Location: Horticultural Crops Disease and Pest Management Research Unit
Project Number: 2072-22000-046-024-G
Project Type: Grant
Start Date: May 1, 2022
End Date: Oct 31, 2023
Objective:
1. Evaluate triazole fungicides for use as a soil drench for management of boxwood blight.
2. Compare the efficacy of foliar spray vs. soil drench applications of triazole fungicides for management of boxwood blight.
Approach:
Evaluation by detached leaf assays: Each of 5 triazole fungicides and a water control will be applied to 20 Buxus sempervirens ‘common’ in 11.25 liter containers grown in a greenhouse. For each fungicide treatment, 10 plants each will be treated by foliar spraying and directly drenching the container media (120 plants total). After 48 h, then weekly for 12 weeks, 1 leaf will be collected from the interior and 1 from the exterior canopy of each plant. These leaves will then be inoculated with a spore suspension of C. pseudonaviculata in the lab and placed in microwell plates. Leaves will be rated 3 times per week for 2 weeks for presence of aerial mycelium and percent diseased tissue. Symptoms of phytotoxicity and plant growth regulation (PGR) will be visually estimated. An ANOVA model will be used to estimate the effect of fungicide treatment and application method on weekly incidence and weekly area under the disease progress curve as well as phytotoxicity and PGR. The experiment will be repeated twice.
Evaluation by chemical analysis: Each of 5 triazole fungicides and a water control will each be applied to rooted cuttings of Buxus sempervirens ‘common’. Each treatment will be applied using two application methods with at least 3 replicate plants for each method. Treatment will be applied directly to the media as a soil drench or pipetted onto the upper inch of stem tissue. After 10 days, the plants will be cut at the soil surface and frozen. Each sample will be analyzed and the amount of the applied fungicide in each third of the shoot tissue will be quantified. A MANOVA will be used to estimate the effect of application method and fungicide treatment on each third of the plant. Chemical analysis will take place in the OSU Mass Spectrometry Center.
