Baseline Sensitivity and Control Efficacy of Pyraclostrobin Against Botryosphaeria dothidea Isolates in China

Abstract

Botryosphaeria dothidea is an important fungal pathogen that causes apple ring rot, which can significantly reduce apple yield. Fungicide applications are the main control measure of apple ring rot worldwide. Pyraclostrobin is a quinone outside inhibitor (QoI) fungicide that has yet to be registered for control of B. dothidea in China. Baseline sensitivity of B. dothidea to pyraclostrobin (EC50 of mycelial growth inhibition) was assessed for 97 isolates collected in Shandong Province. The EC50 values ranged from 0.7010 to 7.1378 μg/ml with the mean value of 3.0870 μg/ml and displayed a unimodal frequency distribution. After cultured on fungicide-free PDA medium or on apples for multiple generations, the B. dothidea–resistant isolates (RST) remained resistant to pyraclostrobin, but exhibited similar virulence as the susceptible isolates (ST). Cross-resistance investigation revealed that pyraclostrobin was not cross-resistant to tebuconazole, flusilazole, carbendazim, and iprodione. Field evolution showed that pyraclostrobin at 200 and 250 g a.i./ha provided greater than 80% control efficacy against apple ring rot disease when applied as a therapeutic or preventive fungicide. The efficacy was similar to fungicides that have been registered for apple.

Determination of pyraclostrobin residue in wax gourd and its dietary risk assessment

“…However, it is vulnerable to some diseases of early blight, gray mold, powdery mildew, and which seriously affect the yield and quality of wax gourd (Jiang et al, 2018). Pyraclostrobin has a good control effect on powdery mildew, gray mildew, downy mildew and other diseases (Bowness et al, 2016;Chen et al, 2012;Fan et al, 2019;Skandalis et al, 2016).…”

Efficacy of Dimethyl Trisulfide on the Suppression of Ring Rot Disease Caused by Botryosphaeria dothidea and Induction of Defense-Related Genes on Apple Fruits

“…Unfortunately, the major commercial cultivars like red fuji, golden delicious, gala, and red delicious are highly susceptible to B. dothidea (Guan et al, 2015). Therefore, fungicide application is still the primary method to control apple ring rot worldwide (Fan et al, 2016(Fan et al, , 2019. Previous studies showed that synthetic fungicides including fludioxonil, fluazinam, pyrisoxazole (Song et al, 2018), difenoconazole, tebuconazole, prochloraz, trifloxystrobin (Dai et al, 2017), tebuconazole (Fan et al, 2016), and pyraclostrobin (Fan et al, 2019) exhibit great potential for inhibiting the apple ring rot.…”

“…Therefore, fungicide application is still the primary method to control apple ring rot worldwide (Fan et al, 2016(Fan et al, , 2019. Previous studies showed that synthetic fungicides including fludioxonil, fluazinam, pyrisoxazole (Song et al, 2018), difenoconazole, tebuconazole, prochloraz, trifloxystrobin (Dai et al, 2017), tebuconazole (Fan et al, 2016), and pyraclostrobin (Fan et al, 2019) exhibit great potential for inhibiting the apple ring rot. However, the overuse of synthetic chemical pesticides leads to the development of fungicide resistance and causes environmental pollution and health problems.…”

Endophytic bacterium Pseudomonas protegens suppresses mycelial growth of Botryosphaeria dothidea and decreases its pathogenicity to postharvest fruits

“…Currently, chemical fungicides are still the primary strategies for controlling apple ring rot disease ( Dai et al, 2017 ; Song et al, 2018 ; Fan et al, 2019 ). However, these fungicides were potentially hazardous to human health, other non-target organisms, and the natural environment.…”