Agronomic management of sorghum to help with sugarcane aphids

With warming temperatures and March upon us, many growers are looking toward their summer crops and starting to think about acreage and planting decisions.  While there has been much concern over the last several years about the increased presence of the sugarcane aphid, growers should know there are several things that they can do now and in the next several weeks to maximum sorghum growth and productivity while minimize the impact of these pests. 

Hybrid Selection:

Hybrid selection is probably the most effective and cheapest way to help manage against sugarcane aphids.  Through the last several years, many hybrids have been identified to have varying degrees of tolerance to sugarcane aphid pressure.  Below is the current up-to-date list of tolerant sorghum hybrids that have been both proven in university trials and are currently commercially available. 

Resistant_hybrids
Tolerant sorghum hybrids.

It should be noted that these hybrids are resistant or tolerant in the truest sense.  With increased number of resistant weeds, we have denoted resistances either the inability to control or complete insensitivity.  Using this mentality, a resistant hybrid would no longer be affected by the sugarcane aphids.  Unfortunately, this is not the case.  These hybrids are resistant in that they provide some level of resistance to these pests not complete elimination of the treat.  This is why many people will refer to these hybrids are tolerant or susceptible. 

Planting:

While selecting a tolerant hybrid is increasingly important, it is only the first step.  Timely planting can be argued to be the most important step into a successful grain sorghum crop in Oklahoma.  Timely planting will greatly improve sorghum yields.  The major contributing factor to this is trying to avoid having critical sorghum growth stages during sub-optimal times of the year (i.e. sorghum flowering and grain fill during the end of July and the first of August).  Outside of the panhandle, the optimum time for planting sorghum is typically from early April through early May.  The further into May growers plant, the risk is increased that they will be pairing flowering or grain fill during hot, dry conditions.  It must be stated that this is only a guideline and some years May plantings will produce suitable yields; however, the risk associated is typically much higher compared to earlier planting.  Recent work at Oklahoma State University (multiple locations across northwest Oklahoma) documented at nearly 30% decrease in crop yield associated with Mid-May plantings compared to Mid-April. 

Yield by date
Percent of total yield associated with planting date.  Data is averaged from multiple locations in northwestern Oklahoma.

The benefits of earlier planting are more evident in current production systems due to the sugarcane aphids.  With earlier plantings, growers should be looking for the crop to reach the later stages of soft dough or hard dough prior to infestation.  This makes these pests only a minor yield limitation, compared to earlier infestations.  These pests will still have to be managed at harvest but yield in field is less impacted. 

Historically, if growers could not plant during the month of April, it was advised to delay planting until June.  However, with increased presence of sugarcane aphids, this will not always successfully save the crop.  Additionally, compared to years ago, double-crop planting has become a riskier practice.  This is because by the time the crop has reached the critical reproductive stages, sugarcane aphids will have built up on full-season sorghum and heavy infestations will be more impactful on these younger (already highly stressed) plants.  This does not mean double-crop production is not worth considering, but other critical management practices (i.e. tolerant hybrids and timely chemical applications) become more critical than with full-season production systems. 

Overall, proper agronomic management can help a sorghum crop that would otherwise not provide suitable or profitable production.  These, however, are not silver bullets and will solely help growers minimize potential risks associated with sorghum production and sugarcane aphids. 

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Chemical options for aphid management in canola

With recent indication of aphids starting to building in some canola acres in southern Oklahoma, it is important to not only when and how to manage these pests but what are our chemical options.  An updated list of these can be found at: 

http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-3045/CR-7667web2016.pdf

It is not clear if these pests will continue to build or even move into more canola growing areas of the state; however, growers need to make sure to start scouting fields to not let these pests build this early during the green-up and spring develop.  As always, if you are mixing insecticides and herbicides/fertilizers when making these application, check the labels for detailed mixing restrictions and instructions.  

Aphid management in Oklahoma Canola Fields

Tom A. Royer, Extension Entomologist

Heath Sanders and Josh Lofton provided me with some pictures of a canola field that appeared to have significant winterkill (Figure 1) but it turned out that it had a severe aphid infestation. It looked like they were a mixture of green peach and turnip aphids (Figure 2). Canola fields need to be scouted regularly starting NOW.

Green peach aphids are pale green to yellow (and sometimes pink) with long cornicles and antennae and measure 0.08 inch. They occur in winter and spring on leaves and cause stunting and defoliation as they feed and build numbers. They can also transmit plant disease-causing viruses such as cauliflower mosaic and turnip mosaic viruses.

Turnip aphids are small, pale gray-green aphids that measure 0.06 inches with dark bars along the top of their abdomen, and very shortened cornicles with black tips.

Look for aphids on the underside of the leaves. Later, when plants have bolted, they will be on leaves and racemes.

Research at OSU found that and average of one green peach aphid per plant can reduce seed yield by about 0.5 lb. per acre. Latest quote for June Futures for canola at Fargo, ND USDA is canola can be contracted for about $0.18 per lb. https://www.ams.usda.gov/mnreports/ms_gr111.txt. Dr. Sholar says that a more realistic price is $0.14 per lb. Let’s assume application costs are $10.00 per acre. A simple calculation shows that an infestation of 143 aphids per plant X 0.5 lb. loss per aphid (71.5 lb.), x $0.14 per lb. would result in a loss of about $10.00 per acre, equal to the cost of the application. This is the ECONOMIC INJURY LEVEL (EIL). We typically set the ECONOMIC THRESHOLD (ET) below the EIL, in this case at 80% of the EIL (143 aphids x 0.8) = 114 aphids per plant) to give time to schedule an application before the EIL is reached. Table 1 is a set of suggested ECONOMIC THRESHOLDS, based on the cost of the application and a price of $0.14 per pound of canola.

aphidthresholdcost

Australian research suggests that a treatment threshold for turnip and cabbage aphids on racemes is 20% infested racemes.

CR-7667, Management of Insect and Mite Pests in Canola, contains current aphid control recommendations and is available online at http://pods.dasnr.okstate.edu/docushare/dsweb/HomePage. Remember, green peach aphid is known to develop resistance to pyrethroids, which are the primary registered insecticides for use in canola. Consider rotating with another non-pyrethroid (Carbine before or after petal fall, or Transform after petal fall) if another application is required. Thorough coverage of an insecticide application is necessary to obtain optimal control.

In 2015, Transform® insecticide registrations were canceled due to concerns about honeybee exposure. Transform was re-registered for use in canola on October 14, 2016, but can be applied only AFTER petal fall. With all pesticides, review label restrictions for applications during bloom, to avoid exposure to foraging honeybees. The Oklahoma Department of Agriculture Food and Forestry has a Managed Pollinator Protection Plan and a website that can assist growers and beekeepers to keep in good communication with each other if pesticide applications are required http://www.ag.ok.gov/

Decisions on late planted canola

With October underway, planters will be running through the field on a daily basis.  For canola fields, planting should be nearing completion.  While planting conditions have been great for many others have not had as good of luck.  Additionally, even growers that have had good planting conditions, these have not lasted for long in a lot of locations.  Good conditions have quickly changed into heavy pounding rains, good moisture followed by rapid drying and crusting, armyworm feeding, or more recent flooded conditions.  With this, many growers have been left with a decision of whether it is too late to plant, either initially or with replants.   

There are quite a few factors that need to go on when making this decision.  The first is, if growers are replanting, what kind of stand do they currently have.  For canola, often a descent stand with good fall growth is a good stand.  The hardest part of growing canola in Oklahoma seems to be getting a good stand after winter.  Marginal stands with good growth will be a lower risk and potentially higher reward than better stands and less growth.  Canola does not need a lot of individual plants to make a good to descent crop.  It has the potential to branch and utilize space in a thinner stand to develop more yield per plant later in the season.  However, grower should make sure they there is at least enough canola to make a stand in the spring even if winter kill reaches nearly 30-50% of current stands.  If growers decide to terminate their current stand, they need to evaluate both time and conditions on whether a replant will be successful.  With the critical time for canola planting closing in on us, growers will need to make planting a top priority in the coming week.  With descent soil moisture and forecasted mild conditions, growers should have until the end of the week (October 15th) to get canola in the ground and growing to still have a good chance at getting a good crop.  Without soil moisture, “dusting in” this late will be a major risk.  With cooler conditions on the horizon, canola growth will be severely restricted and lag behind the potential it had a couple weeks ago.  Planting after the 15th should not be advised, except for in very specific situations.  Planting this late in the fall could heavily rely on the first major freeze event occur well into the month of December for the crop to be very successful.  An early- to mid-November freeze could do in a later planted crop. 

The second thing a grower needs to evaluate is the planting conditions.  This will be true for both initial and replanted canola.  Good moisture, with limited drying could allow the grower to plant a little shallower than they would have in the last week or two.  This shallower planting will allow the canola to emerge quick and get better growth compared to planting near 1”.  Three quarters to a half inch is a good depth for canola into good soil conditions.  Without this good soil moisture at or near the surface, growers will have to plant much deeper. This deeper planting will make getting a quick stand in these late conditions more difficult. 

The final thing growers need to be thinking about, especially planting late, is other management practices.  These will include weed management, fertility, and pest management.  With late planting, crop stresses should be minimized to allow for unimpeded growth.  Therefore, growers need to make sure they are starting with a clean system, making sure they have optimum fertility, and making sure to scout and spray early for vegetative feeders (particularly foliar feeding worms).  

If growers can get canola planted timely and make sure to minimize other stress, many should still be able to have a great canola year this year.  With potentially better costs on the horizon, it is looking like a good canola crop will be a great cash crop for Oklahoma this year. 

Canola update: Planting and beyond

With recent rains, planting should be well underway or will start shortly.  Many growers have been concerned with not being able to get any canola planted in recent weeks due to too much or too little soil moisture.  While production system issues may exist, canola planted within the next couple of days to weeks is well within the recommended window and those planted in the next couple of days is right in the prime planting time.  While most research has shown September 20th through the 25th as the best time for planting.  However, these are working on averages and the conditions of last week (hot temperatures with excessive drying conditions right before a projected major rain) was not optimum for canola planting.  With regional soil moisture and cooler temperatures forecasted for the current week, this week may be the best time to get canola into the ground.  With the cooling conditions, however, we need to make sure to be timely with planting as canola will need time and growing days to get enough growth prior to the first frost to optimize winter survival.  The good news is there is plenty of time for growers to get seed into the ground and current 10-day forecast look to be prime for drying but not quick drying resulting in crusting and poor emergence and more reasonable temperatures. 

When canola has been planted, we cannot completely leave canola in order to do other fall activities.  Two major activities should be at the front of growers’ minds following planting.  First need to be N management.  While all nutrients need to be managed in canola in accordance to a soil sample collected, most other nutrients will have already been applied or applied with an in-furrow application.  However, planting is the time to make sure there are N-rich strips in all fields.  Many growers will think putting these strips in all production fields, especially in canola, is excessive but we are coming off a year were getting enough N for optimum production was challenging.  Additionally, high amounts of rainfall in late-spring, summer, and early fall could make N management in the spring challenging again.  Therefore, it is critical that growers make placing N-rich strips in the field to make spring N applications more manageable a priority this fall.  For further information on N-rich strips and setting up N management practices, please visit: osunpk.com or a short 101 video on N-rich strips can be found at https://www.youtube.com/watch?v=kJ3DSwWYgE8.

The other thing that needs to be a primary concern for growers in scouting and controlling foliage feeding worms in their planted canola.  These can be diamondback moth larvae or fall army worms or a combination of the two.  This was a major issue last fall and these pests were found in such high numbers that they were able to completely destroy entire fields.  While these were only in a couple of fields, it could be any field so growers need to make sure to scout throughout the early stages of the fall.  If last year is any sign, these pests can go from non-detected to catastrophic within a couple of days, therefore, growers need to be in their fields as often as possible (remember this is a major issue with both canola and wheat fields).  The critical limit to target an application is one worm per square foot and most pyrethroids can be used as a control measure or more advanced insecticides.  For further information check the most updated insect management in canola at: http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-3045/CR-7667web2015.pdf.

worm_damage_canola
Early season worm damage on canola seedling.

While planting conditions throughout the last several weeks might not have been optimum for many growers, things are starting to look better for getting the crop in the ground in a timely manner and off to a good start.  While it is easy to do with planting, harvesting, and cattle to manage, growers cannot plant and walk after from their canola crop.  With the good yields from last year still fresh in everyone’s mind, it is critical that the crop be managed properly in order to get the most out of this crop.  For further information on canola management, N-rich strips, or fall worm management, feel free to contact your local county educator, district agronomist, or specialist directly. 

Canola planting in Oklahoma

Come the beginning of September, most grower should have one thing on their mind.  No this should not be dove hunting, but rather planting.  When it comes to canola producers, it is this time of the year that many want to start getting seed into the ground if moisture is present.  With recent rainfall throughout a good portion of the state, this decision is starting to being made this week. 

Should this be done:

Determining whether you should plant early or not depends on your situation.  First and foremost, for insurance purposes, insurable planting begins on or after September 10th and goes through October 10th.  This would basically call for waiting until at least this Saturday to start planting.  However, with moisture, many producers would be more apt to plant into good conditions than to wait for the optimum timing and plant.  This is understandable; however, there are other things that need to be considered.

canola_pd

Early planting:

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 when planting canola 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 average light frost (November 2nd, NOAA), 10 weeks before the first hard 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 practice.  However, with increased vegetative material, a 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. 

Managing early planted canola:

Recent research projects at Oklahoma State University have begun to look into the use of PGR to manage fall canola growth.  Results of these trials have been somewhat mixed.  While a PGR that restricts growth when the canola is planted early or a PGR which increases root growth when applied to late-planted canola did not decrease yields, no yield benefit were found either.  These results currently show that the addition of these PGR to most winter canola producers are not cost effective as a means to manage planting dates with our canola crop.  Additionally, while not significantly, higher yields were typically seen when the canola was planted on-time rather than outside of the optimum window and then managed with PGR.  Furthermore, most PGRs are not labeled for use in winter canola production.  Those that are labeled for use are labeled under a different use (i.e. fungicide) and therefore application as a PGR would be considered an off-label application. 

pgr_canola

Overall, winter canola planting can be a challenging time full of decisions that will influence the productivity of the remainder of the production season, especially in Oklahoma when September through October can have highly variable weather.  An optimum planting time for canola will typically occur around the 20th of September.  No-till growers need to start making this decision earlier as these soils have a tendency to restrict growth and become cooler faster than conventionally tilled soils.  Even if producers wait until the last two weeks in September to start planting canola and moisture is not present at that time, the planting window stretches for several weeks beyond that time.

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 contact your local county extension office, regional agronomist, or myself with any other issues. 

Using Canola as a crop rotation for winter wheat

Article from Josh Bushong- NW Area Agronomy Specialist

Years like this make it very challenging to make critical decisions on what will work on your farming operation. Due to low commodity prices, managing farm inputs and deciding what to plant can be very daunting tasks. Many producers are rethinking or possibly considering planting canola for the first time this year. Winter canola has been successfully grown in north central Oklahoma for the past 13 years. There have been a few instances where drought, spring freezes, or other weather events have limited production, but as I recall the wheat didn’t fare much better in those cases either. Past performance has shown us that if it is a good year for wheat it will be a good year for canola as well.

Weed control in continuous wheat systems can be very challenging. What few options there are have become even fewer. OSU has documented that some populations of ryegrass and cheat in Oklahoma have developed resistance to ALS herbicides that are commonly applied to wheat. Weeds can cause significant economic damage by not only limiting yield by competition but also by increasing price discounts at the grain elevator through dockage or foreign material (FM). While dockage is usually just a weight deduction FM can cause significant price reductions. I have seen instances where the wheat was so trashy that a grain elevator wouldn’t even let the producer dump the load and in other cases the wheat had to be sold as mixed grain.

When penciling out budgets for the fall, it is important to not only factor in the production from this season, but also consider how canola can add value to your operation for years to come. Many wheat producers have grown canola for the main purpose of cleaning up weedy wheat fields. Since canola is a winter broadleaf crop it serves this purpose great. The best option to control winter annual grassy weeds like feral rye, ryegrass, cheat, bromes, jointed goatgrass, rescuegrass, wild oats, etc. is to utilize different herbicide modes of action that are not available in a continuous wheat system. In canola there are graminicides (herbicides that control grasses) like Select, Assure, and Poast as well as non-selective herbicides like glyphosate if a Roundup Ready cultivar is used. These herbicides have shown to be very effective in controlling these hard to manage grassy weeds. Just one year in canola can reduce dockage and FM in the following wheat crops by 85-100%.

In addition to cleaning up troublesome weeds, canola can also increase the amount of forage and grain yield of the following wheat crops. OSU research has shown a significant 20-25% increase in wheat forage and 10-15% increase in grain yields. Wheat producers have reported a 10-50% yield increase in wheat yields. A wheat stocker operator in Kingfisher county mentioned that his stockers average 50 pounds per head more when grazed on wheat fields that followed canola compared to stockers grazing on continuous wheat.

When debating on whether or not to plant canola this fall, remember that adding it to your crop rotation will add economic benefits for years to come. Sometimes it is difficult to see the value of cleaner fields, more forage, and increased yields. Canola is a great weed management tool and it can improve our wheat’s quality and quantity. Benefits of Adding Canola into the Rotation Josh Bushong NW Area Agronomy Specialist Oklahoma State University August 2016