|
|
|
|
May 12, 2020
In This Edition:
|
|
Note from Pennington:
Assessing freeze injury to wheat in Michigan
By Dennis Pennington, MSU wheat specialist (pennin34@msu.edu)
and Jeff Andresen, State Climatologist
An arctic-origin air mass brought unseasonably cold weather and widespread hard freeze conditions to much of Michigan last Friday and Saturday, May 8-9. (See Figure 1). In northern sections of the state, the event followed an almost daily series of freezing overnight temperatures back to May 4.
The freezing conditions on May 8-9 were generally advective (horizontal movement of a cold air mass) in nature (vs. more typical radiative freeze events with vertical release of heat to the atmosphere under relatively clear, calm conditions). There were breezy, cloudy conditions continuing at many sites throughout the evening.
Another distinguishing factor of this event was the very dry, low humidity nature of the air mass. Dewpoint temperatures during the event generally remained in the teens, resulting in little or no visible frost on the soil or vegetation (black frost conditions).
The coldest temperatures statewide were observed across interior western sections of the Upper Peninsula and across interior sections of the southwest half of Lower Michigan where low-mid 20s Fahrenheit were common.
Minimum temperatures were somewhat milder across the eastern Upper Peninsula southward through northern and eastern sections of the Lower Peninsula (28-33 degrees F.) due to the moderating influence of “lake effect” clouds and snow showers.
A representative vertical cross-section of temperatures during the event is given in Figure 2 from the Enviroweather tower site near Sparta. The 5-minute mean air temperatures measured at 66 feet (brown), 33 feet (orange), 5 feet (red), and 4 inches (green) above the surface collectively dropped below freezing at approximately 9:30 p.m. and remained there until about 8 a.m. on Saturday, May 9 (approx. 10.5 hours).
With advective freeze conditions (described above) and a persistent 5-15 mph wind (blue vertical bar graph just above the temperatures) throughout the evening and early morning hours, temperatures at the different levels generally remained within 2 degrees F. of one another, with only weak inversion conditions (increasing temperatures with height) near the ground surface.
The duration of temperatures below 28 degrees F., a common threshold for cold injury, varied significantly across the state, ranging from zero hours across eastern sections to as much as nine hours across interior sections of west central and southwestern Lower Michigan and the western Upper Peninsula.
Below the surface, 2” bare soil temperatures during the event generally ranged from the upper 40s F. in the south to the upper 30s Fahrenheit in the north.
Winter wheat tolerance to sub-freezing temperatures is highly dependent on growth stage. In young, tillering wheat, the growing point remains below the soil surface where it is protected from very cold temperatures.
Feekes 6 marks the beginning of jointing or rapid stem elongation, where the developing head is moved up the stem and emerges. Feekes 6 is when you can feel/see one node above the soil surface.
Feekes 7 and 8 are marked by two and three detectable nodes, respectively. The developing head is located just atop the uppermost node.
It is this developing head that is of utmost concern. If conditions get cold enough, water in the extracellular space freeze causing the cell walls to burst. The severity of this damage will determine how much yield loss to expect.
Wheat that is in the jointing stage (Feekes 6-9) can tolerate temperatures down to 24 degrees F. for only about two hours. As wheat progresses in development toward boot, cold tolerance is reduced.
Damage during the jointing stage appears as leaf yellowing or burning, death of the growing point, splitting or bending of the lower stem and a “corn silage” odor. Yield reduction is moderate to severe and is dependent on how many florets are damaged.
More information on growth stage, damage and yield effect can be found in Table 1.
Table 1. This table shows temperatures that cause freeze injury to wheat at spring growth stages, as well as symptoms and yield effect of spring freeze injury. Source: Spring Freeze Injury to Kansas Wheat, KSU Extension Bulletin C-646, Shroyer, Mikesell and Paulsen, 1995.
| Growth Stage |
Approximate
Injurious Temperature
(two hours) |
Primary Symptoms |
Yield Effect |
| Tillering |
12 F (-11 C) |
Leaf chlorosis; burning of leaf tips; silage odor; blue cast to fields |
Slight to Moderate |
| Jointing |
24 F (-4 C) |
Death of growing point; leaf yellowing or burning; lesions, splitting, or bending of lower stem; odor |
Moderate to Severe |
| Boot |
28 F (-2 C) |
Floret sterility; spike trapped in boot; damage to lower stem; leaf discoloration; odor |
Moderate to Severe |
| Heading |
30 F (-1 C) |
Floret sterility; white awns or white spikes; damage to lower stem; leaf discoloration |
Severe |
| Flowering |
30 F (-1 C) |
Floret sterility; white awns or white spikes; damage to lower stem; leaf discoloration |
Severe |
| Milk |
28 F (-2 C) |
White awns or white spikes; damage to lower stems; leaf discoloration; shrunken, roughened, or discolored kernels |
Moderate to Severe |
| Dough |
28 F (-2 C) |
Shriveled, discolored kernels; poor germination |
Slight to Moderate |
To assess a plant for viability, slice open the stem longitudinally at the uppermost node with a sharp knife. Locate the developing head. A normal head should be white to yellow-green and turgid. A damaged head may be off-white or brown in appearance and have a silage odor.
How cold and length of the cold period will have an impact on how many florets may be damaged. The level of damage on each head and the number of damaged heads in a field will be directly related to final crop yield.
Also check the health of lower stems. Often freeze damage shows up as swollen nodes or lesions on the stem near the nodes. This could increase the risk of lodging.
Affected tillers may remain green, but if the growing point dies, growth will stop. Where you see chlorotic leaves emerging from the whorl, the growing point in that tiller is likely damaged.
It may take a week after a freeze event before the impacts are fully known. Scouting too early may result in inability to identify damage.
Kansas State University published a very informative bulletin with good diagnostic pictures. Click here to find that bulletin.
If you have any questions or concerns please direct them to Dennis Pennington, MSU Wheat Extension Specialist at pennin34@msu.edu or (269) 832-0497. As you scout your fields, please report any damage to help us track where in the state there are problems.
Figure 1. Minimum temperatures (°F) across Michigan, May 9, 2020. Data obtained from the MSU Enviroweather information system and the National Oceanic and Atmospheric Administration.
Figure 2. The 5-minute mean air and soil temperatures (°F) and wind speed (mph) at Sparta at 7 p.m. May 8 through 7 p.m. May 9. Data obtained from MSU Enviroweather Information System.
|
|
New! Video on sub-freezing temperature damage to wheat
By Dennis Pennington, MSU wheat specialist (pennin34@msu.edu)
Watch this excellent video featuring MSU wheat specialist Dennis Pennington showing how to dissect a wheat seedling to determine whether sub-freezing temperatures have damaged or killed the growing point or head of a wheat plant.
Click here to watch the full 4 ½-minute video filmed yesterday.
|
|
This Thursday: Special focus at MSU Extension Virtual Breakfast on wheat freeze damage and other possible crop damage
During the overnight period of May 8-9, temperatures across MI reached the upper teens to mid-20s. This is the lowest temperature recorded on this date since overnight lows started being recorded in 1942. This record late freeze could have some serious impacts on wheat, alfalfa and soybeans.
The MSU Extension Field Crops Team will adapt the Thursday, May 14 Virtual Breakfast to cover freeze topics.
 Dennis Pennington, MSU Extension wheat specialist will discuss the impacts to the wheat crop and address the potential for wheat freeze damage in parts of Michigan; Phil Kaatz, MSU Extension forages educator will cover impacts to the alfalfa crop; and Mike Staton, MSU Extension soybean educator will cover impacts to the soybean crop.
MSU’s agricultural meteorologist Jeff Andresen will describe the details of the freeze event. Formal presentations will run from 7-7:30 a.m. this Thursday. There will be an extended question-and-answer period for participants following the formal presentations.
Click here for more information about the Virtual Breakfast live online meetings. Visit the webpage to sign up for the Virtual Breakfasts and you will receive a weekly email with instructions for connecting to each meeting.
Computer Zoom connection. Participating is easy and free! You can join the live meeting via Zoom using a computer, tablet, mobile device or regular phone line. If you are new to Zoom, simply download the Zoom app<https://zoom.us/download> and you will be ready to join online every week to see visuals shared by presenters.
Click here to sign up to receive each Virtual Breakfast Zoom link, which are sent out separately. <http://eepurl.com/gm-PIv> If you are unable to sign up online, call the Lapeer County MSU Extension office at 810-667-0341 to receive instructions on how to join.
Or listen by cell phone. A call-in by phone option is also available but it still requires that you complete the registration form above.
Archived recordings. If you cannot join at 7:30 this Thursday, the recorded presentation will be on-demand through the MSU Extension field crops website. (http://www.canr.msu.edu/field_crops/).
You can also stay up-to-date on what is happening in Michigan field crops by ‘liking’ the MSU Extension Field Crops Team Facebook page (https://www.facebook.com/MSUEFieldCrops/), or by following us on Twitter @MSUEFieldCrops. You can also see what the MSU Extension Field Crops Team is up to via Spotify (click <https://open.spotify.com/show/5tDpZAfaqeKewZDEzV1usu>); YouTube (click <https://www.youtube.com/channel/UCPxaNf0IATV_B7MJdBxMH1w>), and Apple Podcasts (click <https://podcasts.apple.com/us/podcast/michigan-field-crops/id1461704431>).
2020 Virtual Breakfast schedule
- May 14 - Post-emergence weed control with Erin Burns updated to Freeze Damage with Dennis Pennington, Phil Kaatz, Mike Staton and Jeff Andresen
- May 21 - Wheat issues for 2020 with Dennis Pennington
- May 28 - Dry bean planting with Scott Bales
- June 4 - Alternative forages with Kim Cassida
- June 11 - Sugar beet Cercospora and BEETcast with Daniel Bublitz
- June 18 - Drainage design considerations with Ehsan Ghane
- June 25 - Farm stress with Eric Karbowski
- July 2 - Organic field crop production with Vicki Morrone
- July 9 - Insects taking flight with Chris DiFonzo
- July 16 - Stored grain with special speaker
- July 23 - Tar spot and white mold with Martin Chilvers
- July 30 - Cover crops after wheat with Dean Baas
- Aug. 6 - Irrigation and diseases with Lyndon Kelley and Martin Chilvers
- Aug. 13 - Alfalfa autotoxicity with Kim Cassida
- Aug. 20 - Grain marketing with Aleks Schaefer
- Aug. 27 - Wheat planting with Dennis Pennington
- Sept. 3 - Corn silage mycotoxins with Manni Singh
- Sept. 10 - Industrial hemp with Kurt Thelen
The “virtual breakfast” calls are organized by Phil Kaatz, MSU Extension educator in forage management and field crops in Lapeer County. For more information, you may contact him directly at kaatz@msu.edu<mailto:kaatz@msu.edu.
|
|
Deadline May 15 -- Only 3 more days!
Register now for the new Michigan Wheat Yield Contest
The Michigan Wheat Program (MWP) has launched the first Michigan Wheat Yield Contest to recognize outstanding wheat growers in the Great Lakes State.
If you want to put your wheat to the test, enter before May 15 for the opportunity to become one of Michigan’s outstanding “wheat warriors.”
 The Michigan Wheat Yield Contest is modeled on the successful 5-year-old National Wheat Yield Contest sponsored by the National Wheat Foundation (NWF).
We know Michigan wheat farmers produce much more than the national average of 49 bushels per acre, particularly in 2016 when Michigan had an average 89 bushels per acre yield!
What we don’t know, is which farmers grew it best in Michigan and what they did to achieve those yields.
The Michigan Wheat Yield Contest offers Michigan growers an opportunity to compete against one another, as a way to inspire creative thinking to solve production challenges in Michigan. Winners will be chosen as a straight-up highest per bushel yield in irrigated and dryland wheat for both red and white wheat.
How to Enter. To make contest entry easy, the Michigan Wheat Program has partnered with the NWF to utilize their contest registration form and entry process. Michigan farmers’ data will be used by the Michigan Wheat Program to determine the home-state winners.
To sign up for the Michigan contest and the National Wheat Yield Contest (they must go together), click here to visit the NWF website. The registration and $125 entry fee are due May 15, 2020. This is the final deadline for the 2020 harvest.
Usually, the entry fee will be covered by one of the ag businesses you work with. Questions may be directed to your ag business representative. National sponsors of the contest that also cover registration fees are: Bayer/WestBred, BASF and Corteva/Pioneer. If you are utilizing one of these companies, complete your registration form but DO NOT PAY. The registration fees will be covered after the rest of your registration is submitted.
What You Can Win. Michigan’s top winners will receive free registration and lodging at the Great Lakes Crop Summit in Mt. Pleasant in January 2021. Also, recognition and awards at the Michigan Wheat Program’s Annual Meeting in March 2021; and will be highlighted in a special publication honoring Michigan’s top yielding farmers.
We call those top yielders “wheat warriors!” and by winning one of the categories in the state contest, they become members of that special “wheat warriors” club. As the contest develops, there will be more opportunities for those growers.
|
|
Calendar of events
 With the ban on public meetings due to the COVID-19 pandemic, there’s not much on the events calendar.
Due to the shut-down of MSU and MSU Extension until the fall, our Summer Field Day will not occur in the traditional format. The Michigan Wheat Program board, staff and research team are working to find the best virtual format to present the research plots and provide interaction with growers.
- June 10 – Michigan Wheat Program Field Day, format to be determined.
|
|
|
|
|
|
|
