Foliar and Soil Treatments of <i>Brassica napus</i> That Elicit Antibiosis in <i>Brevicoryne brassicae</i>

Abstract

In screenhouses, foliar and soil applications of induced resistance (IR), nutrient deterrence (ND), and soil amendment (SAM) treatments to canola, Brassica napus L., reduced fitness in an aphid pest, Brevicoryne brassicae L. Effects of different combinations and doses of IR, ND, and SAM on aphids were compared with those of labeled doses of Carbosulfan and a control. Dose differences between treatments and the control were found for several measures of B. brassicae fitness, including Kaplan–Meier functions, reproduction time, effective fecundity (Md), intrinsic rates of natural increase (rm), relative growth rate (RGR), and generation time. Progeny, development/pre-reproductive period, and percent progeny nymph survival were also significantly different from the control. Carbosulfan was the most rapidly acting treatment; however, 1 mM salicylic acid (SA) produced statistically significant reductions in aphid fitness compared to the control, followed by 1 mM citric acid (CA), 0.5 mM SA, and 0.5 mM CA. Silicon (Si) at 50 kg/ha was the most effective ND approach. Ammonium sulfate (AS) only decreased fitness at 25 kg/ha. The SAM combinations of both elemental sulfur (ES) and bio-sulfur (BS) treatments with compost (Cp) also yielded statistically significant aphid fitness reductions. These results provide context for future exploration of IR, ND, and SAM approaches to improve canola yield and reduce aphid damage.

Keywords

• biological interactions
• bio-sulfur
• citric acid
• organic compost
• plant resistance inducers
• salicylic acid