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The cucurbit yellow stunting disorder virus (CYSDV) transmitted by Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) has caused significant reductions in fall melon (Cucumis melo L.) yields in Yuma County, Arizona. In a recent landscape-based study, we found evidence that cotton and spring melon fields increased abundance of B. tabaci and spread of CYSDV infection in fall melon fields. Here, we show that a statistical model derived from data collected in 2011-2012 and based on areas of cotton and spring melon fields located within 1,500 m from edges of fall melon fields was sufficient to retrospectively predict incidence of CYSDV infection in fall melon fields during 2007-2010. Nevertheless, the slope of the association between areas of spring melon fields and incidence of CYSDV infection was three times smaller in 2007-2010 than in 2011-2012, whereas the slope of the association between areas of cotton fields and incidence of CYSDV infection was consistent between study periods. Accordingly, predictions were more accurate when data on areas of cotton alone were used as a basis for prediction than when data on areas of cotton and spring melons were used. Validation of this statistical model confirms that crop isolation has potential for reducing incidence of CYSDV infection in fall melon fields in Yuma County, although isolation from cotton may provide more consistent benefits than isolation from spring melon., (© The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Theory indicates that landscape composition affects transmission of vector-borne crop diseases, but few empirical studies have investigated how landscape composition affects plant disease epidemiology. Since 2006, Bemisia tabaci (Gennadius) has vectored the cucurbit yellow stunting disorder virus (CYSDV) to cantaloupe and honeydew melons (Cucumis melo L.) in the southwestern United States and northern Mexico, causing significant reductions in yield of fall melons and increased use of insecticides. Here, we show that a landscape-based approach allowing simultaneous assessment of impacts of local (i.e., planting date) and regional (i.e., landscape composition) factors provides valuable insights on how to reduce crop disease risks. Specifically, we found that planting fall melon fields early in the growing season, eliminating plants germinating from seeds produced by spring melons after harvest, and planting fall melon fields away from cotton and spring melon fields may significantly reduce the incidence of CYSDV infection in fall melons. Because the largest scale of significance of the positive association between abundance of cotton and spring melon fields and CYSDV incidence was 1,750 and 3,000 m, respectively, reducing areas of cotton and spring melon fields within these distances from fall melon fields may decrease CYSDV incidence. Our results indicate that landscape-based studies will be fruitful to alleviate limitations imposed on crop production by vector-borne diseases.