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Louisiana Rice Notes – 5

Louisiana Rice Notes – 5 published on No Comments on Louisiana Rice Notes – 5

by: Dustin Harrell

Louisiana Rice Notes – 5 – PDF

Blast found in Jupiter

Many things have happened over the past couple of weeks in regard to the Louisiana crop.  Probably the most important is that leaf blast has been identified in two Vermilion Parish rice fields.  Both fields are growing the medium grain variety Jupiter, which is considered moderately susceptible to blast.  One field is approximately at the mid-tillering growth stage of development and the other is almost at green ring.  With the early sighting of leaf blast in Jupiter many questions have arisen regarding fungicide applications for blast.  The most often asked questions are: How bad does the leaf blast have to be before deciding to trigger a two fungicide application strategy to control the blast?  If you do decide to apply two fungicide applications, what timings are recommended?  These are excellent questions, and Dr. Groth has quickly put together information regarding these blast questions plus a whole lot more…

Leaf blast has started to show up in the area on the variety Jupiter. Blast disease is caused by the fungus Pyricularia grisea and is one of the most important diseases of rice in the world and the Mid-South. Yield losses as high as 90 percent have been observed in Louisiana because of this disease. Blast can infect rice from the seedling stage to near maturity. The leaf blast phase most commonly occurs between the seedling and late tillering stages. Leaf spots start as small white, gray or blue-tinged. They enlarge quickly under moist conditions to either oval or diamond-shaped spots or linear lesions with pointed ends with gray or white centers and narrow brown borders. Leaves and whole plants can be killed under severe conditions. The most important aspect of leaf blast is that it provides inoculum for infecting the panicles. Fungicides are not normally used at this stage unless you are losing the stand. The best control method is to restore or deepen the flood so all of the soil in the field is covered with water.

Scouting for blast should begin early in the season during the vegetative phase and continue through to heading. Scout the entire field, examining plants at several different locations. Blast is more commonly found in fields where (a) the field has a history of disease, (b) the variety is susceptible, (c) high nitrogen rates are used, (d) the field has sandy soils, (e) the rice was planted late (late-planted rice is more likely to encounter foliar disease problems than early-planted rice), (f) along the edges of tree lined fields, most importantly (g) the rice is growing under upland (no flood) conditions. Draining for straighthead and water weevil control may increase the incidence and severity of blast. These conditions should be avoided whenever possible. Also, as the percentage acreage of blast-susceptible varieties increases, the probability of an epidemic increases because more wind-borne spores pass between fields.

Correct identification of rice leaf blast is critical (Figure 1). Several diseases and disorders have similar symptoms, but control practices are not justified for these other diseases. There is a lot of diversity of lesion type so examine several different lesions at several different locations in the field. If identification is in doubt, leaf samples can be placed in a moist chamber to induce sporulation and identified by spore type (Figure 2) under a microscope.

Figure 1. Correct identification of leaf blast is critical to effective disease control.

Not Blast

brown spot

 

 

 

Brown Spot

 

 

 

 

 

stackburn

 

 

 

Stackburn

 

 

 

 

 

chemical damage

 

 

 

Chemical Damage

 

 

 

 

 

 

BLAST

blast

 

 

 

 

 

 

 

 

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blast3

 

 

 

 

 

 

 

 

 

 

 

Figure 2. Blast spores.

blast spores

 

 

 

 

 

 

 

 

 

 

 

If leaf blast is in the field or has been reported in the same general area, and if the variety is susceptible, fungicidal applications are advisable to protect the head from rotten neck and panicle blast.  The only fungicides that have activity against blast are the strobilurins Trifloxystrobin and Azoxystrobin.  Trifloxystrobin containing fungicides (Stratego and Gem), are slightly more effective against blast than Azoxystrobin (Quadris, Quilt, and Equation) but they are all effective. I am not sure if Gem is commercially available. Most of the time leaf blast should not be sprayed unless it is killing the rice plants. Normally a single application will control blast on a susceptible or moderately susceptible variety. The rice should be sprayed at 50-70% heading to protect the neck and panicle branches.  If a variety is very susceptible or leaf blast is still very active on susceptible varieties two applications are needed, one at 2-4 inch boot to reduce the inoculum in the field and the second to protect the head.  Remember as little as a 5 day delay in the heading application can greatly reduce control.

 

Upcoming

May 28          Southwest Rice and Soybean Field Day, Fenton. (morning)

May 28          Vermilion Parish Field Day, Lake Arthur. (afternoon)

June 16          Acadia Parish (Rice Research Station South Farm) Field Day, Crowley

July 1             Rice Research Station Field Day, Crowley.

 

Contact Information

Dustin Harrell           Rice Specialist & Research Agronomist                         (337) 250-3553    dharrell@agcenter.lsu.edu

Don Groth                 Rice Pathologist                                                                   (337) 296-6853    dgroth@agcenter.lsu.edu

Eric Webster             Rice Weed Specialist &                                                       (225) 281-9449    ewebster@agcenter.lsu.edu

Assistant Southwest Regional Director

Steve Linscombe     Senior Rice Breeder & Southwest Regional Director   (337) 296-6858    slinscombe@agcenter.lsu.edu

Mike Stout                Rice Entomologist                                                               (225) 892-2972    mstout@agcenter.lsu.edu

Mike Salassi         Rice Economist                                                                        (225) 578-2713    msalassi@agcenter.lsu.edu

 

Challenges with N management in high moisture conditions

Challenges with N management in high moisture conditions published on No Comments on Challenges with N management in high moisture conditions

Josh Lofton and Beatrix Haggard- LSU AgCenter

The 2015 corn season has started off very challenging for the majority of the state. Much of the corn that has been planted was planted later within the optimum window, while several producers are still trying to decide on whether to plant the final intended acres (A great article about late-planted corn was recently published by Dr. Erick Larson at MSU http://www.mississippi-crops.com/2015/04/07/are-we-going-to-get-this-corn-crop-planted/).  While corn that was planted on time is up and most has a pretty good stand, new challenges are arising with N fertilization in the wet conditions around the state. Much of this corn is between the V2 to V6 leaf stage and has good growth. However, only a limited number of acres have had any measureable N applied. This has increased interest in aerial application of part or all of the intended fertilizer as urea. While these applications have the potential to be very beneficial and common – especially in the delta of Mississippi on high clay ground, according to Dr. Bobby Golden at MSU – correct decisions and appropriate management are needed to get the most benefit.

The first thing that needs to be decided is whether the crop needs this shot of fertilizer or if it can be delayed until the ground applicator is suitable. Aerial application will be more costly per acre than ground applications. The best way to determine if the crop needs this application will be the crop itself. Symptoms of N deficiency are an overall pale crop and shortened growth. However, these symptoms are also associated with cold and/or wet conditions. While poorly drained soils and N deficiencies can be highly associated with each other, field pattern can be a way to determine if the crop as a whole is stressed or just low areas (i.e., is the short, pale corn in a localized area or across the field).

Corn seedlings under high moisture conditions
Corn seedlings under high moisture conditions

Once areas have been identified as not just localized areas of poor drainage, other issues must be addressed. One such issue is whether the crop is suffering from an N or S deficiency. These two are often confused with the other. Typically, location on the plant can be used to gauge whether N or S is the most likely culprit, with N traditionally being on lower, older growth and S being on the new growth. However, in young, developing plants these traditional deficiency locations are not 100 percent. While determining if an N or S deficiency is present is critical, often these two will probably be present in most Louisiana systems. Additionally, if no S has been put out, then managing for both N and S will probably be necessary, especially if substantial time will pass before successive fertilizer applications.

The next factor that needs to be determined is how much N to apply. This decision will be entirely based on the farm operation. There are pros and cons for both urea and UAN, but both can be used to produce optimum growth and productivity. In this regard, producers can apply their entire intended N applications as urea aerially. Though expensive, this provides the luxury of not having to fit in another application when drier conditions arrive (especially as further planting of grain sorghum, soybeans and cotton are probably also intended). On the other hand, if UAN has been purchased and is the intended fertilizer for the majority of the N management, a smaller application can be applied as urea to provide some flexibility until drier conditions exist. These applications should include at least 50 to 100 lbs of N per acre (as urea and ammonium sulfate) and anywhere from 10 to 20 lbs of S per acre (as ammonium sulfate). This ensures adequate N and S for the stressed crop. However, if making these applications, it is important to readjust further N application to account for this additional application. Additionally, splitting N applications into a couple smaller applications can minimize N losses associated with the current adverse environmental conditions being experienced.

The final management decision that should be made is whether or not to treat the aerially applied urea or not. This decision often comes down to economics rather than agronomics. From an N management perspective, the application of urease inhibitors (NBPT) on aerial applied (without incorporation) should be the standard. This is due to the fact that up to 50 percent of applied urea can be lost through volatilization if the conditions are unfavorable. Furthermore, the application of a nitrification inhibitor (DCD or nitrapyrin) may also be warranted, but this has little to do with the application and environmental conditions now and more to do with soils and environmental conditions that will be experienced in the upcoming season. Further details are provided in the following link: http://louisianacrops.com/2015/04/06/choosing-to-use-n-inhibitors-or-not-in-mid-south-corn/.

Treated urea
Treated urea

Even though this corn season has had a challenging start, overall this current crop that has been planted shows promise. Therefore, management decisions should be taken that will help maintain this potential. However, with current prices, inputs must be warranted prior to application r to ensure return on the investment. Therefore, producers must watch their crop and weather on these applications. For further questions or comments feel free to contact:

Beatrix Haggard, state soil fertility specialist, bhaggard@agcenter.lsu.edu

Josh Lofton, field crop agronomist, jlofton@agcenter.lsu.edu

Louisiana Rice Notes – 4

Louisiana Rice Notes – 4 published on No Comments on Louisiana Rice Notes – 4

by: Dustin Harrell

PDF version – Rice Notes 4_April 17

Rain, Rain and More Rain…

Over the past 10 days all we have seen is rain, rain and more rain.  Very little rice has been planted in Northeast Louisiana.  In Southwest Louisiana however, I would estimate that 90 to 95% of the rice has been planted and most of that rice has emerged and is moving along nicely.  In fact, when the rains first started last Friday, many producers’ fields in Southwest Louisiana had already been flushed or were in need of flushing because they were low on soil moisture.  So the rains were initially a welcome reprieve.  The problem is that the rains never let up.  Over the weekend at some locations received over 5 inches and even more throughout this week.  The rain really stopped pretty much all field work this week.   However, in many cases it has not stopped rice growth because the weather has been warm and the sun has come out from time to time.  If we look at the temperatures and rainfall at the Rice Research Station in Crowley, you will see that it rained six out of the last seven days with a total rainfall of 6.4 inches.

Rainfall

 

 

 

 

 

 

 

 

During that same time, it has been fairly warm with a mean daily temperature of 71.5oF.  Often we use accumulated DD50 units to help predict rice growth and development.  DD50 heat units are an estimate of accumulated daily heat units above 50oF and are an estimate of a day’s thermal quality for growth.  It is calculated by taking the average of the daily high and low air temperature in oF and subtracting 50oF.  The short of it is that the more DD50 heat units we accumulate the faster the rice will grow and develop.  Typically, we would estimate that seedling rice will grow a new leaf somewhere between every 100 to 175 accumulated DD50 heat units.  At the Rice Research Station from last Friday (April 10) to this Thursday (April 16) we received approximately 151 DD50 heat units.  Most of my research plots moved from 2- to 3-leaf rice to 3- to 4-leaf rice this week.  All of this is to say that even though we field activities have stopped this week rice growth and development has not.  Of course, all of this DD50 discussion assumes good growing conditions for rice and not for rice which has been submerged under water.

This brings me to the most ask question I have received this week.  When seedling rice is submerged under water, how long can it survive?  Well this is a question that really does not have an exact answer and does not (as far as I know) have research based information to base the answer on.  Typically, the survival of a seedling would be related to several things including how deep the water was over the rice, variety or hybrid grown, water temperature, the “health” of the seedling prior to submergence, and so on.  So with all of these different variables in play you can see that this question would not have a one size fits all answer.  So to answer this question I polled all of the best rice farmers, consultants, and researchers I could to find the consensus was that under the current temperatures that we have and if the flood was not very deep over the top of the seedling we would feel confident that the rice could survive 5 to 7 days.  After that time, the stand would probably start to thin.

So if the rice in the area was growing this week, assuming it was not under water, we can assume that the weeds were also growing.  Which brings me to the next group of questions I was asked this week.  All of which were related to herbicide applications and wet conditions.  There are several scenarios that I was asked and so I wanted to share a few thoughts on the subject.  One is that photosynthetic inhibitors herbicides, like propanil, need good growing conditions, good weed contact, and need to be rainfast prior to the next rainfall event to work best.  So if the weeds are small, and covered with water, or you are not sure how long you will have before the next rainfall event, you may want to hold off on the application until conditions are more favorable for the herbicide activity.  After all, you are paying for the herbicide and the application costs, so you may as well get the most of what you are paying for.  Another situation, I would caution you about is applying Command treated fertilizer into a standing flood when you are expecting even more rain.  The Command treated fertilizer and the herbicide can move in the water during standing water conditions in the field when the application is followed by high winds. In this scenario, the Command can move from the high side of the field to the low end or even from the top cut of a field to the bottom cut of a field.  In these situations the Command would be concentrated (higher than the labeled rate) on one side which could damage the rice and would be diluted (lower than the labeled rate) on the other side of the field, which would provide poor residual weed control.  The same thing could occur where you apply the Command treated fertilizer into standing water, raising the flood yourself followed by wind and water movement.

 

10 Things you need to know about rice sheath blight

  1. Current rice varieties range from moderately resistant to very susceptible.
  2. Sheath blight is a soil-borne disease and is not transmitted by wind-borne spores. The pathogen moves up the plant and from plant to plant by surface hyphae.
  3. The thicker the rice, the more severe sheath blight is.
  4. The more nitrogen fertilizer used, the more severe sheath blight is.
  5. The sheath blight pathogen also causes aerial blight in soybeans and attacks many other crops and weeds, making it difficult to eliminate in a field.
  6. If sheath blight is detected in 30% or more of the stops in a field while scouting susceptible and very susceptible varieties, fungicide applications are advised to reduce damage. For moderately susceptible and moderately resistant varieties, the percentage increases to 50%.
  7. The best timing for a sheath blight fungicide application is at the boot growth stage (2-4 inch panicle).
  8. Fungicide applications to suppress sheath blight should be applied before 50%-70% heading. Application as few as five days after this growth stage will provide poor control of sheath blight. Allow time to obtain a fungicide, schedule the application, and adjust for poor weather conditions.
  9. Under heavy sheath blight pressure or when growing very susceptible varieties, two applications may be needed to effectively suppress sheath blight.
  10. Fungicide-resistant sheath blight pathogen populations have been found in south central Louisiana and are spreading rapidly. A sound fungicide resistance management system is needed.

 

Did you know… that according to the USDA – National Agriculture Statistics Service, the United States produced approximately 221 million hundred weight of rice in 2014?  That rice has a value of approximately 3.1 billion dollars. Well, did you know that the population of China can consume that much rice in approximately 12 days!  With that in mind, how important do you think the China market would be if we could gain access to it for U.S. grown rice?  Just a little food for thought!

Additional Information

Louisiana Rice Notes is published biweekly to provide timely information and recommendations for rice production in Louisiana. If you would like to be added to this email list, please send your request to dharrell@agcenter.lsu.edu.

This Information will also be posted to the LSU AgCenter website where additional rice information can be found. Please visit www.LSUAgCenter.com.

Upcoming 

May 28 – Southwest Rice and Soybean Field Day, Fenton.

June 17 – Acadia Parish (Rice Research Station South Farm) Field Day, Crowley.

July 1 – Rice Research Station Field Day, Crowley.

Choosing to use N inhibitors or not in Mid-South corn

Choosing to use N inhibitors or not in Mid-South corn published on 1 Comment on Choosing to use N inhibitors or not in Mid-South corn

by: Beatrix Haggard and Josh Lofton

The drying conditions in recent days have resulted in a percentage of corn finally being planted.  While most producers are focused on planting, these intense planting conditions will result in a short window for N fertilization. With this narrowed window between planting and N fertilization, it is time to start thinking about N management. In recent years, conditions at or near fertilization have resulted in high potential loss of applied N. These losses not only are detrimental to the surrounding environments but also to the production system, resulting in insufficient available N supply to the crop. The use of N inhibitors has been an increasingly common production practice in an attempt to minimize in-season losses. While the use of N inhibitors is a valuable tool for potentially decreasing N loss, proper management and proper selection are critical to decrease losses successfully.

Selection of the proper inhibitor is potentially the most critical aspect and can be challenging because of the numerous options available. Determining the right inhibitor varies, depending on N source, N application method, and field/environment.

Chemical names to ask for:

  • Urease inhibitors – NBPT (N-(n-butyl)thiophosphoric triamide), or NPPT (N-(n-propyl)thiophosphoric triamide)
  • Nitrification Inhibitors – Nitrapyrin, or DCD (dicyandiamide)

DSC_0167

 

 

 

 

 

 

 

 

Figure 1. Untreated urea at 240 lbs N/acre.

 

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Figure 2. Super U urea at 240 lbs N/acre (NBPT and DCD).

 

 

Urease inhibitors:

Urease inhibitors function by inhibiting the urease enzyme, a natural enzyme in the soil system that hydrolyzes urea into ammonium. By doing this, urease inhibitors attempt to minimize volatilization losses during periods favorable to volatilization (dry, windy, urea on surface). When environmental conditions exist, namely moisture, urease inhibitor activity is diminished, allowing the urease enzyme to break down the urea. Urease inhibitors work very well with granular fertilizers because these are frequently surface-applied with limited to no incorporation. With surface application of granular fertilizers, volatilization is the primary potential loss, at least during early season when adequate moisture does not exist. However, these inhibitors are not only beneficial on granular fertilizers. Substantial volatilization can occur with liquid fertilizers that are surface-applied in warm, dry conditions with little soil moisture. When these same fertilizers are incorporated, such as being knifed-in in lieu of surface-applied, as little as 1-5% of applied N is typically lost through volatilization. Therefore, urease inhibitors are most effective when urea-containing fertilizers are surface-applied, whether liquid or granular, without incorporation.

Nitrification inhibitors:

Nitrification inhibitors function by inhibiting the soil bacteria, which are required for nitrification to occur. Inhibiting nitrification keeps more N as ammonium for longer periods of time. This is beneficial because it can limit or minimize both leaching and volatilization losses, both of which occur as nitrate compared to ammonium. These inhibitors have the potential to be the most universally beneficial in high rainfall and irrigated systems especially. However, the benefit of these products has not been widespread in research trials conducted across the Mid-South. A two-year study conducted at the LSU AgCenter, however, did show that these inhibitors can be beneficial in Louisiana systems. The best management of these inhibitors is to know their limitations. Research conducted at the LSU AgCenter as well as other research around the US indicate that these products last only 10-30 days. Therefore, these inhibitors provide early season “protection” of the N fertilizer, but N can still be lost after the nitrification inhibitor has degraded.

Coated-fertilizer:

Unlike the other inhibitors, coated-fertilizers do not inhibit any process within the soils system but slowly release N from the coated source throughout the season. By slowly releasing N into the soil system, these inhibitors minimize only the amount of N applied that can be lost through individual loss mechanisms. These N sources are promising at minimizing both volatilization, denitrification and leaching. However, few if any coated liquid sources are currently or will be commercially available in the near future. Therefore, these must be used solely on granular fertilizer sources. Additionally, because the fertilizer is slowly available, N available from the applied fertilizer during early season growth is minimal. Therefore, high amounts of residual soil N need to be available, or supplemental N fertilizer needs to be supplied.

 

Nitrogen inhibitor products have the potential to be very beneficial tools at managing N fertilizer additions in Louisiana production systems. However, if mismanaged, not only do you lose the benefit of applied inhibitors but also narrow the economic potential of the production system. Therefore, time needs to be given to selection of a particular inhibitor to fit the system as well as proper management within the production system.

 

If you have any further questions, please contact your local extension agent or specialist.

Beatrix Haggard, Upland Row-Crops Soil Fertility Specialist – (318)498-2967

Josh Lofton, Agronomist – (318) 498-1934

As corn planting has begun, don’t forget about the wheat crop

As corn planting has begun, don’t forget about the wheat crop published on No Comments on As corn planting has begun, don’t forget about the wheat crop

Josh Lofton, Trey Price, Boyd Padgett, Beatrix Haggard, and Steve Harrison- LSU AgCenter

As warmer and drier conditions have arrived in Louisiana, corn planting has greatly picked up.  In doing so, a lot of attention has shifted away from the winter wheat to corn.  However, while these environmental conditions greatly benefit corn planting, they also are near optimum growing conditions for the winter wheat crop.  Much of the early and on-time planted wheat around the state should have at least a couple of nodes, if not already at the boot, heading, or flowering growth stages.  Furthermore, much of the late-planted wheat has utilized these conditions to quickly progress from tillering to jointing and should also have at least a couple of visible nodes, and could be at or near boot or heading stages, especially with early maturing wheat varieties.  With this rapidly progressing wheat crop and the warming environmental conditions, increased disease incidence could be a growing issue.

Earlier in the season in juvenile wheat, many “hot spots” of stripe rust were noted throughout the state.  Even in resistant varieties, stripe rust may occur in juvenile wheat subsiding as plants mature.  In some of these “hot spots”, stripe rust progressed far enough to trigger applications of tebuconazole (Folicur and generics) or propiconazole (Tilt and generics).  Since conditions have warmed up, the ongoing stripe rust epidemic has slowed and in some cases halted.  The stripe rust epidemic may re-start if the weather pattern returns to cool and wet conditions.  Reports of leaf rust, a disease preferring warmer temperatures, at low levels have been coming in from southern Louisiana.  Leaf rust also has the potential to reach severe levels and lower yield potential.  Heavy levels of Septoria leaf blotch have been noted in early-planted wheat at the Macon Ridge Research Station.  In most years this disease does not progress far enough upwards in the wheat canopy to require fungicide applications; however, Septoria leaf blotch can be severe and limit yield in some cases.  Producers should scout fields for these and other diseases beginning at jointing.  If fungicide applications are warranted for these diseases, there are many effective products available.  Solo products or premixes containing a triazole (Group 3) are effective at slowing disease progress and preserving yield.  Applications are usually not warranted or legal after wheat has begun to flower.

Leaf rust in wheat.
Leaf rust in wheat.

Due to the excessively wet spring, many want to continue to manage N in this aging wheat crop.  However, we must take into consideration both the wheat conditions and age before continuing to manage N.  Once the wheat crop exceeds the 2 node stage, the economic return for additional N has diminished greatly.  Furthermore, once the crop has reached flag-leaf, little to no additional benefit can be gained from additional N applications.  Another aspect to consider are the crop conditions.  With the overall wet and frequent cool conditions, certain wheat field’s yield potential has decreased.  This does not mean that this year’s wheat crop cannot be productive but it does mean that additional N is probably not warranted.

For further questions or comments please contact your local extension agent or state specialist

Josh Lofton, Wheat State Specialist, jlofton@agcenter.lsu.edu

Boyd Padgett, Wheat Pathologist, bpadgett@agcenter.lsu.edu

Trey Price, Field Crop Pathologist, pprice@agcenter.lsu.edu

Cold snap could have impact on winter wheat crop

Cold snap could have impact on winter wheat crop published on No Comments on Cold snap could have impact on winter wheat crop

Josh Lofton and Steve Harrison- LSU AgCenter

Louisiana has experienced a relatively mild winter across much of the state.  This has allowed for some “catch-up” growth for a winter wheat crop that was planted in poor conditions early in the season or with better conditions very late in the fall.  However, recent colder conditions have all but stopped growth.  This is typically not an issue but with the increased over-winter growth, questions always arise as to the potential damage that cold temperatures might have on a more advanced wheat fields.  This is especially true with temperatures forecast in the lower 20’s for two consecutive nights this week.  While this  is a very reasonable question to ask, the answer is not as straight-forward and depends on growth stage, duration of cold temperatures, amount of foliage covering the growing point, soil temperature, soil moisture, and wind, among other factors.

The two most important factors  are the potential low temperatures and the duration of these cold temperatures.  Critical cold temperatures for the wheat depend on the growth stage of the crop when the cold occurs.  As can be seen from the table below (Kansas State University Extension Service), the wheat crop is least susceptible to cold temperatures during the tillering.  Wheat becomes more susceptible to cold damage as the crop progresses towards the heading stage and is  very susceptible to cold temperatures during heading.  Most of the state’s wheat crop is probably at or near jointing but some fields clearly showing one or two nodes.    During  jointing, 24°F for greater than 2 hours can cause moderate to severe negative effects on growth and yield for the current crop.  The most detrimental impact of these temperatures will be death of growing points resulting in loss of those.  This will often occur on the main stem of the tillered wheat as it is the most advanced.  Death of growing points will effectively terminate any yield that could have been expected from that tiller and may lead to development of new tillers from the base of the wheat plant.  While extensive tiller death would only occur if the crop was greatly advanced or temperatures get down to the mid-teens for an extended amount of time, which is not expected.

weather damage to wheat at different growth states

 

Growing points should be evaluated about a week after the hard freeze occurs.  This allows damaged tissues to start showing symptoms of discoloration and damaged stems to wilt.  Health of the growing point can be evaluated by removing the most advanced stem at the soil level  and splitting the stem.  A growing point can be identified by locating stacked plant tissue that looks similar to a beehive above the current visible nodes.  If this tissue is white, firm and fleshy, the growing point is still active and productive.  However, if the growing point is discolored and limp, the growing point is no longer active and that tiller will cease to grow and produce.

 

Photo courtesy of ncagr.gov
Photo courtesy of ncagr.gov

Determining the extent of the damage from this cold spell  and potential yield losses will be difficult until plants have time to start recovering.  Severely damaged field will put up new tillers from the soil line in about 10 – 14 days.  The damaged tillers will wilt and bleach out.  However, evaluation of the crop following the weather will give a better indication of the total damage.  There will be some superficial leaf damage and leaf discoloration in less advanced fields, but this is not likely to cause yield losses.  The hope is that the crop has adequate foliage covering the growing points, thus limiting tiller death.  For questions or concerns following these temperatures contact your local extension agent or state-specialist.

Josh Lofton- State Wheat Specialist, jlofton@agcenter.lsu.edu

Louisiana Rice Notes – Issue 2

Louisiana Rice Notes – Issue 2 published on No Comments on Louisiana Rice Notes – Issue 2

PDF VERSION FOUND HERE

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Acephate found on exported rice

A detectable a level of acephate (an organophosphate insecticide) was identified in a recent shipment of rice by a receiving country’s grain inspection service. This is the third time acephate has been detected in U.S. exported rice the past three months.

In Louisiana, acephate is labeled for use for control of stinkbugs, corn ear worm, salt marsh caterpillar and the threecornered alfalfa hopper in soybeans. It is also labeled for use to control thrips, plant bugs and stinkbugs in cotton. One advantage of acephate has over pyrethroid insecticides for control of stink bugs is its longer residual. However, acephate is not labeled for use in rice to control stink bugs.

The origin of the acephate on the exported rice is unknown. It is very possible that a drift event from a nearby soybean field being sprayed with acephate (Orthene) to control stinkbugs occurred, which contaminated the rice. Although the exact origin of the acephate is unknown, one thing that we do know is that if acephate continues to show up in U.S. exported rice, it will surely undermine our efforts to promote and sell our high quality rice to export markets. So please, make every effort to ensure that acephate does not find its way on U.S. rice in the future. The future of our industry depends on it.

 

2014 Louisiana rice crop worth over $670 million

Every year the LSU AgCenter tabulates the value of Louisiana agriculture commodities and publishes this information in the Louisiana Agriculture Summary of Agriculture and Natural Resources. This publication serves as a historical record of the Louisiana cropping season and estimates how agriculture industries contribute to our state’s economy. The Agriculture Summary for the 2014 cropping season is still being put together. However, the preliminary rice data has been completed.

Rice acreage in Louisiana increased from 410,902 acres in 2013 to 456,047 acres in 2014. Medium-grain production increased from approximately 4% in 2013 to 14% in 2014.  Much of this increase in medium-grain production was due to the decrease in rice acreage in California. The variety Jupiter was the predominant medium-grain grown.

The 2014 rice crop began with a cool and wet March. This delayed much of the drill-seeding and caused a slight increase in water-seeded acreage. The cool March also slowed the early season growth and development. Disease and insect pressure were average to below average in 2014. Daytime and nighttime high temperatures were not excessive during grain fill. Harvest season was again marred with wet conditions, which led to delayed first crop harvest and postponed the onset of the ratoon crop. The wet conditions also slightly decreased the ratooned acres in southwest Louisiana. The mild temperatures coupled with below average disease and insect pressure led to high crop yields with excellent milling and grain quality traits. Average yield in 2014 was 7,539 pounds per acre, slightly lower than the record yield of 7,600 pounds per acre set in 2013.

The 2014 Louisiana rice crop was harvested by 1,040 producers. The gross farm value of the state’s rice crop was $515.7 million for 2014, $21 million (4 percent) more than the year before. The higher acreage, combined with high yields, accounted for the significant increase in overall farm-gate value in 2014. Value added of $154.7 million, when combined with farm-gate value, brought the total value of rice production in Louisiana to $670.4 million.

The Louisiana Agriculture Summary of Agriculture and Natural Resources publication from 2000 to 2013 can be found online on the LSU AgCenter’s website at: http://www.lsuagcenter.com/agsummary/.

Do you know which parishes grew the most rice in 2014?

Twenty-nine Louisiana parishes grew rice in 2014.Table 1 below indicates the total estimated acres per parish.

acres

Rice Base Program Survey 2014

We will wrap up the rice extension base program summary this Friday. So if you have not responded and you want your voice heard, be sure to fill out a survey. Remember, the purpose of the survey is to determine your thoughts and get your input on the Louisiana Rice Extension Program. Do you enjoy reading Louisiana Rice Notes? Do you attend field days? Do you use the DD50 program? Do you use the RiceScout mobile application? Should we make more mobile applications? Do you like the Rice Verification Program? All in all, what can the statewide rice extension program do to improve our service to you in the future? Let us know your thoughts. If you misplaced your original e-mail you can use this link ( 2014 Rice Program Survey) to take the survey. Thank you in advance for your participation.

Upcoming

Feb. 10         Louisiana Rice Council & Louisiana Rice Growers Association Annual Joint Membership Meeting, Jennings

Feb. 11-13  Louisiana Agricultural Technology & Management Conference,          Marksville

Feb. 12        Northeast Louisiana Rice Forum, Delhi

Feb. 25        Stored Rice Insect Management Workshop. Crowley.

July 1         Rice Research Station Field Day, Crowley.

 

Random Rice Facts

Did you know that the Rice Research Station was established in 1909 in Crowley, LA? Well, did you know that Crowley was not the only town in Louisiana that wanted to be the home of the Rice Experiment Station? It is true. When the announcement was made in 1908 that a rice Louisiana Agriculture Experiment Station was to be established in southwest Louisiana, most of the citizens in the area were thrilled about the project. Formal proposals were made from three southwest Louisiana towns for the honor to be selected as the home of the experiment station. The proposals contained generous donations of land, resources and money to begin the experiment station. Special committees from each town pitched the advantages of selecting one of the locations in their district as the home of the station. Eleven potential tracts of land were offered in all. In the end, it was a 60-acre tract of land located one mile west of Crowley that got the final nod. Several attributes made Crowley the selected destination: 1) the soil was representative of the rice belt, 2) the land was well-drained, 3) the town was readily accessible because it had “a public wagon road that could be traveled by many people, on two sides, and can be observed from trains on two railroads, and one railroad having a spur already located on the property,” and 4) because the site was favorable for studying rice rotational crops. The Police Jury of Acadia Parish appropriated $3,000 toward the purchase of the land, and the citizens of Crowley and the surrounding vicinity donated another $3,500, in cash, for construction of necessary buildings and infrastructure…Can you name the other towns who gave formal proposals?

Station                                                                                                                     Original Rice Experiment Station. Crowley, LA.

AV-1011 update

The Section 24 (c) for AV-1011 (the bird repellent seed treatment) application was officially withdrawn on Friday morning. A section 18 application was submitted to EPA on Friday afternoon. As you know, part of this application required documentation of economic loss from the 2014 season to establish need. It would be very unlikely that the Section 18 would be granted without this information. Thank you all who contributed testimonials and examples of economic loss to include the application. EPA has assured LDAF officials they will expedite processing the application since we are rapidly approaching the season. I will let you know as soon as we hear something new.

Answer:

Jennings and Lake Charles. A canal company offered to donate all the land needed if the experiment station was located on its land. State Senator H.C. Drew of Lake Charles offered land he owned near Edgerly and financial support for the establishment of the Rice Experiment Station.

Additional Information

Louisiana Rice Notes is published biweekly to provide timely information and recommendations for rice production in Louisiana. If you would like to be added to this email list, please send your request to dharrell@agcenter.lsu.edu.

This information will also be posted to the LSU AgCenter website, where additional rice information can be found. Please visit www.LSUAgCenter.com.

 

 

 

Cover crop management decisions

Cover crop management decisions published on 1 Comment on Cover crop management decisions

Josh Lofton and Beatrix Haggard, LSU AgCenter

  • Now is the time when most cover crops shift from fall and winter growth to spring growth.
  • Evaluate spring management of cover crops based on intended purpose, cover crop planted, and successive crop.
  • Termination needs to have already occurred or needs to occur shortly.
  • For soybeans and cotton
    • Difficult cover crops to terminate (reproductive legumes or Brassicas) should be terminated or should be shortly.
    • Cover crops that are easy to terminate (cereals and vegetative legumes) should be terminated to allow for two to four weeks of non-actively growing cover crops.

As with most years in Louisiana, the transition between January to February represents the beginning of the coming production season. With this transition, warm temperatures, at least for periods, can be expected. For those that have planted cover crops, this period can be very critical. During these warm periods, certain cover crops begin to transition from winter to summer growth. This can be beneficial or can begin to have detrimental effects depending on both the intent of the cover crop and the cover crop planted. Below are short explanations of how this altered growth can influence the production system based on purpose and cover crop.

Cover:

During this shift from winter to summer growth, more rapid growth can be expected from most crops. This is especially true for the early spring legumes, such as the vetches, clovers and winter peas. These legumes can transition from only minor cover to almost full soil coverage. Cereals can increase coverage during this period as well; however, most cereals have established full soil coverage in the fall during tillering. As with the cereals, the Brassicas (tillage radish) cover has already established most of its soil coverage in the fall.

Nutrient contributions:

Nutrients taken up and, therefore, potentially reapplied for the successive cash crop can be highly variable. For legumes, optimum N fixation occurs during this early- to late-spring growth, which usually occurs during reproductive growth. While higher N content can be achieved during this reproductive growth, higher C:N ratios can result in less immediate available N contents. Tissue tests will aid in determination of this. For cereals, nutrient uptake occurs rapidly during late-tillering and around jointing. However, as with legumes, higher C accumulation can result in limited release during the cash crop’s growing season. The Brassica crops have accumulated most of the nutrients by early season growth. This is evident by signs of stress that can be seen during this time of year. Early shedding of leaves can result in nutrient release during pre-planting and during the early growth; however, this early tissue decomposition could be detrimental as early N release can be lost from the soil during high rainfall conditions.

Picture of forage radishes growing in Winnsboro, LA. Yellowing indicates the radish has taken up all the available nutrients (probably N) in the soil system
Picture of forage radishes growing in Winnsboro, LA. Yellowing indicates the radish has taken up all the available nutrients (probably N) in the soil system

Moisture uptake:

The cover in which this is most critical are cereal covers but can be evident in the other covers as well. For cereals, which have past jointing, moisture uptake from the cereal can be rapid. This is critical for the cover to continue with reproductive growth. However, this can be detrimental for the successive crop because much of the soil profile moisture can be diminished prior to termination.

Termination:

During this time of year, termination needs to be considered. If the field in which cover crops are planted is to be planted in corn, now is the time for termination. This will not only allow for breakdown of the cover crop but also has the potential to break the “green bridge,” which should be broken for two to four weeks for best IPM practices. However, this decision is more difficult if soybeans or cotton will be the successive crop.  If planting is later in the year and the cover crop is easy to terminate (cereals), terminations could be delayed, especially if soil cover is desired. Legumes can be easy to terminate if done timely. This would consist of terminating before loss of vegetative cover and growth. If legumes are terminated late, complete termination of the cover crop can be difficult. For Brassica covers, termination is dependent on the growth of the crop. Similar to other covers, the “green bridge” needs to be broken. However, this can be more difficult because of the fleshy roots of these Brassicas. Additionally, with the warming temperatures, most of these Brassica covers have begun to turn reproductive. Once these covers have gone reproductive, chemical termination is unlikely. If these conditions exist, Brassica covers need to be terminated immediately. Determining if these are reproductive will involve looking into the whorl of the leaves, where the reproductive structure begins (as in the pictures).

 

Reproductive structure of the Brassica cover crops.
Reproductive structure of the Brassica cover crops.

 

Beginning growth of the reproductive structure of the Brassica cover crops. Oftentimes this structure can be hidden within the leaf whorls. Termination should have or needs to occur shortly.
Beginning growth of the reproductive structure of the Brassica cover crops. Oftentimes this structure can be hidden within the leaf whorls. Termination should have or needs to occur shortly.

 

For additional information, feel free to contact:

Josh Lofton, Field crop agronomy, LSU AgCenter, jlofton@agcenter.lsu.edu

Beatrix Haggard, Soil Specialist, LSU AgCenter, bhaggard@agcenter.lsu.edu

Wheat Disease Management Update

Wheat Disease Management Update published on No Comments on Wheat Disease Management Update

Trey Price and Boyd Padgett- LSU AgCenter

 

If not properly managed, diseases can negatively impact yield and quality. Leaf rust and stripe rust are the most troublesome diseases producers have to manage. Based on LSU AgCenter tests, yields may be reduced by 50 percent by rusts. This demonstrates the need to effectively manage these diseases to optimize profits. Other diseases that occur less frequently or are not as widespread are bacterial streak, stem rust, leaf and glume blotch, barley yellow dwarf, and head scab. These diseases can significantly affect yield when conditions favor disease development.

 

Proper disease identification is the first step toward an effective disease management strategy. Diseases need to be correctly identified in individual fields prior to applying a fungicide. Knowing the environmental conditions that favor disease development and what varieties are susceptible to specific diseases will aid in proper identification.  Keep in mind that several symptoms may resemble diseases, but are not.

 

Stripe rust development is most aggressive when temperatures are 50 to 65 degrees F in the presence of intermittent rain or dews (six to eight hours). However, development can occur when temperatures range from near freezing to 70 degrees F. Initial infections on seedling wheat may not have the characteristic striping pattern that occurs on older plants. Seedling infections often occur in thumb-sized clusters on the leaves, as opposed to a random distribution that occurs with leaf rust. Infections may appear as linear rows of small yellow to light orange pustules (stripes) on the lower leaves during late winter or early spring. Striped patterns are typical of infections in older pants. If conditions remain favorable for development, pustules may cover the entire upper leaf surface, as well as portions of the head. A lifecycle (infection to reproduction) can be completed within seven to 10 days under optimum conditions. Stripe rust has been confirmed at the Macon Ridge Research Station in Winnsboro in F5 stage wheat. Conditions favorable for development are prevalent this time of year. Unless disease becomes severe, applications usually are not needed at this stage, but susceptible wheat varieties should be monitored for disease development. If necessary, fungicide applications are usually most efficacious at flag leaf stage (F8). Strobilurin and triazole fungicides or pre-mixes with both chemistry types are very effective at reducing disease incidence and severity and preserving yield. For a list of susceptible varieties, please refer to ratings from 2013 and 2014 available at: http://www.lsuagcenter.com/en/crops_livestock/crops/WheatOats/Variety+Trials++Recommendations/.

 

Stripe rust in wheat.
Stripe rust in wheat.

 

 

Leaf rust is usually evident later in the season than stripe rust. This is because the leaf rust pathogen requires warmer temperatures for development. Initial symptoms of leaf rust begin as light yellow spots, usually on the lower foliage. As the disease develops, small pin-point pustules form on the upper leaf surface. Pustules are brick or dark red and occur randomly on the leaf. Similar to stripe rust, pustules can cover the entire leaf surface if conditions remain favorable for development. The disease develops optimally when nighttime temperatures are 50 to 70 degrees F and leaves remain wet for six to eight hours. Leaf rust has not yet been found in Louisiana this year. Management recommendations for leaf rust are similar to those for stripe rust, and a list of susceptible varieties is available at the above URL.

Leaf rust in wheat.
Leaf rust in wheat.

 

Septoria/Stagonospora leaf and glume blotch is caused by the fungi Septoria or Stagonospora. Symptoms are similar for both diseases. Small elliptical lesions initiate on the lower leaves and progress up the plant if conditions remain favorable for disease development. As the lesions mature, the centers are straw-colored with small, raised black fruiting bodies (dots). The fungus can survive on infected wheat debris. Similar conditions favor the development of leaf and glume blotch diseases caused by Stagonospora and Septoria. Most fungicides are efficacious on these diseases; however, applications usually are not necessary unless disease progresses upwards to the flag leaf.

 

Septoria leaf blotch in wheat.
Septoria leaf blotch in wheat.

 

 

Management Considerations

 

Genetic resistance is not bulletproof. This resistance can break down over time with pathogen populations evolving to overcome resistance. For example, in 2010, stripe rust was observed in AGS2060 (a stripe rust resistant variety). Therefore, agents, producers and consultants should always scout crops beginning no later than early spring. In some cases, leaf and stripe rust can develop to very low levels in the fall. Early detection will allow producers to plan for the spring.

 

When genetic resistance erodes and disease is identified in resistance varieties, a fungicide application may be needed. Typically, a single application at flag leaf emergence (F8) is adequate for managing most foliar diseases of wheat. Strobilurins may be applied alone; however, to optimize the effectiveness of these products, they must be applied before infection by the stripe rust pathogen. Please refer to the table below for more specific information.

 

Fungicide(s)        
Class Active ingredient Product Rate/A  (fl. oz) Septoria leaf blotch Stripe rust Leaf rust Harvest Restriction
Strobilurin Picoxystrobin 22.5% Aproach SC 6.0 – 12 VG E2 VG Feekes 10.5 and 45 days
Fluoxastrobin 40.3% Evito 480 SC 2.0 – 4.0 VG Feekes 10.5 and 40 days
Pyraclostrobin 23.6% Headline SC 6.0 – 9.0 VG E2 E Feekes 10.5
Triazole Metconazole 8.6% Caramba 0.75 SL 10.0 – 17.0 VG E E 30 days
Propiconazole 41.8% Tilt 3.6 EC3 4.0 VG VG VG Feekes 10.5
Prothioconazole 41% Proline 480 SC 5.0 – 5.7 VG VG 30 days
Tebuconazole 38.7% Folicur 3.6 F3 4.0 VG E E 30 days
Prothioconazole19%Tebuconazole 19% Prosaro 421 SC 6.5 – 8.2 VG E E 30 days
Mixed modes of action4 Metconazole 7.4%Pyraclostrobin 12% TwinLine 1.75 EC 7.0 – 9.0 VG E E Feekes 10.5
Fluxapyroxad 14.3%Pyraclostrobin 28.6% Priaxor 4.0 – 8.0 VG VG2 VG Feekes 10.5
Propiconazole 11.7% Azoxystrobin 7.0% Quilt 200 SC3 10.5 – 14.0 VG E E Feekes 10.5
Propiconazole 11.7% Azoxystrobin 13.5% Quilt Xcel 2.2 SE 10.5 – 14.0 VG E E Feekes 10.5
Prothioconazole 10.8%Trifloxystrobin 32.3% Stratego YLD 4.0 VG VG VG Feekes 10.535 days
Cyproconazole 7.17%Picoxystrobin 17.94% Aproach Prima SC 3.4-6.8 VG E VG 45 days

1Efficacy categories: NL=Not Labeled; NR=Not Recommended; P=Poor; F=Fair; G=Good; VG=Very Good; E=Excellent; — = Insufficient data to make statement about efficacy of this product.

2Efficacy may be significantly reduced if solo strobilurin or SDHI products are applied after stripe rust infection has occurred.

3Multiple generic products containing the same active ingredients also may be labeled in some states. Products including tebuconazole include: Embrace, Monsoon, Muscle 3.6 F, Onset, Orius 3.6 F, Tebucon 3.6 F, Tebustar 3.6 F, Tebuzol 3.6 F, Tegrol, and Toledo. Products containing propiconazole include: Bumper 41.8 EC, Fitness, Propiconazole E-AG, and PropiMax 3.6 EC. Products containing propiconazole + azoxystrobin include: Avaris 200 SC.

4Products with mixed modes of action generally combine triazole and strobilurin active ingredients. Priaxor is an exception to this general statement and combines carboxamide and strobilurin active ingredients.

 

 

Realize that, in general, fungicides are effective against fungal diseases ONLY, but NOT effective against bacterial (black chaff) or viral diseases. Application timing and sprayer setup are just as important as the fungicide choice. Ideally, fungicides should be applied before disease onset or when disease incidence is very low. The residual activity of the fungicide may be lost too soon if applied too early. Apply too late, and disease severity may be too high to arrest disease development.

 

Sprayers should be configured to optimize coverage. Poor coverage of a good fungicide could result in poor disease control. Coverage is affected by gallons per acre, pressure, nozzle size, nozzle type, and nozzle spacing. Aerial fungicide applications should deliver fungicides in 4 to 5 gallons of total solution per acre and ground applications should be configured to deliver 10 to 20 gallons per acre.

 

Nozzles should be selected that deliver small droplets (200 to 300 microns). Nozzles configured to reduce drift potential will usually result in poor coverage. Boom height and nozzle spacing should be adjusted to the manufacturer’s specifications. A boom height too high will increase the potential for drift, and a boom height too low will not provide adequate overlap for the nozzles. Pressure should be adequate to force fungicide down in the canopy.

 

On a final note, remember that an effective disease management program will only be successful when all of the components are working together. Efforts must be made to correctly identify the diseases. Choose high-yielding, disease-resistant varieties, and make timely applications of an efficacious fungicide when necessary.

 

For more information concerning disease management in wheat, contact your local LSU AgCenter county agent/specialist or agricultural consultant.

N management in wheat

N management in wheat published on No Comments on N management in wheat

Josh Lofton, Steve Harrison, and Beatrix Haggard- LSU AgCenter

As we transition from January to February and wheat begins to show spring growth, it’s time to think about applying topdress N fertilizer. Most wheat is around Feekes 5 (green-up; http://varietytesting.tamu.edu/wheat/docs/mime-5.pdf) growth stage, and it’s time to begin applying topdress N. Decisions on N fertilization rate and timing dramatically  influence final yield, and N mismanagement can certainly be a limiting factor. However, N management in wheat is not as cut and dry as it can be in other crops. This is true for not only N application rates but also application timing.

Current recommendations are to apply 90-120 lbs N ac-1 throughout the growing season, split between all applications; however, these rates can vary depending on soil type, previous crop and crop condition. That means if 15 lbs N ac-1 was applied preplant, an in-season application should be between 75 and 105 lbs N ac-1. These application rates seem fairly straight forward, but attempting to manage around changing crop conditions (lush growth or stunted) or environmental conditions can be quite challenging. The major challenge for N application in wheat comes with determining how to split N applications and when those splits should occur. Currently, splitting in-season N application into two or even three topdress applications is considered the best management practice for wheat. This is due to N loss that can occur because of volatilization, leaching or denitrification. However, the most critical time for N application to have a yield benefit is late winter or early spring just prior to jointing. An initial application after jointing will limit yield potential of the crop. Furthermore, as the wheat progresses further, the benefit of N application is minimal or non-existent (by flag leaf). Therefore, N fertilizer should be applied in two to three applications between green-up and jointing with only rescue application between jointing to beginning emergence of the flag leaf.

While determining the optimum time to apply N fertilizer may seem perplexing, let your crop help you make your decision. For late-planted or wheat that did not properly develop in the fall, earlier N application (late January) is typically needed to help stimulate tillering. These applications are not needed on more developed wheat, and early topdress N application to well-tillered and advanced wheat could result in premature spring growth and subsequent yield loss if late freezes occur. Properly developed wheat in south Louisiana should probably receive an initial N application in early February, while north Louisiana should start to apply N by mid-February. However, these are just generalizations. Watch the wheat crop for signs of rapid development during warm conditions. If splitting N applications, the second application should follow the initial application by 14-28 days, allowing the crop time to green-up from the initial application and begin rapid spring growth.

While N management during in-season applications is the primary concern, managing S and, to a lesser degree, P can be critical during these stages as well. The benefit of S applications is not as wide-spread as N applications. Deficiencies are typically found on non-clay soils with lower amounts of organic matter; however, significant response can still be found on clay-textured soils with adequate organic matter content. Similar to N, S can be lost from the soil system through leaching during heavy precipitation events. Where this is an issue, the application of initial N application with urea and ammonium sulfate will minimize S issues. Managing P issues in-season for the wheat crop can be more challenging. Even if P is adequate in the soil system, cold and wet conditions can minimize the amount of P that can be taken up by the crop. If P deficiencies are present, the application of DAP as an N source cannot only help supply N needed for in-season application but also provide available P to the growing crop until conditions return where the crop can access soil-available P.

Josh Lofton, State Wheat Specialist, LSU AgCenter, jlofton@agcenter.lsu.edu

Sulfur deficiency in a wheat crop.  Note the similarity to N deficiency but occurs in the upper canopy. (Photo courtesy of R. Weisz)
Sulfur deficiency in a wheat crop. Note the similarity to N deficiency but occurs in the upper canopy. (Photo courtesy of R. Weisz)
Phosphorous deficiency in tillering wheat crop. (Photo courtesy of R. Weisz)
Phosphorous deficiency in tillering wheat crop. (Photo courtesy of R. Weisz)

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