volume 19 number 19 - - - university of wisconsin crop manager - - - july 26, 2012 ·...
TRANSCRIPT
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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!