Lovage

Lovage's own flower umbels attract the predators that clear aphids, and cutting back an infested flush lets it regrow clean.

Dense clusters of tiny insects packed onto shoot tips, flower buds, and the undersides of young leaves. Curled, cupped, or distorted new growth that never opens properly. A sticky shine on the leaves - and on whatever sits under the plant - that later goes black with sooty mold. Tiny white cast skins left behind where a colony has been feeding. Ants running steadily up and down the stems, which is often the first thing you notice. Mottled, streaked, or misshapen leaves that do not grow out can mean a virus the aphids brought with them rather than the feeding itself.

Knock the colonies off with a hard jet of water and repeat every few days - on most plants that alone ends it. Pinch out or prune off the worst-infested tips rather than treating the whole plant. If colonies keep rebuilding, spray insecticidal soap or horticultural oil directly onto the insects, covering leaf undersides, and repeat weekly until they are gone; treat early or late in the day, and never spray a wilted or heat-stressed plant. Avoid broad-spectrum insecticides - they kill the ladybugs, lacewings, and parasitic wasps that were about to solve the problem for you, and aphid numbers usually come back worse afterward. Anything you spray must be labeled for the plant you are treating; follow that label and observe its pre-harvest interval. On anything you eat, wash leaves, heads, and buds well before use, since aphids hide down in crowns, folds, and tight growth.

Go easy on nitrogen: the soft, lush growth that heavy feeding produces is exactly what aphids breed on. Check new growth once a week through spring and early summer so you catch colonies while they are still small, and rub the first few out with your fingers. Leave flowering plants nearby and skip broad-spectrum sprays - ladybugs, lacewings, hoverflies, and parasitic wasps do most of this work for free, and they only stay if there is something for them to eat. Keep ants off the plant where you can, since they protect aphids from those predators. Water steadily so plants are not stressed, and check any new plant over before you bring it home or move it indoors, since aphids usually arrive on something else.

Aphids are small soft-bodied sap-suckers - green, black, gray, pink, or waxy white, and mostly wingless - that gather in dense colonies on the tenderest new growth: shoot tips, buds, and the undersides of young leaves. They breed extremely fast in mild weather, so a few can become hundreds inside a week. Their feeding curls and distorts soft growth, and the sticky honeydew they excrete coats everything below and turns black with sooty mold. Ants often farm and defend the colonies for that honeydew. A few aphids are normal on almost any plant and a healthy plant shrugs them off; only dense, persistent colonies do real damage, and some aphids also spread plant viruses as they feed.

On lovage this is often a celery-type Septoria, the same family of leaf spots that hits other umbellifers. Do not crowd lovage up against carrots, parsnips or celery, and cut the plant back for clean regrowth if the lower leaves blight.

Small brown, dark, reddish or purple-bordered spots and blotches on the leaves during prolonged humid, rainy spells, sometimes enlarging and merging, with premature yellowing or leaf drop on the worst-affected growth.

Remove badly affected leaves and improve airflow; that is normally the whole of it. The plant flushes clean new growth once the weather turns. Fungicide is seldom warranted for a cosmetic leaf spot on an established plant.

Give the plant airflow - space, thin or prune it rather than letting the growth mat together - avoid overhead watering, and water early in the day so the foliage dries. Rake up and remove fallen leaves, which is where these fungi overwinter, and keep the plant unstressed and properly watered.

A catch-all for the various fungal leaf-spot diseases that blotch foliage in warm, humid, wet weather. They spot and yellow the leaves and sometimes bring on early leaf drop, and they are worst on crowded, shaded or overhead-watered plants and on anything already stressed. On a healthy, well-sited plant they are a cosmetic nuisance that comes and goes with the weather rather than a real threat.