The potential of strip cropping to suppress potato late blight

Context

Crop diversification through intercropping is known to suppress disease severity and incidence. Strip cropping is an adaptation of intercropping in which strips are made wide enough e.g. 3 m or wider to allow management with tractor-pulled equipment. There is, however, little evidence of the efficacy of disease suppression in strip cropping. Furthermore, it is unclear how and to which extent the choice of companion crop species affects the suppression of diseases.

Objective and Methods

Here we determine how potato late blight, caused by Phytophthora infestans, is affected by strip cropping potatoes with three different companion crops: grass, maize or faba bean. Potato late blight severity and tuber yield were determined in field experiments in the Netherlands during three years that differed in both weather conditions and timing of the onset of the epidemic.

Results

Strip cropping with grass or maize lowered disease severity compared with potatoes grown in monoculture. Across the three years, the average severity over the observation period was significantly lower in the strip-crop with grass (0.040) or in the strip-crop with maize (0.053) than in the potato monoculture (0.105). Strip-cropping with faba bean did not significantly reduce the average severity. In 2021 and 2022, strip cropping with grass resulted in the highest potato yields (per m² potato area) (25.9 and 38.9 t ha⁻¹ potato area in 2021 and 2022, respectively), which was 31–33 % higher than the monoculture (19.8 and 29.2 t ha⁻¹). Despite the observed reduction in disease in potato strip-cropped with maize, it resulted in similar yield per unit area of potato as the monoculture, presumably due to competition for light with the taller maize plants.

Conclusion

Together these results show that strip cropping, when integrated with other control measures, can be used to reduce late blight severity. A short non-competitive companion crop species, grass, was effective in simultaneously reducing late blight and enhancing tuber yield.