Some producers throughout Oklahoma have been delayed in getting their wheat crop established due to fall armyworm and/or the rainfall we have had throughout October. While we are now outside of the optimum planting window for grain-only wheat production, the good news is that late-planted wheat can still yield well if environmental conditions cooperate and if producers make a couple management adjustments.
Seeding rates: The main problem with late-planted wheat is reduced tillering and slowed canopy closure when compared to earlier-planted wheat. On average, wheat plants sown in early- to mid-October will produce 2-3 tillers/plant. At a seeding rate of 60 lbs/acre (20-25 seeds/ft2 depending on seed size), the 2-3 tillers/plant can help us achieve the 60-70 heads/ft2 needed to maximize grain yield. Wheat planted in early- to mid-November may only produce 1-2 tillers/plant. Therefore, seeding rates right now should be increased by as much as 50% and increased by as much as 100% if planting gets delayed past mid-November. So, if a producer uses a 60 lbs/acre seeding rate during the optimum planting time, the seeding rate should be increased to around 90 lbs/acre for right now and then increased to 120 lbs/acre past mid-November.
There may be questions too on replanting decisions during this time of year. This can be a challenging decision, but the first step is to count the number of plants in different parts of the field to assess the stand. A thin but uniform stand will have more yield potential than one that is thick in some areas but nonexistent in others. During the optimum planting time, a thin but uniform stand (50% of the target stand for example) would likely be enough to keep, given adequate fertility and favorable weather conditions that would allow for tillering to help compensate. However, a similar scenario for a wheat field emerging at this time will need help. After assessing the stand, areas with thin or nonexistent stands should be filled in to reach your desired stand target. If replanting into an existing stand, it should be done at an angle (up to 45 degrees) to minimize damage to the existing stand.
Fertility: Late-planted wheat will need all the help it can get when it comes to fertility. The root system for late-planted wheat will likely not be extensive enough to intercept a significant amount of soil phosphorus until the spring. An in-furrow application a P fertilizer (50 lbs/acre of DAP for example) can be of great benefit. With this, the fertilizer is closer to the young seeding, and the plant can get to it sooner. Nitrogen fertilizer can also be used to encourage tillering. However, rather than increasing fall N rates, late-planted fields should be put at the top of the list for topdressing in January or February. There is most likely enough N available between residual soil N and any starter fertilizer N for growth this fall since wheat in grain-only production does not need much N (up to 20-25 lbs/acre) in the fall to get good establishment. Using N-rich strips can aid in determining when to apply topdress N, and a more accurate amount to apply can be determined using sensor-based methods.
Variety selection: It is most likely too late to make any switches in variety selection. If there is an opportunity to change varieties though, using a variety with good tillering ability and earlier maturity may be of benefit. A good tillering variety can help compensate for the less available time this fall for tiller development; whereas, a low-tillering variety may not be able to produce any tillers this fall. Late-planted wheat may also result in delayed development in the spring and force the grain fill period to be shorter by occurring later when environmental conditions are likely warmer and drier. An earlier maturing variety could be used to offset this chance that grain fill occurs during suboptimal conditions.
Pests: Finally, it is important not to short-change a late-planted wheat crop in terms of pest management. Remember that a late-planted crop has less competitive ability than an early-planted crop. Control insect pests as soon as thresholds are reached, and make herbicide applications while weeds are still small and have not yet removed large amounts of nutrients and soil moisture.
This article was written by Dr. Tom Royer, Extension Entomologist
Lanie Hale, from Wheeler Brothers sent a picture of “window paned” wheat from a field that he had scouted. He counted 3 fall armyworms per row foot from his visual count (which is treatment threshold) but when he looked closely at his photo on his computer, he saw 15 worms in an area the size of his hand (they were very tiny, and probably newly hatched). It is easy to miss some of these little worms in the field because they hide in residue and are very tiny.
Look very closely for “window paned” leaves and count all sizes of larvae. Examine plants along the field margin as well as in the interior, because they sometimes move in from road ditches and weedy areas. The suggested treatment threshold is 2-3 larvae per linear foot of row in wheat with active feeding. Numerous insecticides are registered for control, but they are much more susceptible when caterpillars are small. We won’t get relief from fall armyworms until we get a killing frost, so keep vigilant!
Consult the newly updated OSU Fact Sheets CR-7194 Management of Insect and Mite Pests of Small Grains for control suggestions.
Soil temperatures in Oklahoma can be hot when planting in late August to early September for forage-only or dual-purpose wheat (Figure 1). Seed that was planted into soils with temperatures above 85° F may result in delayed germination or prevent wheat seedling emergence. In addition to the soil moisture status since planting, listed below are two factors that may cause poor early stand establishment when wheat is sown into hot soils.
Figure 1. Maximum soil temperature at a 4 inch depth under bare soil over the past three weeks near Altus. We can assume that the maximum soil temperature at shallower depths was likely higher. Data is from Oklahoma Mesonet.
High temperature germination sensitivity: This is a more elaborate way of saying that some wheat varieties do not germinate well in hot soil conditions. This is not to say that the seed will not germinate at all, but it may not germinate until the soil temperature has lowered. Keep in mind too that this sensitivity can vary from year to year. For example, a sensitive variety like Ruby Lee may germinate fine in 90° F soils one year and only produce a 10% stand in the same soil conditions the next. When sowing early, it is best to plant varieties first that do not have high germination sensitivity (e.g., Duster, Gallagher). Soil temperatures typically begin to cool by about September 20 due to lower air temperatures and/or rainfall events. Waiting until at least mid September to plant sensitive varieties can help reduce the risk of this issue. A rating of high temperature germination sensitivity for wheat varieties can be found in the OSU Fact Sheet PSS-2256 Factors Affecting Wheat Germination and Stand Establishment in Hot Soils.
Coleoptile length: The coleoptile is the rigid, sheath-like structure which protects the first true leaf and aids it in navigating and reaching the soil surface. Once the coleoptile breaks the soil surface, it will stop growing, and the first true leaf will emerge. If the coleoptile fails to reach the soil surface, the first true leaf will emerge below ground and usually takes on an accordion-like appearance (Figure 2A-B). If this happens, the plant will die.
Figure 2A and 2B. Example of two different wheat seedlings in which the coleoptile failed to break the soil surface. The first true leaf emerged below the soil surface and resulted in this accordion-like appearance.
The coleoptile length for most wheat varieties today can allow for the seed to be safely planted up to 1.5 inches deep. Under hot soil conditions though, the coleoptile length tends to be decreased. Therefore, “dusting in” early-sown wheat at ¾ to 1 inch depth and waiting on a rain event may result in more uniform emergence than trying to plant into soil moisture at a deeper depth if soil moisture is not available in the top 1 to 1.5 inches of the soil profile. A rating for coleoptile length for wheat varieties can be found in the OSU Fact Sheet PSS-2142 Wheat Variety Comparison (P.S. we are working on updating this).
Fall armyworm was a significant pest for producers in Oklahoma last year, and this year is setting up to be the same scenario. It is out in full force already in some areas, and you may have seen or heard Dr. Tom Royer recently discuss how this insect has been active over this summer, especially on bermudagrass and fescue pastures. Wheat planting is already underway in some areas of the state. As wheat planting progresses here in September, producers need to check their wheat fields very regularly after seedling emergence. Fall armyworm can decimate large fields within a few days. Scout for fall armyworms by examining plants in several (5 or more) locations in the field. A good place to start is along the field margin as they sometimes move in from the road ditches and weedy areas, but make sure to examine the interior of the field as well. Fall armyworms are most active in the morning or late afternoon.
Fall armyworms are small (3/8-1 1/2″) and can be easily overlooked (top photo). Feeding on leaves gives a transparent (“window paned”) appearance (bottom photo). Photos courtesy of Dr. Tom Royer.
Be on the lookout for “window paned” leaves, and count all sizes of larvae. The suggested treatment threshold is 2-3 larvae per linear foot of row in wheat with active feeding. Numerous insecticides are registered for control, but they are much more susceptible when caterpillars are small. We will not get relief from fall armyworms until we get a killing frost. So make sure to keep scouting regularly, especially with this early-planted wheat!
Fall armyworm can cause significant damage like this across large areas very quickly, so scout early and scout often. Photo courtesy of B. Boeckman.
Control suggestions for fall armyworm are available in the OSU Fact Sheets CR-7194 Management of Insect and Mite Pests of Small Grains.
The 2017-2018 wheat growing season is setting up similar to last year with many producers wanting to target more of the forage side of wheat production given the low commodity prices. That, coupled with the available soil moisture from the rainfall throughout August, has prompted some producers to get the drills rolling already over the past week in some parts of the state. As planting gets going, here are a couple considerations when it comes to planting dates and seeding rates for winter wheat in Oklahoma.
The optimal window for dual-purpose wheat for most of Oklahoma is between September 10-20 (approximately day 260 in Figure 1). This window represents a trade-off between maximizing forage production while minimizing potential grain yield loss. Earlier planting dates, last week into this week for example, will provide more fall forage potential, but this is usually not recommended unless the wheat is intended to be produced for grazing, or “grazeout.” Planting dates for grain-only producers will be at least 2-3 weeks later than what is the ideal dual-purpose planting date for your area. For many areas in Oklahoma, this will be around mid-October (approximately day 285 in Figure 1).
Figure 1. Forage and grain yield potential in relation to the day of the year. Every 1,000 kg/ha is equal to approximately 900 lb/acre or 15 bu/acre. Ideal planting dates for dual-purpose wheat in Oklahoma are mid-September (i.e., approximately day 260). Planting for grain-only should occur at least 2-3 weeks after dual-purpose planting (i.e., mid-October or approximately day 285).
Producers in forage-only or dual-purpose management should plant 1.5-2x the amount of seed that is recommended for grain-only production. For example, data collected in north-central Oklahoma has showed that increasing the seeding rate from 60 to 120 lb/acre can increase fall forage potential by as much as 500 lb/acre for a mid-September planting date (September 11 in Figure 2). The increase in forage potential by using this higher seeding rate can justify the cost of the extra seed. OSU recommends 120 lb seed/acre for most areas of Oklahoma, including irrigated fields in the Panhandle. Seeding rates for dryland fields in the Panhandle for this type of management can be lowered to 90 lb/acre. OSU recommends a 60 lb/acre seeding rate for grain-only production when planted during that optimal mid-October time. Dryland fields in the Panhandle can have their seeding rate lowered to 45 lb/acre. If planting happens to get delayed in November this year, seeding rates will need to increase to provide enough available tillers to still maintain maximum grain yield potential.
Figure 2. Fall forage yield collected in north-central Oklahoma as affected by seeding rate and planting date. Source: PSS-2178.
More information about dual-purpose wheat management can be found in the fact sheet PSS-2178 Dual-purpose Wheat: Management for Forage and Grain Production.
This article was written by: Dr. Bob Hunger, Extension Wheat Pathologist, & Dr. Tom Royer, Extension Entomologist, Department of Entomology & Plant Pathology Oklahoma State University
Planting date: Much of the winter wheat in Oklahoma is sown with the intent of being used as a dual-purpose crop. In such a system, wheat is grazed by cattle from late fall through late winter/early spring and then harvested for grain in early summer. In a grain-only system, wheat is generally planted in October, but in a dual-purpose system wheat is planted in early to mid-September to maximize forage production. Planting wheat early significantly increases the likelihood that diseases and insect pests such as mite-transmitted viruses, the aphid/barley yellow dwarf complex, root and foot rots, and Hessian fly will be more prevalent and severe. For more detailed information on planting date and seed treatment considerations on wheat, see CR-7088 Effect of Planting Date and Seed Treatment on Diseases and Insect Pests of Wheat at http://wheat.okstate.edu/wheat-management/seeding/CR-7088web2012.pdf.
Mite-transmitted virus diseases: These virus diseases are transmitted by wheat curl mites (WCMs) (Figure 1), and include wheat streak mosaic (WSM), high plains disease (also called wheat mosaic), and Triticum mosaic (TrM). WCMs and these viruses survive in crops such as wheat, corn, and sorghum as well as many grassy weeds and volunteer wheat. In the fall, WCMs spread to emerging seedling wheat, feed on that seedling wheat, and transmit virus to the young wheat plants. During 2016 and 2017, these mite transmitted virus diseases (especially WSM) were severe across much of the wheat growing areas of Oklahoma as well as in many of the other Great Plains states. Weather is a determining factor in the increased incidence and severity of these virus diseases, but another major contributor is the lack of control of volunteer wheat and other grassy weeds that serve as alternative hosts for the mite and the viruses. Often, an infected field of commercial wheat is growing immediately adjacent to a field left fallow during the fall and winter (Figure 2). The fallow field contained abundant volunteer wheat and grassy weeds from which WCMs carrying Wheat streak mosaic virus (WSMV) spread into the commercial field. Wheat infected in the fall will be severely damaged the next spring. Hence, it is imperative to do yourself and your neighbors a favor by controlling volunteer wheat and grassy weeds in fields left fallow – especially, if they are adjacent to commercial wheat fields.
Seed treatments and insecticides are not effective in controlling the mites or these mite-transmitted virus diseases. However, planting later in the fall (after October 1 in northern OK and after October 15 in southern OK) and controlling volunteer wheat are two practices that can be employed to help manage these diseases. It is extremely critical that volunteer wheat is completely dead for at least two weeks prior to emergence of seedling wheat because WCMs have a life span of 7-10 days. Thus, completely killing or destroying volunteer wheat for a period of at least two weeks prior to emergence of seedling wheat will greatly reduce mite numbers in the fall. There are several winter wheat varieties that have resistance to either WSM or the curl mites, but the adaptation of these varieties to Oklahoma is limited. Additionally, the resistance is not an absolute resistance to the disease. Hence, severe and continuous disease pressure can overcome the resistance although disease effects typically is less as compared to a susceptible variety. For more information on mite-transmitted virus diseases, see OSU Fact Sheet 7328 Wheat Streak Mosaic, High Plains Disease and Triticum Mosaic: Three Virus Diseases of Wheat in Oklahoma) at: http://wheat.okstate.edu/wheat-management/diseasesinsects/EPP-7328%20three%20virus%20diseases%20of%20wheat.pdf.
Aphid/barley yellow dwarf (BYD) complex: Viruses that cause BYD are transmitted by many cereal-feeding aphids (Figure 3.). BYD infections that occur in the fall are the most severe because virus has a longer time to damage plants as compared to infections that occur in the spring. Several steps can be taken to help manage BYD. First, a later planting date (after October 1 in northern Oklahoma and after October 15 in southern Oklahoma) helps reduce the opportunity for fall infection. Second, some wheat varieties (e.g., Duster, Billings, Gallagher, Iba, Bentley, Tatanka, and Winterhawk) tolerate BYD better than other varieties; however, be aware that no wheat variety has a high level of resistance to the aphid/BYD complex. Third, control aphids that transmit the viruses that cause BYD. This can be done by applying contact insecticides to kill aphids, or by treating seed before planting with a systemic insecticide. Unfortunately, by the time contact insecticides are applied, aphids frequently have already transmitted the viruses that cause BYD. Systemic seed-treatment insecticides containing imidacloprid or thiamethoxam can control aphids during the fall after planting. This may be particularly beneficial if wheat is planted early to obtain forage. Be sure to thoroughly read the label before applying any chemical.
Hessian fly: Hessian fly (Figure 4.) infestations can occur in the fall and spring. Fall infestations arise from over-summering pupae that emerge when climate conditions become favorable. In states north of Oklahoma, a “Hessian fly free” planting date often is used to help limit fall infestations by Hessian fly. However, such a planting date does not apply in Oklahoma because Hessian fly can emerge in Oklahoma as late as December (Figure 5).
Delayed planting (after October 1 in northern Oklahoma, and after October 15 in southern Oklahoma) can help reduce the threat of Hessian fly, but a specific “fly free date” does not exist for most of Oklahoma as it does in Kansas and more northern wheat-growing states. This is because smaller, supplementary broods of adult flies emerge throughout the fall and winter. Some wheat varieties are either resistant (e.g., Duster, Gallagher, SY Flint, and LCS Wizard) or partially resistant [e.g., LCS Chrome, Everest, Ruby Lee (at cooler temperatures)] to Hessian fly infestations. Hessian fly infestations can be reduced somewhat by destroying volunteer wheat in and around the field at least two weeks prior to emergence of seedling wheat. Seed treatments that contain imidacloprid or thiamethoxam will also help reduce fly fall infestations, especially if combined with delayed planting and volunteer destruction. For more information on Hessian fly, see OSU Fact Sheet EPP-7086 Hessian fly Management in Oklahoma Winter Wheat at: http://wheat.okstate.edu/wheat-management/diseasesinsects/EPP7086hessianflyinoklahoma.pdf.
Root and foot rots: These are caused by fungi and include several diseases such as dryland (Fusarium) root rot, Rhizoctonia root rot (sharp eyespot), common root rot, take-all, and eyespot (strawbreaker) (Figure 6). During the late spring of 2016 and 2017, several samples of wheat were received that were diagnosed as being affected by take all and other root rots. This could indicate a greater incidence of wheat root rots in 2017-18, but the incidence and severity of root rots is highly dependent on weather conditions so it is impossible to predict their incidence and severity this early.
Controlling root and foot rots is difficult. There are no resistant varieties, and although fungicide seed treatments with activity toward the root and foot rots are available, their activity usually involves early-season control or suppression rather than control at a consistently high level throughout the season. Often, there also are different “levels” of activity related to different treatment rates, so again, CAREFULLY read the label of any seed treatment to be sure activity against the diseases and/or insects of concern are indicated, and be certain that the seed treatment(s) is being used at the rate indicated on the label for activity against those diseases and/or insects. Later planting (after October 1 in northern Oklahoma and after October 15 in southern Oklahoma) also can help reduce the incidence and severity of root rots, but planting later will not entirely eliminate the presence or effects of root rots. If you have a field with a history of severe root rot, consider planting that field as late as possible or plan to use it in a “graze-out” fashion if that is consistent with your overall plan. For some root rots, there are specific factors that contribute to disease incidence and severity. For example, a high soil pH (>6.5) greatly favors disease development of the root rot called take-all. OSU soil test recommendations factor in this phenomenon by reducing lime recommendations when continuous wheat is the intended crop. Another practice that can help limit take-all and some of the other root rots is the elimination of residue. However, elimination of residue by tillage or burning does not seem to affect the incidence or severity of eyespot (strawbreaker).
Seed treatments: There are several excellent reasons to plant seed wheat treated with an insecticide/fungicide seed treatment. These include:
- Control of bunts and smuts, including common bunt (also called stinking smut) and loose smut. The similarity of these names can be confusing. All affect the grain of wheat, but whereas common bunt and flag smut spores carryover on seed or in the soil, loose smut carries over in the seed. Seed treatments are highly effective in controlling all the bunts/smuts. If common bunt (stinking smut) was observed in a field and that field is to be planted again with wheat, then planting certified wheat seed treated with a fungicide effective against common bunt is strongly recommended. If either common bunt or loose smut was observed in a field, grain harvested from that field should not be used as seed the next year. However, if grain harvested from such a field must be used as seed wheat, treatment of that seed at a high rate of a systemic or a systemic + contact seed treatment effective against common bunt and loose smut is strongly recommended. For more information on common bunt & loose smut, see: http://www.entoplp.okstate.edu/ddd/hosts/wheat.htm and consult the “2017 OSU Extension Agents’ Handbook of Insect, Plant Disease, and Weed Control (OCES publication E-832),” and/or contact your County Extension Educator.
- Enhance seedling emergence, stand establishment and forage production by suppressing root, crown and foot rots. This was discussed above under “Root and Foot Rots.”
- Early season control of the aphid/BYDV complex. This can be achieved by using a seed treatment containing an insecticide. Be sure that the treatment includes an insecticide labeled for control of aphids.
- Control fall foliar diseases including leaf rust and powdery mildew. Seed treatments are effective in controlling foliar diseases (especially leaf rust and powdery mildew) in the fall, which may reduce the inoculum level of these diseases in the spring. However, this control should be viewed as an added benefit and not necessarily as a sole reason to use a seed treatment.
- Suppression of early emerged Hessian fly. Research suggests that some suppression can be achieved, but an insecticide seed treatment has little residual activity past the seedling stage.
Authored by: David Marburger and Bob Hunger
Wheat streak mosaic (WSM) was a significant disease issue for a number of producers in Oklahoma this past year (Figure 1). This disease, caused by wheat streak mosaic virus, is transmitted by the wheat curl mite (Figure 2). This mite can survive from one wheat growing season to the next on a number of different grass species, but primarily on volunteer wheat. Some like to refer to these host weeds or volunteer wheat during the summer fallow period as the “green bridge.” One of the best ways to manage this disease is controlling the wheat curl mite by eliminating the green bridge, and this can be done with tillage or a herbicide application. Since the life span of the wheat curl mite is about two weeks, volunteer wheat needs to be dead (i.e., no green tissue) for at least two weeks prior to the emergence of the newly planted wheat crop. If you spray glyphosate two weeks prior to emergence of the new wheat crop, for example, this will likely not control the wheat curl mite as the volunteer wheat will not be dead (no green tissue) for that minimum two week period.
Figure 1. Symptoms of wheat streak mosaic.
Figure 2. Wheat curl mites on a leaf surface at approximately 30-40x magnification. Source: Texas A&M.
With the current wheat prices, rain that has fallen, and rain in the forecast (trying not to jinx it here), producers especially in southern Oklahoma are going to be ready to plant by the end of August into early September to target more fall forage. In that scenario, volunteer wheat needs to be controlled right now in order to have that plant tissue dead for the minimum two week period prior to the emergence of the new wheat crop. For producers who will be planting a little later than this, there is a little bigger window for controlling that volunteer wheat yet, but it is something to keep at the top of your to-do list.
More information on wheat streak mosaic and wheat curl mites can be found in the OSU Fact Sheet EPP-7328 Three Virus Diseases of Oklahoma.
The full report for this year’s variety performance tests is now available on the wheat.okstate.edu website. You can also access it by clicking here.
I want to thank the Small Grains Extension crew, our Oklahoma State University Extension personnel, our farmer cooperators, and the participating seed companies for another successful year for the variety testing program! I also want to thank the Oklahoma Wheat Commission and Oklahoma Wheat Research Foundation for their financial support!
At the time of writing this report, 2017 Oklahoma wheat production is estimated to be approximately 89.1 million bushels, which is about 35% less than the 2016 production (Table 1) and 9% less than the 2015 production. The lower total grain production is the result of less wheat acres in the state this year. The 4.5 million planted acres was down 10% compared to the previous year, and with low wheat prices during the season, harvested acres were down as well. Number of harvested acres is estimated at 2.7 million, which is 23% less than in 2016 (Table 1). Despite the lower harvested acres, the statewide average yield is projected at 33 bu/ac. This is 6 bu/ac (18%) less than the record-tying 2016 state average but 4 bu/ac (12%) greater than the previous ten-year average.
The 2016-2017 wheat growing season can be characterized overall by periods of rainfall and near optimal growing conditions at critical times. The growing season got an early start with rainfall in late August, prompting producers interested in targeting fall forage to begin planting. Planting continued to move rapidly during early September, and most of the wheat at this time was sown into adequate soil moisture and emerged rapidly. Wheat intended for grain-only was sown during the average timeframe of early- to mid-October. A majority of the wheat sown at this time also had adequate soil moisture for good establishment, but most of the Northwest and Panhandle regions of the state were not as fortunate. Dry soil conditions in those regions resulted in suboptimal stands or no germination at all. After mid-October, little precipitation fell throughout the state for the remainder of the fall, and temperatures were above normal. Crop conditions during the early part of the growing season were rated mostly good, but with the lack of rainfall during the latter part of fall, crop conditions began deteriorating by the end of November. Fortunately, most of the wheat that was sown into adequate soil moisture was able to establish adequate above- and below-ground growth before going into winter dormancy.
Warmer than normal temperatures continued throughout much of the winter. January and February are normally very dry months for the southern Great Plains. Fortunately, much of the state received two to four inches of precipitation during mid-January. While some of the precipitation came in the form of ice in the Woodward area, it did not do much damage to the crop. It also provided the soil moisture needed for some wheat to germinate in the Northwest and Panhandle regions that had been sown in dry conditions.
With the above-average temperatures during the winter, plants broke winter dormancy ahead of normal, and spring green-up advanced quickly. The first hollow stem growth stage was reached for many varieties before the end of February, almost two weeks ahead of normal. Another round of widespread showers fell across much of the Wheat Belt on February 20, excluding the Panhandle and northeastern parts of the state. For some areas, this provided a boost to help plants recover from grazing injury. Other areas, especially south central Oklahoma, did not receive as much of this needed rainfall, and as a result, some grazed wheat pastures did not recover as well. Considering the warm temperatures during spring green-up, the prevailing thought was that much of the wheat would be mature and harvested by mid-May. However, temperatures returned to normal and slightly below normal during mid- to late-March. Many areas received another round of rainfall at the end of March, providing adequate soil moisture as the wheat crop transitioned into reproductive growth. Cool temperatures and adequate soil moisture persisted throughout heading and grain fill, favoring kernel filling. One abnormal weather event that occurred this year was a foot of snow that accumulated in the Panhandle on the last weekend in April. This did result in lodged plants and some lower test weight values, but the overall effect on yield was not as detrimental as expected at the time.
Most wheat was mature in southwestern Oklahoma by the middle of May and by the end of May in the central part of the state. Producers for the most part were not delayed by rainfall events, and with the dry weather during June, much of the wheat was harvested timely and quickly. Overall, harvest was almost complete in the state by late June.
Yields throughout Oklahoma were variable depending on location but were above average overall. Part of this variability was due to overgrazing and whether an area caught or missed a rainfall event that occurred only about every three to four weeks throughout the beginning of 2017. Field averages of 30 to 40 bu/ac were the norm across much of the state, but higher averages, even into the 60 to 70 bu/ac range, were not uncommon in some areas. Test weights throughout harvest remained at or above 60 lb/bu for early-harvested fields and did not drop much below the upper 50’s towards the end of harvest.
Different insect pressures were a concern at times during the growing season, but few were widespread, overlapped, or season-long. Some of the wheat planted in late August into early September was hit hard by fall armyworm, and some fields had to be replanted. Dead tillers on varieties susceptible to Hessian fly showed up on early planted wheat in areas of southwest Oklahoma during mid-fall, but only a couple reports of Hessian fly were documented during the spring. The dry weather in northwest Oklahoma through the winter provided ideal conditions for winter grain mite and brown wheat mite to thrive on wheat plants coming out of winter dormancy. Aphids were not really on the radar screen of most producers until mid-March, but this turned out as not as big of a problem as has been observed in other previous years. Despite the low aphid numbers, it was not hard to find Barley Yellow Dwarf (BYD) as flag leaves and heads started to emerge. While there was quite a bit of purpling and yellowing associated with BYD, there was not as much stunting as sometimes observed with early-season transmission of the virus. Wheat Streak Mosaic (WSM), transmitted by the wheat curl mite, was a significant issue for producers around the state, but the majority of the affected areas seemed to be concentrated in areas of southwestern and northwestern Oklahoma, as well as the Panhandle region. Yield reductions were definitely apparent in fields infected with WSM.
The warm temperatures and available moisture during the fall prompted the development of some foliar diseases, primarily leaf rust. Leaf rust spores were able to survive the winter due to mild conditions, but the disease was slowed by hot temperatures and lack of available moisture during spring green-up. However, when temperatures returned to normal during mid- to late-March, the abundant inoculum present allowed leaf rust to become one of the top diseases for producers across most of the state. The presence of leaf rust during 2017 was abnormal compared to previous years as it developed sooner and persisted through grain fill while also reaching a wider geographic area. In addition to leaf rust, stripe rust was present, but at low to moderate levels in isolated areas and not as widespread throughout the state as it was in 2015 and 2016. Because of the impact that both rusts have had over the past couple years, producers were more open to apply a foliar fungicide to susceptible varieties, with many fields throughout the state receiving at least one fungicide application. Variety trial results from Apache, Chickasha, and Lahoma indicated again this year that producers were well justified in spraying many of these acres. Grain yield of the variety Bentley, for example, resulted in a 27 bu/ac increase at Lahoma when treated once with a foliar fungicide at flag leaf emergence. Our results at Lahoma also showed the power of genetic resistance to disease in varieties such as Doublestop CL Plus in which the fungicide treated plots only resulted in a 1 bu/ac increase in yield over the non-treated plots.
Oklahoma Harvest Continues in the Panhandle, Is Wrapped up in All Other Regions of the State for the Most Part
Report by the Oklahoma Wheat Commission
The Oklahoma wheat harvest is complete in most areas from the Oklahoma/Texas border to the Oklahoma/Kansas border. In the Panhandle region harvest is in full swing with producers working on the dryland wheat harvest and irrigated harvest. Yields have not been as positive in the Panhandle regions on both the dryland and irrigated wheat. A lot of dryland wheat yields have been reported in the mid 20’s with a lot of irrigated wheat yields reported in the mid 40’s to mid 50’s. Heavy rains with severe hail has also impacted areas between Boise City and Guymon. Elevators in the Panhandle region are planning on taking in approximately 50 to 55% of the crop they took in last year. Protein levels in the Panhandle region have been holding up even on the irrigated wheat for the most part. While a lot of the dryland wheat is above 12% protein even with the slightly lower percentages in the irrigated wheat, producers and elevator managers are hoping for an 11.8 to 11.9% average for the region. Test weights for the region are averaging 60 to 61 lbs./bu. Harvest around the Guymon and Hooker areas is 70 to 75% completed with harvest out by Boise City approximately 40% completed.