Abstract
Irrigated almond orchards in Spain are increasing in acreage, and it is pertinent to study the effect of deficit irrigation on the presence of pests, plant damage, and other arthropod communities. In an orchard examined from 2017 to 2020, arthropods and diseases were studied by visual sampling under two irrigation treatments (T1, control and T2, regulated deficit irrigation (RDI)). Univariate analysis showed no influence of irrigation on the aphid Hyalopterus amygdali (Blanchard) (Hemiptera: Aphididae) population and damage, but Tetranychus urticae Koch (Trombidiformes: Tetranychidae) damage on leaves was significantly less (50–60% reduction in damaged leaf area) in the T2 RDI treatment compared to the full irrigation T1 control in 2019 and 2020. Typhlocybinae (principal species Asymmetrasca decedens (Paoli) (Hemiptera: Cicadellidae)) population was also significantly lower under T2 RDI treatment. Chrysopidae and Phytoseiidae, important groups in the biological control of pests, were not affected by irrigation treatment. The most important diseases observed in the orchard were not, in general, affected by irrigation treatment. The multivariate principal response curves show significant differences between irrigation strategies in 2019 and 2020. In conclusion, irrigation schemes with restricted water use (such as T2 RDI) can help reduce the foliar damage of important pests and the abundance of other secondary pests in almond orchards.
Highlights
Water used for crop irrigation faces shortages in the near future due to lower rainfall in the Mediterranean basin and increased evapotranspiration, according to the latest study published by the European Environmental Agency on climate change, impacts, and vulnerability in Europe [1].Almond is considered a drought-tolerant species and its response to water scarcity has been defined in many studies under deficit irrigation, which minimizes loss of production and increases fruit quality [2,3,4,5]
The present study focused on how crop irrigation management can impact the presence and population of some arthropod pests and the damage they produce, as well as the effect on beneficial arthropods, in an almond orchard, and collaterally the presence of the most important diseases observed during the study
This study focused on two irrigation strategies: T1, irrigation control, and T2, regulated deficit irrigation (RDI)
Summary
Water used for crop irrigation faces shortages in the near future due to lower rainfall in the Mediterranean basin and increased evapotranspiration, according to the latest study published by the European Environmental Agency on climate change, impacts, and vulnerability in Europe [1]. Almond pests (and diseases) were little studied in Spain until this recent change in acreage and management, but new interest has led to studies on how they affect the crop in this new situation [19,20,21,22,23]. The effects of deficit irrigation on arthropod populations and diseases are not usually considered in scientific production, but recent changes in crop management in Spain to more productive methods have promoted such studies in super-intensive olive [34,35] and irrigated almond [23,36] orchards. The present study focused on how crop irrigation management can impact the presence and population of some arthropod pests and the damage they produce, as well as the effect on beneficial arthropods, in an almond orchard, and collaterally the presence of the most important diseases observed during the study. The most important result obtained after this long-term study is that T2, with regulated deficit irrigation (RDI) treatment, produced a sensible reduction in damage inflicted by two-spotted spider mites and a smaller population of leafhoppers compared to T1, with more irrigation
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