Control of potato powdery scab caused by Spongospora subterranea by foliage cover and soil application of chemicals under field conditions with naturally infested soil
2020
Tsror (Lahkim), Leah | Lebiush, Sara | Hazanovsky, Marina | Erlich, Orly
Powdery scab (PS), caused by Spongospora subterranea, reduces the quality and marketability of potatoes worldwide. Disease symptoms include lesions on the tuber surface and root galling, which may lead to yield losses. In the current study we report a sustainable approach to reduce PS by manipulating soil temperature during tuber initiation. Plant cover with nonwoven fabric significantly reduced PS on tubers by 54%–69% in 2017 and 84%–93% in 2019, compared to the control, and root galling by 96% in 2019, due to an increased average minimum and maximum soil temperature of 1.8 and 4.2 °C in respective years. Additional preplanting soil treatments were also evaluated in naturally infested soil. In 2017, disease incidence and severity were significantly reduced using 2.5 or 5 L a.i./ha fluazinam in broadcast application or in‐furrow, and by 0.375 or 0.75 L a.i./ha flusulphamide applied in‐furrow. In 2019, disease incidence and severity were significantly reduced by the broadcast application of fluazinam, and 75 kg/ha calcium cyanamide, but the latter had a negative impact on yield. Soil fumigation with metam sodium resulted in a 98% reduction in PS. Root galling was significantly reduced by calcium cyanamide, metam sodium, and fluazinam in the 2019 trial only. Foliar application of resistance‐inducing phosphonates combined with fluazinam application had no additive effect on PS incidence and severity. Integrated approaches such as tolerant cultivars, soil testing, preplanting fungicide application, and sustainable means of control such as foliage cover for a short period may be implemented in order to control the disease and minimize damage.
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