How to Treat White Rot

Updated November 21, 2016

White Rot appears on vegetation such as trees and some plant life, including onions and garlic. The soil-borne disease appears as a white, sometimes fluffy, fungus on plants or trees. The disease can cause great damage to an entire crop if left untreated. According to Lisa Lieberman, author of " New Fungicides Control White Rot in Onions, Garlic," in California, 13,000 acres of cropland were affected by white rot between 2006 and 2009. Although no consistent cure exists for white rot, both preventive and treatment measures, are available

Spray trees or bushes with a fungicide spray once blossoms appear until trees are harvested or after first frost. Home improvement stores, nurseries or hardware stores typically sell tree fungicides. Follow the directions on the back of the fungicide to ensure appropriate application.

Inspect trees and bushes to find all white rot fungus spots. J.W. Travis, J.L Rytter and A.R. Biggs, authors of "White Rot," point out that white rot affects trees and bushes such as chestnut, birch, blueberry, apple and peach trees. Look for spots that appear as white blisters or a circular canker spots.

Sterilise pruning equipment with rubbing alcohol or a bleach and water mixture. Prune all infected branches or blossoms off the tree or bush in early spring or late fall using sharp sterilised shears. Remove any pieces of bark that contain canker areas or blisters with a sterilised pruning knife. According to Sherman Thomson and Scott Ockey, authors of "Slime Flux," prune branches laterally and remove bark to create an oval shaped area parallel to the trunk. Sterilise the shears or pruning knife in between cutting to prevent the spread of the white rot.

Identify whether the land has contained white rot on crops in the past. Remove recently infected soil and replace with unaffected soil. This procedure works with smaller infected areas and not entire rows or crops. Clean and sanitise farming equipment before and after it is exposed to areas infected with white rot.

Plant the chosen crop with plenty of space between plants. White rot spreads quickly and horizontally through root systems. If new crops such as onions are grown in a past-infected area, it is advisable to grow crops from seed rather than sets.

Examine plants for white rot. Common crops affected by white rot include onions, garlic, chives, shallots and leeks. Look for yellowing or dying foliage. Drooping plants often signify dry rot on the roots of the plant. Pull one plant out of the ground to examine the bulbs. White rot will appear as a whitish, fluffy, cotton-like fungus with black specks.


Irrigate or water crops and trees regularly to prevent drought spells. Drought creates optimal conditions for white rot to emerge. White rot fungus grows quickly. Monitor both trees and crops frequently for signs of disease.


Apple trees most susceptible of white rot include the jersey mac, empire and golden delicious. Be proactive and watch for signs of white rot. Once the fungus becomes settled within an entire field it cannot be uncontaminated.

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About the Author

Steph Radabaugh has been writing on gardening and mental health care since 2005. Her articles have helped people create beautiful gardens and sparked the interest of state lawmakers in Iowa's health-care organizations. Radabaugh has a Master of Science in industrial organizational psychology and has pursued her Doctor of Philosophy in research psychology.