From grasses to forbs: Implementing flowering cover crops to enhance arthropod-mediated ecosystem services

Grass cover crops, such as rye and wheat, are extensively used in commercial watermelon fields to protect seedlings against wind damage but these cover crops are reported to act as alternative host plants for pests which can move into the crop. Additionally, grass cover crops do not provide resources to support beneficials (i.e. natural enemies and pollinators). This results in intense spray programs to control pests and the use of managed pollinators to secure yields. In contrast, forbs (flowering cover crops) can provide extra resources such as alternative non-crop prey, nectar, and pollen. We hypothesized that alternative flowering cover crops can enhance natural enemies and wild pollinators to control pests while minimizing pesticide applications and underpin yields without stocking managed pollinators.

The study was conducted at three locations across Indiana, one field per location. At each location, we established eight treatment plots with five replicates (40 plots of ~0.22 ha each per location). Treatments included i) bare ground, ii) cereal rye, iii) rye + crimson clover, iv) rye + hairy vetch, v) crimson clover, vi) hairy vetch, vii) buckwheat, and viii) mustard. Treatments ii-vi were established in Fall 2022, whilst treatments vii-viii, in Spring 2023. Weekly surveys were conducted from May to September 2023 recording density and diversity of natural enemies, pollinators, and pests. Quantity (fruit set) and quality (weight) were recorded at harvest. Results from this trial will be presented.