountains

BSC-Ursa Minor 53

We tested the hypothesis that an opportunistic endophytic fungus, Botryosphaeria dothidea, that frequently infects and causes dieback in species of chaparral shrubs in the Santa Monica Mountains during drought events, may spread to grape vineyards in the Santa Monica Mountains. Recently a dominant chaparral species in coastal exposures of the Santa Monica Mountains, Malosma laurina, has undergone extensive dieback in low elevation, dry sites, in response to historic drought in California, but less dieback in high elevation moist sites. M. laurina frequently grows adjacent grape vineyards. Thus we hypothesized that fungal isolates from a low elevation, dry vineyard would have higher incidence of B. dothidea, than a high elevation, moist vineyard. We tested this hypothesis by isolating the fungus from twelve samples at each location. Greater than 75% of the samples produced fungal growth on potato dextrose agar. We found two cultures from the low elevation vineyard and one from the high elevation vineyard, to have colony morphology similar to B. dothidea. We isolated DNA from each culture and used genetic markers of internal transcribed spacer (ITS), elongation factor 1α (EF1), and beta tubulin 2 (BT2) to identify the fungus. None of these three samples were B. dothidea. However all three samples are considered close relatives of B. dothidea and the sample at the low elevation dry site was Diplodia seriata, an anamorph of Botryosphaeria obtusa. We interpret this to mean that Botryosphaeria dothidea has not jumped from native chaparral species to grape vineyards, at least at the two sites examined in the Santa Monica Mountains. One possibility is that the standard irrigation of grape vineyards in the Santa Monica Mountains has maintained their ability to ward off Botryosphaeria infestation during historic drought in California whereas this has not been the case for non-irrigated Malosma laurina.