Hot Water Seed Treatment

New Service

The Plant Diagnostic Lab, in collaboration with the Vegetable Extension Program, is excited to announce the launch of our newest service, hot water seed treatment. This service isis supported in part by a UConn CAHNR Innovation in Extension Programming Award and a grant from the New England Vegetable & Berry Growers Association.

The goal of hot water seed treatment is to eradicate pathogens that infest seeds. Hot water treatment enables you to start with clean seed, and strong cultural management practices (i.e. crop rotation, field sanitation, scouting, etc.) will still be important to implement on plants that grew from hot water treated seed. It is important to note that while hot water seed treatment can eliminate pathogens on and in seeds, it neither protects nor guarantees that plants will remain disease free throughout the growing season.

What is hot water seed treatment?

Important considerations to take before submitting seed for hot water treatment:

  1. Determine if the seed you’d like to treat is commonly associated with diseases caused by seedborne pathogens (see the section below).
  2. Determine if the seed you’d like to treat is a good candidate for hot water treatment (See the section below). Treating large-seeded crops such as beans, peas, cucurbits, corn, etc. that are not listed on Table 1 is not recommended because the temperature required to treat these seeds can kill the outer seed tissue and prevent germination.
  3. Determine if your seed has already undergone hot water treatment or if it has been primed. This information is not always easy to find, so it is important to contact your seed supplier with specific questions. A few seed companies conduct hot water treatment, and treating the seeds a second time will damage the seeds and affect germination. Additional questions to ask include: have the seeds been certified disease-free? Were the seeds produced in a specific way to minimize exposure to seedborne pathogens?
  4. Determine if your seed has a fungicide or insecticide treatment coating. This coating will wash away during hot water seed treatment, therefore rendering the coating useless. If the seed has a clay coating, this coating will also wash away but will not be detrimental to the seed.
  5. Determine the age of the seed. Only treat seed that you plan to use within 1 year. Hot water treated seed does not remain viable for as long as untreated seed.

Crop types & diseases eligible for hot water seed treatment

Please read the tables below carefully. If you do not see a particular crop listed, we are not currently able to perform hot water seed treatment on it. Please contact us at with any questions.

Complete list of crops eligible for UConn's Hot Water Seed Treatment

Beet/Chard Collards Pepper
Brussel sprouts Cress Radish
Broccoli Eggplant Rutabaga
Cabbage Kale Shallot
Carrot Kohlrabi Spinach
Cauliflower Lettuce Sweet potato* (roots/cuttings/sprouts)
Celeriac Mint Tomato
Celery Mustard Turnip
Cilantro/Coriander Parsley Yam* (tubers)

*Processing fee and shipping/handling policies will vary by situation. Please email us to discuss if you plan on submitting potato or yam tissue.


The below table is a general reference of the diseases treated when using hot water seed treatment.


Diseases Treated

Beet / Swiss Chard Phoma/Canker, Beet downy Mildew, Cercospora leaf spot
Brassicas Alternaria leaf spot, Bacterial leaf spot, Black leg, Black rot
Carrot Alternaria blight, Bacterial leaf blight, Cercospora leaf spot, Crater rot, Foliar blight
Celery / Celeriac Bacterial leaf spot, Cercospora leaf spot, Septoria leaf spot, Phoma crown and  root rot
Eggplant Anthracnose, Early blight, Phomopsis, Verticillium wilt
Lettuce Anthracnose, Bacterial leaf spot, Lettuce mosaic virus, Septoria leaf spot, Verticillium wilt
Onion Purple blotch, Stemphylium leaf blight, Basal Rot, Botrytis blight, Smudge, Black mold
Parsley / Cilantro Bacterial leaf blight, Alternaria leaf blight, Black rot, Cercosporoid leaf blight, Septoria blight
Pepper Anthracnose, Bacterial leaf spot, Cucumber mosaic virus, Pepper mild mosaic virus, Tobacco mosaic virus, Tomato mosaic virus
Spinach Anthracnose, Cladosporium leaf spot, Cucumber mosaic virus, Spinach downy mildew, Fusarium wilt, Stemphylium leaf spot, Verticillium wilt
Tomato Alfalfa mosaic virus, Anthracnose, Bacterial canker, Bacterial speck, Bacterial spot, Cucumber mosaic virus, Early blight, Fusarium wilt, Leaf mold, Septoria leaf spot, Tomato mosaic virus, Tobacco mosaic virus, Verticillium wilt, Double virus streak