These are the preliminary results from the Oklahoma State University grain sorghum hybrid trials. Complete summaries will be provided following harvest. Data from the hybrid trials in the panhandle will be provided following harvest. These trials should be harvested near the end of October. If there are any questions or comments please feel free to contact your local extension educator or myself directly.
Canola planting is right around the corner. While last season’s canola crop had mixed results with many growers not achieving the yields they expected, there are several things growers can do prior to planting that can pay off later in the season and promote crop productivity and success.
Weed control is vital for canola production. Successful use of herbicides can help control problematic grassy weeds, which is one of the primary benefits of integrating canola in Oklahoma production systems. Within the canola production season, most canola yield losses associated with weed competition is early in the growing season. Once the crop is established, it can typically outcompete most weeds. However, this is only true if the crop was maintained weed-free up until this point. Therefore, preplant herbicide programs are essential to make sure the crop established into weed-free conditions. While there are a limited number of herbicide active ingredients that are labeled for preplant use in canola, those labeled are typically quite effective at managing weeds within the crop. Most growers would benefit from a preplant program that integrated a residual herbicide to delay in-season applications until the crop has been established. This is why one of the better preplant herbicides options is Trifluralin. Trifluralin can help manage most fall weed species as long as the seedbed is relatively clean and the herbicide is incorporated into the soil within 24-hours of application. This is why Trifluralin is a good option for producers that integrate tillage practices, as tillage can both clean the seedbed and incorporate the herbicide after application.
Fewer options are available for no-till canola producers. Glyphosate is really the primary option for pre-plant herbicide application, since incorporation cannot be done. Glyphosate can still be used with using conventional canola cultivars, as long as the application is made prior to emergence. Additionally, glyphosate can only control weeds that have already emerged and does not have any residual control. This results in the need for further applications in-season. Oklahoma State University is currently evaluating several other preplant herbicide options but as of this time these are all off label and considered illegal applications.
Soil nutrient management is also a practice that can help canola establish and achieve good early season growth. While we are very close to planting, soil testing and fertilizer applications are still a management practice growers can do to help the crop. Soil test results should help guide fertilizer applications but enough P and K are needed at planting and early in the fall. However, higher rates of both P and K are frequently associated with products that contain relatively high amounts of N. While canola does need N in the fall, too high of N fertilizer applications can lead to excessive fall growth and in-turn potentially higher winterkills. Enough N should be applied to ensure the crop does not stress but limit fall growth. Most growers should be able to utilize the 1/3 and 2/3 method, where only up to a third of the N is applied in the fall and higher rates are applied at green-up in the spring.
One application that has shown benefit in canola has been an application of N and P with the seed at planting. While these applications do not always translate to increased crop yields, especially if fields are not low pH or low STP, but can promote early season growth and increased root growth. These applications can either be applied in-furrow or beside the row. However, it must be cautioned that, due to the salt sensitivity of winter canola, in-furrow fertilizer applications cannot be made at rates as high as in wheat crop. This application provides both N and P to the canola crop early in the crop cycle and allows it to achieve good growth early in the season.
Probably the most important management considerations are the decisions grower make around planting. While other practices discussed can alter early season growth, these considerations will directly influence the growth of the crop.
There are several cultivars that are well adapted to Oklahoma systems. These include both conventional and glyphosate-tolerant cultivars. While there is a good amount of flexibility in the glyphosate-resistant cultivars, as they can utilize glyphosate to clean up weedy spots in the fields, yields from the conventional varieties have been competitive if not slightly higher when compared side-by-side in the Oklahoma State Variety trials. Challenges with conventional cultivars, i.e. limited broadleaf weed control, can typically be overcome with adequate early season weed control and adequate plant populations. These conventional varieties have value when growers will double-crop, especially soybean, behind canola as the conventional canola cultivars can be easily controlled with glyphosate. However, with increasing glyphosate-resistant summer weeds and the availability of auxin resistant summer crops, these glyphosate resistant canola cultivars can be a viable option in double crop systems.
Traditional planting dates range from September 10th through October 10th. However, optimum planting usually is during the last 10 days of September for the northern part of the state and the end of September through the first of October for the southern part of the state. When planting early, many producers just want to ensure that enough growth has been achieved before the first killing freeze to store enough reserves in the plant and rooting system to survive the winter. This is a good thought to always have during planting but canola only needs around 6 weeks of growth to increase the likelihood of winter survival. Planting on September 6th would result in 8 weeks before the first average light frost (November 2nd, NOAA), 10 weeks before the first freeze (28F, November 14th, NOAA), and 12 weeks before the first killing freeze (24F, November 25th, NOAA). If a large amount of growth was the only factor in achieving high winter survival and good stands in the spring, then planting into good conditions as early as possible would be the best practices. However, with increased vegetative material, high amount of water and nutrients will be needed to sustain the plant in later winter and early spring. This increased stress can result in diminished winter survival and spring stands. Pushing these planting dates back into late-September into early October can greatly increase winter survival chances in most years.
Several factors go into a successful canola crop. While many of these factors are associated with environmental conditions, proper management of planting will help with early season growth and over-winter survival, allowing growers their best chance at a successful crop in both good and poorer years.
We at Oklahoma State University wish all producers a safe and productive planting time. If any further guidance is needed regarding planting issues feel free to contract your local county extension office, regional agronomist, or myself.
Canola harvest is in full swing with the end right around the corner for much of Oklahoma. This has been a trying year for many across canola growing regions in the state. This has been no different for the Oklahoma State variety testing program. Yields from both Kingfisher and Fairview were relatively disappointing due to high winter loss, poor conditions during early reproductive, and some hail damage during reproduction. However, Pond Creek, Chickasha, and Fort Cobb yielded relatively well. The other four locations will be harvested within the next week to 10 days depending on weather. Keep checking back for other locations.
This spring has been a challenging one for many producers throughout the state. Most crops have struggled at some point during the spring. To date the Oklahoma sorghum crop this year can be fit into three categories, with some growers dealing with all three. Oklahoma sorghum producers are not immune to this and their seasons can probably be fit into three general categories. First are that growers were able to get the crop in a timely manner, had good conditions, and the crop is up and growing. While we would like to see this on most acres, this has not been the case. Most of the sorghum fell into the other two categories. Either growers have not been able to get into their fields and still have sorghum in bags waiting to be planted or were able to be planted but have marginal stands. For growers that have yet to plant, the question has become whether or not to continue with grain sorghum planting. While most growers have to work through the financials on their individual farms, growers still have the ability to establish fields and be quite productive. Historically, we have advised growers at this stage to hold off planting until late-season in order to minimize the impact of traditionally challenging environmental conditions experience in late-June and early-July. However, sugarcane aphids have made the success of late season crop more dependent on insecticide applications. Therefore, if growers are willing to budget 2 insecticide applications and be proactive on scouting and applications, this is still a potential option. Other growers that have stands in the field and question on whether to maintain stands or terminate and replant. This can be a difficult discussion and there can be quite a few things growers must consider before making this decision. As a general rule, if growers have between 18k-20k active plants per acre, adequate yields can still be achieved without an additional seeds planted, especially this late in the season and if the plants still have a reasonably even stands. If stands are spotty or skipping, growers can decide to plant certain areas of the field, while maintaining others. If growers have less than 18k active plants per acre and growers decide that replanting must occur, several times growers can get away with over-seeding the crop over the current stands as opposed to completely terminating and completely replanting. If growers over-seed, it is recommended that growers look at planting around half of the initial seeding rate.
The validity of this critical 18k plant population to maintain a crop depends on several factors. As previously mentioned stand distribution is a critical component. An even stand can maintain high enough canopy coverage to cover the soil surface in order to help maintain soil moisture and help compete against weeds. Another critical aspect is the hybrid that was planted. Hybrids that have lower tillering potential would require higher populations to achieve adequate yields. Without these tillers there just might not be enough heads/acre in order to maintain yields. However, hybrids with better tillering potential can sustain these lower populations while still maintaining adequate yields.
When growers have achieved stands, both weed control and fertility issues start to emerge. If growers have made a large application on fertilizer preplant, especially N, with the current weather patterns we have experienced in the las several weeks, a good portion of this may have already been denitrified or leached deep into the soil profile. This means growers need to be proactive with side-dress applications. To trigger these, growers best option is to make sure to have N-rich strips throughout their fields. If not, growers need to look for overly pale, stunted sorghum and be timely with an application. Nitrogen fertilizer is not the only thing influenced by the moisture in these fields. High levels of moisture and decrease the efficacy of many preplant herbicide programs. Growers many need to make subsequent herbicide applications. This becomes very critical as several chemicals need to be applied prior to the sorghum plant reaches ~30 inches tall.
Sorghum stands with uneven stands (left) of even (right), those on the right still might produce adequate yields.
The challenges that this summer will hold for sorghum producers is still in question. However, it must be noted that sugarcane aphid numbers are growing and moving north through Texas. MyField website numbers as of May 25th, indicate the shift from populations solely in the Gulf Coast to several populations moving into south-central Texas. While there is little need for Oklahoma producers to be concerned at this point, growers need to make sure they are aware of the moving population. If growers are active on their scouting management plans and timely with insecticide applications, most growers in recent years have noted minimal impact of the pest on overall yields. However, if growers get behind, sugarcane aphids will be a challenge for them throughout the season. Currently OSU recommendation for applications are an average of 100 aphids per leaf blade. To scout for aphids, growers need to identify 4 to 5 locations that are representative of the field and collect 5 to 6 plants at each location. For each plant, growers need to look at the underside of the lowest most fully green leaf and the high most fully developed leaf. If the plant is at flag leaf or later in reproductive stages, growers should scout the leaf under the flag leaf. While counting aphids in-field on leaves can be a challenge, a good rule of thumb is 100 aphids per leaf is approximately the size of a quarter to half dollar. As populations tend to congregate on the leaves, growers should also look for multiple smaller populations.
With the recent temperatures experienced across the state in the last week, many growers may be wondering about the damage to their canola crop. Prior to talking about the recent freezes, we need to look at the status of the crop as a whole.
This last winter was one that had several unique challenges. While this had not been the coldest winter we have had in recent years, periods of severe cold weather definitely hurt the crop. Part of this was due to the overly warm fall that most of the state experienced. These warm conditions lead to excessive growth of the crop, leading to crop stem reaching nearly 2 feet in isolated conditions. While much of that state did receive periods of cold and chilling conditions prior to any major freezes, these were mixed with multiple day stretches of over 80°F. This resulted in the crop not being able to properly harden-off and the crop was still somewhat sensitive to freezing temperatures. This meant that freezing temperatures around Thanksgiving and severe freeze (-5 to -20°F) around the 14th of December resulted in fields or areas of the field seeing substantial winter kill. Most of these fields have been seen north of the I-40 corridor; however, area agronomist, Heath Sanders, has seen a number of fields in SW Oklahoma having moderate to severe winter kill. While the outlook may sound bleak, one of the most positive aspects of winter canola is its ability to overcome thinner stands by flexing and increasing branch production during reproductive growth. Therefore, a couple of plants per square foot can still produce adequate yields. Additionally, many of the canola plants may look like they have been completely winter killed but are showing “tillers” out of the base of the plant. While these will not have the same yields as the primary stem, they can help overcome some of the yield losses that can be expected.
This brings us to recent freezing events. The damage that spring freezes can cause to winter canola greatly depend on temperature, time at specific temperatures, growth stage, and moisture. Soil moisture at time of freezing can drastically help save a crop that might otherwise see much higher freeze damage. Another positive about the freezes in the last 7-10 days is that the canola crop has been in the rosette to bolting stages. During these stages, canola can recover from mid- to low-20s temperatures for 1 to 7 hours with relatively little yield loss. Longer consecutive hours, however, can result in substantially increased plant damage, which could state to add up to noticeable yield losses. Therefore, the positively aspect out the crop is that most of the crop should still be in a relatively good conditions (as it pertains to freeze damage). The major loss over the last week might have come at the expense of the “tillers” from plants that were partially killed during the winter. Many of these lateral branches have seen significant damage and many will probably not successfully produce.
As we look forward to the remainder of the season, it is important to be able to identify cold damage to the developing crop and know when the most sensitive periods occur. Typical freeze damage and canola response, at each growth stage, that can be expected are below.
Rosette– Leaf burning can be expected; however, this is typically solely cosmetic. As temperatures warm, new leaves should start to emerge from the rosette. If no new growth is seen, severe enough damage could have been experienced that growth and yield may be limited.
Bolting– Similar to the symptoms that can occur during the bolting stages as they did during rosette but these symptoms can occur not only on the leaves but the stem. These symptoms include a discoloration of the tissue, resulting in the leaves and stems turning yellow, purple, or white. Even with some damage, these plants should progress to flowering with little or no issue. In more severe conditions, the still will be split or crack. While this should have little effect on the plants ability to continue growth, these split stems may increase lodging and provide a port secondary diseases.
Flowering and pod development– Cold temperatures at flowering can be far more damaging. Unopened buds should still produce viable flowers (depending on temperature and time at that temperature). Open flowers or pods can be more damaged by colder temperatures. Flowers can abort or not produce viable seed following a major freeze event. Early pods can become malformed and potentially terminate. These will produce a permanent twisted and curled appearance.
One thing is certain, these cooler temperatures helped slow maturation, if only for a short time. This may help the crop in the coming weeks as freezes later in the season could potentially be more damaging the further the crop matures. One thing must be noted, even with areas of field being killed over winter, we still must treat the field in the appropriate manner to ensure the crop following canola will still receive the benefits. This includes making herbicide applications (as the canola crops still allows for it) to help control problematic winter weeds.
Below is the most recent stand counts (plants per square foot) and a qualitative measure on winter survival (10- no evident winter kill; 1- nearly 100% winter kill; 0- no living canola remaining).