Pests
Symptoms Clusters of tiny soft green or black insects on the growing tips and the undersides of leaves, often so small they look like dots. Leaves may start to curl or feel sticky. You might notice ants walking up the stems; ants actually farm aphids for the sweet liquid they produce, so ants are a good early warning sign.Clusters of tiny soft insects on new growth and leaf undersides. Leaves curl, yellow, or become sticky with honeydew. Sooty black mold may follow. Cause Aphids are tiny soft-bodied insects that breed very fast in warm weather, so a few quickly turn into crowds on the soft new growth at the tips. Too much fertilizer makes that soft growth they love, so going easy on feeding helps keep them down.Several aphid species (most often green peach and potato aphids) colonize tomatoes. They reproduce asexually and explosively in warm weather, so a few founders become dense colonies on tender new growth within days. Soft, nitrogen-flush growth from over-fertilizing is especially attractive, which is why feeding history drives outbreak severity as much as weather. Organic treatment Spray the clusters directly with a strong jet of water from a hose; this dislodges most of them. For a persistent infestation, apply insecticidal soap or neem oil spray, making sure to coat the leaf undersides where the aphids cluster.Blast off with strong water jet. Apply insecticidal soap or neem oil directly to colonies. Introduce ladybugs or lacewings. Prevention Plant marigolds or nasturtiums near your tomatoes; both attract beneficial insects that feed on aphids. Avoid over-fertilizing with high-nitrogen fertilizer, which produces the soft, fast-growing shoots that aphids prefer.Plant marigolds and nasturtiums nearby. Avoid excess nitrogen fertilizer which creates soft, aphid-attractive growth. Encourage beneficial insects.
Symptoms Large sections of leaves or whole stems stripped very quickly, sometimes overnight. Look for fat green caterpillars up to 4 inches long that blend almost perfectly into the stems and leaves. The easiest way to find them is to look for the dark green or black droppings they leave on leaves below.Large green caterpillars (up to 4 inches) stripping foliage. Leaves disappear rapidly. Black droppings on leaves. Cause These are the caterpillars of a large moth. The moth lays eggs on the leaves in early summer, and the caterpillars grow big (up to about four inches) through mid and late summer, eating a lot of leaves fast. They spend the winter in the soil, so a bed left undug can carry them into next year.Larvae of the five-spotted hawk moth (Manduca quinquemaculata). Adult moths lay eggs on tomato foliage from early summer; the caterpillars feed and grow through mid-to-late summer, reaching up to about four inches and defoliating fast because a single large larva eats a great deal. They pupate in the soil over winter, so the prior season's population carries forward in an unworked bed. Organic treatment Hand-pick and drop them in a bucket of soapy water; it's simple but effective. If you find any with small white oval capsules stuck to their backs, leave those alone; parasitic wasps have already laid eggs on them and the wasps will take care of the rest.Hand-pick; they are well camouflaged but easy to remove. Apply Bt (Bacillus thuringiensis) spray. If white cocoons visible on back, leave them; parasitic wasps are doing the work. Prevention Turn or till the soil in autumn to expose and kill overwintering pupae. Planting dill or fennel nearby attracts predatory wasps that prey on hornworms.Till soil in autumn to kill overwintering pupae. Plant dill and basil nearby to attract predatory wasps.
Symptoms Lots of tiny round holes in the leaves, making them look like they've been peppered with a hole punch, most noticeable on seedlings and young plants. The beetles themselves are tiny, shiny, and black; they jump when disturbed, which is how they got their name.Tiny round shot-holes in leaves, especially on seedlings and young plants. Small shiny black beetles jump when disturbed. Cause Flea beetles are tiny black beetles that jump when you disturb them and chew small round holes in leaves. They come out in spring and hit young seedlings hardest, because small plants do not have many leaves to spare. Bigger, established plants shrug off the same chewing.Several flea beetle species. They overwinter as adults and emerge in spring, so pressure is heaviest early, on seedlings and freshly set transplants whose small leaf area makes the shot-hole feeding proportionally damaging. Established plants with ample foliage tolerate the same beetle numbers easily, which is why the timing of the attack matters more than its size. Organic treatment Cover seedlings with row cover fabric to keep beetles off young plants. Sprinkle diatomaceous earth (a fine powder made from fossilized algae) around the base and on the leaves; it damages soft-bodied insects on contact. Neem oil spray also works.Use row covers on seedlings. Apply diatomaceous earth. Neem oil spray. Prevention Wait to transplant until plants are large and well-established; flea beetles cause the most damage to small seedlings. Larger, established plants can usually tolerate some feeding without major harm.Delay transplanting until plants are large. Use transplants rather than seeds.
Symptoms A fine stippling or scattering of tiny yellow or white dots across the upper surface of leaves, making them look dull and washed out. In heavier infestations you may see fine webbing on the undersides of leaves. Spider mites are barely visible to the naked eye; hold a white sheet of paper under a leaf and tap; if you see tiny dots moving, that's them. Worst in hot, dry weather.Fine stippling or yellow dots on leaves. Fine webbing on leaf undersides. Leaves may bronze, dry out, and drop. Worst in hot dry weather. Cause Spider mites are tiny mites (so small they look like moving dust) that love hot, dry, dusty weather and multiply incredibly fast, so they tend to flare up late in summer. Plants that are short on water suffer the most, so keeping plants watered and dust down is the best defense.Twospotted spider mite (Tetranychus urticae) and relatives. They thrive in hot, dry, dusty conditions and complete a generation in under a week in summer heat, so populations explode late in the season. Drought-stressed plants are far more vulnerable, which makes consistent watering and dust suppression the primary cultural controls rather than an afterthought. Organic treatment Spray the plant, especially the leaf undersides, with a strong jet of water repeatedly over several days to knock off mites and disrupt their colonies. Follow up with neem oil or insecticidal soap applied to the undersides of leaves.Blast with water repeatedly. Apply neem oil or insecticidal soap to leaf undersides. Increase humidity around plants. Prevention Keep plants well-watered in hot weather; water-stressed plants are far more vulnerable. Avoid dusty, dry conditions around the garden if possible.Keep plants well-watered in hot weather. Avoid dusty conditions. Introduce predatory mites.
Diseases
Symptoms Dark brown spots with a target-ring pattern (concentric rings, like a bullseye) appear on the lowest leaves first. Those leaves yellow and drop, and the disease works its way up the plant over the season.Dark brown spots with concentric rings on lower leaves first; affected leaves yellow and drop, and the disease spreads upward through the plant. Cause Early blight is a fungus that lives in old plant debris and soil and splashes up onto the lowest leaves in warm, wet weather, which is why it starts at the bottom and climbs. Planting tomatoes in the same spot builds it up. Heirlooms are not bred to resist it, so moving the planting and mulching the soil are the main defenses.The fungus Alternaria solani. It overwinters on infected debris and in the soil, then splashes up onto the lowest leaves in warm, wet weather, so infection starts low and climbs. Repeated tomato plantings build soil inoculum. Most heirlooms lack the partial early-blight tolerance bred into some modern hybrids, so unmanaged heirlooms tend to defoliate faster; rotation and mulch to block soil splash are the core preventions. Organic treatment Remove affected leaves as soon as you see them and bag them for the trash, not the compost. A copper-based fungicide slows the spread. Mulch around the base to stop soil splash, which is how the fungal spores travel from the ground up onto the leaves.Remove affected leaves immediately. Apply copper-based fungicide preventively. Mulch soil to prevent splash-up. Prevention Move your tomatoes to a new spot each year, because the spores persist in the soil. Water at the base, never overhead. Stake or cage plants so leaves stay off the ground with good airflow. Heirlooms lack the blight resistance some hybrids carry, so these habits matter more.Rotate tomatoes every 3 to 4 years. Water at soil level. Space plants for airflow and prune to open the canopy. Stake to keep foliage off the ground.
Symptoms Water-soaked patches that turn brown and expand fast on leaves and stems; this disease moves very quickly and can destroy a plant in a matter of days. In humid weather you may see white fuzzy growth on the leaf undersides. It is the most serious tomato disease in the garden.Water-soaked, rapidly expanding brown patches on leaves and stems; white fuzzy growth on undersides in humid conditions. Can destroy plants in days. Cause Late blight is a fast, destructive disease whose spores blow in on wind and rain rather than starting from the soil. In cool, wet weather it can kill a plant in a few days. Because it arrives through the air, the best protection is pulling out any infected plant right away; heirlooms are not bred to resist it.The oomycete Phytophthora infestans, the pathogen behind the Irish potato famine. Its spores travel on wind and rain over long distances and infect leaves, stems, and fruit directly, spreading explosively in cool, wet weather. Because the inoculum arrives airborne, rotation helps little; resistant varieties and immediate removal of infected plants matter most, and heirlooms almost never carry the late-blight resistance genes bred into a few modern hybrids. Organic treatment Remove and immediately bag and bin all affected plant material; do not compost any of it. A copper-based fungicide can help as a preventive in wet spells. If a plant is badly affected, pull it entirely so it cannot spread to neighbors.Remove and destroy all affected material immediately; do not compost. Apply copper fungicide preventively in wet conditions. Prevention Good airflow is your best defense: stake and space plants so air moves through. Never leave tomato debris in the garden over winter. Because heirlooms rarely carry late-blight resistance, choose a resistant variety only if this disease has hit your area before, and watch closely in cool, wet weather.Ensure excellent airflow. Never leave tomato debris in the garden over winter. Choose a resistant variety where late blight recurs, since heirlooms rarely carry resistance.
Symptoms Small circular spots with a dark brown border and a pale gray or tan center, appearing first on the lower leaves, sometimes with a faint yellow ring. Over time the spotted leaves yellow and drop.Small circular spots with dark borders and pale gray centers, starting on lower leaves; spots may carry yellow halos. Cause Septoria leaf spot is a very common tomato fungus. Like early blight it overwinters in old debris and soil and splashes onto the lower leaves in warm, humid weather, working up the plant. The same habits that slow early blight, moving the planting, watering low, and mulching, keep it in check.The fungus Septoria lycopersici, one of the most common tomato leaf diseases. Like early blight it carries over on debris and infected soil and spreads by water splash onto lower foliage in warm, wet, humid weather, defoliating from the bottom up. Heirlooms carry no bred resistance, so the same moisture-management and sanitation practices, rather than a single spray, are the fix. Organic treatment Remove and discard affected leaves right away; do not compost them. Apply a copper-based fungicide. Keep the plant staked and prune very dense growth so air moves through.Remove affected leaves. Apply copper fungicide. Ensure good air circulation through spacing and pruning. Prevention Rotate your tomatoes to a new spot each year. Water only at the base, never overhead. Mulch around the base to prevent soil splash. Heirlooms are not bred to resist leaf-spot diseases, so airflow and sanitation carry the load.Rotate crops. Water at soil level. Mulch around plants. Open the canopy for airflow.
Symptoms The plant wilts on hot afternoons and recovers at night at first, then whole branches yellow and wilt for good, often on just one side of the plant or one side of a leaf. Cut a wilted stem lengthwise near the base and you may see brown streaking inside. There is no cure once a plant is infected.Non-uniform yellowing and wilting, frequently on one side of the plant or one half of a compound leaf; early on the plant wilts in the heat of the day and recovers overnight, then collapses. Vascular browning is visible in a split lower stem. Cause These are two soil fungi that get in through the roots and clog the plant's water pipes, so it wilts and dies. They live in the soil for years. Modern hybrids are often bred to resist them (the V and F on the tag), but heirlooms usually are not, which is why heirlooms are more likely to wilt.Two soilborne fungi, Fusarium oxysporum f. sp. lycopersici and Verticillium dahliae, which invade through the roots and plug the water-conducting vascular tissue. Both survive in soil as resting structures for many years (Fusarium favors warm soils, Verticillium cooler ones). This is the defining heirloom vulnerability: most heirlooms lack the V and F resistance genes bred into modern hybrids (the VFN codes), so they are fully susceptible where the pathogens are established. Cherokee Purple is a notable heirloom exception with some tolerance. Organic treatment There is no spray that cures a wilted plant; remove and bag badly affected plants so they do not seed the soil further. Focus on protecting the rest: keep plants watered evenly and avoid wounding the roots. Next year, plant into a fresh bed and choose resistant varieties if you can.No curative treatment exists; rogue out and destroy infected plants. Manage by prevention: long rotation, good drainage, resistant rootstock for grafting, or container culture in fresh medium. Prevention This is the big one for heirlooms: most heirlooms have little or no resistance to these two soil fungi, while many hybrids are bred to resist them (look for V and F on a hybrid's tag). Rotate tomatoes out of a bed for several years, keep soil well drained, and if wilt has struck before, grow heirlooms in containers of fresh mix or graft them onto resistant rootstock.Long rotation (4 to 6 years out of the bed). Maintain drainage and avoid root injury. Where wilt is established, use resistant (VF) rootstock for grafting or grow heirlooms in containers of pathogen-free mix; heirlooms carry no bred resistance.
Symptoms A dark, sunken, leathery patch on the bottom (the blossom end) of the tomato, opposite the stem. It hits the first fruits of the season most and is not contagious.Dark, sunken, leathery patch at the blossom end of the fruit; affects the first fruits most and is not contagious. Cause Blossom end rot is not a bug or an infection. It happens when the fruit cannot get enough calcium, almost always because watering swung from wet to dry and back. Calcium travels with water, so steady, even watering, not adding calcium, is what prevents it. Even calcium-rich soil gets it when watering is uneven.Not an infection but a calcium-delivery failure in the developing fruit. Calcium moves with water, so when soil moisture swings between wet and dry (or roots are damaged), the fast-growing blossom end is starved of calcium and its cells break down. It tracks watering consistency, not soil calcium levels, and large-fruited heirlooms show it more severely than small types. Organic treatment Mulch around the plant and water deeply and consistently; blossom end rot comes from uneven moisture, not a nutrient shortage, so steady watering is the real fix. Remove affected fruit so the plant can put energy into the next ones.Mulch to maintain even soil moisture. Water consistently. Remove affected fruit. Prevention The single most important prevention is consistent watering. Avoid disturbing the roots at the base of the plant, and do not over-fertilize with high-nitrogen fertilizer. Large heirloom fruit is especially prone, so keep moisture even once fruit sets.Consistent watering is the key prevention. Avoid root disturbance. Do not over-fertilize with nitrogen.
Symptoms Splits in the skin of ripening fruit, either rings around the stem end (concentric) or lines running down the sides (radial). Cracks often appear after a heavy rain that follows a dry spell.Radial (vertical, down the sides) or concentric (rings at the stem end) splits in the skin of ripening fruit, typically after rapid water uptake such as heavy rain following a dry period. Cause Cracking happens when the inside of the fruit swells faster than the skin can stretch, usually after a big drink of water following a dry stretch. Thin-skinned heirlooms split more easily than tougher-skinned hybrids.Cracking occurs when rapid changes in soil moisture make the fruit interior expand faster than the skin can grow. Radial cracking is the more serious form and worsens in hot, humid weather. Variety matters: many heirlooms are thin-skinned and large-fruited and split more readily than crack-resistant hybrids, so heirlooms are among the more crack-prone tomatoes. Organic treatment Cracks cannot be undone, so pick cracked fruit promptly and use it quickly before it rots or attracts insects. The real work is prevention through even watering. Fruit that is close to ripe can be picked just before a big rain to beat the cracking.No treatment reverses a crack; harvest promptly to avoid secondary rot and insect entry. Manage by keeping moisture even. Prevention Keep soil moisture as even as you can: water deeply and regularly during dry spells, and mulch to buffer the swings. Many heirlooms have thin skins and crack easily, so pick ripe fruit right away, especially before heavy rain.Maintain even soil moisture through deep, regular watering during drought and mulch to buffer fluctuations. Harvest near-ripe fruit ahead of heavy rain; heirlooms are more crack-prone, so pick promptly.
