Evaluating Natural Products for Control of Black Spot Disease on Roses

Black spot caused by the fungus Diplocarpon rosea Wolf. is the most widespread disease in ornamental roses. Frequent applications of environmentally non-benign chemical fungicides are necessary to effectively prevent and control this disease. Ecological and environmental concerns about frequent fungicide applications are growing, and public demand for safer alternatives to fungicides is increasing. This study evaluated water extracts and essential oils from holy basil (Ocimum gratissimum L.), sweet basil (Ocimum basilicum L.), English thyme (Thymus vulgaris L.), and ‘Scotch’ spearmint (Mentha x gracilis Sole) for suppression and control of black spot disease in roses as compared with a commonly used fungicide. The results revealed that weekly treatments with essential oils of ‘Scotch’ spearmint and English thyme produced significantly lower black spot rating as compared with a water control, and the fungicide treatment had lower black spot rating than all treatments, except the ‘Scotch’ spearmint essential oil and the English thyme essential oil. Our results demonstrate that essential oils of English thyme and ‘Scotch’ spearmint hold promise as biopesticides for control of black spot on roses as an alternative to chemical fungicides. The use of essential oils for suppression or control of black spot on roses would benefit environmental health, and minimize human exposure to pesticides in general

Quantitative field testing Rotylenchulus reniformis DNA from metagenomic samples isolated directly from soil.

A quantitative PCR procedure targeting the ?-tubulin gene determined the number of Rotylenchulus reniformis Linford & Oliveira 1940 in metagenomic DNA samples isolated from soil. Of note, this outcome was in the presence of other soil-dwelling plant parasitic nematodes including its sister genus Helicotylenchus Steiner, 1945. The methodology provides a framework for molecular diagnostics of nematodes from metagenomic DNA isolated directly from soil

Quantitative field testing Heterodera glycines from metagenomic DNA samples isolated directly from soil under agronomic production.

A quantitative PCR procedure targeting the Heterodera glycines ortholog of the Caenorhabditis elegans uncoordinated-78 gene was developed. The procedure estimated the quantity of H. glycines from metagenomic DNA samples isolated directly from field soil under agronomic production. The estimation of H. glycines quantity was determined in soil samples having other soil dwelling plant parasitic nematodes including Hoplolaimus, predatory nematodes including Mononchus, free-living nematodes and biomass. The methodology provides a framework for molecular diagnostics of nematodes from metagenomic DNA isolated directly from field soil

Specificity of the Rr- β-TUB qPCR primers under standard PCR conditions from known numbers of <i>R. reniformis</i>.

<p><i>R. reniformis</i> DNA was isolated from vermiform J2s serving as the template. The Rr-β-TUB-primed reactions. Abbreviation, R.r. - <i>R. reniformis</i>. Lane 1, 1000 R.r.; Lane 2, 1000 R.r.; Lane 3, 1000 R.r.; Lane 4, 100 R.r.; Lane 5, 100 R.r.; Lane 6, 100 R.r.; Lane 7, 10 R.r.; Lane 8, 10 R.r.; Lane 9, 10 R.r.; Lane 10, 1 R.r.; Lane 11, 1 R.r.; Lane 12, 1 R.r.; Lane 13, 1 R.r.; Lane 14, No DNA; Lane 15, No primers.</p

Number of nematodes per 500 cm³ of soil used in field assay.

<p>Number of nematodes per 500 cm³ of soil used in field assay.</p

Amplification characteristics of the Rr-β-TUB qPCR primers under standard PCR conditions on metagenomic DNA isolated directly from soil collected at the South Farm (SF) and cotton (Ct) sites.

<p>The number of nematodes whose DNA was isolated is provided below the amplicon in each reaction. Rr-β-TUB primed reactions. Lane 1, SF1; Lane 2, SF2; Lane 3, Ct1 sample 1; Lane 4, Ct2 sample 2; Lane 5, Ct3 sample 3; Lane 6, No DNA; Lane 7, No Primers.</p

Screening of Hg-unc primer pairs.

<p>Lane 1, Hg-unc 9; Lane 2, Hg-unc 22; Lane 3, Hg-unc 31; Lane 4, Hg-unc 52; Lane 5, Hg-unc 115; Lane 6, Hg-unc 101; Lane 7, Hg-dys-1; Lane 8, Hg-nep-1; Lane 9, Hg-unc 89; Lane 10, Hg-unc 78; Lane 11, Hg-MRCK-1.</p

DNA amplification of the Hg-unc78 from metagenomic DNA samples.

<p>Lanes 1–3, metagenomic DNA including 1 SCN J2; Lanes 4–6, metagenomic DNA including 10 SCN J2; Lanes 7–9, metagenomic DNA including 100 SCN J2; Lanes 10–12, metagenomic DNA including 1,000 SCN J2; Lane 13, cloned gene without primers (control); Lane 14, without DNA (control); Lane 15, positive control, amplification product is Hg-unc 78 amplified from the cloned gene.</p

<i>R. reniformis</i> β-tub primers for qPCR assay.

<p><i>R. reniformis</i> β-tub primers for qPCR assay.</p