93

What’s New?

Agronomy Field Day at Marshfield Research Station .... 93

Crops

Vegetable Crop Update 8/7/13 ...................................... 93

Have these Recent Cool Temperatures Impacted my 2013

Soybean Crop…In Short Not Yet ................................. 93

Corn Production in the Northern Corn Belt: The Tillage X

Rotation Interaction ...................................................... 94

Will Corn Mature Before Frost? ................................... 94

Predicting Maturity Date of Late-Planted and Uneven Corn

.................................................................................... 94

Plant Disease

Plant Disease Diagnostic Clinic (PDDC) Summary ....... 94

Insects and Mites

Wisconsin Pest Bulletin 8/8/13 ..................................... 95

Agronomy Field Day at Marshfield Research Station

There is going to be an Agronomy Field Day at the

Marshfield Agricultural Research Station on Wednesday, August 14th. It will be held at the north location at M605 Drake

Avenue, Stratford. It will go from 10:00 to 3:00 with a lunch at

12:00 for a small price. Attendees can earn CEUs. If you have

any questions about the event please contact Jason S. Cavadini

by phone at 715-687-4624 Ext. 17 or by e-mail at

jcavadini@wisc.edu.

Scroll down to the bottom of this newsletter to view the flyer

for this event.

Vegetable Crop Update 8/7/13

The 15th issue of the Vegetable Crop Update is now

available. This issue contains late blight updates and

information on late blight control. To view this update click

here.

Have these Recent Cool Temperatures Impacted my 2013 Soybean Crop…In Short Not Yet

Shawn Conley, Soybean and Wheat Extension Specialist

Delayed soybean plantings coupled with unseasonably cool

temperatures in late July and early August have many growers

and crop consultants concerned over the stage and state of the WI soybean crop. Though NASS reports March 1 to August 3

GDU accumulation (base 50 F) to be normal, developmentally

the early planted WI soybean crop is tracking ~7 days behind

normal. At Arlington WI our early planted High Yield Study is

just entering the R5 crop growth stage (seed is 1/8 inch long in

the pod at one of the four uppermost nodes on the main stem

with a fully developed trifoliolate leaf node).

Image 1. Fourth node pod and bean of R5 plant. Image

courtesy of D. Marburger.

Though cool temperatures can reduce photosynthesis and

crop growth rate (Table 1), they also extend the number of

days in a specific growth stage which allows total dry matter

(TDM) to equilibrate thus limiting potential yield loss in early reproductive stages (Board and Kahlon; Seddigh and Jolliff,

1984 a,b). However if cool conditions (< 50 F) due continue

through seedfill or an early frost appears then significant yield

loss can occur due to reduced seed size and/or number (Board

and Kahlon) (Table 1). In short we are ok to date we just need

average temps moving forward and no early frost to finish this

crop off.

Volume 20 Number 22 - - - University of Wisconsin Crop Manager - - - August 8, 2013

94

Table 1. Summary of cold stress effects on soybean

physiology, growth, and yield componets. Taken from: Board

and Kahlon.

Literature cited: J.E. Board and C.S. Kahlon. Soybean Yield Formation. What Control it and How it Can be Improved. In Soybean

Physiology and Biochemistry.

http://www.lsuagcenter.com/NR/rdonlyres/84746337-8BFE-

4903-BEB8-

420D0D2B7271/82639/InTechSoybean_yield_formation_what

_controls_it_and.pdf

Seddigh, M. and Jolliff, G.D. (1984a). Night temperature

effects on morphology, phenology, yield and yield components

of indeterminate field-grown soybean. Agron J. 76: 824-828.

Seddigh, M. and Jolliff, G.D. (1984b). Effects of night

temperature on dry matter partitioning and seed growth of

indeterminate field-grown soybean. Crop Sci. 24: 704-710.

USDA NASS. Wisconsin Crop Progress. Vol 13. Number 18.

Corn Production in the Northern Corn Belt: The Tillage X Rotation Interaction

Joe Lauer, Corn Agronomist

The corn-soybean rotation has become dominant in the Corn

Belt of the U.S in the last 30-40 years. When compared to

other systems like the wheat system of the Middle East and the

rice systems of the Far East that have been in place for

centuries, it is a relatively new cropping system. Many

agronomists are concerned about the sustainability of this

system and there is some evidence that with the development

of resistant weeds and insects that it might be challenged significantly in the near future.

To read the full article, scroll down to the end of this

newsletter.

Will Corn Mature Before Frost?

Joe Lauer, Corn Agronomist

During cool growing seasons, especially when planting

is delayed due to wet spring conditions, growers are

concerned about whether their corn is vulnerable and will

reach maturity before normal frost dates. Often the range

in planting dates have implications at harvest time,

especially for silage because grain and dairy producers

often negotiate the sale of corn in fields that are borderline

for development.

To read the full article, scroll down to the end of this

newsletter.

Predicting Maturity Date of Late Planted and Uneven Corn

Joe Lauer, Corn Agronomist

During cool growing seasons, especially when planting is

delayed due to wet spring conditions, growers are concerned

about whether their corn is vulnerable and will reach maturity

before normal frost dates. Often the range in planting dates

have implications at harvest time, especially for silage because

grain and dairy producers often negotiate the sale of corn in

fields that are borderline for development (Figure 1).

To read the full article, scroll down to the end of this

newsletter.

Plant Disease Diagnostic Clinic (PDDC) Summary

Brian Hudelson, Ann Joy, Erin DeWinter and Joyce Wu, Plant Disease Diagnostics Clinic

The PDDC receives samples of many plant and soil samples

from around the state. The following diseases/disorders have

been identified at the PDDC from July 27, 2013 through

August 2, 2013.

Plant/Sample Type, Disease/Disorder, Pathogen, County

FORAGE CROPS,

Alfalfa, Aphanomyces Root Rot, Aphanomyces euteiches,

Dane

Alfalfa, Crown Rot, Fusarium spp., Dane, Grant

Alfalfa, Pythium Root Rot, Pythium sp., Dane, Grant

Alfalfa, Rhizoctonia Root Rot, Rhizoctonia solani, Dane

FRUIT CROPS,

Apple, Root/Crown Rot, Pythium sp., Fusarium sp., Clark

Blueberry, Chlorosis, None, Langlade

Blueberry, Fruit Rot, Colletotrichum gloeosporioides,

Langlade

95

Follow us on

Blueberry, Gray Mold/Botrytis Blight, Botrytis cinerea,

Langlade

Blueberry, Phomopsis Canker, Phomopsis sp., Langlade

Blueberry, Sphaeropsis Canker, Sphaeropsis sp., Langlade

Blueberry, Water Stress, None, Langlade

Pear, Anthracnose, Gloeosporium sp., Racine

Pear, Chemical Toxicity, None, Racine

Raspberry, Root/Crown Rot, Phytophthora sp., Pythium sp.,

Rhizoctonia sp., Fusarium sp., Jefferson, La Crosse, McHenry

(IL)

VEGETABLES,

Potato , Late Blight, Phytophthora infestans, Dunn

Pumpkin, Bacterial Leaf Spot, Xanthomonas campestris pv.

cucurbitae, Grant

Tomato, Bacterial Speck, Pseudomonas syringae pv. Tomato,

Grant

Tomato, Herbicide Damage, None, Brown

Tomato, Septoria Leaf Spot, Septoria lycopersici, Grant, Sauk

SOIL,

Soybean Soil, Soybean Cyst Nematode, Heterodera glycines,

Oconto

For additional information on plant diseases and their control,

visit the PDDC website at pddc.wisc.edu.

Wisconsin Pest Bulletin 8/8/13

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. 13 of the Wisconsin Pest Bulletin is now available at:

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

http://datcpservices.wisconsin.gov/pb/pdf/08-08-13.pdf

10:00 a.m. – Meet and greet

10:20 a.m. – Introduction and Station Update Jason Cavadini, Assistant Superintendent/Agronomist, Marshfield ARS

10:30 a.m. – 2013 Forage Production and Supply, Alfalfa/Grass Mixtures Dan Undersander, UW Forage Agronomist

11:00 a.m. – Nutrient Movement in Wet and Dry Soil Conditions John Peters, UW Soil Scientist

11:30 a.m. – Effects of Nutrient & Cropping Systems on Surface Runoff Bill Jokela, USDA Soil Scientist

12:00 p.m. – Lunch Brats, chips, and beverages will be available for $5

1:00 p.m. – Fall Grown Oats in Forage Production

Wayne Coblentz, USDA Dairy/Forage Scientist

1:30 p.m. – Making Decisions With Late Planted Soybeans Shawn Conley, UW Soybean/Small Grain Specialist

2:00 p.m. – Addressing Forage Needs and Soil Issues Dave Robison, Forage/Cover Crop Agronomist

Location: Marshfield Agricultural Research Station (North Farm)

M605 Drake Avenue Stratford, WI

Take County Road C 1 mile West of Highway 97

For more information contact Jason Cavadini Email: jcavadini@wisc.edu Phone: 715-305-5347

Agronomy Field Day

Marshfield Agricultural Research Station

August 14, 2013

This event is

free and open

to the public

Bring water

samples for free

nitrate testing

by USDA

microbiologist,

Mark Borchardt

CEU credits are

available for

Certified Crop

Advisers

University of Wisconsin – Extension United States Department of Agriculture Wisconsin Counties Cooperating Providing Equal Opportunities in Employment and Programming

July 2013 Field Crops 28.426 - 100

Corn Production in the Northern Corn Belt: The Tillage X Rotation Interaction Joe Lauer, Corn Agronomist

The corn-soybean rotation has become dominant in

the Corn Belt of the U.S in the last 30-40 years. When compared to other systems like the wheat system of the Middle East and the rice systems of the Far East that have been in place for centuries, it is a relatively new cropping system. Many agronomists are concerned about the sustainability of this system and there is some evidence that with the development of resistant weeds and insects that it might be challenged significantly in the near future.

Figure 1. How can you tell if a cropping system is changing?

The objective of this study was to measure the response of tillage in a rotation trial that has increasing amounts of continuous corn. The experimental unit is the plot of ground, so the analysis uses rotation cycles to measure the effect of rotation and tillage on the soil.

The conventional tillage (CT) treatment in this study used a fall chisel plow followed by 2x spring field cultivator tillage treatments. Both CT and no-tillage (NT) treatments were then planted with a no-till planter that used a 13-wave coulter, followed by trash whippers, and double disk openers. For a description of the rotation sequences, see Table 1.

Table 1. Crop Sequence for 2-Crop Rotation Experiment at Arlington, WI (C= Corn, S= Soybean)

Rotation Sequence

Year

1 2 3 4 5 6 7 8 9 10

1 C C C C C C C C C C 2 S S S S S S S S S S 3 C S C S C S C S C S 4 S C S C S C S C S C 5 C C C C C S S S S S 6 C C C C S S S S S C 7 C C C S S S S S C C 8 C C S S S S S C C C 9 C S S S S S C C C C 10 S S S S S C C C C C 11 S S S S C C C C C S 12 S S S C C C C C S S 13 S S C C C C C S S S 14 S C C C C C S S S S

Rotated corn has a 13-17% yield advantage over continuous corn (Figure 2). Second-year corn yields 5-7% greater than continuous corn. Third- fourth- and fifth-year corn yields the same yield as continuous corn. Modern corn hybrids and management practices have the same rotation response as older hybrids and practices.

Conventional tillage increases corn grain yield 3-6% compared to no tillage (Figure 3). However, there is an interaction.

Tillage does not affect corn yield the first year following soybean (CS or 1C in Figure 4). In the second and third consecutive year of corn, tillage interacted with rotation less consistently improving yield 3-6% in the second year, and 8-10% in the third year.

In conclusion, if rotation is used, then there is no need to do tillage in the first year of the rotation. As the number of consecutive years of corn increase, tillage may be necessary to maintain corn yield.

page 2

Figure 2. Corn yield response to rotation at Arlington, WI. CC= continuous corn, CS= corn-soybean rotation, xC= number of consecutive years of corn following five years of soybean.

Figure 3. Corn yield response to tillage in a corn-soybean rotation at Arlington, WI.

Figure 4. The interaction between rotation and tillage in a corn-soybean rotation at Arlington, WI. CC= continuous corn, CS= corn-soybean rotation, xC= number of consecutive years of corn following five years of soybean.

Figure 5. Extending crop rotation improves grain yield of all crops. Data derived from Lauer, 2004-2012 (Arlington, Control treatments).

University of Wisconsin – Extension United States Department of Agriculture Wisconsin Counties Cooperating Providing Equal Opportunities in Employment and Programming

Figure 2. Typical corn kernel development in Wisconsin.

Figure 1. Corn silage yield and quality changes during development.

July 2013 Field Crops 28.47 - 101

Will Corn Mature Before Frost? Joe Lauer, Corn Agronomist

During cool growing seasons, especially when planting

is delayed due to wet spring conditions, growers are concerned about whether their corn is vulnerable and will reach maturity before normal frost dates. Often the range in planting dates have implications at harvest time, especially for silage because grain and dairy producers often negotiate the sale of corn in fields that are borderline for development.

Most hybrids require about 55 to 60 days to develop from the silk stage to physiological maturity. Hybrid maturity differences in development time occur primarily from emergence to silking, not from silking to maturity.

Most concern exists when corn does not reach the silk stage (R1) until early August or later. Killing frosts can easily occur by late September, so corn silking in early August would not be safe from major yield reductions due to frost until early October.

Figures 1 and 2 describe typical development of corn silage yield and quality and of a corn kernel. At the dent stage (R5), corn has accumulated 75-85% of silage yield and 60-75% of grain yield and needs about 27-32 days to avoid significant yield reductions due to frost (Table 1). In order to avoid yield reductions caused by frost, corn intended for silage should be silking by late August, while corn intended for dry grain should reach the dent stage by September 1.

To predict whether corn will mature before frost note the hybrid maturity, planting date and tasseling (silking) date of the field. For silage, add 42-47 days on to this date to predict 50% kernel milk, while for grain, add 55-60 days to predict maturity. These dates are guidelines which will require further in-season decisions as the season unfolds.

Table 1. The relationship between kernel growth stage and development.

Stage Calendar days

to maturity GDUs to maturity

Percent of maximum yield Grain Silage

Moisture content (%) Grain Silage

R1: Silking 55-60 1100-1200 0 45-50 --- 80-85 R2: Blister 45-50 875-975 0-10 55-60 85-95 80-85 R3: Milk 35-40 750-850 10-30 60-65 70-85 80-85 R4: Dough 30-35 650-750 30-60 65-75 60-70 75-80 R5: Dent 27-32 425-525 60-75 75-85 50-55 70-75 R5.5: 50% Kernel milk 13-18 200-300 90-95 100 35-40 65-70 R6: Black layer 0 0 100 95-100 30-35 55-65

page 2

University of Wisconsin – Extension United States Department of Agriculture Wisconsin Counties Cooperating Providing Equal Opportunities in Employment and Programming

August 2013 Field Crops 28.47-102

Predicting Maturity Date of Late-Planted and Uneven Corn Joe Lauer, Corn Agronomist

During cool growing seasons, especially when planting

is delayed due to wet spring conditions, growers are concerned about whether their corn is vulnerable and will reach maturity before normal frost dates. Often the range in planting dates have implications at harvest time, especially for silage because grain and dairy producers often negotiate the sale of corn in fields that are borderline for development (Figure 1).

Most hybrids require about 55 to 60 days to develop from the silk stage to physiological maturity. Hybrid maturity differences in development time occur primarily

from emergence to silking, not from silking to maturity (Figure 3). Growers are concerned when corn does not reach the silk stage (R1-Figure 2) until early August or later. Killing frosts can easily occur by late September, so corn silking in early August would not be safe from major yield reductions due to frost until October.

Figure 1. Wisconsin corn planting progress (Data source: USDA-NASS).

Figure 2. Corn silking (R1). Photo by W. Hoffman.

Figure 3. Typical time span of vegetative and reproductive stages during the life cycle of corn.

90 d RM

100 d RM

110 d RM

Vegetative (50-80 d) Reproductive (55-60 d)

Planting R1 Silking R6 Black layer

Figure 4. Corn silage yield and quality changes during development.

0

5000

10000

15000

20000

0

500

1000

1500

2000

Jul11V11

Jul21V14

Jul31R1

Aug10R2

Aug20R3

Aug30R4

Sep10R5

Sep21R5.5

Oct5

R5.8

Milk per TonMilk per Acre

Milk per Acre (lb/A)Milk per Ton (lb/T)

Harvest date

Pioneer 3578Arlington, WI‐1993

page 2

Figures 4 and 5 describe typical development of corn silage yield and quality and of a corn kernel. At the dent stage (R5), corn has accumulated 75-85% of silage yield and 60-75% of grain yield and needs about 27-32 days to avoid

significant yield reductions due to frost (Table 1). In order to avoid yield reductions caused by frost, corn intended for silage should be silking by late August, while corn intended for dry grain should reach the dent stage by September 1.

Table 2 describes the effect of environment on kernel development of full- and shorter-season hybrids planted on different dates at Arlington, WI. The growing season of 2009 was characterized as cool and wet, while 2012 was hot and dry. The number of days to get from silking (R1) to the denting stage (R5) was 28-45 days depending upon the year and planting date. For kernels to develop from silking to 50% kernel milk required 45-62 days.

To predict whether corn will mature before frost note the hybrid maturity, planting date and tasseling (silking) date of the field. For silage planted early, add 42-47 days on to this date to predict 50% kernel milk, while for grain, add 55-60 days to predict maturity. These dates are guidelines which will require further in-season decisions as the season unfolds.

Table 1. The relationship between kernel growth stage and development of corn for normal planting dates.

Stage Calendar days to 

maturity GDUs to maturity 

Percent of max yield Grain              Silage 

Moisture content (%)Grain                Silage 

R1: Silking  55‐60  1100‐1200 0 45‐50 ‐‐‐  80‐85

R2: Blister  45‐50  875‐975 0‐10 55‐60 85‐95  80‐85

R3: Milk  35‐40  750‐850 10‐30 60‐65 70‐85  80‐85

R4: Dough  30‐35  650‐750 30‐60 65‐75 60‐70  75‐80

R5: Dent  27‐32  425‐525 60‐75 75‐85 50‐55  70‐75

R5.5: 50% Kernel milk  13‐18  200‐300 90‐95 100 35‐40  65‐70

R6: Black layer  0  0 100 95‐100 30‐35  55‐65

Table 2. Kernel development of full- and shorter-season corn hybrids at Arlington, WI.   2009 2010 2011  2012

Planting dates  April 10‐June 15 April 14‐June 18 April 13‐June 17  March 28‐June 15

GDUs (May 1‐July 15)  932  1156 1038  1253

GDUs (July 15‐Oct 1)  1069 1327 1264  1309

   

Full‐season Hybrid   Pioneer 35F40 Pioneer 35F40 Pioneer 35F44  Pioneer 35F48AM1

Relative Maturity (days)  105 d RM 105 d RM 105 d RM  105 d RM

R1: Silking date  July 24‐Aug 16 July 16‐Aug 11 July 20‐Aug 9  July 9‐Aug 6

R5: Denting date (DAS) †  Sep 3‐Sep 28 (41‐43) Aug 16‐Sep 21 (31‐41) Aug 18‐Sep 14 (29‐36)  Aug 10‐Sep 9 (32‐34)

R5.5: 50% Kernel milk date (DAS) Sep 20‐DNM (57‐DNM‡) Sep 2‐ Oct 11 (48‐61) Sep 6‐Oct 10 (48‐62)  Aug 31‐Sep 28 (48‐53)

Forage yield (T DM/A)  11.0‐7.2 10.0‐7.5 10.1‐7.2  8.7‐7.3

Grain yield (bu/A)  224‐118 255‐51 224‐155  236‐106

Grain moisture (%)  24‐40 15‐40 17‐29  19‐50

   

Shorter‐season hybrid  Jung 7426VT3 Jung 7426VT3 Dekalb DKC48‐37  ‐‐‐

Relative Maturity (days)  96 d RM 96 d RM 98 d RM  ‐‐‐

R1: Silking date  July 25‐Aug 17 July 16‐Aug 12 July 19‐Aug 7  ‐‐‐

R5: Den ng date (DAS) †  Aug 31‐Oct 1 (38‐45) Aug 18‐Sep 18 (33‐38) Aug 20  Sep 12 (28‐36)  ‐‐‐

R5.5: 50% Kernel milk date (DAS) Sep 18‐DNM (54‐DNM) Aug 30‐Oct 12 (45‐61) Sep 4‐Oct 7 (48‐61)  ‐‐‐

Grain yield (bu/A)  271‐144 235‐138 231‐177  ‐‐‐

Grain moisture (%)  20‐41 13‐39 15‐27  ‐‐‐

† DAS= Days a er silking; ‡ DNM= Did not measure

Figure 5. Typical corn kernel development in Wisconsin.