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kochia weed seed dormancy years

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As kochia germinates early in the spring, delayed seeding and pre-seeding tillage or pre-seeding herbicides will help reduce in-crop weed densities. Crop rotations that use a combination of early and late sown crops and alternating seeding dates on individual fields will help keep kochia populations in check. Because the majority of kochia seeds don’t live for more than one year, preventing seed production for a single year will help reduce kochia problems. Mowing or cutting for feed are effective ways of controlling kochia seed production, as long as the plants have not yet set seed.

Kochia has been used as a livestock feed during feed shortages resulting from drought. As a forage crop, kochia is noteworthy because it has good drought tolerance, salinity tolerance, good leafiness, high yields, and has high protein and carbohydrate content.

Preharvest glyphosate (Roundup, Touchdown) treatments may be effective if kochia has set seed but is not yet mature. Immature seed will absorb glyphosate which can affect kochia seed viability. Usually, however, preharvest glyphosate is economical only if perennial weeds are present, as most field crops are normally cut before kochia seeds become mature and viable. Similarly, post-harvest herbicide treatments are not likely to be worthwhile unless other weeds are present or kochia is about to set seed.

Cultural

Kochia resistance to Group 2 herbicides exists in Manitoba. Group 2 herbicides include products such as Refine Extra, Ally, Pursuit, and Odyssey (refer to tables for additional Group 2 products). Herbicide resistance in kochia developed on fields where there was repeated use of Group 2 herbicides over several seasons.

Kochia (Kochia scoparia), also known as summer cypress and burning bush, is a weed on the increase in parts of Manitoba, particularly in the southwest region of the province. It is a weed native to Asia and central Europe, and was introduced to Canada as an ornamental planting by European immigrants. It can be difficult to manage, mostly because of its ability to spread and quickly establish itself as a major weed, particularly during drought years.

If you notice patches of kochia in your field, and you sprayed under good growing conditions at the correct weed stage using full recommended herbicide rates, consider collecting some kochia seed for herbicide resistance testing. At present, Ag Quest based out of Minto, Manitoba offers commercial herbicide resistance testing.

Kochia seeds are short lived in the soil, with most of the seeds dying after one year. Therefore, most kochia problems result from plants that set seed the previous year. Kochia germinates in the early spring and is quite tolerant of frost. Because of its early germination, it is often in advanced stages of growth when other broadleaf weeds are ready to spray. Although kochia mainly germinates in the early spring, additional flushes can germinate throughout the growing season making it difficult to control.