ISHS Acta Horticulturae 272: Symposium on Bedding and Pot Plant Culture
POTENTIAL FOR TRANSFER OF PYTHIUM ULTIMUM IN PRODUCTION OF SEEDLING GERANIUMS WITH SUBIRRIGATION AND RECIRCULATED SOLUTIONS |
| Authors: | Renee K. George, John A. Biernbaum, C.T. Stephens |
| Abstract:
Forty day old geranium (Pelargonium X hortorum L.H. Bailey "Ringo Scarlet") seedlings were transplanted, into 10 cm x 9 cm plastic pots, containing one of four levels of Pythium ultimum Trow inoculated media (I), non-inoculated media (NI), or non-inoculated media drenched with metalaxyl (NIM). One each of I, NIM and NI pots were placed in 24 plastic trays and subirrigated with a recirculated nutrient solution. P. ultimum was isolated from all the plants grown in inoculated media (I) except the zero inoculum level. Level of infestation was sufficient to cause stem and root rot in most infested plants as early as two weeks after planting. Plant mortality had occurred in 75% of the infested plants harvested at four and eight weeks. No Pythium ultimum was isolated from the media, roots or plants of the NI and NIM plants at any harvest. There was no significant difference between plant and root dry weights of the NI and NIM plants. At eight weeks, P. ultimum was isolated from the residue filtered from the two water reservoirs of the systems containing pots with the high level of inoculum. | |
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