# Seed treatment methods: seed treating drum, seed health and temperature control URL: https://leafwrit.com/uk/seed-treatment-guide/ Reviewed: 2026-10-29 **Seed treatment should answer a diagnosed seed-health problem.** Cereal disease testing, physical disinfection, chemical dressing and germination priming have different purposes. Seed-lot condition and the proposed treatment method both matter; a seed treating drum does not identify the pathogen or determine which process the seed can tolerate. ## Cereal seed tests and treatment thresholds **Test a representative cereal seed sample before deciding on a disease treatment.** Sample **before cleaning or drying** and keep a farm-saved seed crop separate from other grain bulks. ### The test method changes the threshold Distinguish **A, an advisory treatment threshold**, from **S, the regulatory minimum**, and **HVS, the regulatory higher voluntary standard**. The advisory examples below concern specific crops and tests: - Wheat bunt warrants treatment when spores are present on seed. - Microdochium infection thresholds differ: **over 10% for wheat**, **over 30% for barley**. - Barley leaf stripe warrants treatment above **2% infection in an agar test**, or when detected in a molecular test. - Barley net blotch has an advisory threshold of **over 15% infection**. Visual inspections typically take up to **24 hours**, washes and molecular tests **one to ten days**, and agar plates **seven to ten days**. The certified-seed standards apply to **second-generation seed used in commercial crop production**. Bunt, smut, Microdochium infection and barley leaf stripe are separate diagnostic questions. An agar test, a seed wash and a molecular test examine material in different ways, so a percentage from one cannot be read against the threshold of another. Test each grain bulk as its own lot, so keep seed from different origins separate. ## Hot water seed treatment is not the same as seed priming, presowing treatment or seed priming technology **Hot-water seed treatment reduces seedborne pathogens.** The crop determines the required temperature and duration. ### Crop-specific hot-water examples The crop-specific hot-water examples are **122°F (50°C) for 20 minutes** for broccoli and cucumber, **122°F for 25 minutes** for cabbage and tomato, and **118°F for 30 minutes** for lettuce. Water that is too hot can injure seed; water that is too cold may fail to eradicate pathogens. Hot-water treatment is less effective on large or extremely fragile seed, pelleted seed, primed seed, fungicide-treated seed and old seed. Hot-water disinfection reduces seedborne pathogens, particularly bacterial pathogens. The process depends on uniform temperature, which a water bath with precise temperature and timing control provides more consistently than a pan on a stove. Priming, which influences germination, is a different process from the crop-specific temperature and duration used for pathogen reduction. ## Damping off disease treatment begins with diagnosis **Damping off can kill seedlings before emergence as well as after they appear.** Possible causes include **Pythium, Phytophthora, Rhizoctonia and Fusarium**. It is a syndrome with multiple possible causes, not the name of one organism. No fungicides are available to gardeners for damping off, so treatment, onion seedlings included, comes down to prevention: - Raise seedlings in commercial growing compost, which is usually free of damping off organisms, and use new pots and trays; if you reuse them, brush off soil, wash and disinfect them. - Sow thinly to avoid crowding. - Water with mains water where possible, and do not overwater. - Keep seedlings well ventilated to reduce humidity. Damping off is especially damaging in spring, when low light and low temperatures slow seedling growth, but it can occur at any time of year. ## Seed treatment by crop: corn, bean, pea, sunflower, flax and sweet corn seed A corn (maize) seed treatment, bean seed treatment, treated pea seeds, sunflower seed treatment, flax seed treatment, treated sweet corn seed or treated pumpkin seeds all start from the same three facts: the crop, the diagnosis or pest named on the label of the treatment, and the lot of seed. Active substances that appear in searches for seed fungicides and insecticides (captan, thiram, thiabendazole, thiophanate-methyl, azoxystrobin, fipronil, chlorpyrifos, clothianidin, cyantraniliprole and neonic or neonicotinoid treatments) are names to look up, not recommendations: whether a product containing one of them may be used on your crop is settled by the register entry and the label of the product, so search the product in the [HSE register guide](/uk/hse-gb-pesticides-approval-register/). Treated seed stays labelled: keep the bag tag with the field record, and keep treated seed out of food and animal feed. Untreated seed has no label of this kind, which is why the seed lot, the test and the decision to treat go into the record. For named treatments see the pages for Cruiser, Gaucho, Vibrance and Maxim. ## Seed treatment types: inoculant, biofertiliser, micronutrient, polymer and seed care Not every seed treatment protects against a disease or pest. An inoculant seed treatment (rhizobium, azospirillum, mycorrhiza), a biofertiliser, a micronutrient treatment (zinc, molybdenum), humic or gibberellic acid, a polymer coat and seed care coatings supply nutrition, growth or handling properties. Their nutrient function is covered in the [organic crop-protection guide](/uk/organic-crop-protection/); a claim to control a named disease or pest is a plant protection claim and belongs to the label of a registered product. ## Seed treating drum and calibrated application **Redigo Pro requires Bayer-approved seed-treatment application equipment, accurately calibrated for its rate.** The product rate is **67 ml/100 kg seed**, equivalent to **0.67 L/tonne**, with a maximum of **one treatment per batch**. The preparation has to be homogeneous before use. Containers exceeding **20 litres** need mechanical handling assistance. The crop list includes winter and spring wheat, oats and barley, durum wheat, rye and triticale. Test batch quality, including germination and vigour, before processing. A seed-dressing machine must meet the named product's instructions: calling it a batch drum does not establish Bayer approval. Redigo Pro provides only partial control of barley leaf stripe, insufficient for seed multiplication. Its ergot recommendation has limited supporting evidence: combine the treatment with seed-hygiene and agronomic measures. ## Match the disease-control claim to the diagnosis Redigo Pro's disease organisms include Microdochium nivale, Fusarium culmorum, Tilletia caries, Ustilago species and Penicillium. Each claim has its own stated outcome: improved establishment, symptom reduction, control or partial control. Pyrenophora graminea leaf stripe and Claviceps purpurea ergot are different diagnoses. ## A list of fungicides used for seed treatment needs a crop and diagnosis A list of fungicides for seed treatment starts from the seed crop, the test result and the disease claim: the crop, disease and claimed level of control on the label have to match the test. Do not use Redigo Pro on sprouted, cracked, skinned or otherwise damaged seed, or on seed above **16% moisture**. Label treated sacks or bag tags with the required precautions. Keep treated seed out of food and animal feed, and secure it from people, pets, livestock and wildlife. ## Representative sampling and lot preparation Diseased seed lots can contaminate healthy ones. Brush sampling equipment with water and detergent before and between lots, and allow it to dry. Keep farm-saved seed segregated. Choose cereal tests for the suspected diseases. Wheat checks include bunt and Microdochium seedling blight; ergot, loose smut, Septoria nodorum and Fusarium tests may be relevant where disease is suspected. Barley checks include loose smut, leaf stripe and net blotch where not previously present; add ergot, covered smut and Fusarium graminearum tests if a problem is suspected. Test all seed for organic production for germination and seedborne diseases. Seed merchants can supply lot test certificates. ## Chlorpyrifos, fipronil and neonicotinoid seed treatments in Great Britain In the HSE pesticide register no product is listed with chlorpyrifos, fipronil or a neonicotinoid (thiamethoxam, imidacloprid, clothianidin) as an active substance, so a seed dressing built on one of them is not something you can buy and use on a British farm. Cruiser SB contains the neonicotinoid thiamethoxam and was put forward as an emergency seed treatment for sugar beet. For the 2025 crop in England the Minister denied that application. An old decision for an earlier season does not give permission for a later one, so check Defra's page for the season you are sowing before you plan around it. Grain Guard is a different kind of case. It is a mancozeb fungicide sold in the United States for treating wheat, oats, barley, rye, sorghum, safflower and rice seed in the drill box or planter box at planting time, under a US label. No product of that name is in the HSE register, and seed treated with a plant protection product may only be marketed and used if that product is authorised for that use. A British grower who wants a seed treatment for cereals should start from the products that are on the register for the crop and the disease. The same rule applies to any other active substance you find in an advert, a seed catalogue or a neighbour's advice: look the product up in the [HSE register guide](/uk/hse-gb-pesticides-approval-register/), and if the product is not there, do not treat the seed with it. ## Bean seed fly treatment: what protects the seed Bean seed fly (Delia platura) attacks seeds and seedlings of field beans, peas, alliums, sweetcorn, asparagus, cereals and vegetable brassicas, and the first sign is usually patchy emergence because the larvae feed on seeds and cotyledons. Eggs are laid mainly in freshly disturbed soil, especially near manure and crop residues, and anything that slows germination and shoot vigour raises the risk, such as low temperatures and sowing too deep; crops sown in later spring or early summer are at greater risk. Burying organic debris from previous crops should reduce the risk, and adults can be monitored all season with sticky and water traps (yellow, blue and white all work). No thresholds are established. A bean seed fly seed treatment therefore sits on top of these measures, not in place of them: look up the product in the [HSE register guide](/uk/hse-gb-pesticides-approval-register/), check that bean seed fly or Delia is on the label for your crop, and record the treated seed lot as described above. ## Next step See the [product documents](/uk/hse-gb-pesticides-approval-register/) and the [biological-input guide](/uk/organic-crop-protection/).