Integrated winter mechanical–chemical protection using aluminum-mesh wrapping and soil-belt plus malathion for management of red palm weevil (Rhynchophorus ferrugineus) in Zahidi date palm seedlings, Jahrom, Iran

Abstract Jahrom County in Fars Province, Iran, serves as a major center for date palm and citrus cultivation. In recent years, the red palm weevil ( Rhynchophorus ferrugineus ) has severely threatened date production. We conducted a two-season field trial to evaluate an integrated winter management strategy that combines mechanical exclusion with chemical treatment for protecting young Zahidi date palms ( Phoenix dactylifera L.). This study reports a field evaluation of a combined wintertime approach — pruning, a single targeted trunk spray of malathion, a clay upper-belt, and a fine-mesh aluminum trunk wrap sealed at the base with local soil — and, to our knowledge, is the first explicit field trial assessing this specific combination for two-year-old Zahidi seedlings in Jahrom, Iran. The trial evaluates both protective efficacy and operational feasibility under local arid/semi-arid winter conditions. Across two consecutive winter seasons—Dec 2022–Feb 2023 and Dec 2023–Feb 2024, we treated two-year-old Zahidi seedlings under three management regimes. In the integrated treatment (n = 43), we pruned excess fronds and petiole bases, sprayed trunks with malathion (0.2% w/v), applied an upper clay-belt around the upper trunk below remaining fronds, wrapped the trunk with fine-mesh aluminum which was secured only at its upper edge with wire, and sealed the lower edge of the mesh by covering it with soft, dry soil (hereafter ‘lower soil-seal’). In the chemical-only treatment (n = 36), we sprayed trunks once with malathion. In the untreated control (n = 70), we left the seedlings without intervention. Infestation assessment: Seedlings were inspected monthly (December–February each winter) for external and internal signs of R. ferrugineus attack. At each inspection trained observers recorded presence/absence of infestation based on a standardized checklist: visible entry holes or galleries, brown/amber oozing sap or fermented exudate, fresh frass (sawdust), wilting of inner fronds, a foul fermenting odour, audible gnawing when the trunk was held near the ear, and any toppling or structural failure. Because intensity of damage was not measured at the time of the trial, we recorded binary presence/absence for statistical comparisons; however, for future studies we recommend a simple 0–3 severity scale (0 = no sign; 1 = early signs such as frass or small entry holes; 2 = moderate tunneling or wilting; 3 = severe internal damage or trunk collapse). The integrated treatment protected all 43 palms, and our monitoring revealed no infestation during the study. In contrast, eight of the 36 palms that received malathion only became infested, while 20 of the 70 untreated palms showed infestation over the two seasons. Under the specific conditions of this two-winter field trial, the integrated winter strategy was associated with no observed infestations in the integrated group (0/43) and a lower infestation incidence than chemical-only and untreated controls. These results are encouraging for early-stage seedling protection but require confirmatory randomized trials across multiple sites and seasons before recommending wide adoption.