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Set-up Treatments in Glyphosate-Tolerant Soybeans

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AgSolutions Advisor April 2015 Set-up Treatments in Glyphosate-Tolerant Soybeans Written by: Drew Thompson Weed management in soybeans can mean many things to different people, but most growers would agree
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AgSolutions Advisor April 2015 Set-up Treatments in Glyphosate-Tolerant Soybeans Written by: Drew Thompson Weed management in soybeans can mean many things to different people, but most growers would agree that one of the key results of an effective weed management program is a clean field at harvest. This allows for efficient combining, high-quality grain and maybe some bragging rights at the coffee shop due to the esthetic appeal of the field. With glyphosate-tolerant soybeans, the goal of having a weed-free field at harvest is very achievable through tillage or a burndown, followed by a post-emergent application of glyphosate once all the weeds have emerged. An enhanced burndown may also be required if a grower is faced with glyphosateresistant weeds. However, if the goal of a weed management program is to obtain clean conditions at harvest and optimal yields, the above strategy may not be enough. Many factors, beyond the absence of weeds at harvest, need to be considered to ensure optimal yields. New tactics, including the use of a residual herbicide product as a set-up treatment, may need to be employed. The degree to which weeds impact the yield potential of a soybean crop is strongly dependent on the dynamics of the weed population. Weed density, species and size relative to the crop all influence the level of potential damage. Weed dynamics also influence the stage of soybean development at which irreversible yield loss will occur, also known as the critical point. Heavy weed densities, the presence of species with rapid early-season growth and weeds that emerge prior to the crop are the most damaging and tend to negatively impact yield at earlier stages of soybean growth. 1 A glyphosate-tolerant soybean field with any of the aforementioned weed challenges can still be managed to ensure weed-free conditions at harvest. However, failure to control these weeds early enough will result in reduced yield potential. Using a set-up residual herbicide prior to the emergence of the weeds, or in combination with the burndown, can help create more favourable conditions for optimal yield. A set-up residual treatment reduces the number of weeds emerging with the crop, allowing early-season development with minimal weed pressure. This can also delay the critical point and allow for a wider application window for a post-emergent herbicide, without risking yield loss. Environmental conditions can impact soil moisture, and soil moisture can drastically influence the degree to which weed pressure impacts soybean yield potential. Research done at the University of Guelph looked at yield loss due to weed pressure over 22 years at their Elora Research Station. 2 During years with adequate moisture, average yield losses due to weed pressure was 23%. Dry years, with inadequate levels of moisture resulted in weed-related yield losses of 84%. These results demonstrate that the effects of stresses tend to be compounding in nature, where the impact of a single stress is far less then when multiple stresses are encountered. Predicting the soil moisture conditions of the upcoming year is not possible. Regardless, there is little doubt that most fields will have weed pressure. And while a set-up residual herbicide that minimizes weed pressure will be helpful under all environmental conditions, it will be even more beneficial if additional stresses from dry weather develop. Soybean population can also influence the degree to which weed pressure impacts yield potential. Recent research out of the University of Wisconsin 3 examined various soybean seeding rates under two different weed management programs. The first used a residual set-up treatment followed by a post-emergent application, and the second program relied solely on a post-emergent treatment. Across all seeding rates, the first program consistently increased yield relative to the post-herbicide-only treatments (Figure 1). Interestingly, the largest percentage gains from the residual set-up herbicide program were achieved with the lowest seeding rates. These results are speculated to be due to limited early season competition faced by the weeds from the crop in the post-herbicide-only situation, allowing the weeds to become increasingly competitive and damaging. This research helps demonstrate the value of a set-up residual herbicide, particularly for growers who may be considering reduced seeding rates (e.g. to help alleviate the risk of white mold) DATA 2013 DATA 70 Residual f/b Post program Post only program 50 Residual f/b Post program Post only program Yield (bushels/acre) Yield (bushels/acre) Seeding Rate (000 s Seeds/Acre) Seeding Rate (000 s Seeds/Acre) Figure 1. Impact of seeding rate and herbicide program on soybean yields over a two-year period. Results adapted from the research of DeWerff et al. (2014). Overall, glyphosate-tolerant soybeans have long been associated with providing a means to ensure clean conditions at harvest. However optimal yields require the ability to manage variable weed dynamics, unpredictable environmental conditions and the flexibility to incorporate cultural practices not related to weed control. BASF has a broad portfolio of soybean herbicide products with residual activity that can help address these challenges. This helps ensure that fields are set up for optimal yield and the ability to visit the coffee shop with pride. Talk with your local BASF field representative to see what solutions are best for your fields. References: 1) Retrieved Feb 15, ) Retrieved Feb 15, ) DeWerff, R.P., Conley, S.P., Colquhoun, J.B. and Davis, V.M Can Soybean Seeding Rate be Used as an Integrated Component of Herbicide Resistance Management? Weed Science (62): AgSolutions Advisor April 2015 Fungicides and Straw Quality Written by: Rob Miller As many will recall, the fall of 2013 was very wet, resulting in fewer acres of wheat planted. Due to a harsh winter and later spring, winterkill was substantial in some areas in The wheat crop was variable all season long and maturity-wise, about 10 to 14 days behind normal. However, depending on where you lived in the province, some yields were higher than expected, though still below the provincial trend line of 78 bu/ac. 1 This meant that straw was in high demand with prices ranging from 4 to over 6 cents per pound in the swath. 1 As a result, straw inventories were depleted, leaving growers searching for bedding alternatives, including bailing soybean straw and corn stalks. The fall of 2014 was very similar to that of 2013, with an estimated 600,000 acres of winter wheat planted in Ontario. 1 However, most of the wheat was planted later than normal and in adverse conditions. What are the implications for the impending wheat crop? It is still too early to make accurate predictions, but given the low straw inventories and shortage of wheat acres, quality straw will likely be in high demand throughout Harvesting straw as a secondary commodity can provide farmers with additional income. If you are a livestock producer or have a market for your straw, its value can be significant. Other uses for straw include using it as mulch for horticulture, as a supplement in cattle rations, as winter insulation for concrete at construction sites and for absorption purposes along roadsides to reduce run-off. Straw quality is very important with most growers and end-users stating dustiness is often the reason for reduced prices. 2 In fact, most of the dust associated with straw can be attributed to leaf diseases; the brightness of the straw also serves as a measure of quality. 2 Leaf diseases such as septoria leaf blotch (Septoria tritici) and leaf rust (Puccinia triticina) are the most common in Ontario. Selecting a cereal variety that is more tolerant to these leaf diseases is your first step towards improving the quality of cereal straw. The application of fungicides can also control leaf diseases, resulting in improved straw quality, less dust and increased standability. So, what can you do to increase straw yield potential? Cereal variety selection is very important when determining straw yield, as some varieties are much taller than others. Increasing nitrogen rates can also result in taller plants and increases in straw yield. However, excessive nitrogen levels can also lead to lodging. 2 Research conducted at the New Liskeard Research Station in 2012 by the Ontario Cereal Crops Committee (OCCC), demonstrates that adding additional nitrogen, in conjunction with spraying a fungicide, can not only improve wheat grain yields, but straw yield as well. 3 Researchers evaluated 23 different spring wheat varieties, comparing standard and managed programs. The standard program consisted of applying 120 lbs/acre of nitrogen while the managed program applied the same rate of nitrogen in combination with a fungicide application at heading to control fusarium head blight. The data presented in Figure 1 illustrates that some wheat varieties responded to a fungicide application more than others. The responses ranged from negative pounds per acre to over 800 pounds more straw per acre with a single fungicide application. The average across all varieties was 335 pounds more straw per acre when a fungicide was applied at heading versus the untreated check. Straw Yield OMAF Smart Trials AVG 335 lb/ac 600 Lbs/ac Variety Figure 1. OCCC variety trials, New Liskeard, Ontario, In 2014, BASF conducted small plot trials to compare straw yield when using either a 1- or 2-pass fungicide system. Spring wheat was planted at the Bryanston Research Farm north of London in May. Winter wheat was unable to be used for these trials due to severe winterkill. Two trials with four replications each were established. Nitrogen was applied at 120 lbs/ac across the entire trial area, and Twinline fungicide was applied with a herbicide just prior to flag leaf emergence (Zadok scale 37). Caramba fungicide was applied at 20-50% flower to control leaf diseases and fusarium head blight. The results in Figure 2 are similar to the OCCC trials conducted in When a fungicide such as Caramba was applied at heading, approximately 300 pounds more straw per acre was observed across 8 replicates versus the untreated check. The 2-pass fungicide system also demonstrated an additional straw yield increase lbs/ac bu/ac Check Caramba Twinline f/b Caramba 70 Untreated Caramba Twinline f/b Caramba # of obs = 8 # of obs = 8 Figure 2. Spring wheat straw yield after either a 1- or 2-pass fungicide application. (BASF internal trials, Bryanston, Ontario, 2014.) Figure 3. Spring wheat grain yield comparing untreated check, 1- and 2-pass fungicide programs (BASF research trials, Bryanston, Ontario, 2014). Not only is there an increase in straw yield, but there is also an increase in grain yield as well. Caramba applied at heading resulted in an average increase of 7.8 bu/ac compared to the untreated check. A 2-pass program of Twinline followed by Caramba at heading resulted in a 10.0 bu/ac increase (Figure 3). The debate continues amongst producers regarding the benefits of bailing straw versus spreading it on the field. Some growers want the nitrogen (N), phosphorus (P) and potassium (K) returned to the soil as well as the increase in organic matter, by keeping straw on the field. Others look at the market and see more value in selling their straw, especially when prices are high. This is a decision that each producer needs to make on a field-byfield basis. Either way, growers can increase both their grain and straws yields, as well as improve straw quality if the wheat crop is properly managed using sufficient nitrogen in conjunction with fungicides. References 1. Johnson, P. Field Crop Report. Seasonal Summary for Cereals. aspx?fileticket=bkuoandvcyi%3d&tabid= Cereal Straw Production. University of Kentucky. 3. Ontario Cereals Crop Committee. AgSolutions Advisor April 2015 Identity-Preserved Soybeans: Weed Management Written by: Drew Thompson Identity-preserved (IP) soybean production refers to a system where soybeans are grown under contract, following set guidelines to ensure the harvested crop meets the purity and/or quality parameters demanded by the end user. 1 The end users for most of Canada s IP soybean crop are international food manufacturers. These manufacturers have specific requirements as the quality of the raw soybean is crucial to ensuring their end products have the customer-desired characteristics. The physical quality of the bean is also important; end users want soybeans that are free from cracks, stains or dirt and possess intact seed coats. Since quality requirements associated with IP soybeans are above those of the crush market, a premium is typically paid for the crop. From an IP soybean buyer s perspective, the premium, or price above the current market helps ensure supply by enticing producers to grow soybeans with the desired qualities. For producers, the premium can be viewed as a reward for meeting quality standards. However, in order for IP soybeans to be economical the premium must cover additional management requirements associated with IP production. Variety selection is typically the most important factor when considering the economics of IP soybean production. Many varieties are given IP status based on their composition qualities, such as % oil, % protein, % sugar, etc., and just as the composition will vary so too can the yield potential. Selecting varieties that are adapted to the conditions of your farm (e.g. maturity zone, soil type suitability) with good yield potential is crucial for economic success. Weed control is another important factor to consider since the vast majority of IP soybean varieties are conventional or without a herbicide tolerance trait (e.g. glyphosate-tolerant or GT). As with all soybeans, the primary goal of weed control in IP soybean production is to ensure that weeds do not negatively impact the yield of the crop. However, more intensive weed management is required to achieve this goal when using varieties that do not have the option for post-emergent treatments of non-selective herbicides. A good starting point for weed management in IP soybean production is to adopt the mindset that weed control must extend beyond the years of soybean production. Rotational crops for IP soybeans such as corn and cereals provide opportunities to use a wider range of herbicides, as few options exist to control certain weeds in IP soybeans (e.g. perennial weeds such as thistles or Tufted vetch, see Figure 1). By ensuring effective weed control in rotational crops, weed pressure and challenges can be drastically reduced in the years of IP soybean production. As mentioned earlier, there aren t many powerful, nonselective herbicides available for post-emergent weed control in IP soybeans. This is not to say that there are no options for effective weed control in this crop. However, it is important to point out that the lack of post-emergent tools means greater attention must be given to the selection and proper use of other herbicides. A pre-plant or pre-emergent residual herbicide program is an excellent foundation for IP soybean production. Residual products minimize earlyseason weed competition and keep the weeds in check until the crop canopy can provide control by shading out the weeds. There are many residual products and programs available on the market, but the ideal program is one that brings multiple modes of action and includes control of any resistant biotypes (Figure 2). Climatic conditions play a major role in the success of residual products. Limited moisture can result in activation failure and excess moisture can dilute the products. Unfavourable moisture conditions and weed programs which do not target all species can both lead to weed escapes. Timing is crucial to effectively control these escapes. The vast majority of post-emergent products available for conventional soybeans have limitations regarding the size of weed the products can control, where smaller weeds are generally easier to control. Most post-emergent products also have crop stage restrictions, meaning that if an application is made after the labeled maximum crop stage damage and yield loss can occur. Background knowledge of herbicides including weed size and crop stage restrictions, time-sensitive scouting to identify any escapes and the ability to take action quickly are all necessary factors for the management of weeds in IP soybean production. Any weeds that do escape control, even at levels that may not significantly impact yield, pose an additional challenge for IP soybean production. Escaped weeds often do not mature as early as the crop and remain succulent at harvest (Figure 3). When this weed material passes through the Figure 1. Perennial weeds, such as Canada thistle or perennial sow-thistle, are best controlled in rotational crops, as few options exist for control in IP soybeans. Source: BASF Internal Research Trial, Maryhill, ON, Figure 2. Relying on a single mode of action will not provide effective control of resistant biotypes, such as triazine-resistant lamb s-quarters. Source: BASF Internal Research Trial, Maryhill, ON, Figure 3. Scattered weed escapes may not have a big impact on yield but can cause seed quality issues at harvest. Source: BASF Internal Research Trial, Maryhill, ON, 2013. combine moisture is released resulting in direct stains on the beans or dampening of the seed to which dirt may stick, causing dirt tags. Since the physical appearance of the crop is a quality parameter associated with IP soybeans, staining or tags may result in the crop failing to meet grade standards. Delaying harvest until the weeds naturally dry down, either by senescence or a killing frost, is an alternative option. However, this is not commonly adopted as suitable weather is never a given around harvest time and other quality issues may arise due to the wet-dry cycles common with fall weather. Harvest aids that control and dry down the weeds prior to harvest are another option. When applied properly harvest aids can help get the combine in the field quickly while still maintaining the quality of the seed. Harvest aids can also help control problematic weeds, reducing the pressure for subsequent crops. Some IP contracts will stipulate which harvest aid products may or may not be used, so be sure to clarify any restrictions prior to application. Overall, growing high-quality crops is something that all producers strive to accomplish. With IP soybeans, the quality standards are higher, but this high quality is linked to a premium price. And while this premium can be viewed as a reward for quality, it should be viewed as a reward for the management required to achieve such quality. References: 1) en-us/default.aspx. Retrieved February 28, 2015.
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