Pests
Symptoms Blobs of white froth like spit on the stems in late spring, with a tiny bug hidden inside. It looks worse than it is.Frothy white spit-like foam on stems in late spring, with a small nymph hidden inside. It looks alarming but rarely harms an established sage plant. Cause Young spittlebugs hiding in the foam while they feed. There are usually only a few, and they do little real harm.Spittlebug nymphs sheltering in their own foam while sipping sap. Numbers are usually low and damage is mostly cosmetic. Organic treatment If the froth bothers you, spray it off with a hose. You usually do not need to do anything else.Knock them off with a strong spray of water if you find them unsightly; no treatment is needed for plant health in most cases. Prevention Keep sage in full sun with room around it and do not overwater; healthy plants handle small pests.Give plants full sun and airflow and do not overwater; vigorous sage shrugs off minor pests.
Symptoms Leaves look dusty, speckled, or faded, sometimes with fine webbing, usually in hot dry spells or on indoor plants.Fine stippling or bronzing of the leaves and faint webbing, most common on plants in hot, dry, dusty conditions or stressed indoor plants. Cause Very small mites that multiply in hot, dry conditions and feed on the leaves.Tiny sap-sucking mites that build up in hot, dry, still air, especially on dusty or drought-stressed foliage. Organic treatment Spray the leaves with water every few days to wash the mites off; insecticidal soap works if there are a lot.Rinse the foliage with a strong spray of water to knock mites down, repeating every few days; insecticidal soap helps in bad cases. Prevention Keep air moving, rinse dust off in hot weather, and do not let potted sage dry out to the point of stress.Maintain good airflow, hose off dust in hot spells, and avoid drought stress on containers, which invites mites.
Symptoms Chewed, ragged holes in the leaves and shiny slime trails, mostly on young plants in damp shade.Ragged holes chewed in leaves and slime trails, mainly on young or newly set plants in damp, shady spots. Cause Slugs and snails eating the leaves at night; they like damp, shady, crowded spots.Slugs and snails feeding at night, favored by wet mulch, crowding, and shade around young plants. Organic treatment Pick them off after dark, clear away damp hiding spots, and use slug traps or pet-safe bait near young plants.Hand-pick at night, remove damp hiding places, and use traps or iron-phosphate bait around vulnerable seedlings. Prevention Give sage a sunny, well-drained, open spot; slugs avoid dry, sunny ground.Plant in full sun with good drainage and space plants for airflow; a dry, sunny site is unfriendly to slugs.
Symptoms Now and then, tiny hopping bugs on the leaves, usually only on stressed or crowded plants.Occasional small hopping insects on the foliage, more likely on stressed or crowded plants than on healthy sage. Cause Small sap-sucking insects that sometimes turn up. Sage has few pest problems and rarely needs treatment.Sap-feeding insects that occasionally find sage; the plant has few serious pests and rarely needs spraying. Organic treatment Spray them off with water, or use insecticidal soap for heavy numbers; more air and less stress usually fixes it.Rinse them off with water or use insecticidal soap if numbers climb; improving airflow and removing stress usually resolves it. Prevention Keep sage in full sun with room around it; healthy plants rarely get these bugs.Full sun, lean soil, and good spacing keep sage unstressed and unattractive to these pests.
Diseases
Symptoms Leaves wilt and yellow and the plant dies back even though the soil is wet, often with a dark, rotted spot where the stems meet the ground. This is the main thing that kills sage, and it comes from staying too wet.Wilting, yellowing, and dieback that does not recover with watering, often with a darkened, decayed base at the soil line. It is the main disease of sage and is tied to wet soil and poor drainage. Cause A rot that takes hold when soil stays soggy or the weather is hot and muggy, attacking the roots and base. The real cause is wet soil, not cold.Soil-borne water molds and fungi that attack the roots and crown of plants sitting in saturated, poorly drained soil. Wet feet and humid heat, not cold, are the underlying cause. Organic treatment Once the base is rotting there is no fix, so pull out and throw away the plant. The answer is preventing it with good drainage, not curing it.There is no cure once the crown is rotting; remove and discard affected plants and fix drainage. Focus on prevention, not rescue. Prevention Use well-draining soil in full sun, water deeply but rarely, and never let sage sit in soggy ground. On heavy soil, plant on a mound and give plants room.Plant in well-drained soil in full sun, water deeply but infrequently, and never let sage sit wet. On clay, use a mound or raised bed and space plants for airflow.
Symptoms A dusty white coating on the leaves, more likely in muggy weather or on crowded plants. It does not usually kill sage but makes it look and taste worse.A white to gray powdery film on the leaves, most likely in humid weather or on crowded, poorly ventilated plants. It weakens the plant and taints the flavor but is rarely fatal. Cause Fungi that like warm, damp, still air around crowded plants. Poor airflow makes it worse.Fungi favored by warm, humid, still air, especially where plants are crowded or shaded. Damp, stagnant conditions raise the risk. Organic treatment Pick off the coated leaves, give the plant more air, and water at the soil instead of over the top. The spring trim helps too.Remove affected leaves, thin for airflow, and avoid overhead watering; the spring prune also opens up the canopy. Prevention Leave room between plants, plant in full sun, water at the base, and trim to keep it open. Good air movement is the key.Space plants well, site in full sun, avoid overhead watering, and prune to keep the plant open. Airflow is the main defense.
Symptoms Branches wilt and yellow, often on one side, and do not bounce back. It is a soil disease that can stay in the ground.Sudden wilting and yellowing of branches, sometimes on one side of the plant, that does not recover; a soil-borne wilt that can persist in the ground. Cause A fungus in the soil that blocks the plant's water pipes. It builds up where the same kinds of plants grow year after year.A soil-borne fungus that plugs the plant's water-conducting tissue. It builds up in soils where susceptible plants are grown repeatedly. Organic treatment There is no fix once a plant has it, so remove it and do not replant sage in the same spot. Better drainage and airflow help.There is no cure; remove affected plants and avoid replanting sage or other susceptible crops in the same spot. Improve drainage and airflow. Prevention Use well-drained soil, and start new sage in a fresh spot rather than where a wilted plant grew.Plant in well-drained soil, rotate the planting site when starting new plants, and avoid ground with a history of wilt.
