Digital Corner

What’s Happening to my Winter Wheat? 

by Dale Cowan

Winter Wheat planting for the most part concluded in the later days of October. The Growing Degree Day (GDD) accumulations slowed considerably in late October. Wheat planted on October 25^th has accumulated roughly 275 GDD, subtract from that 130 GDD for emergence that leaves 145 GDD and considering it takes 90 GDD for a leaf to develop, we likely have only have 1 or 2 leaves on the main stem and possibly a single tiller. What does that mean for crop development and winter survival?

There are two important physiological processes that are critical to the wheat crop at this time. First one is called Vernalization. The other we call Cold Acclimation or cold tolerance or winter hardiness all leading to dormancy for over wintering survival.

Vernalization is the process where the growing point at the crown transitions to reproductive growth. This is brought on by exposure to colder temperatures. This process allows for heads to be formed in the spring next year. Vernalization temperatures can vary by variety but generally a 6-to-8-week period of temperatures below 9C is sufficient. Plants do not need to be emerged to become vernalized once seeds begin germination and are subject to colder temperatures, they can become vernalized. This assures that next spring we have heads emerging on the main stem and tillers. Often in Ontario colder temperatures in late fall are sufficient to complete vernalization process.

Cold Acclimation and Vernalization overlap. Both begin in the fall once soil temperatures drop below +9C. At temperatures below this level there is an inverse relationship between temperature and the rate of cold acclimation. Winter wheat plants will acclimate twice as fast at crown temperatures of 0 C compared to +5 C. Once this process starts, the degree of cold hardiness, and the maintenance of low temperature tolerance, are directly related to the sequence of temperature changes that the crown tissue is exposed to during the fall and winter. Cold acclimation can be stopped, reversed or restarted by changes in temperature! The optimal soil temperature for acclimation is thought to be near +3 Celsius. Winter wheat normally does not reach its maximum cold hardiness potential until after freeze-up in late fall early winter. (David Struthers, Winter Cereals Canada Inc., Yorkton, SK Ken Greer, Western Ag Labs, Saskatoon, SK)

In Ontario we may not reach optimum cold hardiness until into late January or February. Although we think of wheat going dormant with the onset of cold temperatures, it never really stops growing it continues to respire but at extremely low rates. . As we experience fluctuating temperatures in the Southwest part of the province in late fall, early winter it is not unusual to see better root and crown development in late January compared to late November. It will depend on accumulations of GDD.

Early planting promotes extensive root, crown and tiller development to help the plant over winter successfully. Later planting is not necessarily disadvantaged as long as we have suitable weather, avoid extremes in temperatures and have sufficient insulating snow cover to greatly improves survivability.

On our Website we began tracking GDD this fall. On January 1^st we will reset the GDD accumulations to zero. We will track daily GDD accumulations throughout the winter and early spring. Once we see accumulations between 250 to 320 GDD we should see green up occurring. This is the time we evaluate , survival, plant density, uniformity and determine a Nitrogen management strategy.

Winter wheat is one of the most management responsive crops we grow. Understanding critical growth stages guides our management decision to optimize returns.

Evaluating plant stands and subsequent nutrient applications, will be enhanced by upcoming technology, more to come.

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by Kent Wolfe

Seed selling season is definitely in full swing right now and as we discuss your variety requirements with you for next year, one item that is sometimes gets overlooked in the discussion is the different treatment options that are available and how they can contribute to improved yields at harvest. You hear us talk about the importance of planning and how it needs to be done on a field by field basis the same holds true for seed success. The first and most important decision is still the variety choice, you have to start with the right variety for the field it is being planted into but treatment options or combinations of them can definitely complement your yield potential with the variety. What I would like to look at are the four main seed applied groups of products that are available to us and their main role to maximize your soybean yields.

Fungicide seed treatments are the basic treatment, the main role of this treatment is to manage two different types of pathogens, seed born fungal pathogens like Phomopsis seed decay fungus and soil born pathogens like Pythium, Fusarium, Phytophthora and Rhizoctonia. We have a couple of different offerings depending on the which seed partner you are getting your seed from Vayantis IV is a relatively new product that has four active ingredients. It is a combination of metalaxyl-m (Group 4) sedaxane (Group 7) fludioxonil (Group 12) and picarbutrazox (Group U17) fungicide products. Acceleron Basic is a combination of Prothiconazole (Group 3) Metalaxyl-m (Group 4) and penflufen (Group 7). Both are excellent products that provide early season protections against diseases.

Insecticide seed treatments are another option that will provide early season protection against wireworm, seed corn maggot, bean leaf beetle, aphids, white grubs and leafhoppers. Fortenza is a non class 12 (Cyantraniliprole) insecticide which is the main product available for seed that comes into the branch treated from the processor. The other option that use to be the standard insecticide product a few years ago is CruiserMaxx a class 12 neonicotinoid (Thiamethoxam) This treatment option is only available at some of our bulk treatment sites and requires that a pest assessment has been completed for the field being planted with the treated seed and that you have taken the IPM course in the last 5 years. Effective on March 31/ 2023 the PMRA legislated that the use rate be reduced from 83 ml/ 100 kg of seed down to 50 ml/ 100 kg. The main difference with this rate change is now wireworm is not on the label for early season protection.

Inoculants are another treatment option that benefits the soybean plant with improved nodule formation, increased nitrogen fixation and enhanced nutrient availability to support early root and shoot growth. Optimize ST is a specially selected Bradyrhizobium janonicum inoculant and LCO (lipochitooligosaccharide) technology that is viable on the seed for up to 220 days.

These treatment options are simply just that, options that can range from a single base fungicide treatment to multiple combinations of different products. Some may have a fit and positive economic response potential; some could be just considered good insurance while others may not a fit on your farm at all. Take the time to have the discussion and work thorough some scenarios on a field-by-field basis with your seed specialist at your local Co-operative and chose the right mix for you.

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A Quick Look at the Final Yield Component: Kernel weights

By Dale Cowan

With all things being equal the difference in yield amongst hybrids is largely attributed to differences in kernel weights. We express kernel weights by weighing a thousand kernels (TKW) in grams. We can then use this to understand yield differences and to determiner the number of kernels to make a bushel of corn. Currently I am reviewing the results of the AGRIS 2023 Hybrid Corn Plots. So far the average yield is 218 bushels across all hybrids with yield range of 108 to 268 bushels per acre a TKW average of range of 359 grams resulting 70,818 kernels in a bushel of corn. The range in TKW is 280 to 440 grams resulting in a range of 90,800 to 57,781 kernels per bushel. Quite a range in hybrid yield components.

I often like to look at one hybrid in many locations to see the range in the same genetics impacted by the growing environment and management. Looking at DeKalb 5360 we see an average yield of 221 and range of 148 to 268 bushels per acre. The TKW averages 365 and varies by a range of to 326 to 408. This is an average of 69,654 kernels per bushel to a range of 77,987 to 62,313 kernels to make a bushel. The DON mycotoxin ranging from 0.3 to 7.6 ppm.

Quite a range in measured values, same genetics but impacted by environment and management practices. The lowest yield is from a plot not sprayed for Tar Spot.

The TKW does explain a lot of the yield variance. What impacts on the kernel weights?

Environment: sunshine moderate temperatures optimizing CHU accumulations, adequate moisture ahead of reproductive period

Balanced and adequate supply of essential nutrients especially N, P, S and Zn these elements have a high harvest index. Healthy crop canopy – fungicides keep the factory green and producing sugar to fill kernels

Kernel fill is divided into 2 phases - Lag and Linear

The Lag Phase is from R1 to R3 which basically sets up kernel size and the Linear Phase that runs from R4 to R6 that represents the time period of rapid grain fill. The linear phase lasts approximately 40 days. To produce 200 bus corn, 5 bushels per acre per day needs to be accumulated. Approximately 60% of the starch that accumulates in the kernels is  from the ear leaf. Leaves that are above and below are important but become less important the further away they are on the stalk from the ear. During the day the stalk becomes an important storage site for the photosynthate, then it is translocated to the ear at night.

Yields and high TKW are function of genetics, environment and management working together.

We are committed to leading with the right seed, feeding the crop, and protecting the crop . All the components work together. Knowing the field and matching the strengths of the hybrid against the weakness in the field is a good strategy. Follow up with current soil tests to determine the right nutrient package. Protect plant health and grain quality to make sure all the other inputs contribute to heavy kernel weight.  

It is difficult to generalize in a year of extremes. We need to be careful not to generalize too much, things can be situationally specific. And we lose some of the insight that makes fields unique. With today’s technology we can be more site specific in evaluating inputs that support high TKW. Reaching out to your Crop Specialists to review any data you may have such as yield maps and soil test results can be time well spent. This year’s output is next year’s input.