Integrated Weed Management in High Density Fruit Orchards

Abstract

Despite the productivity, achieving long-term sustainability and maintaining plant biodiversity have become the pivotal goals in orchard floor management, especially along tree rows. Thus, the paradigm of eradicating weeds in the tree row using chemical herbicide or repeated soil tillage needs to be substituted with more sustainable alternatives. This study was conducted in two commercial apple and peach orchards in Marche region (Italy). Two integrated mechanical approaches, integrated mowing (mower and brush or disc) and integrated tillage (blade weeder and integrated mowing), were compared with the standard herbicide system in a 2-year trial. Weed species diversity, soil coverage, and weed biomass production, including, gas exchange parameters, trunk cross-sectional area (TCSA), fruit yield and quality were measured. Overall, both integrated practices demonstrated approximately 82%, 91% and 113% more species diversity, soil coverage, and weed biomass production, respectively, than herbicide systems. No significant differences were found in terms of tree gas exchange parameters, growth and fruit yield. However, a few fruit quality parameters such as fruit firmness, soluble solids content (SSC) and dry matter content responded positively to the integrated practices. These results suggest that the integrated mechanical approaches of weed management increased orchard biodiversity, and had no adverse effects on tree growth, fruit yield, and quality. The average costs per hectare associated with chemical weed control were 66.5% and 72% lower, respectively, compared to integrated tillage and integrated mowing. However, the government subsidies provided to the orchardists to encourage sustainable management practices were able to offset such additional costs.

Soil Nitrogen and Weed Biodiversity: An Assessment under Two Orchard Floor Management Practices in a Nitrogen Vulnerable Zone in Italy

“…The most dominant weed species in the integrated mowing and herbicide plots were perennial dandelion (Taraxacum officinale Weber) and annual birdeye speedwell (Veronica persica Poir.). However, a full list of weed species identified over two years can be found in our previous study by Mia et al [19]. In 2019, the number of weed species was reduced in the apple but increased in the peach orchards, while an opposite result was obtained for weed biomass production.…”

“…This maintenance of covered soil using integrated mowing throughout the experimental period is advantageous for system sustainability, even though it needs to be controlled with repeated interventions to reduce the possible competition for water. In contrast, the soil remained bare in the herbicide plot, resulting in lower weed biodiversity, but it requires less weeding intervention and management cost [19]. It was worth noting that the year had a great effect on species diversity and weed biomass productions in both orchards (Table 2), and this could be due to the climatic variations and chemical residual effects.…”

“…It was worth noting that the year had a great effect on species diversity and weed biomass productions in both orchards (Table 2), and this could be due to the climatic variations and chemical residual effects. A total of 48 weed species were observed in both orchards over two years, where the total number of annual, perennial, and geophyte species were 30, 14, and 4, respectively [19]. The most dominant weed species in the integrated mowing and herbicide plots were perennial dandelion (Taraxacum officinale Weber) and annual birdeye speedwell (Veronica persica Poir.).…”

“…Thus, they can deliver N into the soil during the process of decomposition [17,18]. For this reason, an eradication of understory vegetation along the trees row is not desirable in sustainable orchard floor management [19]. Managing orchard floors with living vegetation is a good agricultural practice to reduce the risk of potential leaching of nitrates [16].…”

“…Therefore, an integrated mowing system was developed for sustainable orchard management with two advanced tools: a rotary brush weeder and a mower, where the rotary brush weeder facilitates bending the weed plant stems close to the tree trunk, avoiding any trunk damage. At the same time, mowing the weeds does not disturb the soil, and it deposits the mowed residues in the soil surface along the row [19,24]. Eventually, they are used as mulching materials, but in any case, ensure covered soil with spontaneous vegetation along the tree row.…”