Using Koch’s Postulate to Identify the Causative Agent of Dieback in Malosma laurina During Historic Drought in California

Coastal Southern California has a Mediterranean-type climate, meaning that it experiences warm, dry summers and cool, wet winters. Recently, California has been experiencing an unprecedented drought, possibly as a result of climate change. Malosma laurina is a typically hearty chaparral plant is known for being resistant to drought due to its deep rooting depth, but even it is being negatively affected by drought and is experiencing dieback. Some of this dieback is caused by a Botryospharae fungal infection, which blocks xylem conduits and stops water flow through the plant. With a looming El Niño, this study seeks to understand the relationship between rain, fungus, and M. laurina in attempts to predict what the long term effect rain might have on the spread of the fungal infection. In a laboratory setting, we found no significant difference between the length of fungal infection in hydrated and water stressed plants. We also found no evidence that this fungus is using fusicoccin to further dehydrate the plants