@article{fichtner_hesterberg_smyth_shew_2006, title={Differential sensitivity of Phytophthora parasitica var. nicotianae and Thielaviopsis basicola to monomeric aluminum species}, volume={96}, ISBN={0031-949X}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-33644892775&partnerID=MN8TOARS}, DOI={10.1094/phyto-96-0212}, abstractNote={ Aluminum (Al) is toxic to many plant pathogens, including Thielaviopsis basicola and Phytophthora parasitica var. nicotianae. Because fungi-toxicity of Al has been described in soils over a wide pH range, multiple species of Al may be responsible for pathogen suppression. The goals of this work were to determine the sensitivity of T. basicola and P. para-sitica var. nicotianae to Al over a range of pH values, quantify the toxicity of monomeric Al species to production of sporangia of P. parasitica var. nicotianae and chlamydospores of T. basicola, and detect the accumulation of Al in pathogen structures. A complete factorial treatment design was used with Al levels ranging from 0 to 100 μM and pH levels ranging from 4 to 6 in a minimal salts medium. The chemistry of test solutions was modeled using GEOCHEM-PC. Colonies were grown in 5% carrot broth, and after 1 or 2 days, the nutrient solution was removed, colonies were rinsed with water, and Al test solutions were added to each of four replicate plates. After 2 days, propagules were counted and colonies were stained with the Al-specific, fluorescent stain lumogallion. The oomycete P. parasitica var. nicotianae was sensitive to multiple monomeric Al species, whereas sensitivity of T. basicola to Al was pH-dependent, suggesting that only Al3+ is responsible for suppression of this fungal pathogen. Chlamydospore production by T. basicola was inhibited at pH values <5.0 and Al levels >20 μM, whereas sporangia production by P. parasitica was inhibited at Al levels as low as 2 μM across all pH values tested. The lumogallion stain was an effective technique for detection of Al in fungal tissues. Aluminum accumulated in sporangia and zoospores of P. parasitica var. nicotianae and in nonmelanized chlamy-dospores of T. basicola, but not in cell walls of either organism. The differential sensitivity of the two organisms may indicate that true fungi respond differently to Al than members of the oomycota, which are more closely related to plants. }, number={3}, journal={Phytopathology}, author={Fichtner, E. J. and Hesterberg, Dean and Smyth, T. J. and Shew, H. D.}, year={2006}, pages={212} }
 @article{fichtner_benson_diab_shew_2004, title={Abiotic and biological suppression of Phytophthora parasitica in a horticultural medium containing composted swine waste}, volume={94}, ISSN={["1943-7684"]}, DOI={10.1094/PHYTO.2004.94.7.780}, abstractNote={ Horticultural potting media have been amended with compost to enhance biological suppression and with Al2(SO4)3 to enhance abiotic suppression of plant pathogens, but these factors have not been simultaneously incorporated into the same medium. In this study, the efficacy of aluminum (Al)-amended potting medium containing 20% composted swine waste (CSW) was assessed for control of Phytophthora parasitica (syn. P. nicotianae), a soilborne pathogen causing damping-off of many horticultural bedding plants. Steamed and unsteamed media were amended with no Al or Al at 0.0079 g of Al g-1 of medium with an Al2(SO4)3 solution at either pH 4 or pH 6. Infested leaf disks were buried for 2-day durations beginning 0, 6, 13, and 21 days after Al amendment. The number of sporangia produced on infested leaf disks was assessed. A similar experiment was conducted to determine the effect of steaming and Al amendments on pathogen populations. Medium treated with the pH 4 solution consistently reduced sporangia production between 38 and 65% on day 0, but no Al effect was noted at subsequent time points. The pH 6 amendment did not consistently affect sporangia production. Exchangeable Al levels decreased over time, and abiotic suppression was only observed at >2 μM Al g-1 of medium. Pathogen populations were occasionally affected by steaming and Al. Sporangia production in unsteamed medium was reduced by 50% on leaf disks buried on days 6, 13, and 21, but not on day 0. Al amendment of a 20% CSW potting medium enhanced suppression of P. parasitica and abiotic suppression occurred before biological suppression developed. }, number={7}, journal={PHYTOPATHOLOGY}, author={Fichtner, EJ and Benson, DM and Diab, HG and Shew, HD}, year={2004}, month={Jul}, pages={780–788} }