White patches, pale streaks, or an overall bleached look on tomato fruit usually trace back to sunscald, the single most common cause of white discoloration on garden tomatoes. But “turning white” can mean different things depending on where the discoloration appears and whether it affects the fruit, the leaves, or both. Heat stress that stalls ripening, fungal diseases like powdery mildew, insect feeding damage, and even herbicide drift can all produce whitish symptoms on tomato plants, and each calls for a different response.
Sunscald Is the Usual Suspect
If you see a large, pale or papery white patch on one side of a tomato, especially the side facing the afternoon sun, you are almost certainly looking at sunscald. The damage looks a lot like a sunburn because that is essentially what it is. Research going back decades has shown that sunscald results from the combined action of intense light and heat on exposed fruit tissue, which diverts energy away from normal photosynthesis and triggers destructive reactions in the cells.1Scientia Horticulturae. Induction of sunscald damage in tomatoes under natural and controlled conditions The affected area first turns white or yellowish-white, then becomes thin and papery, and can eventually collapse or invite secondary rot.
Sunscald almost always appears on green or partially ripe fruit that has suddenly lost its leaf canopy. This is why it often shows up after aggressive pruning, after a disease strips the foliage, or when a branch breaks under the weight of fruit and exposes tomatoes that had been shaded. Varieties with sparse foliage or a more open growth habit are also more vulnerable. The key detail is that the fruit needs to have been previously shaded; tomatoes that develop under full sun from the start tend to build up a degree of tolerance. It is the abrupt transition from shaded to exposed that does the most harm.
When Heat Alone Keeps Fruit From Coloring
Sometimes the issue is not a localized white patch but a tomato that simply refuses to turn red, staying pale, yellowish-white, or developing hard white tissue inside. This points to heat stress rather than sunscald. The two problems are related but distinct. Sunscald is a surface burn; heat-induced ripening failure is a whole-fruit metabolic disruption.
Tomatoes develop their red color through the accumulation of lycopene, a pigment whose production depends on enzymes that are sensitive to temperature. When fruit temperatures climb too high, the genes responsible for ripening-related processes are suppressed, slowing ethylene production, lycopene accumulation, and cell-wall softening.2Plant Physiology. Reversible Inhibition of Tomato Fruit Gene Expression at High Temperature The result is fruit that stays stubbornly pale or develops uneven coloring, with hard white or yellow shoulders that never ripen. Daytime air temperatures above roughly 95°F (35°C) are enough to trigger the problem, and night temperatures that stay above 75°F (24°C) make it worse because the plant never gets a cool recovery period.
The encouraging news is that the word “reversible” in the research is literal. If temperatures drop back into a more moderate range, ripening often resumes and the fruit eventually colors up. You can help the process along by picking nearly mature fruit and letting it finish ripening indoors at room temperature, away from the extreme heat.
Powdery Mildew and White Mold on Leaves and Stems
If the whiteness you are seeing is on the leaves or stems rather than on the fruit, fungal disease is the more likely explanation. Powdery mildew is the classic culprit. It shows up as dusty white patches on the upper surfaces of leaves and, in severe cases, on the stems. A powdery mildew outbreak documented on greenhouse-grown tomatoes found white pustules primarily on the upper leaf surfaces, with only rare involvement of the undersides, while stems were very severely affected.3Plant Pathology. Tomato powdery mildew The fungus thrives in warm, dry conditions with moderate humidity, which is why it can appear even in the absence of rain, unlike many other tomato diseases that need wet foliage.
White mold, caused by a different fungus called Sclerotinia sclerotiorum, is another possibility, especially in cooler, humid conditions. White mold produces fluffy, cotton-like growth on stems and can girdle and kill the plant if left unchecked. It is a recognized threat to tomato production and can significantly reduce yields.4Journal of Phytopathology. Physiological and biochemical responses of tomato plants to white mold affected by manganese phosphite Where powdery mildew looks like someone dusted the leaves with flour, white mold looks more like wet cotton that clings to stems near the soil line or at pruning wounds.
Neither disease typically causes white patches directly on the fruit in the way sunscald does, but they can indirectly lead to pale or poorly ripened fruit by damaging foliage so badly that the plant cannot photosynthesize enough to support normal fruit development. Severe powdery mildew can also defoliate the plant, which circles back to sunscald: once the leaves are gone, exposed fruit burns.
Insect Feeding That Leaves White or Pale Spots
Small, irregular whitish or clouded spots on the surface of a tomato, sometimes with a slightly sunken or corky texture, often come from piercing-sucking insects. Stink bugs are the biggest offender. When a stink bug pushes its needle-like mouthpart into a green tomato, it injects digestive enzymes and feeds on the tissue underneath. The result is a pale, spongy spot that becomes visible as the fruit ripens. The brown marmorated stink bug in particular causes heavy feeding injury on tomatoes, which rank among the most susceptible vegetable crops to this pest.5Oxford Academic. Seasonal Abundance, Host Suitability, and Feeding Injury of the Brown Marmorated Stink Bug, Halyomorpha halys (Heteroptera: Penatomidae), in Selected Vegetables
Stink bug damage is easy to confuse with other disorders because the white spots do not always appear until the fruit starts to color. You may harvest what looks like a perfect green tomato only to find cloudy white patches developing as it ripens. The spots are cosmetic and the fruit is still safe to eat, but the texture in those areas is mealy and unpleasant. If you are consistently seeing this pattern, look for stink bugs hiding on the undersides of leaves and along stems, especially in late summer when their populations peak.
Other insects that can leave pale feeding marks include whiteflies and certain species of thrips, though their damage tends to show up more on the foliage than on the fruit itself. Whitefly infestations are especially easy to spot because the tiny white adults fly up in a cloud when you disturb the plant.
Viral Diseases and Blotchy Ripening
Some viruses cause tomato fruit to develop uneven patches of color, including pale or whitish marbled areas that never ripen normally. Pepino mosaic virus (PepMV) is one of the better-studied examples. Research on glasshouse-grown tomatoes found that PepMV infection led to a range of fruit quality defects including blotchy ripening, gold marbling, and gold spot symptoms directly attributed to the virus.6Plant Pathology. Effect of Pepino mosaic virus on the yield and quality of glasshouse‐grown tomatoes in the UK In practice, these symptoms can look like irregular pale or whitish streaks against a background of red or pink, giving the fruit a marbled appearance.
PepMV is primarily a greenhouse problem and spreads easily through handling, contaminated tools, and even recirculated irrigation water. Home gardeners growing outdoors are less likely to encounter it, but it is not impossible, especially if transplants come from an infected greenhouse source. Unlike sunscald or heat stress, viral discoloration affects multiple fruit in random patterns rather than clustering on the sun-exposed side of individual tomatoes. If your fruit shows streaky, marble-like pale patches and you have ruled out environmental causes, a viral issue may be at play.
Herbicide Drift and Chemical Bleaching
A less common but sometimes devastating cause of white or bleached-looking tomato tissue is herbicide drift. Tomatoes are famously sensitive to several herbicides, and the chemicals do not have to land directly on your plants to cause harm. Volatile herbicides applied to nearby lawns, farm fields, or even compost made from treated grass clippings can reach your tomato patch in concentrations too low to detect by smell but high enough to damage the plants.
Research on the herbicide quinclorac, widely used on rice crops, demonstrated that even simulated drift at low application rates can impair tomato plant growth, and that residue levels and half-lives in the tissue increased with higher rates and repeated exposures.7PubMed Central. Influence of simulated Quinclorac drift on the accumulation and movement of herbicide in tomato (Lycopersicon esculentum) plants Herbicide damage on tomatoes can show up as bleached or whitened leaf tissue, curled and distorted new growth, or pale fruit. The aminopyralid family of herbicides, common in broadleaf lawn weed killers, is another frequent offender. If your plants suddenly develop pale, twisted growth and you or a neighbor recently applied any weed killer, herbicide drift is worth investigating.
How to Tell the Causes Apart
With so many possible explanations, the key to sorting them out is paying attention to exactly where the whiteness appears and what pattern it follows.
- One-sided fruit patches: A large white area on the sun-facing side of the fruit, especially after foliage loss, is sunscald.
- Overall pale fruit: Tomatoes that stay uniformly white, yellow-white, or develop hard white internal tissue during a heat wave point to heat-induced ripening failure.
- Dusty white leaf coating: Powdery white film on the tops of leaves is powdery mildew. Fluffy cotton-like growth on stems near the soil is white mold.
- Small cloudy spots: Irregular, slightly sunken pale marks scattered across the fruit surface, visible mainly at ripening, suggest stink bug or other insect feeding.
- Marbled streaks: Uneven pale or gold marbling across fruit that otherwise looks healthy is suggestive of a viral infection like PepMV.
- Twisted, bleached new growth: Distorted growing tips with pale or whitened leaves appearing suddenly across the whole plant suggest herbicide exposure.
Preventing White Patches on Fruit
Because sunscald and heat stress are by far the most common reasons for white tomato fruit, prevention starts with managing sun exposure and temperature. Shade cloth is one of the most effective tools available. A study comparing shaded and unshaded tomato production found that shading not only eliminated sunscald on fruit but also increased marketable tomato production by about 35% compared to growing without shade.8Scientia Horticulturae. Effects of the modification of light intensity by color shade nets on yield and quality of tomato fruits A 30% to 50% shade cloth draped over a simple frame is usually enough to take the edge off intense afternoon sun without reducing light so much that yields suffer.
Beyond shade cloth, maintaining healthy foliage is your best natural defense against sunscald. Resist the urge to over-prune indeterminate tomato varieties. Those leaves are doing important work shading the fruit beneath them. If a disease has already stripped the foliage, draping lightweight row cover or even an old bedsheet over the plant during the hottest part of the day can prevent the newly exposed fruit from burning.
For heat-related ripening failure, there is less you can do to change the weather, but picking fruit at the “breaker” stage, when the first blush of color appears, and finishing ripening indoors avoids the worst effects. Mulching heavily around the base of plants also helps moderate soil temperature, which in turn reduces root stress and keeps water uptake more consistent.
Preventing fungal diseases like powdery mildew is largely about airflow. Space plants generously, prune lower branches that touch the ground, and avoid overhead watering that keeps foliage damp. For stink bugs, floating row covers can physically exclude the insects from the fruit, though this is more practical in small gardens than in large plantings. Removing weeds and debris around the garden reduces overwintering habitat for stink bugs heading into the following season.
Can You Eat Tomatoes With White Spots?
This depends entirely on the cause. Sunscalded tomatoes are safe to eat; you can simply cut away the damaged white or papery area and use the rest. The flesh underneath may be a bit tougher or less flavorful, but it poses no health risk. Similarly, tomatoes with white shoulders from heat stress are safe, just not as appealing. Cut away the hard white tissue and enjoy the rest.
Stink bug feeding spots are also harmless to you. The affected areas are mealy and unappetizing, so most people trim them off, but there is nothing toxic about them. Tomatoes with viral marbling are safe as well; PepMV and similar viruses are plant pathogens that do not infect people.
Where you should exercise more caution is with fruit showing active fungal growth. Powdery mildew itself is a leaf disease and rarely grows on fruit, but if white mold has progressed to the point of visibly covering the fruit or the stem immediately attached to it, discarding the fruit is the safer call. And any fruit from plants damaged by herbicide drift should not be eaten. While low-level herbicide residues may fall below detection limits in some cases, the risk is not worth taking, especially since the off-flavors from herbicide-damaged plants make the fruit unpleasant anyway.
Interior White Tissue and Other Lookalikes
Sometimes the white you are noticing is not on the surface but inside the fruit when you slice it open. Hard, white, pithy cores or white veins running through the flesh are common in tomatoes stressed by high temperatures during fruit set. This internal whiteness is essentially undeveloped placental tissue that never filled in with juice and pigment. It is more common in certain varieties, particularly large-fruited beefsteak types, and tends to worsen during prolonged hot spells. The tissue is tough and flavorless but not harmful.
Another lookalike worth mentioning is blossom-end rot, which starts as a pale or water-soaked spot on the bottom of the fruit and eventually turns dark and leathery. Early-stage blossom-end rot can look whitish before it progresses to its more recognizable brown or black form. The underlying cause is a localized calcium deficiency in the developing fruit, typically driven by inconsistent watering rather than by a true lack of calcium in the soil.9Oxford Academic (Annals of Botany). A Cellular Hypothesis for the Induction of Blossom-End Rot in Tomato Fruit If you catch blossom-end rot at the white-spot stage, evening out your watering schedule can prevent further fruit from developing the problem.
Gray or white concentric rings on the skin of ripe tomatoes, sometimes with tiny cracks radiating from the stem end, are a form of fruit cracking, not a disease. These rings form when the fruit swells rapidly after a heavy rain or deep watering following a dry spell. The outer skin cannot stretch fast enough and micro-tears form, which then heal over with whitish scar tissue. Consistent moisture is the best prevention, and mulch goes a long way toward buffering the soil between rainfalls.