Analysis of tree-ring chronologies from the Patagonian Andes yields evidence for the 18.6 yr lunar nodal term in drought/flood. The mean discrepancy between epochs of drought/flood and the nodal tide since AD 1600 is 0.7¿2.2 yr, but the polarity of the signal is apparently bimodal. From nodal epoch 1750.0 through 1898.9 droght and tide were in phase, whereas prior to 1750.0 and subsequent to 1896.9 drought and tide were out of phase. There is evidence also for the solar cycle drought signal in the data.