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White Mold

White Mold

Sclerotinia sclerotiorum

Fungalalso: Sclerotinia, Cottony rot, White mould

A fungal rot that strikes a wide range of vegetables, coating stems, leaves, and pods with a cottony white mold and rotting them through. White mold thrives in cool, damp, crowded plantings and is especially troublesome on beans, lettuce, cabbage, carrots, and tomatoes. Its hard black resting bodies let it survive in the soil for years.

🔎 How to spot it

Look first for a soft, watery rot on stems, leaves, pods, or fruit, soon covered with a fluffy white cottony mold in damp conditions. The surest sign is the hard, black, irregular resting bodies, the sclerotia, that form in and on the rotted tissue, looking like mouse droppings or small lumps of coal. Infected stems may bleach white and wilt above the rot.

🥀 Damage it causes

White mold rots stems, crowns, pods, and fruit, wilting and killing the parts above the infection and often the whole plant. It can cause stem and crown cankers, root rot, seedling damping-off, and blossom and fruit rot, and it ruins harvested produce in storage. A bad case can take out patches of a bean or lettuce planting.

🔬 What causes it

White mold is caused by the fungus Sclerotinia sclerotiorum, which survives in soil for years as hard black sclerotia. In cool, moist conditions these sprout to release spores that infect through flowers and dying tissue, and the disease then spreads plant to plant by contact. It develops fastest at 68 to 77 F in dense, humid canopies that stay wet.

🛡️ Prevent it

Open up the canopy for airflow and faster drying: space plants widely, avoid heavy nitrogen that builds dense growth, and stake or trellis where you can. Water at the base in the morning rather than overhead. Rotate with non-host crops such as corn and small grains, and remove and destroy infected plants, sclerotia and all, so they do not seed the soil.

🧯 If it is already here

There is no cure for an infected plant, so pull and destroy affected plants promptly, including the black sclerotia, and do not compost them. Improve air movement and reduce moisture right away. Because the fungus persists in soil for years, the real management is cultural: rotation, spacing, and sanitation, since fungicides give limited help in the home garden.

💡 Good to know

The hard black sclerotia are both the diagnostic clue and the reason white mold is so persistent, since they can wait in the soil for many years between host crops. The disease loves a dense, humid canopy, so the same airflow and spacing that fight gray mold and downy mildew also hold white mold back.

🌱 Plants it affects

362 plants in the library can be affected by this problem

Adirondack Blue PotatoAdzuki BeanAfrican MarigoldAgapanthusAgeratumAji Amarillo PepperAlice du Pont Mandevilla🥔All Blue PotatoAmethyst Falls WisteriaAmish Paste TomatoAnaheim PepperAnemoneAngelique TulipAngeloniaAnnabelle Smooth HydrangeaAnnual VincaApeldoorn TulipApril Tryst CamelliaArizona Sun Blanket FlowerArugula🥕Atomic Red CarrotAugust Beauty GardeniaAutumn Joy SedumBachelor's ButtonBanana PepperBarbara Karst BougainvilleaBeauregard Sweet PotatoBecky Shasta DaisyBee Balm🍅Beefmaster TomatoBenarys Giant ZinniaBengal Tiger CannaBetter Boy Tomato🥬Bibb Lettuce🍅Big Beef TomatoBig Boy TomatoBlack BeanBlack Beauty EggplantBlack Beluga LentilBlack Cherry TomatoBlack Krim Tomato🥬Black Seeded Simpson Lettuce🥕Black Spanish RadishBlack-Eyed PeaBlack-eyed Susan VineBlood OrangeBloomsdale SpinachBlue Bird DelphiniumBlue Bird Rose of SharonBlue FescueBlue Lake Green BeanBok Choy🥕Bolero Carrot🍅Box Car Willie TomatoBrandywine TomatoBroad Windsor Fava BeanBroccoli RabeBrunneraBrussels SproutsBurning BushButtercrunch LettuceButterfly Blue Pincushion FlowerButterfly Marguerite DaisyButterfly WeedCafe au Lait DahliaCalabrese BroccoliCaladiumCalendulaCalibrachoaCalifornia Giant ZinniaCalifornia PoppyCampanulaCannellini BeanCardinal FlowerCarolina GeraniumCarolina JessamineCarolina Reaper PepperCayenne PepperCelebrity Tomato🥬Champion CollardsChantenay CarrotCheddar CauliflowerCherokee Purple TomatoCherry Belle RadishChicoryChinese BroccoliClimbing HydrangeaClimbing Prairie RoseCocktail Vodka BegoniaColeusCollard GreensCoral Drift Groundcover RoseCosmic Purple CarrotCosmosCranberry BeanCreeping PhloxCubanelle PepperCupani Sweet PeaDaikon RadishDandelion

For educational and informational purposes only. Disease management advice is general guidance drawn from university cooperative extension sources; always identify a problem positively and read and follow the label on any product before use, especially around food crops, children, and pets.