Pigweeds

Pre-Harvest Herbicide Treatments for Weed Desiccation

Note from Sarah: As a drive the insect scouting loop in Paulding County, I am noticing many fields invested with water hemp which is a great concern in weed control. Other things to make note of are barnyard grass, velvet leaf , marestail and volunteer corn.

By: Mark Loux

Source: https://agcrops.osu.edu/newsletter/corn-newsletter/2022-28/preharvest-herbicide-treatments-weed-desiccation

Waterhemp infestation.

There are plenty of fields with late-season weed problems this year. Weeds that come through the crop canopy late may be small or spindly or sparse enough to be handled easily by a combine. Other fields can benefit from a preharvest herbicide treatment to kill/dissociate weeds, which makes harvesting easier and can reduce weed seed production and foreign matter in harvested grain. Information on preharvest herbicide treatments for field corn and soybeans can be found in the “Weed Control Guide for Ohio, Indiana, and Illinois”, at the end of those crop sections (pages 75 and 146 of the 2022 edition). Products listed for corn include Aim, glyphosate, 2,4-D, and paraquat, and for soybeans include Aim, dicamba, paraquat, glyphosate, and Sharpen. Keep in mind that Aim and Sharpen have relatively narrow spectrums of activity, and will be less effective than the others across a broad range of weed species (i.e. make sure the target weed is something that they actually control). Continue reading →

Late-Season Waterhemp – The Goal is Stopping Seed

Flowering Waterhemp

By Mark Loux OSU Extension

In our windshield scouting of soybeans this year we have seen a lot of weed-free fields.  This makes sense given the shift toward Xtend, LibertyLink, LLGT27, and Enlist soybeans over the past several years, which provides us with effective POST options for our major weed problems – common and giant ragweed, marestail, and waterhemp (now if we could just get rid of the baggage some of these traits carry).  We are however getting many reports of late-season waterhemp as it grows through the soybeans and becomes evident.  This also makes sense given that statewide we are in the midst of an overall increase in waterhemp, and continue to move up the curve in terms of the number of fields infested and the size of the infestations.  Prevention and management of waterhemp and Palmer amaranth has been one of the primary goals of our state and county educational programs for half a decade or more.  And one of the most important points about waterhemp and Palmer that we try to get across is their capacity for prodigious seed production – 500,000 to upwards of a million seeds per plant – and what this means for their ability to rapidly ramp up populations, infest equipment, etc. Continue reading →

Distribution of Waterhemp and Palmer Amaranth in Ohio

By: Mark Loux and Bruce Ackley, OSU Extension

The maps that accompany this article show our current knowledge of waterhemp and Palmer amaranth distribution in Ohio.  These are based on information from a survey of OSU Extension County Educators, along with information we had from samples submitted, direct contacts, etc. We still consider any new introductions of Palmer amaranth to be from an external source (brought in from outside Ohio) – hay or feed, infested equipment, CRP/cover/wildlife seedings.  Palmer is not really spreading around the state, and as the map shows, we have had a number of introductions that were immediately remediated.  The number of counties where an infestation(s) is being managed is still low, and within those counties, the outbreak occurs in only a few fields still.  Waterhemp is much more widespread in Ohio and is spreading rapidly within the state from existing infestations to new areas via equipment, water, animals, etc.  We do not have Ag Educators in all counties, and even where we do, infestations can occur without us knowing about them.  Feel free to contact us with new information to update the maps. Continue reading →