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Copper spots on cannabis leaves can indicate various issues, but they're not typically associated with calcium, phosphorus, or potassium deficiencies. Here's what you should consider: Likely Causes of Copper Spots: Copper spots on cannabis leaves are often a sign of fungal or bacterial infections, such as copper deficiency or a condition called copper toxicity. However, it's crucial to confirm the diagnosis by closely examining the affected leaves and considering other symptoms. Rule Out Nutrient Deficiencies: While calcium, phosphorus, and potassium deficiencies can cause various leaf symptoms, including discoloration and spots, they typically manifest differently from copper spots. Calcium deficiency often results in necrosis (death) at leaf tips or edges, while phosphorus and potassium deficiencies may cause dark spots or purple hues on leaves, but not necessarily copper-colored spots. Consider Other Factors: Evaluate environmental conditions such as humidity levels, temperature fluctuations, and airflow. High humidity combined with inadequate airflow can create conditions conducive to fungal or bacterial growth, leading to leaf spots. Inspect for Pests: Check for signs of pests like spider mites, thrips, or leafhoppers, which can damage leaves and cause spots. Pests may leave behind trails or feeding marks that resemble copper spots. Addressing the Issue: Once you've identified the likely cause of the copper spots, take appropriate action. If it's a fungal or bacterial infection, consider using fungicides or bactericides labeled for use on cannabis. Ensure proper ventilation, avoid overwatering, and maintain optimal environmental conditions to prevent further spread of the issue. By carefully examining your plants, ruling out potential causes, and taking appropriate corrective measures, you can address the copper spots on your cannabis leaves and promote healthy growth.