Task 5 Research
Principal Investigator(s): Raul Cabrera
We mutually agree for Raul I. Cabrera to deliver the following during the period of July 1, 2009 to June 30, 2010 using funds from the Rio Grande Basin Initiative:
- Continue evaluating the water and nutrient use of three Texas native street trees (Ulmus crassifolia, Celtis laevigata and Maclura pomifera) infested by the parasitic xylem-tapping leafy mistletoe (Phoradendron spp.). We will monitor water and nutrient use by mistletoes in mature infected trees growing under a range of landscape management conditions (trees in undisturbed, native wooded areas and in highly-managed urban environments). This includes physiological determinations of water relations and nutrient status (stomatal conductance, water potential, chlorophyll, tissue nutrient concentrations) in both the mistletoe and its hosts through the seasons. As the second component of this research, we have successfully infected container-grown cedar elms (Ulmus crassifolia) with mistletoes and we will monitor its growth, and once they reach an adequate we will measure, by mass-balance approaches, water and nitrogen fertilizer use by the whole plants in comparison to non-infected (control) plants, both under stressful and optimal management conditions.