Lovage Herb

A soil-borne fungus (*Sclerotium rolfsii*) that attacks plant stems right at the soil line during hot weather. It hits over 500 different plant species. Two telltale signs to look for: white fan-shaped fungal growth on the lower stem, mulch, and soil surface, and tan-brown spherical sclerotia (they look like mustard seeds) on infected tissue. Most active during sustained heat with humid conditions.

Triggers: Optimal at 86°F (30°C) soil and air temperature with humid conditions. Inactive below 70°F. Most damaging during sustained mid- to late-summer heat waves. It extends further north in warmer-than-normal seasons.

Risk fades when: Sustained cooler weather — highs below 80°F and overnight lows below 70°F for 5+ days — reduces fungal activity. The sclerotia (resting bodies) persist in soil for years, so resolution is seasonal, not curative.

A seedling killer caused by several different fungi working together. It hits vegetables, flowers, herbs, microgreens, and cover-crop seedlings the same way — seeds rot before they emerge, or young seedlings collapse right at the soil line. Wet seed-starting mix and poor airflow in seedling trays are the classic conditions.

Triggers: Wet soil or starting mix, poor drainage, seedlings packed too tightly, contaminated trays or media, and stagnant air all favor damping-off.

Risk fades when: Drying the soil surface and improving airflow slows new spread. Collapsed seedlings don't recover, but the rest of the tray can be saved.

A water mold (not a true fungus) that attacks roots and crowns in waterlogged soil. It's most dangerous in heavy, poorly drained soil after extended rain — basically any time water sits around plant roots for days.

Triggers: Pythium infects from 50-95°F as long as the soil stays saturated. Phytophthora capsici is most active at 75-85°F. What matters most is how long the soil stays waterlogged, not just whether it rained.

Risk fades when: Risk fades when soil returns to field capacity (normal drained moisture). How long that takes depends on your soil — sand drains in hours, clay can take days.

Aphids are soft-bodied sap-sucking insects that cluster on tender new growth. Most established plants tolerate moderate populations and will outgrow damage on their own, but aphids are the most important plant virus vectors in the garden, transmitting more than 100 plant viruses including potato leafroll, cucumber mosaic, and turnip mosaic. Honeydew excreted while feeding supports sooty mold growth and attracts ants that protect aphids from natural enemies.

Triggers: Optimal development at ~75°F (green peach aphid) per UC IPM Floriculture; melon aphid develops fastest above 75°F. Many species heat-intolerant above 90°F and crash in mid-summer. Soft new growth and over-fertilization with high N favor population buildup. Females give live birth parthenogenetically most of growing season — one generation in ~1 week under optimal conditions.

On Lovage: Tender spring growth attracts sap feeders.

Prevention: Blast with water and encourage beneficial insects.

Risk fades when: Per UC IPM and Clemson HGIC, populations crash in mid-summer heat (>90°F) for many species, return in cooler conditions

Bolting is a plant deciding, earlier than the gardener wants, that it is time to reproduce. The stalk shoots up, leaves turn coarse and bitter, and no amount of cutting the stalk off reverses it. Two separate cues drive it, and confusing them leads to the wrong fix. The first is vernalization. MSU Extension explains that most winter-hardy biennial and perennial crops need a certain number of hours at cool temperatures, after reaching a certain size, before they will flower - and that the period before a crop becomes responsive to those cool temperatures is its juvenile period. Some biennials have no juvenile period at all and can even vernalize as seed. So for spring-sown biennials such as Florence fennel, a string of cool days or nights can precondition the plant to flower sooner than desired. The second cue is the opposite: heat and lengthening days. Cool-season greens sown in spring race into flower as summer arrives, which is what happens to mache and upland cress. Both routes end the same way. The plant switches from making leaves to making seed, and the harvest is over. Note that heat and day length lengthen together, so the two are easily conflated.

Triggers: MSU Extension: in addition to daylength requirements, most winter-hardy biennial and perennial crops need a certain number of hours at cool temperatures, after they have grown to a certain size, before they will flower - a process called vernalization. The time, or leaf stage, before a crop becomes responsive to vernalizing temperatures is its juvenile period; not all vegetable biennials have a juvenile period, and some can vernalize as seed. For some spring-planted biennial crops, a string of cool days or nights can precondition them to flower sooner than desired, and this unwanted premature flowering is called bolting. Brussels sprouts, cabbage, collards and kohlrabi need longer to vernalize and are less threatened by early spring cool temperatures. University of Delaware Extension: bolting in cabbage, collards and kale, and buttoning in cauliflower, can occur if early-planted crops are subjected to low temperatures between 35 and 50°F for ten or more continuous days. NOTE ON EVIDENCE: the cool-season salad crops here - mache and upland cress - bolt in response to heat and lengthening days rather than to vernalization, and no species-specific extension source was retrieved for either. Angelica archangelica is monocarpic: it flowers once and dies, so its bolting ends the plant rather than merely the harvest. Florence fennel is susceptible from both directions - a cold check early or heat and root disturbance later. Basil and brassicas have their own dedicated entries.

On Lovage: Heat and drought push tall seed stalks early.

Prevention: Maintain even moisture and harvest young growth promptly.

Risk fades when: Bolting cannot be reversed. Cutting off the flower stalk does not restore leaf quality, because the plant has already switched. Harvest whatever is still usable, promptly, and move on. Everything useful is preventative. Sow in succession every two to three weeks so a young planting is always coming on. Time crops to mature in cool weather - spring plantings finished before midsummer, or autumn plantings as days shorten. Avoid checking growth: transplant carefully without disturbing roots, keep moisture even, and do not let plants sit dry. For spring-sown biennials such as Florence fennel, avoid transplanting too early into cold ground, since a run of cool nights after the juvenile period can vernalize the plant and trigger bolting weeks later. Choose varieties described as bolt-resistant or long-standing. And let a bolted plant flower if you can spare it - the umbels of fennel, lovage and angelica are excellent for beneficial insects.

Flopping happens when stem strength can't support the plant's mass — usually because the plant grew too fast, didn't get enough sun to build strong stems, or got too much nitrogen which pushes soft leafy growth at the expense of structural strength. Rain and wind compound the problem by weighing down soft tissue. Some plants are inherently floppy — peony, dahlia, delphinium, large mum, tall sunflower — and need staking from the start. Others normally hold themselves up but flop when grown in shade or overfed. Stake early (in spring before plants have grown into their support) rather than late (when stems are already bent and a stake just preserves the deformity). Pruning or pinching tall plants when young encourages branching and reduces flop risk.

Triggers: Per MSU Extension: full sun produces sturdy self-supporting plants; shade or over-fertilization produces soft top-heavy growth. Rain and wind accelerate flop. Plants with naturally heavy blooms (peony, dahlia, large lily, hollyhock) need staking from start.

Risk fades when: Stake early in spring before too much growth. Late staking just preserves the bend. Pinch tall plants when young to encourage branching. Reduce nitrogen feeding if plants are floppy and overgrown.

Covers parsley, dill, cilantro, lovage, and angelica leaf-spot pressure from host-family fungi — especially Septoria on parsley and cilantro. Causes small tan to brown leaf spots, yellowing, and defoliation during wet, humid, splashy weather.

Triggers: Wind-driven rain, dew drips, overhead irrigation, tools, handling wet plants, infected debris, and seedborne inoculum all drive spread.

Risk fades when: Spread depends on wet foliage, splash, dew, and wet-plant handling. A dry period lowers immediate new infection risk.

A powdery mildew of carrot-family herbs such as dill, parsley, fennel, and cilantro. It coats leaves and stems with a white-to-gray powdery growth, and heavy infection yellows and weakens foliage and taints flavor. Unlike most leaf diseases it spreads in warm, dry weather with high humidity, and does not need leaf wetness.

Triggers: Powdery mildew thrives in warm, humid conditions and, unlike most fungi, does not require leaf wetness; rain actually suppresses it. Shade and crowding raise risk.

Risk fades when: Sustained heat above about 90°F slows powdery mildew. Two such days reduces active pressure; existing colonies remain on infected leaves.

Premature dieback covers a range of end-of-season behaviors. Annual herbs (basil, cilantro, dill) decline naturally as days shorten and temperatures cool — this is normal once flowering has happened. Tender perennials in cold climates may die back to the ground when frost arrives. But premature dieback before its time can signal: cold snap below the plant's tolerance, root disease (Fusarium, Verticillium, Pythium), pest pressure (root-feeding larvae), or simply the plant having reached the natural end of its cycle. Annual basil typically dies after first frost; if basil dies in mid-summer, that's a sign to investigate. Tender perennial herbs in zone 5-6 die back annually and regrow from roots — that's normal. Distinguishing 'natural cycle complete' from 'plant has a problem' is about timing and visible symptoms.

Triggers: Most herb dieback is natural end-of-season. Mid-season dieback usually indicates root disease, pest damage, or severe drought stress. Investigate visible signs before assuming normal cycle.

Risk fades when: Natural dieback of annual herbs at season end is expected. Mid-season dieback warrants investigation: dig up the plant, check roots for rot/galls, examine stems for borer damage.

Scales are immobile sap-sucking insects under protective waxy or hardened covers. Soft scales produce sticky honeydew that supports sooty mold; armored scales cause direct dieback. They are primarily pests of woody plants and perennial herbs — fruit trees, berries, citrus, bay, rosemary — rather than annual vegetables. Females are sedentary as adults; the mobile 'crawler' stage that hatches in late spring/early summer is the target for control.

Triggers: Most species: one generation/year in north; multiple in south. Lecanium overwinters as 2nd-instar nymphs on twigs; crawlers emerge June-July. San Jose scale overwinters as 2nd instar on bark; crawlers May-June. Stressed plants more susceptible; ant attendance protects scales by deterring parasitic wasps.

Risk fades when: The vulnerable stage is the mobile crawler, which appears in a narrow late-spring to early-summer window depending on species; once crawlers settle and form their protective covering, sprays are far less effective, so the treatable risk window closes after crawler emergence (Penn State Extension, UMN Extension).