Plant problems

When a plant wilts in the heat of the day, stays stunted despite good soil, and the roots turn out to be covered in swellings, root-knot nematodes are the usual explanation.

Bright orange-yellow spots on apple leaves, sometimes with tiny black dots inside them, are cedar-apple rust - a disease that literally cannot complete its life cycle without a nearby cedar or juniper tree.

A tunnel of brown frass leading to the core of an otherwise normal-looking apple is codling moth - the classic "worm in the apple," and timing is everything for controlling it.

Onion leaves with pale, silvery streaks and tiny black specks are showing thrips damage - a tiny, hard-to-see pest that can genuinely reduce bulb size if left unmanaged in a dry summer.

Eggplant flowers that open, look fine, then drop without ever becoming fruit are responding to the same temperature and stress triggers as tomatoes and peppers - with a slightly narrower comfort zone.

Ragged or perfectly round holes in brassica leaves usually come down to one of three caterpillars or a flea beetle. Here is how to tell them apart and what actually stops them.

Onions that stay skinny and garlic that never divides into cloves usually trace back to day length, planting time, or crowding - not disease.

Basil that develops dark, fuzzy patches - especially on the underside of leaves - almost always has downy mildew, a fast-spreading disease that has become common in basil crops worldwide.

A white, flour-like dusting on pea or bean leaves late in the season is powdery mildew - a different (though related) fungus from the one on squash, and usually a sign the crop is simply near the end of its run.

Brussels sprouts that never tighten into firm little heads, staying small, loose, or leafy instead, usually come down to heat, timing, or feeding rather than the variety being wrong.

Fuzzy white growth on a microgreens tray, or seeds that just sit there without sprouting, both trace back to the same handful of indoor-growing conditions - and they're easy to tell apart and fix.

When brassicas wilt in the heat despite moist soil and the roots are swollen and club-shaped instead of straight, clubroot is the likely cause - and it changes what you can grow there for years.

A vigorous, deep-green plant that stubbornly refuses to flower is usually a plant getting exactly one thing too generously: nitrogen.

Citrus leaves that yellow in an uneven, blotchy pattern that doesn't match the leaf's veins are worth taking seriously - this can be ordinary nutrient deficiency, or in some regions, a serious untreatable disease.

Cherries that crack open in the last days before they're ripe are reacting to rain the same way tomatoes do - a sudden intake of water the skin can't keep up with.

Small yellow-and-black beetles chewing holes in cucumber and squash seedlings are cucumber beetles - and the chewing damage is often the smaller problem compared to the diseases they carry.

Plants near a driveway, sidewalk, or road that brown and struggle every spring - even ones that seemed fine the year before - are very often showing salt damage from winter de-icing, not a spring disease.

A squash plant that wilts suddenly and a squash plant covered in small brown bugs are two different problems with two different fixes. How to tell which one you have.

Metallic green-and-copper beetles that arrive in swarms and leave leaves looking like lace. What actually reduces the damage versus what just wastes a summer.

A pale, thin, papery or blistered patch on the sun-facing side of a tomato or pepper is sunscald, not disease - and it usually follows recent pruning or a sudden heat wave.

Some droop after transplanting is completely normal. Here is how to tell that apart from the kind of wilt that means real trouble, and what to actually do about each.

Purplish leaf undersides and stems are usually cold weather doing its normal thing, but persistent purpling in warm soil with stunted growth points to a real phosphorus shortage.

A cane that suddenly wilts at the tip, or snaps easily near the base, on raspberries or blackberries usually points to one of two common cane-boring or cane-blight problems.

A distinctive light-and-dark green mottled pattern on leaves, paired with stunted or distorted growth, usually means a virus - and unlike fungal problems, there is no spray that fixes it.

A potato plant that looks lush above ground but yields a disappointing harvest below is usually a story about heat, water, or timing rather than the variety itself.

A healthy-looking fruit tree or bush that simply never fruits is usually a timing or pollination problem rather than anything wrong with the plant itself.

Shoot tips that blacken and curl like they were burned, on apple or pear, are the signature of fire blight - a bacterial disease that spreads fast and needs prompt pruning to control.

Strawberries that turn soft and brown and grow a fuzzy gray mold, especially in a wet or humid stretch, have botrytis gray mold - extremely common and largely about airflow and quick picking.

A garden that looks devastated after hail or a violent storm usually recovers better than it first appears - the right response in the first few days makes a real difference.

Two common fungal diseases cause brown-spotted, yellowing tomato leaves that work up the plant from the bottom. Here is how to tell them apart and slow them down.

A single hornworm can strip a tomato plant of leaves in days while staying almost invisible. How to spot the signs, find the caterpillar, and control an infestation.

How to recognize an aphid infestation, why they cluster on new growth, and the least-toxic ways to knock them back before they spread virus.

Ragged holes and vanished seedlings overnight almost always mean slugs or snails. Here is how to confirm it and stop the damage without pellets full of metaldehyde.

A white, flour-like dusting across squash and cucumber leaves in late summer is powdery mildew - extremely common, rarely fatal, and manageable if you catch it early.

Seedlings that sprout fine, then suddenly keel over at a thin, water-soaked stem, are victims of damping off - a fungal problem that is almost entirely preventable.

Healthy-looking flowers that drop off tomato and pepper plants without ever becoming fruit are almost always a temperature problem, not a disease or pest.

Squash, cucumbers and melons need separate male and female flowers pollinated together - when that hand-off fails, flowers open, wither and fall with no fruit behind them.

Tall, thin, weak seedlings that flop over are stretching toward light they cannot reach fast enough. The fix depends on how far it has gone.

Lettuce, spinach, cilantro and other leafy crops that suddenly shoot up a flower stalk and turn bitter have bolted - a response to stress, not a mistake you made in growing them.

When the oldest, lowest leaves on a plant turn evenly pale yellow while the newest growth stays green, nitrogen deficiency is the most likely and easiest-to-fix explanation.

Blueberries need genuinely acidic soil, and the single most common cause of poor color and poor growth is soil pH that is simply too high for the plant to take up iron.

Cracks radiating from the stem end of a ripening tomato are almost always about water - specifically, a big swing in how much of it the plant just got.

Bitterness and misshapen fruit in cucumbers are two different symptoms with two different (and both very fixable) causes - inconsistent water, and incomplete pollination.

When nothing comes up where you sowed seed, the cause is almost always one of a handful of ordinary conditions - not bad seed, which is actually the least common explanation.

A bean or pea plant covered in flowers that never turn into pods is almost always dealing with heat, not a lack of flowers - the flowers were never the missing ingredient.