Intercropping decreases plant disease incidence: A global meta-analysis

Intercropping, the simultaneous cultivation of multiple species on a field, has been reported to suppress plant diseases, but there is little insight in the size, consistency and variability of this disease control effect. Here, we synthesize the results of 57 published studies covering 124 trials comparing plant disease incidence in species mixtures and sole crops. We found that, on average across studies and experiments, intercropping significantly reduced disease incidence from an average of 36% (CI: [27%, 45%]) in sole crops to 22% (CI: [16%, 29%]) in species mixtures. There was high variability in the reduction of incidence by intercropping between crop species, pathogens, crop-pathogen combinations as well as studies, but there were no significant differences in disease control between diseases caused by viruses, fungi/oömycetes or bacteria. All crop-pathogen combinations with more than 12 data records yielded a significant average effect of intercropping on disease incidence. The results show that agricultural diversification by intercropping would consistently contribute to disease suppression in agricultural systems, but the size of effect is variable. It is therefore necessary to combine species mixture with other measures to achieve consistent high efficiency.