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Cold, wet soils force changes in weed management


May 3, 2011
By Kristen Callow OMAFRA weed management program lead for horticulture

lambsquartersMay 2, 2011 – Cold wet
soils this spring are likely to wreak havoc with weed management programs.

May 2, 2011 – Cold wet
soils this spring are likely to wreak havoc with weed management programs.

Seeds of many weed species
will stay dormant under cold temperatures, escaping pre-emergence herbicide
programs. Also, those using a stale seed bed technique will find that fewer
weeds will emerge than anticipated and burn-down herbicide applications are
likely to miss many weeds.

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Under these conditions, a
large flush of weeds may occur with crop emergence once temperatures increase.
Heat loving weeds such as pigweed and purslane are particularly likely to wait
to emerge until temperatures climb. At this point in the season, weed species
that can germinate at cooler temperatures such as lamb’s-quarters and
smartweeds (lady’s-thumb) will appear to be more dominant than usual in some
fields, but this can and is expected to change in a hurry.

Scout your fields
continuously after planting to determine how well your pre-emergence herbicides
worked and be prepared to make several post-emergent herbicide applications
this season.