White mold inside stored squash is caused by the pathogen
Sclerotinia sclerotiorum, which produces a watery, odorless rot characterized by
white fluffy fungal growth and the formation of
black, hard sclerotia (resembling rat droppings) within the rotting tissue. This disease can develop in the field or in storage, spreading easily from fruit to fruit through contact, especially when squash are stored touching each other or in damp conditions.
To prevent and manage white mold in storage, follow these critical guidelines:
- Storage Conditions: Keep squash in a dry location with temperatures between 50-70°F and 50-55% relative humidity to inhibit fungal growth.
- Air Circulation: Store squash so they do not touch each other; use cardboard boxes, newspaper, or separate shelves to ensure good air circulation around each fruit.
- Sanitization: Before storage, wipe down squash with a dilute bleach solution (1 part bleach to 10 parts water) or vinegar to kill surface mold spores and bacteria.
- Harvest & Handling: Harvest early to avoid fall rains, leave a small portion of the stem intact to prevent entry points, and handle carefully to avoid damaging the rind, as the fungus enters through wounds.
- Inspection: Remove diseased fruit regularly from storage to prevent the spread of sclerotia and spores to healthy squash.
If white mold is already present inside the squash, the fruit is generally
unsafe to eat if the rot has penetrated the seeds or internal cavity; however, if the mold is limited to the surface,
trimming away the affected area (including a large margin around it) may salvage the rest of a hard winter squash, though the risk of toxin spread remains
