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Gray Mold

Gray Mold

Botrytis cinerea

Fungalalso: Botrytis blight, Gray mould

A common cool, damp-weather mold that turns flowers, fruit, and soft stems into fuzzy gray rot. Botrytis attacks a huge range of plants and is especially troublesome on strawberries, tomatoes, lettuce, beans, and many flowers, both in the garden and after harvest. It thrives wherever air is still, humid, and crowded.

🔎 How to spot it

Look first for tiny, almost clear water-soaked spots that turn brown, on petals, leaves, soft stems, and fruit. Infected tissue goes soft, dark, and wilted, and in humid conditions it is soon covered in a fuzzy brown to gray coat of spores that puffs up in a cloud when disturbed. Rot often starts at a wound, a dying flower, or a point where fruit touches damp soil or another fruit.

🥀 Damage it causes

Gray mold rots flowers, fruit, and stems, and can girdle and kill shoots. It is a major cause of fruit rot on strawberries and tomatoes, often appearing after picking so that fruit collapses in storage. Spent blossoms infected early become the launch point for rot that spreads into healthy fruit and foliage.

🔬 What causes it

Gray mold is caused by the fungus Botrytis cinerea, which feeds on dying and damaged tissue and survives on debris. It needs high humidity, above about 80 percent, and 5 to 8 hours of leaf wetness to infect, and it does best in cool weather around 60 to 70 F. Crowding, poor air movement, overhead watering, and leftover dead leaves and flowers all favor it.

🛡️ Prevent it

Space plants for good air movement and keep the foliage dry by watering at the base in the morning. Remove faded flowers, dying leaves, and fruit before they can become infected, and keep ripening fruit off damp soil with mulch or supports. Avoid heavy nitrogen and overcrowding, and harvest carefully to avoid wounds. Clean up all debris at season end.

🧯 If it is already here

Promptly remove and destroy infected flowers, fruit, leaves, and whole plants showing active fuzzy lesions, ideally when foliage is dry so you do not scatter spores. Improve airflow and reduce humidity right away. Approved organic fungicides can give some protection on high-value crops, but sanitation and drying out the canopy matter far more. Refrigerate harvested fruit promptly to slow storage rot.

💡 Good to know

Botrytis is mainly an opportunist that gets started on dead or injured tissue, which is why removing spent blooms and damaged fruit is so effective. The puff of dusty gray spores released when you brush a rotted fruit is the classic sign. It stays active in cool, damp spring and fall weather when many other fungi slow down.

🌱 Plants it affects

714 plants in the library can be affected by this problem

Acorn SquashAdirondack Blue PotatoAdzuki BeanAfrican Blue BasilAfrican MarigoldAgapanthusAgeratumAgrimonyAji Amarillo Pepper🍓Albion StrawberryAlice du Pont Mandevilla🥔All Blue PotatoAlmondAloe VeraAmbrosia CornAmerican BasswoodAmerican Beauty Dragon FruitAmerican BeechAmerican PersimmonAmethyst Falls WisteriaAmish Paste TomatoAnaheim PepperAnemoneAngelique TulipAngeloniaAniseAnise HyssopAnjou PearAnnabelle Smooth HydrangeaAnnual VincaApeldoorn TulipApple MintApril Tryst CamelliaArbequina OliveArizona Sun Blanket FlowerArkin CarambolaArmenian CucumberAroniaArp RosemaryArugulaAshwagandhaAsian PearAsian PersimmonAtemoyaAtlantic Giant Pumpkin🥕Atomic Red CarrotAucubaAugust Beauty GardeniaAunt Molly's Ground CherryAutumn Joy SedumAvocadoBachelor's ButtonBalsam FirBalsam PoplarBanana PepperBarbara Karst BougainvilleaBartlett PearBay LaurelBayberryBeach PlumBeauregard Sweet PotatoBecky Shasta DaisyBee Balm🍅Beefmaster TomatoBenarys Giant ZinniaBengal Tiger CannaBetter Boy Tomato🥬Bibb Lettuce🍅Big Beef TomatoBig Boy TomatoBilberryBing CherryBitter MelonBlack BeanBlack Beauty EggplantBlack Beauty ZucchiniBlack Beluga LentilBlack Cherry TomatoBlack CrowberryBlack Currant🍉Black Diamond WatermelonBlack Kabouli ChickpeaBlack Krim TomatoBlack RaspberryBlack Sapote🥬Black Seeded Simpson Lettuce🥕Black Spanish RadishBlack Tartarian CherryBlack WalnutBlack-Eyed PeaBlack-eyed Susan VineBlood OrangeBloomsdale SpinachBlue Bird DelphiniumBlue Bird Rose of SharonBlue FescueBlue Lake Green BeanBluecrop BlueberryBocking 14 ComfreyBok Choy

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.