Seed Treatment for Home Gardens
Hot-Water Treatment
Seed-saving is popular among those who collect, grow, and share heirloom seeds. In some cases, seed-saving may be the only source of certain vegetable varieties because it is an heirloom or not provided by seed companies. Whether you are currently a seed saver or hope to save seeds in the future, it is important to know how to prevent seedborne diseases with clean seed and seed sterilization practices. Some of the most common viral, bacterial, and fungal pathogens begin in the seed. These include tobacco mosaic virus, bacterial speck and bacterial spot on peppers, and botrytis neck rot in onions. Keep seed-saving fun and minimize disease risks by following these general tips:
• Purchase, exchange, or save seeds that have been sterilized or certified disease-free. Contaminated seed can be the first source of disease and can cause severe localized or largescale outbreaks.
• Control insects and diseases throughout the growing season. Disease control during this time will greatly improve production of disease-free seeds. Controlling insect pests also helps to reduce the transmission of viral diseases (this can be difficult with aphid-transmitted diseases).
• Only save seed from healthy fruit.
• Sterilize the harvested fruit surface with rubbing alcohol or a bleach solution. This will kill any pathogens that might be on the fruit surface, but will not be effective against diseases living inside the fruit.
• Sterilize the seed surface with a chemical surface treatment. Be aware that chemical and heat sterilizations may cause damage to the seed if the treatments are too strong or too long. There is no guarantee that this will provide 100% disease-free seed, but it will lower the risk of spreading pathogens that are carried on the seed surface. Direct sterilization of seeds may be damaging or impractical for pea, bean, cucumber, sweet corn, beet and some other seeds.
• Treat seeds before planting via a hot-water treatment (see below and next page for instructions.
Treat seeds with a hot-water bath to help prevent bacterial leaf spot, tobacco/tomato mosaic virus, alfalfa mosaic virus, bacterial speck, botrytis neck rot, and other seed-borne diseases that infect vegetables.
Kitchen Procedure for Hot-Water Seed Treatment
Which Seeds to Treat:
• Eggplant, pepper, tomato, carrot, spinach, lettuce, celery, cabbage, turnip, radish, and other crucifers are suggested crops for treatment.
• Do not treat seeds of cucurbits (squash, gourds, pumpkins, watermelons, etc.), as they can be severely damaged.
• Pelleted, primed, or old seed should not be treated.
Some seed is already chemically treated. It is usually colored pink or green and is marked "treated." If untreated seed is purchased, the home gardener can treat seed with such products as Captan, Vitavax, and Freshgard according to the manufacturer's recommendations.
Equipment:
• Water bath (preferably two: one for pre-heating and one for treatment) or two stove-top pots
• Precision laboratory thermometer
• Porous containers to hold seeds such as cheese cloth, cotton cloth, nylon bag, tea infusers, etc.
• Screen for drying the seeds
Hot-Water Seed Treatment Instructions:
1. Contain Seeds: Place seeds to be treated in the porous containers, leaving enough room for the seeds to move around freely. Label each porous container with the seed type.
2. Preheat Seeds: Preheat the first bath/pot to 100°F. Once preheated, place the contained seeds in the first bath for 10 minutes.
NOTE: If you are using just one water bath or pot, take the seeds out after pre-heating and heat bath/pot to the prescribed treatment temperature before putting the seeds back in for the treatment time.
3. Treat Seeds: Preheat the second bath/pot to the recommended temperature for each specific crop (see link below). The temperature of the second bath/pot will range from 118-125°F and the treatment times will range from 20-60 minutes depending, on the crop. Place preheated seeds in the second water bath/pot and be sure to constantly hold the water at the recommended temperature. Ensure that treatment length and temperature are exactly as prescribed to avoid damaging the seeds.
4. Cool Seeds: After treatment, place contained seeds.
5. Dry Seeds: Take the seeds out of the container and spread them in a uniform layer on a screen to dry.
6. Plant seeds right away. Do not store heat-treated seed.