Citrus Greening Disease: The silent killer of citrus groves
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Ngangbam Punita
Citrus is one of the most commonly consumed fruits in the world with commercial cultivation spanning over hundred Nations. In India, citrus ranks as the third most significant fruit crop, trailing bananas and mangoes. Notably, the North Eastern Hill region stands out as a treasure trove of citrus genetic diversity, boasting an impressive array of 23 species, one subspecies, and 68 varieties - a true haven for citrus enthusiasts and researchers alike.
Beyond its juicy appeal, citrus fruits have an impressive resume of health benefits, earning them a spot among the world’s top superfoods. Rich in vitamin C, antioxidants, and anti-inflammatory compounds, citrus fruits have been shown to combat cancer, diabetes, and obesity. But despite their miraculous properties, these fruits are fragile, falling prey to a plethora of fungal, bacterial, and viral diseases that threaten global production.
Among the diseases affecting citrus, Huanglong- bing (HLB) or citrus greening has ravaged global citrus production, resulting in the loss of over 60 million trees worldwide. Tracing its origins to southern China, Huanglongbing’s (HLB) global footprint expands far beyond its initial outbreak.
Intriguingly, India’s encounter with HLB was attributed to Citrus die back in the 1700s, resulting in a hypothesis that the disease was already established in India before spreading to China. In India, the disease has been reported in major citrus growing States such as Manipur, Meghalaya, Assam, Maharashtra, Punjab, etc.
Initially, the disease was suspected as viral due to its graft transmissibility. The 1967 discovery of MLOs further led to strengthening the belief that the causal agent of the disease to be an MLO.
However, advancement in electron microscope and cytochemistry techniques exposed a gram negative bacterial culprit. HLB is associated with a phloem limited unculturable bacteria, Candidatus Liberi- bacter spp. Based on the geographic locations of their origin they have been classified as Candidatus Liberibacter : asiaticus, africanus and americanus.
(To be contd)
Citrus is one of the most commonly consumed fruits in the world with commercial cultivation spanning over hundred Nations. In India, citrus ranks as the third most significant fruit crop, trailing bananas and mangoes. Notably, the North Eastern Hill region stands out as a treasure trove of citrus genetic diversity, boasting an impressive array of 23 species, one subspecies, and 68 varieties - a true haven for citrus enthusiasts and researchers alike.
Beyond its juicy appeal, citrus fruits have an impressive resume of health benefits, earning them a spot among the world’s top superfoods. Rich in vitamin C, antioxidants, and anti-inflammatory compounds, citrus fruits have been shown to combat cancer, diabetes, and obesity. But despite their miraculous properties, these fruits are fragile, falling prey to a plethora of fungal, bacterial, and viral diseases that threaten global production.
Among the diseases affecting citrus, Huanglong- bing (HLB) or citrus greening has ravaged global citrus production, resulting in the loss of over 60 million trees worldwide. Tracing its origins to southern China, Huanglongbing’s (HLB) global footprint expands far beyond its initial outbreak.
Intriguingly, India’s encounter with HLB was attributed to Citrus die back in the 1700s, resulting in a hypothesis that the disease was already established in India before spreading to China. In India, the disease has been reported in major citrus growing States such as Manipur, Meghalaya, Assam, Maharashtra, Punjab, etc.
Initially, the disease was suspected as viral due to its graft transmissibility. The 1967 discovery of MLOs further led to strengthening the belief that the causal agent of the disease to be an MLO.
However, advancement in electron microscope and cytochemistry techniques exposed a gram negative bacterial culprit. HLB is associated with a phloem limited unculturable bacteria, Candidatus Liberi- bacter spp. Based on the geographic locations of their origin they have been classified as Candidatus Liberibacter : asiaticus, africanus and americanus.
(To be contd)