Integrated Management of Citrus Leafminer in the Nursery

Abstract

Citrus is one of the most important fruit crops of Bangladesh in terms of acreage, production and economic value to growers. However, citrus production is severely compromised by citrus leafminer (CLM) affecting both nursery and orchard. Citrus growers conventionally spray different chemicals to control this insect which negatively impact their environment and health. Therefore, alternative management options to conventional practice was required. To provide effective integrated pest management (IPM) option(s) to manage CLM in the nursery, studies were conducted in a commercial horticultural nursery. First, seasonal infestation of this insect was monitored under grower’s management practice. Second, an experimentation was conducted in randomized complete block design with seven treatments each replicated thrice: (i) Sanitation (removal of infested leaves weekly) (ii) Imidacloprid (0.5 ml/L of water) + Sanitation (iii) Detergent mix water (28 gm/L of water) + Sanitation (iv) Spinosad (0.5 ml/L of water) + Sanitation (v) Cypermethrin (1 ml/L of water) + Sanitation (vi) Grower’s conventional practice (Chlorpyrifos @1 ml/L of water) and (vii) untreated control. Seasonal infestation of CLM remained over 30% of the three months (June, July and August) monitored. All the implemented treatments reduced percent leaf infestation, number of mines and larvae per twig compared to untreated control. Sanitation alone substantially reduced leaf infestation to 21.50%, number of mines per twig to 13.33 and number of larvae per twig to 5.11. Combining spraying (Imidacloprid, Cypermethrin, Detergent mix water) with sanitation practice could not provide further control. However, combining a biorational insecticide Spinosad provided a better control and further reduced the leaf infestation, number of mines and larvae per twig. Number of a generalist predator, ladybird beetle was reduced in all treatment plots, however, sanitation alone or in combination with Spinosad spraying, both practice, harmed it less. Citrus growers can be recommended to implement only sanitation or in combination with Spinosad spraying.