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What’s New

Reminder: Wisconsin hosts the 2012 North American

Manure Expo on August 22, 2012 .................................68

Crops

Forage harvests and re-crop considerations following these

drought conditions ........................................................68

Vegetable Crop Update.................................................69

Weeds

Watch out for Poisonous Plants this Summer ................69

Big Weeds found at the Weed Doctor’s Booth at Farm

Technology Days .........................................................69

Insects and Mites

Japanese Beetle Scouting and Thresholds for Corn and

Soybean .......................................................................70

Wisconsin Pest Bulletin ................................................71

Plant Disease

Plant Disease Diagnostic Clinic (PDDC) .......................71

Reminder: Wisconsin hosts the 2012 North American Manure Expo on August 22, 2012

If you are interested in the latest equipment and technology

for professional manure management, plan to attend the 2012

North American Manure Expo on August 22, 2012. Wisconsin

hosts the Expo this year and it will be held at the USDA-Dairy

Forage Research Center farm located just north of Prairie du Sac on State Highway 78.

The 2012 North American Manure Expo will feature field

demonstrations, hands-on product and safety education,

educational sessions, exhibitor booths, and commercial vendor

displays. There is no cost to attend the Expo.

Visit the website http://www.manureexpo.com/ for

directions and up-to-date information on all the activities

associated with this year’s Expo.

The North American Manure Expo is presented by the

Professional Nutrient Applicators Association of Wisconsin,

University of Wisconsin Extension Nutrient Management

Team, USDA-Dairy Forage Research Center and is supported in part by a consortium of land grant universities and

conservation agencies from across the United States.

Scroll down to the end of this newsletter to view the flyer for

this event.

Forage harvests and re-crop considerations following these drought conditions

Vince M. Davis, Extension Weed Scientist

Due to the drought conditions, some growers are considering

harvesting their corn and/or soybean crops earlier than normal

as a forage this year, and furthermore some are considering

planting a second crop to produce more biomass for a fall

forage harvest. There are three important herbicide related considerations for these situations:

1. Has enough time elapsed between previous herbicide

applications and the harvest of the corn or soybean

crop as a forage?

2. Are there any herbicide rotational crop restrictions for

another crop you are considering to plant next?

3. Even if the time between herbicide application and

fall planting is ‘okay’ regarding re-crop restrictions,

are there still concerns of herbicide carryover from

residual herbicides because of little rainfall received

throughout the season?

The first and best recommendation is to make certain you

review the annual herbicide application records, and pay

attention to the dates of these applications. Moreover, check

those herbicide labels for the intervals needed following

application before crop foliage to be feed as a forage. These

restrictions are often different than the pre-harvest intervals for

grain. There are also tables in the 2012 “Pest Management in

Wisconsin Field Crops” manual A3646 to help you out with

finding this information. Table 2-4. “Forage, grazing, and

grain harvest intervals for corn herbicides, page 54” lists these

intervals for many popular corn herbicides, and Table 3-3. “Forage and grain harvest intervals for soybean herbicides.”

lists these intervals for many popular soybean herbicides.

Additionally, Appendix Table 2 lists the planting intervals

required for many rotational crops. Please review this table (as

well as herbicide labels) for restrictions against any plans to re-

crop this fall. For instance, I have heard that fall seeded oats

and peas are among some of the popular choices discussed to

plant for a fall forage crop. Several popular corn herbicides,

like atrazine, would prevent this option for two years.

Moreover, due to lack of rainfall, the potential for herbicides to

‘break down’ or degrade in their biological activity in the soil

also decreased. If their breakdown decreased, then their

Volume 19 Number 19 - - - University of Wisconsin Crop Manager - - - July 26, 2012

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chance to be biologically active and injure sensitive

vegetation(crops) planted following the application increases.

In short, before making any re-crop decisions, please review

your application records and review these tables and your

herbicide labels to insure you won’t have a failure in a

succeeding crop establishment.

Scroll down to the end of this newsletter to view Tables 2-4.

Vegetable Crop Update 7/25/12

The 18th issue of the Vegetable Crop Update is now

available. Click here to view this update.

Watch out for Poisonous Plants this Summer

Mark Renz Extension Weed Scientist, University of

Wisconsin-Madison

As pastures are not productive in much of Wisconsin due to

the drought and the supply of hay remains low throughout the

US, the potential for animal’s to eat and be poisoned by toxic

plants will likely increase over the next several months. To

address this issue we will be posting a poisonous plant

factsheet for livestock in Wisconsin. In this factsheet we

overview what poisonous plants are and under what conditions

they can be toxic to livestock. In addition, we have provided a

list of common poisonous plants found in Wisconsin along

with a description of the level of toxicity and resulting

symptoms from ingestion. Below I will briefly address with

how to manage poisonous plants in fields animals graze as well as purchased hay.

Grazed fields

Poisonous plants: When animals are hungry, their selectivity

decreases and they may eat plants typically avoided. This is

common especially under drought conditions. The only options

to prevent animals grazing poisonous plants in these conditions

are to 1) provide ample forage so animals avoid them, 2)

remove the animals from the infested pasture until ample

forage regrows, or 3) control the poisonous plants in the

pasture prior to grazing (recommended option). If controlling

these plants with an herbicide don’t forget to follow any grazing restrictions present on the label. If no grazing

restrictions are present for the herbicide we still recommend

not grazing for at least a 14-day period as often treatment can

temporarily increase palatability of these plants.

Nitrate Accumulating Plants: Fields with an abundance

pigweeds, common lamb’s quarters, and common ragweed are

common in drought stricken pastures and other fields that

could be grazed. These weeds can result in animal toxicity as

these species take up excessive nitrogen and convert it to

nitrate which can be toxic. This situation is common under

drought conditions we are experiencing, especially if areas

were previously fertilized. If enough of these weeds are eaten animals can be poisoned from excess nitrate. Thus we

recommend controlling these weeds prior to grazing when at

least 20% of the feed is composed of these species. An

herbicide application is the most economical control method

and several options exist that are registered for use in pastures

(consult A3646: Pest Management in Wisconsin Field Crops

for detailed information).

Poisonous plants in harvested forage

As demand for hay continues to be high we expect fields that

typically are not harvested to be baled and sold (e.g. CRP

fields). While much of this hay will not have poisonous plants,

I expect some will and will lead to livestock poisoning. While

animals often avoid poisonous plants in a pasture they lose

much of their ability to not select these plants when they are

hayed and mixed with desirable forage. While some plants lose their toxic properties as they dry, many remain toxic.

Before buying hay I suggest inspecting several bales

thoroughly to make sure that the majority of the material is

palatable forage and not poisonous plants. While all bales

can’t be inspected, spot checks on select bales will avoid the

potential for poisoning from species that require large amounts

ingested (e.g. nightshade species). Unfortunately several

species are toxic at much smaller doses (<5% of feed ingested),

and these are essentially impossible to find in hay when

purchased. These include milkweed species, jimson-weed,

poison hemlock, black locust and white snakeroot. In these

cases the best scenario is to know the field where your feed is coming from and check to see that these weeds are absent

before harvesting and or purchasing. Otherwise the only other

option is to closely monitor the ingestion of the feed and

removal of forage that appears to be weedy and/or avoided by

animals. While this option is far from ideal, it is the best

solution we can offer in these difficult times. If animals start to

show any symptoms of poisoning, contact a veterinarian as

soon as possible.

Big Weeds found at the Weed Doctor’s Booth at Farm Technology Days

Mark Renz, Extension Weed Scientist

This year we had 26 entries into the biggest weed contest.

Past winners such as plumeless thistle and common mullein

were entered as well as a new species, catnip. While the catnip

didn’t win, we estimated that the value of the leaves of this one

plant alone was more than $100. As usual the tall species were very impressive, as we received cattail, giant ragweed, and

common mullein specimens all over 9 feet tall. The FTD

winner was a massive giant ragweed plant, submitted by Steve

Daniels from Shiocton Wisconsin. This ragweed was 113

inches tall and 52 inches wide. Since we calculate the winner

based on the volume of the weed (height x width), the winner

beat other entries of common mullein (108” x 48”) Angelica

(108” x 48”) and horseweed (75” x 29”) that won for

Tuesday’s (tie between mullein and knotweed) and Thursday’s

daily contest. Although we collected several impressive

specimens, none of these plants came close to last year’s

winner, a burdock plant that was 30% bigger this year’s winner (95” x 95”). Perhaps the drought also took its toll on the

biggest weed contest this year in addition to many of our fields.

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We will again be holding this contest next year at FTD in Barron County, so start scouting fields this fall. Weed doctors

are considering entering the competition in 2013 so start

fertilizing your weeds now!

Japanese Beetle Scouting and Thresholds for Corn and Soybean

Eileen Cullen, Extension Entomologist

Japanese beetles have been reported this week feeding on

corn silks (and in one report, kernels) in southeastern

Wisconsin. Japanese beetle scouting and thresholds for corn

and soybean are covered in this article.

Japanese beetles overwinter as late stage grubs within 5

inches of the soil surface in areas surrounding soybean or

cornfields, typically in grassy and turf areas. However, some

grubs can overwinter in soybean fields.

In early summer as temperatures increase, larvae move

closer to the soil surface, where pupation occurs, followed by

adult emergence in June. There is one generation of Japanese beetle per year with adults active in July and August through to

early September.

Photo: Roger Schmidt, University of Wisconsin Madison

Soybean

Adults feed on soybean leaf tissue between leaf veins

leaving a lace-like, skeletonized appearance.

The treatment threshold for Japanese beetle in

soybean is based on percent leaf defoliation and not number of beetles per plant. Treatment should be

considered at 20% leaf defoliation for reproductive

growth stage soybean. (30% for pre-bloom soybean).

Scout for soybean leaf defoliation throughout the field rather

than just along field edges where clusters of Japanese beetles

aggregate and feeding can sometimes be more concentrated.

Field edge/border treatments may be sufficient if damage is

confined to this area, but interior field scouting is

recommended.

In addition to percent defoliation estimates based on

observation of field areas with beetles and obvious defoliation

damage, a systematic field sampling method is to select 10

plants throughout the field choosing a trifoliate from the upper,

middle and lower canopy on each plant. This will give you a

30-leaf sample to assess whether feeding is progressing

through the canopy or only at the upper canopy.

It can be easy to overestimate defoliation percentage. The

following images provide a guide to determining the

percentage insect defoliation on soybean leaves from Japanese

beetle and other leaf defoliating insects such as grasshopper,

green cloverworm, second generation bean leaf beetle. (Images

courtesy of University of Wisconsin-Madison Integrated Pest

and Crop Management IPM Toolkit App for iPad and iPhone).

Do not treat too early for Japanese beetle below the

defoliation threshold of 20%. This is particularly important if

you have twospotted spider mite populations in the field.

Pyrethroid insecticides are labeled for Japanese beetle control

in soybean, but some pyrethroids provide mite suppression

only and may flare, or increase, mite densities. For information

on twospotted spider mites in soybean, please see the WCM

article Dry Weather Increases Risk of Twospotted Spider Mite.

Corn

Consider a foliar insecticide treatment during tasseling and

silking if there are

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3 or more beetles per ear

Silks have been clipped to ½-inch

AND

Pollination is less than 50 percent complete

As field corn pollination period draws to a close, this

threshold can still be applied to later planting dates and

sweet corn at sensitive tasseling and silking stages.

I have heard of at least one report this week from the

Janesville, WI area in southeastern Wisconsin of Japanese

Beetle feeding on kernels within the ear. If this is the case, it’s

likely that beetles are very heavy in the field. The main concern with Japanese beetle feeding is to protect silks for

pollination, and the economic threshold above is based on this

goal. Beetles must be on the outside of the ear, which is

normally the case, to be contacted by insecticide treatment.

As with soybean, obtain a representative field sample in corn

because Japanese beetle may aggregate or clump near cornfield

edges. Edge/border treatments may be sufficient if damage is

confined to this area, but scout inner field locations to confirm.

Additional Resources:

Field Scouting Video: Japanese beetle in soybean and corn,

Integrated Pest Management. University of Wisconsin-

Madison Integrated Pest and Crop Management Program. Full selection of IPM videos available here.

Cullen, E., V. Davis, P. Esker, B. Jensen and M. Renz. 2012.

Pest Management in Wisconsin Field Crops. Publication

A3646. University of Wisconsin-Extension Cooperative

Extension Publishing, Madison, WI. 258 pp.

Wisconsin Pest Bulletin 7/26/12

A new issue of the Wisconsin Pest Bulletin from the

Wisconsin Department of Agriculture, Trade and Consumer

Protection is now available. The Wisconsin Pest Bulletin provides up-to-date pest population estimates, pest distribution

and development data, pest survey and inspection results, alerts

to new pest finds in the state, and forecasts for Wisconsin’s

most damaging plant pests.

Issue No.15 of the Wisconsin Pest Bulletin is now available

at:

http://datcpservices.wisconsin.gov/pb/index.jsp

http://datcpservices.wisconsin.gov/pb/pdf/07-26-12.pdf

UW Extension/Madison Plant Disease Diagnostic Clinic (PDDC)

Brian Hudelson, Ann Joy, Amanda Zimmerman, Adam

Greene, Andrew Pape, Plant Disease Diagnostics Clinic

The PDDC receives samples of many plant samples from

around the state. The following diseases/disorders have been

identified at the PDDC from July 13 through July 20, 2012:

For additional information on plant diseases and their control,

visit the PDDC website at pddc.wisc.edu.

August 22, 2012

USDA Dairy Forage Research Center, Prairie du Sac, WI

Presented by: Professional Nutrient Applicators Association of Wisconsin,

UW-Extension Nutrient Management Team, USDA Dairy Forage Research Center

• Field Demonstrations• Indoor & Outdoor Vendor Displays• Educational Seminars

Professional Application: Innovation & Technology

For more information visit www.manureexpo.com

See you

at the E

xpo!