A cocktail of cow urine and neem oil could offer citrus growers a sustainable and cost-effective alternative to chemical pesticides, according to researchers in India.
Scientists found the natural formation significantly reduced blackfly and citrus psylla, two of the most damaging pests in acid lime — a type of citrus fruit commonly grown in tropical and subtropical regions.
The trial, conducted during the 2022–23 during the post-monsoon citrus flowering season (known locally as the Hast Bahar) in central-eastern India, tested a range of concentrations of cow urine, both on its own and mixed with 2% neem oil, to control sap-sucking pests.
Results showed that 100% cow urine combined with neem oil was the most effective treatment, outperforming untreated controls and lower-concentration mixes.
Following two applications spaced 15 days apart, the top-performing mixture reduced blackfly populations from an average of more than 18 insects per leaf to just 9.7 per leaf, a reduction of nearly 50%.
Citrus psylla, a major vector of citrus greening disease, was also significantly reduced, from around 5.7 psylla per 10 cm twig to just 2.6.
Other treatments using diluted cow urine or cow urine alone showed smaller but still statistically significant reductions.
Neem oil, derived from the seeds of the neem tree (Azadirachta indica), is already well known in agriculture for its natural pest-repelling properties. Its active ingredient, azadirachtin, disrupts insect feeding and reproduction.
Cow urine, meanwhile, contains small amounts of nitrogen, ammonia, and other compounds that can act as deterrents or irritants to soft-bodied insects.
“The combination of the two seems to deliver both direct toxicity and a repellent effect, limiting pest survival and egg laying,” the researchers explained in findings published in the International Journal of Advanced Biochemistry Research.
Crucially, both inputs are permitted under India’s organic farming standards and are widely available to farmers across much of Asia and Africa.
The study used a randomised block design with nine treatment groups and three replications, ensuring robust data. All treatments were applied using a knapsack sprayer once pest levels exceeded economic thresholds.
“Application timing and consistency were key,” the paper said, as natural products tend to degrade more quickly than synthetic sprays.
For farmers seeking alternatives to conventional pesticides, whether due to resistance issues, market demands or cost, this research offers a practical solution.
It may be particularly attractive to small-scale fruit growers, mixed farms using livestock manure systems, or regenerative agriculture projects looking to integrate livestock and horticulture more effectively.
While this trial focused on acid lime, the pests involved affect a wide range of citrus crops including lemon, mandarin and sweet orange.
The researchers recommend further testing across different fruit types and growing conditions, and also suggest studying the effects on beneficial insects, long-term pest suppression and yield outcomes.
