Effect of boric acid on <i>Saprolegnia</i> cyst germination.

<p>The mean number of germinating <i>Saprolegnia</i> cysts counted at 200× magnification 6 h following incubation with different boric acid concentrations.</p

Viability of treated <i>Saprolegnia</i> spores 24 h following removal of boric acid.

<p>Grade 0: no germination, no growing mycelia on the sesame seeds.</p><p>Grade 1: germinating spores, no growing mycelia on the sesame seeds.</p><p>Grade 2: germinating spores, very few growing mycelia on the sesame seeds.</p><p>Grade 3: germinating spores, profuse growing mycelia on the sesame seeds.</p

Protection against natural infection in yolk sac fry.

<p>Survival curve of treated salmonid yolk sac fry and control during the outbreak of saprolegniosis. Note the significant reduction in mortality among treated group (p<0.001).</p

Intermittent exposure to boric acid.

<p>Mortality and hatching rates by the end of the experiment in boric acid treated groups and non-treated control (0.0 g/L).</p

Continuous exposure to boric acid.

<p>Mortality and hatching rates in boric acid treated groups and the non-treated control (0.0 g/L) at the end of the first experiment.</p

Effect of boric acid on <i>Saprolegnia</i> radial growth rate.

<p>The mean radial growth rate of two <i>Saprolegnia</i> sp. following 72 h incubation on glucose yeast agar mixed with different boric acid concentrations.</p

Effect of different boric acid concentrations on the radial growth rate of two <i>Saprolegnia</i> sp. (<i>S. parasitica</i> and <i>S. diclina</i>).

<p>*Based on 3 replicate colonies.</p

Effect of boric acid on the germination and colonization of <i>Saprolegnia</i> spores.

<p>Grade 0: no germination, no growing mycelia on the sesame seeds.</p><p>Grade 1: germinating spores, no growing mycelia on the sesame seeds.</p><p>Grade 2: germinating spores, very few growing mycelia on the sesame seeds.</p><p>Grade 3: germinating spores, profuse growing mycelia on the sesame seeds.</p><p>* Average of 3 replicates.</p

Protection against infection of dead eggs.

<p>Mortality and hatching rates in egg groups intermittently exposed to boric acid (third experiment) compared to non-treated control (0.0 g/L).</p

Viability of treated <i>Saprolegnia</i> spores and zoosporangia during treatment and post-treatment removal.

<p>Fluorescence microscopy showing the viability of boric acid treated <i>Saprolegnia</i> spores and zoosporangia with SYTO 9 stain. <b>a1</b>) Colonization is seen on control seed. <b>a2</b>) Normal zoosporangium sporulating. <b>b1</b>) Non-colonized seed during treatment. <b>b2</b>) Effect on zoosporangium during treatment. <b>c1</b> and <b>c2</b>) Spores and zoosporangium were treated for 24 h with BA and left in sterilized aquarium water (SAW) for another 24 h after treatment was terminated. Germlings can be seen surrounding the seeds in c1. <b>c2</b>) shows a close-up of zoosporangium treated as in c1. <b>d1</b> and <b>d2</b>) Spores and zoosporangium were treated for 96 h in BA and then left in SAW for 24 h after treatment was terminated. There is no colonization on seeds after 96 h BA treatment (<b>d1</b>) and the zoosporangium (<b>d2</b>) appears with condensed staining and a thin wall.</p