Chemical inducers, nutrient management, guava intercropping and insecticides can reduce huanglongbing incidence and severity in Sweet orange

Abstract

Huanglongbing (HLB) or citrus greening is the most economically devastating disease of citrus in the world. HLB is a vector-borne disease and transmitted by Asian Citrus psyllid (ACP). HLB is now a serious threat to the cultivation and expansion of Sweet orange and Mandarin in Bangladesh. As no suitable cure is available against the disease, inducing plant immunity by chemical inducers or nutrient management and intercropping could be an effective way to combat this challenge. In this study, two inducers viz., Bion (Acibenzolar S-methyl) and Bactroban (Bismerthizol), nutrients formulations SICOGREEN® (soil application) and foliar spray, intercropping with guava, spraying guava leaf extract (10%), foliar spray with insect growth regulators (IGR) such as Heron (Lufenuron), insecticides such as Neonicotinoids/Imidachloropid + Thiomethoxam and foliar spray of Beauveria bassiana (Commercial formulation) showed comparatively better performance as compared to untreated control considering both HLB incidence and severity in both locations (Haluaghat and Bhaluka) of Sweet orange orchards. All these treatments reduced HLB incidence by 57.5 to 89.44% and HLB severity by 54.16 to 80.35% in Sweet orange considering both Haluaghat and Bhaluka orchards. The results revealed that Bion (Acibenzolar S-methyl), nutrients formulations SICOGREEN® (soil and foliar application), intercropping with guava, spraying guava leaf extract, foliar spray of insecticides can be integrated to reduce HLB incidence and severity in Sweet orange. Some of these treatments have also some positive effects on plant growth and yield parameters of Sweet orange as compared to control. These results comprehensively suggest that chemical inducers and nutrient management seem a better alternative to control HLB aimed to increase tree lifespan and productivity.