Native grass ground covers provide multiple ecosystem services in Californian vineyards

Abstract

Mechanisms responsible for the success or failure of agricultural diversification are often unknown. Most studies of arthropod pest management focus on enhancing natural enemy effectiveness. However, non‐crop plants can also change crop host quality by reducing or adding soil nutrients or water, and therefore improve or hamper pest suppression. Native perennial ground covers may provide food or habitat to natural enemies and, in terms of competition for soil nutrients or water, be more compatible with crop management than exotic annuals. We conducted a 3‐year vineyard study to examine the impacts of native perennial grasses on pests, natural enemies, crop plant condition and soil properties. We included three ground cover treatments: bare soil with a grower standard drip irrigation; native grasses with drip irrigation; and native grasses with drip irrigation as well as an additional flood irrigation to keep the grasses green and growing during the season. Numbers of leafhopper pests Erythroneura spp. decreased in both native grass treatments, where parasitism rates were higher. Vine petiole nitrate levels were lower in grass treatments, indicating competition for soil nitrogen, which is most often considered to be detrimental. Berry weight was higher in the irrigated treatment but did not differ between the bare soil and non‐irrigated grass treatment. Grape °Brix was similar in the bare soil and native grass treatments, suggesting native grasses did not compromise grape quality. In fact, leaf water stress was lower and soil moisture higher not only in the irrigated grass treatment but, at times, in the non‐irrigated grass treatment, compared with the bare soil treatment. Synthesis and applications. Our work shows that native grasses contribute to a reduction in vineyard leafhopper pests by reducing host quality through competition for soil nitrogen and providing food resources and/or habitat for natural enemies. Native grasses also improve soil water content and may be part of a water conservation program for perennial crops in dry climate regions.

The functional agrobiodiversity in the Douro demarcated region viticulture: utopia or reality? Arthropods as a case-study – A review

“…When opting for a ground cover, preference should be given to a spontaneous colonization by the local flora ( Figure 6A) (Böller et al, 2004), which is adapted to the local environment, may require little or no maintenance, and is admissible to better benefit the native arthropods and pest suppression (reviewed by Daane et al, 2018). Plant species that naturally occur on the ground cover of the DDR vineyards predominantly include: Andryala integrifolia, Bromus spp., Coleostephus myconis, Convolvulus arvensis, Cynodon dactylon, Echium plantagineum, Lolium rigidum, Medicago spp., Ornithopus spp., Silene gallica, Solanum spp., Sonchus spp., Trifolium spp.…”

Electrophysiological and behavioural response of Philaenus spumarius to essential oils and aromatic plants

“…Regardless the positive features of these compounds, the knowledge of their effect on important agricultural pests and availability of commercial formulations for immediate use in agriculture is still in its infancy 28 . Conversely, the use of companion plants to enhance the resistance of the main crop to pests is widespreading rapidly all around the world 29 .…”

Role of grasslands in pest suppressive landscapes: how green are my pastures?

“…Grass is often used as a cover crop in orchards and vineyards, as it helps prevent soil erosion, increases water infiltration, suppresses weeds and can provide nutrition to the crop (Daane et al . 2018). It may also have the potential to aid biological control, with several studies finding predator populations to be more abundant in crops (e.g.…”

“…2013 ; Daane et al . 2018). This often appears to result in higher predation and parasitism levels within the crops (Colloff et al .…”

“…2017; Daane et al . 2018), or distinguishing between different grasslands, such as monoculture vs. mixed prairie (Werling et al . 2014) or native vs. sown pastures (House et al .…”