Open AccessCalcium Interference with Zoospore Biology and Infectivity of Phytophthora parasitica in Nutrient Irrigation Solutions
Author(s) -
S. L. von Broembsen,
J.W. Deacon
Publication year - 1997
Publication title -
phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.264
H-Index - 131
eISSN - 1943-7684
pISSN - 0031-949X
DOI - 10.1094/phyto.1997.87.5.522
Subject(s) - zoospore , sporangium , biology , fertilizer , calcium , germination , botany , spore , agronomy , chemistry , organic chemistry
Calcium, applied as either CaCl2 or Ca(NO3)2 to water or calcium-free soluble fertilizer solution (Peters 20-10-20 Peat Lite Special), affected several important stages of Phytophthora parasitica zoospore behavior relevant to infection and disease spread. Release of zoospores from sporangia was suppressed by Ca 2+ concentrations in the range of 10 to 50 meq. These concentrations also curtailed zoospore motility; 20 meq of Ca 2+ in fertilizer solution caused all zoospores to encyst within 4 h, whereas 94% of zoospores remained motile in unamended solution. In addition, Ca 2+ in the range of 10 to 30 meq stimulated zoospore cysts to germinate in the absence of an organic nutrient trigger, while suppressing the release of a single zoospore (diplanetism) from cysts that did not germinate. In growth chamber experiments, the amendment of the fertilizer solution with 10 or 20 mM Ca(NO3)2 greatly suppressed infection of flood-irrigated, containerized vinca seedlings in a peat-based mix by motile or encysted zoospores of P. parasitica. These results demonstrate that Ca 2+ amendments interfere with P. parasitica zoospore biology at multiple stages, with compounding effects on epidemiology, and suggest that manipulation of Ca 2+ levels in irrigation water or fertilizer solutions could contribute to management of Phytophthora in recirculating irrigation systems.