Symptoms and Signs
Plants are stunted and heads emerge later than normal. Kernels are replaced by dark gray spore masses enclosed in a gray membrane that persists until maturity and is partially covered by floral bracts. If the spore masses are crushed to release spores, they have a distinctive odor, similar to that of decaying fish.
Comments on the Disease
Covered smut spore masses burst during harvest, spreading spores to healthy grain and the soil. The fungi survive from one season to the next on the surface of infested seed or in the soil.
Management
Cultural Control
Use certified smut-free seed. A hot water treatment can eliminate smut fungi from contaminated seed, but it must be used carefully to avoid reducing seed quality.
Chemical Control
Seed treated with contact-type fungicides will control covered smut because the fungus is on the outside of the seed.
| Common name | Amount per 100 lb of seed | REI‡ | PHI‡ | ||
|---|---|---|---|---|---|
| (Example trade name) | (hours) | (days) | |||
| Not all registered pesticides are listed. The following are listed alphabetically. When choosing a pesticide, consider information relating to the pesticide's properties and application timing, resistance risk, honey bees, and environmental impact. Always read the label of the product being used. | |||||
| SEED TREATMENT | |||||
| CARBOXIN | |||||
| (Vitavax-34) | Label rates | 12 | NA | ||
| MODE-OF-ACTION GROUP NAME (NUMBER1): Carboxamide (7) | |||||
| COMMENTS: This product is not registered for use in California, but seed treated in and obtained from another state can be legally used in California even for a pesticide not registered on small grains in California. Contact your retail seed dealer for information and availability. For use on barley, oats, triticale, and wheat. Do not use treated seed for food, feed, or oil purposes. Do not graze or feed livestock on treated areas for 6 weeks after planting. | |||||
| CARBOXIN/THIRAM | |||||
| (Vitavax-200) | Label rates | 24 | NA | ||
| MODE-OF-ACTION GROUP NAME (NUMBER1): Carboxamide (7)/multi-site contact (M03) | |||||
| COMMENTS: This product is not registered for use in California, but seed treated in and obtained from another state can be legally used in California even for a pesticide not registered on small grains in California. Contact your retail seed dealer for information and availability. For use on wheat, barley, and oats. Do not use treated seed for food, feed, or oil purposes. Do not graze or feed livestock on treated areas for 6 weeks after planting. | |||||
| DIFENOCONAZOLE/MEFENOXAM | |||||
| (Dividend Extreme) | 2.0 fl oz | 48 | NA | ||
| MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)/phenylamide (4) | |||||
| COMMENTS: For use on barley and wheat. Do not use treated seed for food, feed, or oil purposes. Do not graze wheat or triticale forage for 55 days after planting and barley for 30 days after planting. Do not plant any crop other than those listed on the label within 30 days to fields in which treated seed was planted. | |||||
| MANCOZEB | |||||
| (Dithane M45) | Barley: 2.7–4.2 oz Wheat: 2.2–3.3 oz Oats: 4–6.3 oz |
24 | NA | ||
| MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M03) | |||||
| COMMENTS: Do not use treated seed for food, feed, or oil purposes. All seed treated with this product must be colored with an EPA-approved dye (40 CFR 153.155) that imparts an unnatural color to the seed to help prevent the inadvertent use of treated seed as food for people or feed for animals. For use on wheat, barley, and oats. Follow label requirements for labeling treated seed. | |||||
| ‡ | Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without personal protective equipment. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases, the REI exceeds the PHI. The longer of the two intervals is the minimum time that must elapse before harvest. |
| 1 | Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with different group numbers are suitable to alternate in a resistance management program. In California, make no more than one application of a fungicide with a mode-of-action group number associated with high resistance risk before rotating to a fungicide with a different mode-of-action group number; for other fungicides, make no more than two consecutive applications before rotating to fungicide with a different mode-of-action group number. |
| NA | Not applicable. |
Text Updated: 04/26
Treatment Table Updated: 07/25