NEWS for North Dakotans
Agriculture Communication, North Dakota State
University
7 Morrill Hall, Fargo, ND 58105-5665
February 26, 1998
Fungicide seed treatments can protect wheat, barley and oat seed from a variety of soil and seed problems, according to Marcia McMullen, plant pathologist for the North Dakota State University Extension Service. Potential problems for these crops in 1998 include seed rot and seedling blight, root rot, various fungal smut diseases, and wireworm.
"Numerous fungicides, either sold as products containing a single fungicide or multiple fungicides, or in combination with lindane insecticide, are available to North Dakota producers to protect against these problems," says McMullen.
Seed rot may occur any year when seed is planted and does not germinate rapidly because of adverse soil temperature or moisture conditions, she says. In 1997, some wheat and durum seed rotted prior to germination because of Penicillium mold. This seed was planted into very dry soils that did not get rain for some time. Protectant or systemic seed treatment products could have protected the seed from seed rot, but none was applied.
Fungicide seed treatments may also protect against seedling blight, a condition that occurs after germination when fungi either on the seed or in the soil attack the emerging seedling. Seed infected with the scab fungus or black point fungi often get seedling blight if not protected by seed treatment.
"Seed sitting in wet soils or cold soils also are more vulnerable to seedling blights," says McMullen. "Many seed treatment products are available to protect wheat, barley and oats from seedling blights. Some are protectants, some are systemic products, and some are combinations of protectant and systemic fungicides."
Common root rot was a severe problem in some fields in 1997, especially in fields with short rotation periods between susceptible crops of hard wheat, durum and barley. Seed treatment of these crops reduces the risk of severe damage from common root rot. Seed treatment products with activity against common root rot include Vitavax Extra, Dividend, Agsco Double R, Flo-Pro Imz, Nu-Zone, Raxil-Thiram and Baytan. All are registered for wheat, but some are not labeled for barley or oats. Check labels of products for crops allowed.
"Loose smut of wheats and barley may be a problem any year," says McMullen. "The loose smut fungus infects through the flowers of the crop and invades the embryo of the new kernel. Infection of this embryo is not visible without special tests. If the infected seed is planted without appropriate seed treatment, the fungus grows along with the growing point of the developing plant, and at heading time, instead of kernels, the grain is replaced with thousands of smut spores."
An embryo test done by the State Seed Department can detect levels of loose smut in barley. Seed treatment is recommended for seed with infection levels greater than 1 percent, says McMullen. The embryo test is not available for wheat, so wheat producers should treat if any loose smut was seen in the seed field the previous year.
Various systemic seed treatment products must be used to control loose smut. Some products containing the systemic fungicide Carboxin are registered for wheat and barley, some are just registered for wheat. Dividend products are labeled for loose smut control in wheat only. Baytan is labeled for smut control in wheat, barley and oats, but it must be applied only through closed application systems by commercial treaters.
"With over 25 seed treatment products registered for small grains in North Dakota, producers must decide which soil and seed-borne problems are their greatest risks, and choose products that will control those problems," says McMullen. "Other factors that may play a role in choice of product used include ease of application, applicator safety, familiarity with the dealer and product, and also price."
See the NDSU Extension Service publication PP-622, "1998 Field Crop Fungicide Guide," for further information on seed treatment products registered for small grains.
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Source: Marcia McMullen (701) 231-7627
Editor: Barry Brissman (701) 231-7866