호박 흰가루병의 피해 해석 및 경제적 방제수준 설정 |
문윤기, 최준근, 강안석 |
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Yield Loss Assessment and Economic Threholds of Squash Powdery Mildew Caused by Sphaerotheca fuliginea |
Youn Gi Moon, Jun Keun Choi, An Seok Kang |
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Abstract |
The experiments were carried out in fields for two years from 2008 to assess yield losses of squash due to powdery mildew caused by Sphaerotheca fuliginea and to determine its economic thresholds. Powdery mildew disease was first observed in late June, about 50 days after field-transplanting, progressed rapidly during late July to early August, and began to reduce from late August. Powdery mildew severity was negatively correlated with squash yields. A positive correlation was observed between fruit weight and % marketable fruits. A simple linear regression model was obtained as Y=.10.399 X + 6607.5 with R2= 0.9700 when squash yields (Y) was predicted using powdery mildew severity as an independent variable(X). Spray threshold for maximizing squash yields without economic considerations was estimated as 6.5% in terms of leaf lesion area with powdery mildew. Economic threshold and economic spray threshold able to compensate the costs of fungicide sprays were determined as 21.6% and 17.3% in leaf lesion area, respectively. |
Key Words:
Economic threshold, Powdery mildew, Spray threshold, Sphaerotheca fuliginea, Squash, Yield Loss model |
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