Intercropping influenced the occurrence of stripe rust and powdery mildew in wheat

• Intercropping of wheat and maize controlled wheat stripe rust by 16.7–45.7%.
• Intercropping of wheat and maize controlled wheat powdery mildew by14.7–27.0%.
• Intercropping of wheat with potato or chili did not show significant disease reduction.
• The above two intercropping patterns increased yield by 150% or more.

The intercropping of three susceptible winter wheat varieties, Lantian 13, Lantian 6, and Tian 94-3, with potato, chili, maize, sunflower, benne or soybean was tested for efficacy in controlling stripe rust and powdery mildew and increasing yields in the field under different ecological conditions in Tianshui, Gansu Province, China, from 2007 to 2009. The relative control efficacies of the intercropping between wheat and maize were 16.7%–45.7% for stripe rust and 14.7%–37.0% for powdery mildew compared to the pure stands of wheat. The yield increased by 52.4%–140.0%. The relative control efficacies of intercropping between wheat and sunflower were 5.9%–28.9% for stripe rust and 11.7%–18.4% for powdery mildew. The yield increased by −1.4%–24.8%. The differences were statistically significant for control efficacy. Therefore, intercropping systems could be used extensively in South Gansu, where machinery is seldom used due to the mountainous landscape, to reduce damage caused by the two major diseases. The intercropping system of wheat with potato or chili did not result in significant differences in disease reduction compared to the pure wheat stands. However, the two crop combinations increased the yield by 150.0% or more. Other intercropping combinations did not result in a significant disease reduction or yield increase.