Huanglongbing (HLB) or Citrus Greening was first observed in Florida in 2005. As a result, Florida orange production has dropped 81% since the 2003-04 season. There is no cure for HLB and current management practices involve the use of bactericides, insecticides, enhanced nutrition programs, soil/water pH modification, and ultimately removal and replanting of citrus trees, thus driving the cost of grove maintenance up 208%. The use of bactericides and insecticides offer only temporary relief and there are concerns over the development of bacterial resistance in the vector over time as well as environmental concerns regarding their use. An effective, environmentally friendly, and cost effective method for addressing HLB is needed. In this work we report on the use of oak leaf water extract that exhibits antibacterial activity in HLB infected citrus trees. Solvent extracted fractions of oak leaf were applied to HLB infected citrus leaves and exhibited a reduction in HLB bacterial titer values over a 7-day period. This same effect was observed in experiments where the entire oak water extract was applied in drench application to HLB infected citrus trees. Mass spectral analyses of fractions that exhibited a greater degree of reduction in bacterial infection over time were conducted. Comparison of peaks in the mass spectral data to a compound library and verification of identity with chemical standards was completed. Possible mechanisms of action will be discussed.

Chemistry of oak (<i>Quercus</i> spp.) water extract and its effect on HLB infected citrus trees

2019 Spring National Meeting

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Chemistry of oak (Quercus spp.) water extract and its effect on HLB infected citrus trees