Month: July 2018

No Pigweed Left Behind – Late-Season Scouting for Palmer Amaranth and Waterhemp

by: Mark Loux

If you don’t already have to deal with waterhemp or Palmer amaranth, you don’t want it.  Ask anyone who does.  Neither one of these weeds is easy to manage, and both can cause substantial increases in the cost of herbicide programs, which have to be constantly changed to account for the multiple resistance that will develop over time (not “can”, “will”).  The trend across the country is for them to develop resistance to any new herbicide sites of action that are used in POST treatments.  Preventing new infestations of these weeds should be of high priority for Ohio growers.  When not adequately controlled, Palmer amaranth can take over a field faster than any other annual weed we deal with, and waterhemp is a close second.  Taking the time to remove any Palmer and waterhemp plants from fields in late-season before they produce seed will go a long way toward maintaining the profitability of Ohio farm operations.  There is information on Palmer amaranth and waterhemp identification on most university websites, including ours –  u.osu.edu/osuweeds/ (go to “weeds” and then “Palmer amaranth”).  An excellent brief video on identification can be found there, along with a fact sheet.  The dead giveaway for Palmer amaranth as we move into late summer is the long seedhead, and those on female seed-bearing plants are extremely rough to the touch.

If you need help with identification, call John at 740-397-0401.

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Overall Drier Pattern into Early August

by: Jim Noel

The pattern change from wet to dry has arrived. For the remainder of July expect temperatures not too far from normal, some days above some days slightly below. Nothing real extreme to note in the temperatures. Humidity will also fluctuate from higher to lower to higher. Overall, moisture in the air will be typical for July. The one thing that will be different is the rainfall pattern. July has been a drier month for many areas. After a few showers or storms early this week, the next rain chance will be late this Friday into the weekend. It appears most should be 0.50-1.0 inches with the range being 0.25 to 3.00 inches. However, after this rain event it looks like rainfall will go back to being limited for the rest of July and possibly into early August.

August is shaping up to be warmer than normal with a drier start and wetter finish.

For the next two weeks the attached rainfall map from NOAA/NWS/Ohio River Forecast Center shows rainfall will average 0.75 to 2.75 inches across Ohio with isolated totals higher and lower than that. The heaviest rains will be to the south and east of Ohio.

Agricultural nutrients targeted in Clean Lake 2020 bill and Kasich Executive Order

by: Peggy Kirk Hall, Associate Professor, Agricultural & Resource Law

Recent actions by the Ohio legislature and Governor Kasich will affect the management of agricultural nutrients in Ohio.   The Ohio General Assembly has passed “Clean Lake 2020” legislation that will provide funding for reducing phosphorous in Lake Erie.  Governor Kasich signed the Clean Lake 2020 bill on July 10, in tandem with issuing Executive Order 2018—09K, “Taking Steps to Protect Lake Erie.”  The two actions aim to address the impact of agricultural nutrients on water quality in Lake Erie.

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Ohio Noxious Weed Identification – Week 21 Palmer Amaranth

Palmer Amaranth

Family: Pigweed, Amaranthaceae.

Habitat: Crop fields, pastures, and roadsides.

Life cycle: Summer annual.

Growth habit: Erect up to 6 ft. high.

Leaves: Prominent white veins on the undersurface unlike redroot pigweed, not pubescent, alternate, without hairs (glabrous), and lance or egg-shaped.  Leaves are 2 to 8 inches long and 1/2 to 2 1/2 inches wide with prominent white veins on the undersurface.  Leaves occur on relatively long petioles.

Flower: Small, green, inconspicuous flowers are produced in dense, compact, terminal panicles that are from 1/2 to 1 1/2 feet long. Smaller lateral flowers also occur between the stem and the leaf petioles (leaf axils).  Male and female flowers occur on separate plants. Each terminal panicle contains many densely packed branched spikes that have bracts that are 3 to 6 mm long; can produce 500 thousand to 1 million seeds per plant.

Roots: Taproot that is often, but not always, reddish in color

Stem: One central stem occurs from which several lateral branches arise.

Similar Plants: Loosely resembles many other pigweed species. Palmer’s petioles are as long or longer than the actual leaf. This plant is hairless and has elongated seed heads. Leaves are typically more diamond shaped than other pigweed species, and occasionally has one hair at the tip of the leaf.

The Problem is……..Palmer amaranth is one of the most difficult weeds to control in agricultural crops.  It developed a major glyphosate resistance problem in the southern US from 2006-2010, and has been spreading in the midwestern US since, causing crop loss and increases in weed management costs. Characteristics that make it a successful annual weed include: rapid growth rate; wide window of emergence (early May through late summer); prolific seed production (upwards of 500,000 seeds/plant); tendency to develop herbicide resistance; and tolerance to many post-emergence herbicides when more than 3 inches tall.

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Frogeye Leaf Spot

by: Anne Dorrence, OSU Extension

Only Susceptible Varieties are Prone to Diseases and May Require a Fungicide Application.

From the scouting reports from the county educators and crop consultants – most of the soybeans in the state are very healthy with no disease symptoms.  However, as the news reports have indicated, there are a few varieties in a few locations that have higher incidence of frogeye leaf spot than we are accustomed to seeing at this growth stage – mid R2 – flowering in Ohio.  Most of the reports to date are along and south of route 70, which based on the past 12 years is where frogeye is the most common.  When this disease occurs this early in the season, where it can be readily observed, this is a big problem and should be addressed right away with a fungicide soon and a second application at 14-21 days later depending on if disease continues to develop and if environmental conditions (cool nights, fogs, heavy dews, rains) continue.  Table 1. Lists the fungicides that have very good activity towards frogeye leaf spot based on University trials around the country (thank you land grant university soybean pathologists in NCERA-137). Note that on this list there are no solo strobilurin fungicides, as we have detected strains of the fungus, Cercospora sojina, that are resistant to this class of fungicides in the state.

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Knox County Crop Conditions

Perfect time to grow corn

by: Chuck Martin, Mount Vernon News

 

The right weather at the right time, along with the right management by farmers, and the crops will respond.

That, essentially, is what has happened with the corn crop so far this year, said Knox County Ohio State University Extension Educator John Barker.

“There was a time, early, when there was a little concern about planting because it was so wet,” he said, “but most of the fields got planted and with the combination of heat and moisture, the corn just took off.”

Some fields were even tasseling out by July 4.

“That’s what we want to see,” said Barker. “The old adage of corn needing to be “knee high by the Fourth of July” is from a time when corn was often not planted as early.

“At one time many farmers didn’t think about planting until May 1, now they expect to be done by May 1.”

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Ohio Noxious Weed Identification – Week 20 Marestail

Marestail

Family: Composite, Asteraceae.

Habitat: Thin turf, agronomic crops, pastures, orchards, fallow fields, waste areas, and roadsides.

Life cycle: Summer or winter annual.

Growth habit: Seedlings develop a basal rosette and mature plants erect are reaching 6 1/2 ft in height.

Leaves: The mature plant has leaves that are entirely without petioles (sessile). Leaves are 4 inches long, 10 mm wide, alternate, linear, entire or more often toothed, crowded along the stem, and hairy. Leaves become progressively smaller up the stem.

Stem: Erect, solid, hairy, reaching 6 1/2 ft in height.

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Foliar Fungicide Use in Corn

by: Pierce Paul, OSU Extension

Foliar diseases, especially Gray Leaf Spot (GLS), are beginning to show up in some corn fields. This is not at all surprising, given that the crop was planted relatively late and it has been wet and humid in some areas. GLS is favored by humid conditions, particularly if temperatures are between 70 and 90 F. Foliar diseases of corn are generally a concern when they develop early and progress up the plant before grain fill is complete. This is especially true when the hybrid is susceptible. In most years, GLS and NCLB usually develop late or remain restricted to the lower leaves. However, if it continues to rain and stays humid, this will likely not be the case this year.

Due to wide variations in planting dates, weather conditions, and hybrid maturities, the corn crop is at growth stages ranging from emergence to tassel across the state. Now is the time to start scouting those early-planted fields for foliar diseases, especially those planted with susceptible hybrids in an area with a history of foliar diseases or in a continuous-corn, no-till fields. Those are the fields most likely to benefit from a fungicide application. Use hybrid susceptibility, weather conditions, field history, and current disease level as guides when making a decision to apply a fungicide.

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