Posts

https://agcrops.osu.edu/newsletter/corn-newsletter

This weeks topics:

• Battle for the Belt: Episode 20

• Weather Update: Heatwave and Scattered Storms Expected

• Hail Damage to Soybean and Corn

• 2023 Ohio Wheat Performance Test- Results Available Online

• Agriculture Technology Field Day

• Lep Monitoring Network Update #12 – High WBC Numbers – Time to Scout!

While African swine fever is not present in the U.S., the deadly animal disease has impacted the global pork industry for years, causing billions of dollars in losses to the market.

Read more here.

Join us for a free program to learn about honeybees from our speakers Robert and Denise Woodruff. They are honey beekeepers themsleves and will share information about hive equipment and tools, food sources for honeybees, bees themselves, honey, and many other interesting facts. There will also be time to ask lots of questions. Registration is not required but is appreciated at the link below. You will receive a confirmation email after registering. Questions about the program can be directed to OSU Extension Allen County Agriculture and Natural Resources Educator Nic Baumer by emailing him at baumer.15@osu.edu or calling (419) 879-9108.

Register at: go.osu.edu/allenhoneybees

Ohio State Weed Lab , The Ohio State University, Bugwood.org

Farmers should be checking their soybean fields for two troublesome and costly weeds – waterhemp and palmer amaranth. These weeds need to be removed before going to seed. They are difficult to control and have caused major financial losses in other soybean growing regions. Battling them will significantly increase the cost of an herbicide program. If not controlled, soybean yields may be reduced 40%.

Waterhemp and palmer amaranth can take over a field faster than most weeds. They can grow 2 to 3 inches per day under ideal conditions. Both weeds are prolific seed producers. One female plant can produce a million seeds in a growing season. Seeds are exceedingly small and can easily be moved in grain, feed, and machinery.

Fortunately, farmers have been able to keep palmer amaranth out of the county. However, fields with waterhemp have been increasing since 2016. Each fall the Hancock County Extension Office surveys soybean fields for surviving weeds at harvest time. From this survey, only 1% of the fields had waterhemp in 2016, 15% in 2020, and 25% in 2022. This number could quickly jump to 50% if farmers do not take steps to prevent the spread to new fields.

Waterhemp is a summer annual that may be two to eight feet tall. Leaves are lanceolate to oblong with smooth margins. Petal-less flowers develop from narrow panicles of spikes from the upper branches of the plant https://www.illinoiswildflowers.info/weeds/plants/water_hemp.htm.  Plants are dioecious, meaning a plant will only have male or female flowers, but not both. This ensures that pollen will come from another plant, which may have resistance to certain herbicides. Thus, waterhemp is known to quickly develop resistance to many common soybean herbicides.

Waterhemp and palmer amaranth are types of pigweeds, but much more difficult to control than the common redroot pigweed. Identifying the type of pigweed in the field is relatively easy by looking for hairs on the main stem. Redroot pigweed will have fine hairs like peach fuzz. Waterhemp and palmer amaranth have no hairs on the stem. Palmer is generally a larger and more robust plant than waterhemp. Its leaves will be broader than waterhemp and its flower/seed stalk is longer and rougher (like sandpaper).

Now that waterhemp has established populations in some fields, farmers will have to be diligent to limit its spread to new fields. The Ohio State University Extension recommends the following steps to keep waterhemp from establishing populations in fields:

• Inspect fields for waterhemp. These weeds will now be taller than the soybean canopy.

The Hancock County Extension office will assist in identification. Waterhemp is considerably different in appearance than giant ragweed and marestail – other late-season tall weeds.

• Scout field borders, adjacent roadsides, flood areas, manure applied fields, and conservation/wildlife area seedings. The latter may contain waterhemp that grew from seed sources collected from states that do not prohibit this weed from being harvested with conservation species.
• Where waterhemp is confirmed, check to see whether plants have mature seed by shaking/crushing parts of the seedhead into your hand or other surface that will provide contrast. Mature seed will be small and very dark.

Plants with seeds and flower stalks should be cut off and bagged (at least the seedheads) and removed from the field, or removed via any other method that prevents seed dispersal in the field.

• If the waterhemp population is too dense to hand remove from a field, a farmer will have to consider two options:

1) do not harvest, but mow areas infested with waterhemp several times to prevent seed production, or 2) harvest infested field(s) after all other fields have been harvested and clean the combine thoroughly before further use.

Harvesting through patches of infested fields first may further spread weed seed throughout the field and contaminate the combine, which can then disperse weed seeds to other fields.

Unfortunately, Hancock County has a few fields that are battling waterhemp. Farmers need to take zero tolerance to waterhemp, which means individual plants need to be removed by hand before they go to seed if found in soybean fields. Once infested a farmer will have serious weed issues in future years.

Farmers will have to change their weed control program for waterhemp since it is likely resistant to glyphosate and other commonly used soybean herbicides. Even if a farmer does not have waterhemp now, they should adjust their herbicide program in the future as if they did. This would include using a burndown program with a mix of herbicides with different modes of action, a pre-emergent with soil residual activity, and removing any waterhemp plants that is not killed by the herbicide program.

So far, farmers have been successful in keeping Palmer amaranth out of Hancock County. Unfortunately, waterhemp has established populations in a few fields across the county. Farmers have the next few weeks to remove individual plants in new fields before they produce mature seed.

Additional information may be found on waterhemp at the following Ohio State University website:   https://iwilltakeaction.com/wp-content/legacy/uploads/files/20200921-factsheet-waterhemp-ada-usdadraft.pdf

Written by Ed Lentz

Professor

Extension Educator, Agriculture and Natural Resources

College of Food, Agriculture, & Environmental Sciences

OSU Extension – Hancock County