David Moseley, Stephenson, Daniel O., Brown, Sebe, Brown, Kimberly Pope, Towles, Tyler, Miller, Donnie K., Copes, Josh, Dodla, Syam, Wang, Jim Jian, Conger, Stacia, Parvej, Md Rasel, Tubana, Brenda S.
In this article:
|Use of harvest aids in Louisiana soybeans|
|Wrapping up soybean production with irrigation|
|July entomology update for Louisiana|
|Molybdenum fertilization increases soybean yield in Louisiana acid soils|
|Petiole sampling for in-season nitrogen management in cotton|
|2020 commercial pesticide applicator recertification options|
|LSU AgCenter Specialists|
Josh Copes, Sebe Brown, Daniel Stephenson, Donnie Miller and David Moseley, LSU AgCenter scientists
Early-planted soybean fields in Louisiana are in growth stage R5.5 to R6 and therefore are approaching the time for desiccation. In Louisiana, desiccating soybeans has become a popular practice, with timely applications improving seed quality and harvest efficiency. Research in Louisiana has shown that harvest seed quality has not been affected by harvest aid application.
Harvest aids are primarily used to promote an earlier, more efficient harvest by desiccating the soybeans and weeds in a field thus providing for an even dry down across the field. To achieve both goals, harvest aids must be applied in a timely manner. Once seed have separated from the white membrane inside the pod, they have reached physiological maturity and will no longer increase in size. At this time, soybean seed are at about 50% moisture content and seed will begin to dry. Any use of a harvest aid prior to the majority of seed reaching physiological maturity will result in a loss in yield, so careful scouting is necessary. Undoubtedly, there will be areas in soybean fields that are not as mature as the majority of the field.
Research conducted in Louisiana established that harvest aids could be applied to soybeans without yield penalty as long as the field is at reproductive growth stage R6.5 or later. At this growth stage the soybean seed in the top four nodes have separated from the white membrane within the pod and seed margins are prominently defined (Figure 1). Plant appearance at growth stage R6.5 will vary by variety so close attention should be made to pods collected from the top four nodes across the field and specifically whether seed have separated from the white membrane (Figure 2, 3) (Griffin and Boudreaux 2011, Louisiana Agriculture magazine Vol. 54, No. 2, Spring 2011).
Applying harvest aids too early not only goes against a product’s label (always read and follow label directions), but can result in significant yield loss due to reduced seed weight. Previous research showed that the maturity group IV soybean yield was reduced by 15.4% when applied to soybeans at seed moisture of 60%, before R6.5 (Boudreaux and Griffin 2011, Weed Technology vol. 25: 38-43). Harvest aid application prior to R6.5 or 40% seed moisture, resulted in yield loss of 15.6 and 4%, respectively, for maturity group V and VI varieties.
Determining when a soybean reaches R6.5 is not the only consideration that must be made before making a harvest aid application. Table 1 gives the label requirements, which must be followed, for harvest aid application timing of several products labeled in soybeans. Each product label provides the timing of when an application can be made. To gain the greatest advantage from a harvest aid application, producers should first determine when their field has reached R6.5, then the application should be made as soon as the label allows. These products were labeled as harvest aids by desiccating weeds and not soybeans. Products would need significant leaf drop in order to provide control because they are contact herbicides and, therefore, good weed coverage is required for control. Producers should also understand that if a harvest aid application is missed or delayed, it may be quicker to allow the field to naturally desiccate than to delay harvest by allowing for the required preharvest interval (PHI) associated with some products.
Table 1. Application timings based on the label of harvest aid products for soybeans.
|Indeterminate varieties||65% of pods have reached a mature brown color or seed moisture is less than 30%|
|Determinate varieties||Plants are mature; beans are fully developed, 50% of leaves have dropped and remaining leaves are yellowing|
|Varieties||Defol 5 (Sodium Chlorate)|
|All soybean varieties||Make application 7 to 10 days prior to anticipated harvest|
|Spray over the top of soybean that have reached physiological maturity (all pods and seeds have no more green color)|
|Indeterminate varieties||Greater than 65% brown pods and greater than 70% leaf drop or when seed is 30% moisture or less|
|Determinate varieties||Beans are fully developed, more than 50% leaf drop, and leaves are yellowing|
Producers have several harvest aid options, though the typical harvest aid application consists of paraquat with an additional nonionic surfactant or crop oil concentrate. With excessive morningglory pressure, growers might consider including carfentrazone (Aim) or saflufenacil (Sharpen) with paraquat to improve desiccation of vines and in situations with high grass pressure, a tank-mix of paraquat with sodium chlorate may be warranted to improve the desiccation of grassy weeds prior to harvest.
Environmental conditions following harvest aid application should be considered when choosing a desiccant. The Gramoxone SL label states that it is rain fast in 15 to 30 minutes after application. The Defol 5 label (sodium chlorate) states that applications should not be made if rainfall is anticipated within 24 hours, and as stated on the label, defoliation will be best on sunny, hot and humid days. The longer it remains on the plant, the better it will perform.
Producers must consider the required PHI associated with each product. When using multiple products, the longest PHI must be adhered to. Labeled rates and comments are presented below in the excerpt from the 2020 Louisiana Suggested Weed Management Guide (Table 2).
Table 2. Labeled rates and comments for preharvest desiccants from the 2020 Louisiana Suggested Weed Management Guide.
|Preharvest Desiccants Active Ingredient and Rate||Formulated
Product and Rate ||Weeds Controlled||Remarks
and Precautions |
|carfentrazone @ 0.016 - 0.023 lb/A||Aim 2EC @ 1-1.5 oz/A|
Add 1% v/v COC
|Better on morningglories than pigweed, sicklepod, etc.||Apply after crop has matured and grain has begun to dry down. More effective on annual vines. Do not apply within 3 days of harvest. Apply in 10 gal. by ground, 5 gal. by air.|
|saflufenacil @ 0.022-0.045 lb/A||Sharpen @ 1 - 2 oz/A|
Add 1% MSO + 8.5 lb/100 gal AMS
|Morningglories and other broadleaf weeds||Apply once soybean has reached physiological maturity (all pods and seeds have no green color). Indeterminate varieties: 65% brown pods, more than 70% leaf drop, 30% or less seed moisture. Determinate varieties: more than 50% leaf drop and remaining leaves are yellowing. Preharvest interval is 3 days.|
|paraquat @ 0.13 - 0.25 lb/A|
paraquat (2 lb/gal formulation) @ 8 - 16 oz/A; paraquat (3 lb/gal formulation) @ 5.4-10.7 oz/AAdd 0.25% v/v NIS; see label
|Desiccation of weeds and soybeans only||Indeterminate varieties: 65% of pods are mature or moisture content is 30% or less. Determinate varieties: 50% leaf drop and remaining leaves are yellow. Some drought stressed weeds will not be desiccated. Do not graze or harvest for hay. Apply in 20 gal. by ground or 5 gal. by air. Preharvest interval is 15 days. Immature soybeans will be injured.|
|sodium chlorate @ 6 lb/A||6 lb/gal formulation @ 1 gal/A|
5 lb/gal formulation @ 1.2 gal/A3 lb/gal formulation @ 2 gal/A
|Desiccation only. Level of weed control is affected by environmental conditions.||Apply 7-10 days before harvest. Apply in 20 gal. by ground, 5 gal. by air. Check label for environmental conditions most favorable for desiccation. Apply under high temperatures and humidity.|
Across the state, redbanded stink bug (RBSB) numbers are increasing as soybeans reach R5. LSU AgCenter entomologists recommend the control of threshold populations of RBSB until the soybeans are out of the field. This means that the inclusion of an insecticide for the control of RBSB with a harvest aid application could be necessary (sodium chlorate cannot be tank-mixed with any insecticide). It is important to keep in mind however, the restrictions placed upon many of the products at this point in the season. These restrictions may include total active ingredient restrictions and PHIs. Acephate, a common recommendation for RBSB control, can only be applied up to 2 lb ai per acre per year in Louisiana. Other insecticides also have increased PHI such as the pre-mix product Endigo, with a PHI of 30 days. It is important to read all label materials prior to any use of labeled product. When label restrictions prevent the inclusion of an insecticide with the harvest aid application, growers should not delay the harvest of soybeans so that the seed can be removed from the field as quick as the label allows.
Figure 1. R6.5 soybean seed.
Figure 2. Soybean pods showing, from left to right, youngest to oldest. Middle pod is an R6.5 seed.
Figure 3. Soybean seed within pods showing, from left to right, youngest to oldest. Middle pod is an R6.5 seed.
Stacia L. Davis Conger, LSU AgCenter engineer, and David Moseley, LSU AgCenter soybean specialist
Despite the last few years of unseasonable August rainfall totals, July and August are the hottest and driest months of the year in Louisiana on a historical basis. Irrigation can become critical to achieving favorable yield when the reproductive growth stages fall within these months. Upcoming considerations for irrigation termination can also have an economic impact.
Recent research from Mississippi State University evaluated three maturity groups (MG), three planting dates, and irrigation water use efficiency (IWUE) on yield and net returns using three varieties of furrow-irrigated indeterminate soybeans (Wood et al., 2019). The IWUE was calculated as the total yield divided by the seasonal volume of irrigation applied. They found that yield and IWUE were highest for the early planting dates, specified as late April. They also found a significant yield bump from planting MG IV soybeans as opposed to MG III and MG V for both early and mid-planting dates (mid-May). Thus, their results indicate that the best IWUE without adversely affecting yield and net returns was achieved by planting MG IV in the early or mid-season planting windows (no later than mid-May). This result occurred despite rainfall totaling more than the 10-year average in July and August for two of the three years of study, showing a strong relationship to increased irrigation requirements when the reproductive period fell within the driest months of the year.
When to terminate irrigation is a strong consideration for every crop in every year. Each additional irrigation event reduces net returns if yield does not increase from the application. Based on results from a furrow irrigation termination study conducted at Mississippi State University using two varieties of determinate soybeans, irrigation initiation should occur no later than R1 (Figure 1) unless there is sufficient moisture to extend past this critical growth stage and terminated after R5.5 (Figure 2) with enough moisture to complete pod filling (Heatherly and Spurlock, 1993). In wet years, irrigation should be applied only during short drought periods occurring between R1 and R5.5; this will lower IWUE but increase net returns. Once the crop reaches physiological maturity (Figure 3), irrigation becomes ineffective. Terminating irrigation prior to R5.5 produced a yield bump, but did not maximize net returns. Utilizing overhead irrigation as opposed to furrow irrigation will likely require additional events past R5.5 due to smaller increases in soil moisture per event (Heatherly, 1999). Heatherly (1999) felt that the described study results were transferrable to indeterminate soybean varieties.
For the second half of July, forecasts show most areas of the state having temperatures greater than 90 degrees with a low rainfall probability. However, forecasts can change in a blink of an eye. Thus, keeping track of soil moisture during the critical growth stages can help with taking advantage of all available rainfall. Combined with terminating irrigation at the right time, irrigation becomes an economical option.
In June, Gov. John Bel Edwards declared July 2020 Smart Irrigation Month in Louisiana at the request of the Louisiana Irrigation Association. This statewide celebration is part of a national effort promoted by the Irrigation Association. Happy Smart Irrigation Month!
Figure 1. A soybean plant at the R1 reproductive growth stage (open flower on the main stem).
Figure 2. A soybean pod that is approximately at the R5.5 reproductive growth stage. The seeds are longer than 1/8 inch (R5) but has not filled the pod cavity (R6).
Figure 3. A soybean pod at approximately the R6.5 reproductive growth stage (physiological maturity). The seed fills the pod cavity, and the white membrane has separated from the seed.
Heatherly, L. G. (1999). “Soybean Production in the Midsouth,” CRC Press LLC, pp. 119-141.
Heatherly, L. G., and Spurlock, S. R. (1993). Timing of furrow irrigation termination for determinate soybean on clay soil. Agron. J., 85(6): 1103-1108.
Wood, C. W., Krutz, L. J., Falconer, L., Pringle, III, H. C., Henry, W. B., Irby, T., Orlowski, J. M., Gore, J., Bryant, C. J., Boykin, D. L., Atwill, R. L., and Spencer, G. D. (2019). Soybean planting date and maturity group selection as a method to optimize net returns above total specified costs and irrigation water use efficiency. Crop Forage Turfgrass Manage., 5:180063, www.doi.org/10.2134/cftm2018.08.0063
Tyler Towles and Sebe Brown, LSU AgCenter entomologists
The bollworm trap counts on the Macon Ridge Research Station have not picked up yet, likely due to most of the corn on station being planted late. Trap catches in Central and South Louisiana have steadily increased over the past two weeks (July 1 to July 14). Reports from the field indicate substantial egg lay in the Red River valley and northern Louisiana Delta parishes just south of the Arkansas border, while much of the cotton in other areas are experiencing a very light egg lay.
In two-gene cotton varieties such as Bollgard II and TwinLink, it is especially important to scout cotton for eggs. The LSU AgCenter recommends applications be made on a 20% egg lay in the 2 gene cotton varieties. However, insecticide applications based on percent egg lay on the newer 3 protein expressing cotton varieties (Bollgard 3, WideStrike 3, TwinLink +) are not recommended. This gives the Bt proteins a chance to work on bollworm neonates. Fruit injury thresholds for both two- and three-protein-expressing cotton varieties are 6% fruit injury of any kind. Once bollworms move into fruiting structures, such as bolls, they are typically shielded from an insecticide application. If applications are necessary, whether on eggs or live larvae, recommended insecticides are Prevathon at 20.0 oz/acre or Besiege at 10.0 oz/acre.
Tarnished plant bug numbers are variable around Louisiana with larger numbers found in fields adjacent to corn. Threshold in blooming cotton is two to three plant bugs per 5 feet of row. Numerous insecticides are available for plant bug control. However, keep in mind that Diamond is an insect growth regulator therefore it will only have activity on nymphs. If broad-spectrum insecticides (pyrethroids, organophosphates) are being used for plant bug control, remember that both can flare spider mites.
Redbanded stink bugs are beginning to trickle into soybeans in northeast Louisiana, while numerous fields in central and south Louisiana have received multiple stink bug applications. Numbers of green and brown stink bugs are increasing around much of Louisiana as well. Redbanded stinkbug thresholds are 16 per 100 sweeps or 1 per 6 row foot with a drop cloth. While green and brown thresholds are nine per 25 sweeps or one per 6 row feet with a drop cloth.
Threecornered alfalfa hoppers (TCAH) are increasing in many fields around Louisiana which leads to questions on what threshold should be followed when controlling hoppers. Based on previous work conducted by Sparks and Newsom (1984), Sparks and Boethel (1987) and subsequent experiments conducted by the LSU AgCenter in the past five years, the LSU AgCenter recommended threshold is “starting at pod set, three nymphs per row foot or one adult per sweep.” This recommendation is based on published data and experiments conducted in Louisiana at LSU AgCenter Research Stations and Louisiana field locations. Independent of yield loss, TCAH can also cause an increase in the “green bean/stem syndrome” that often is present in soybean fields. Green bean syndrome’s exact cause is not known, but we do know that stress plays a large part in the malady. Environmental stress compounded by insect or disease related stress is often the culprit. The picture below is from a TCAH experiment conducted in at the Macon Ridge Research Station to investigate the effects of TCAH on dryland soybeans. The experiment was terminated at the onset of stink bugs and all non-target insects were controlled for the duration of the experiment. The green bean syndrome pictured below is directly related to TCAH feeding. The beans on the left were non-treated throughout the duration of the experiment, the beans on the right were keep free of hoppers. We also observed significant increases in green bean syndrome in both irrigated and dryland soybeans and observed significant differences in yield in dryland soybeans but not irrigated. The take-home message is TCAH are economically important insects that have a documented, data backed economic threshold of one adult per sweep at pod set.
Figure 1. Green stem syndrome caused by threecornered alfalfa hoppers.
Jim Wang, LSU AgCenter School of Plant, Environmental and Soil Sciences, and Syam Dodla, LSU AgCenter Red River Research Station
Soybeans are adaptable to various soil and climatic conditions and are grown on more than 1 million acres annually in Louisiana. Soybean yields are often limited by various abiotic stresses including soil water availability and nutrients. Most soils receive sufficient amounts of phosphorus and potash to maintain adequate levels, but application of micronutrients — molybdenum (Mo), boron (B), iron (Fe), copper (Cu), manganese (Mn) and zinc (Zn) — to correct any deficiencies is relatively limited. In recent years, yield suppression because of micronutrients is becoming more common due to the nature of their sources in soils, their interactions with other elements, and lack of their application over many years. In addition to the soil nutrient level, soil pH plays a major role in micronutrient availability.
Among these micronutrients, molybdenum deficiency is common in acid soils when soil pH is below 6.2, because of its strong bonding to iron/aluminum oxides. Because the majority of Louisiana soils are acidic, available molybdenum could be a significant yield-limiting factor in those soils. In addition, application of sulfate fertilizers can exacerbate the molybdenum deficiency due to the competition between sulfate and plant available molybdenum (in the form of MoO42-) for root uptake sites.
Molybdenum is essential for all plants as a component of nitrogen reductase enzyme in the chloroplasts and helps in conversion of nitrate to nitrite to be assimilated in plant cells. Further, in soybeans and other legumes, molybdenum is an important part of Mo-containing enzyme, nitrogenase, which is needed by root nodule bacteria for fixation of atmospheric nitrogen. For this reason, molybdenum requirement in soybean is greater than other non-legume crops. Molybdenum deficiency symptoms often appear as nitrogen deficiency due to lack of lack of nitrogen fixation by roots.
Currently, there is no adequate diagnostic test offered by soil testing labs because soil extraction of molybdenum is generally low and the detection of molybdenum in commonly used soil testing procedures has poor correlation with crop growth. Therefore, actively addressing molybdenum deficiency in acid soils could help realize greater soybean yield potential. Molybdenum deficiency can be corrected either by the soil or foliar application. Although molybdenum seed treatment is feasible to eliminate the deficiency, past research has shown that molybdenum seed treatment with rhizobia inoculant more than a few hours before planting reduces viable rhizobia inoculant. Producers planning on using a molybdenum seed treatment should treat the seed immediately prior to planting.
Figures 1 and 2 show the summary of a two-year study of molybdenum fertilization for soybean production that was conducted in a Louisiana acid soil Cancienne silt loam (pH 5.6 to 6.2) between 2018 and 2019. The soybean variety ASGROW AG45X8 was planted at seeding rate 120,000 per acre for both years. Molybdenum, as sodium molybdenum, was soil applied in a band within seven days of planting or as foliar spray at R1 growth stage. The soil application at 1, 2 and 4 oz Mo per acre and the foliar application at 0.25, 0.5 and 1 oz Mo per acre were evaluated for yield improvement.
In both years of the study, all soil application treatments of molybdenum fertilizer increased soybean grain yield over the untreated check plot. Molybdenum at 2 oz/a resulted in the highest yield increase over the check by 11% (Figure 1). All foliar treatments in both the study years, also significantly increased soybean grain yield. The foliar application at 0.25 oz/a of molybdenum gave the highest yield increase over the check plot by 17.4%, and the foliar application rate greater than 0.25 oz/a suppressed grain yield slightly compared to 0.25 oz/a (Figure 2).
Figure 1. The effect of soil application of molybdenum on soybean grain yield.
Figure 2. The effect of foliar application rate of molybdenum fertilizer on soybean grain yield.
These results clearly show the potential of molybdenum fertilization in improving soybean grain yield in acid soils. Both soil and foliar application of molybdenum can enhance soybean yield with foliar likely to be more effective. Foliar application can be carried out at R1 or earlier when the soybeans are about 12 inches tall and have enough foliage to absorb the applied molybdenum. It is recommended that soil application of 2 oz/a or foliar application of 0.25 oz/a of fertilizer molybdenum to be used to address molybdenum deficiency in Louisiana acid soils with pH below 6.2.
Rasel Parvej, LSU AgCenter soil fertility specialist; Brenda Tubaña, LSU AgCenter soil scientist; Josh Copes, LSU AgCenter agronomist; and Syam Dodla, LSU AgCenter soil scientist
Nitrogen (N) is the most yield-limiting nutrient in cotton. Maintaining a sufficient and balanced amount of N throughout the growing season is a prerequisite for successful cotton production. Both inadequate and excessive amount of N during the growing season causes problems and reduces cotton yield and profitability. Inadequate N decreases boll and lint production, while excessive N results in continuous vegetative plant growth that delays maturity, increases pest problems, and decreases harvest-aid effectiveness. In addition, excessive N increases off-site environmental impacts.
Nitrogen shortage during the growing season is a more common problem in cotton production than excessive N because N is highly prone to loss from the rootzone through volatilization, leaching, runoff, and/or denitrification. An adequately fertilized cotton field can have N shortage due to excessive rainfall during the growing season that causes water-logged conditions and initiates denitrification loss of N. Excessive rainfall or irrigation also causes leaching loss of N especially in coarse-textured soils with low organic matter and cation exchange capacity (CEC <10) such as loamy sand to silt loam soils. Runoff occurs when rainfall or irrigation rate exceeds infiltration rate. Runoff is laden with N (and other nutrients) and soil sediments that contribute to fertility of receiving waters. Volatilization loss is very significant for urea-based N fertilizers if not incorporated into soils. Therefore, monitoring N status during the growing season is very important for profitable cotton production.
Cotton in-season N status can easily be tracked by different methods such as crop sensing (vegetation indices), measurement of leaf chlorophyll content, petiole (leaf stalk that connects the leaf blade to the main-stem) testing for nitrate-N (NO3-N) concentration, etc. Monitoring petiole NO3-N concentration is the best tool of tracking in-season N status in cotton. This tool allows producers and crop consultants to predict the yield potentials dictated by soil nutrition and environmental conditions and adjust in-season N supply, if needed, to help achieve the highest potential yield. In addition, it helps motivate producers not to apply excessive amount of N at planting and hope for the best, which often causes environmental concerns. Cotton petiole NO3-N concentration typically indicates in-season N need seven to 10 days prior to the onset of N deficiency stress.
A successful petiole NO3-N monitoring program consists of several weekly petiole samplings starting at one week prior to first bloom and continue for four to five weeks after first bloom. At each sampling time, at least 20 uppermost recently mature leaves with petioles on the vegetative stem should be collected. These leaves are usually the third to fifth leaf from the terminal (a quarter-sized main-stem leaf at the top of the plant should be counted as the first leaf). The petiole of each sampled leaf should be separated from the leaf blade, placed in a labeled paper bag, and sent immediately to the plant diagnostic lab for NO3-N, total phosphorus (P), and total potassium (K) concentrations. The total N concentration in leaf blade at first bloom is also important in interpreting petiole NO3-N concentration. Therefore, the leaf blade of the collected sample at first bloom should also be analyzed separately for total N concentration. Leaf blade testing is not required at other sampling times. The K concentration in the petiole is also valuable in monitoring in-season K nutritional stress since K is one of the key nutrients in cotton production.
Cotton petiole NO3-N concentration across the blooming period can be interpreted using the NO3-N concentration in Table 1 and 2. Table 1 consists of Arkansas interpretations and Table 2 consists of Georgia interpretations. The Arkansas interpretation offers higher sufficiency ranges of NO3-N concentration than the Georgia interpretation and should be used for cotton production in Louisiana. Petiole NO3-N concentration in both interpretations peaks before blooming and then gradually declines towards boll maturation. In the Arkansas interpretation, the sufficient petiole NO3-N concentration ranges from 10,000 to 35,000 ppm (1 to 3.5%) at first bloom and 1,000 to 5,000 ppm (0.1 to 0.5%) six weeks after first bloom and the sufficient leaf blade N concentration ranges from 3 to 4.5% at first bloom stage. It is very important to note that these sufficiency ranges of petiole NO3-N concentration across the blooming stages are not the critical levels, but desirable ranges, and NO3-N concentrations below or above these desirable ranges do not directly indicate N deficiency or sufficiency as such because petiole NO3-N concentration is greatly influenced by plant stress caused by several abiotic and biotic factors. However, these sufficiency ranges may indicate in-season N status and incipient problems.
Along with NO3-N concentration, P concentration in petiole during the blooming period is very important in understanding environmental or physiological stress that can influence petiole NO3-N concentration and hence the interpretation. For example, petiole P concentration at first bloom should be >800 ppm and a decrease of >300 ppm petiole P concentration from the previous week during blooming period is a good indicator of water stress and in-season N fertilization decision should be delayed until the next sampling results are received. For proper interpretation of petiole NO3-N concentration, it is very important to make sure that the observed petiole NO3-N concentrations have not been influenced by any stress during the growing season. Therefore, petiole NO3-N concentration should be interpreted and in-season N fertilization decision should be made based on physiological, environmental, and nutritional conditions including crop growth stage, soil moisture status, irrigation events, seasonal rainfall amount, fertilization history, leaf blade N concentration at first bloom, petiole P concentration trend during blooming period, fruiting load, internode length, number of nodes above the white flower, pest damage, heat units, cloud cover, etc.
Overall, monitoring in-season petiole NO3-N concentration is simply a tool that, in combination with other stress indicators, can help make better in-season N management decisions and maximize cotton yield and profitability. This tool is best suited for high yielding cotton fields with irrigation or in high rainfall areas where water does not limit yield. Care should be taken in making in-season N fertilization decisions for fields with a potential for late-season N mineralization from organic materials.
Table 1. Sufficiency ranges of nitrate-N concentration in cotton petiole during blooming period.
Sufficiency ranges of petiole nitrate-N ((NO3-N) concentration
Arkansas interpretation - ppm (mg/kg)
|Time of sampling||Minimum||Maximum|
|1 week before 1st bloom|
|Week of 1st bloom||10,000||35,000|
|Bloom + 1 week||9,000||30,000|
|Bloom + 2 week||7,000||25,000|
|Bloom + 3 week||5,000||20,000|
|Bloom + 4 week||3,000||13,000|
|Bloom + 5 week||2,000||8,000|
|Bloom + 6 week||1,000||5,000|
Table 2. Sufficiency ranges of nitrate-N concentration in cotton petiole during blooming period.
Sufficiency ranges of petiole nitrate-N ((NO3-N) concentration
Georgia interpretation - ppm (mg/kg)
|Time of sampling||Minimum||Maximum|
|1 week before 1st bloom||7,000||13,000|
|Week of 1st bloom||4,500||12,500|
|Bloom + 1 week||3,500||11,000|
|Bloom + 2 week||2,500||9,500|
|Bloom + 3 week||1,500||7,500|
|Bloom + 4 week||1,000||7,000|
|Bloom + 5 week||1,000||6,000|
|Bloom + 6 week||500||4,000|
Source: Mitchell C.C., and W.H. Baker. 1997. Plant nutrient sufficiency levels and critical values for cotton in the southeastern U.S. Proceedings of the Beltwide Cotton Conference, National Cotton Council, Memphis, TN. 1:606-609.
Kim Brown, LSU AgCenter pesticide safety coordinator
Due to the COVID-19 shutdown, many of the state’s recertification meetings were postponed. After meeting with the Louisiana Department of Agriculture and Forestry (LDAF) and the LSU AgCenter administration, both virtual (online/computer-based) recertification training opportunities and face-to-face (in-person) recertification opportunities will be offered to all commercial pesticide applicators certified in Louisiana during the upcoming months in 2020. These meetings are for those applicators that need recertification before the end of 2020.
These trainings will consist of a general pesticide safety format that will serve to recertify commercial pesticide applicators in all categories.
In order to attend the trainings, an applicator must pre-register. If you have already pre-registered for a recertification training that was postponed, we will honor the fees that you have already paid and ask that you let us know what date you would like to attend. The cost for either type of training (virtual or in-person) will be $80.
Tentative schedule for upcoming trainings
8:30 – 11:30 AM training; 11:30 – 1:00 Lunch Break; 1:00 – 4:00 PM Training
August 25 and 26
8:30 – 11:30 AM on both days
September 23 and 24
8:30 – 11:30 AM on both days
October 20 and 21
8:30 – 11:30 AM on both days
8:30 – 11:30 AM Training; 11:30 – 1:00 Lunch Break; 1:00 – 4:00 PM Training
7:30 AM Sign In; 8:00 AM – 3:30 PM
LPMA O&T Meetings
Please contact LPMA; Phone: 225-927-5722 or Email: firstname.lastname@example.org
Bossier City, O&T
As listed above, all trainings will be six hours in length. Two virtual, one-day trainings are scheduled for three hours in the morning and three hours in the afternoon with a large break during the middle of the day to help people try to get their credit in one day. We have also scheduled four virtual training opportunities that are two-day trainings (three hours each day) to allow people a much longer break between both sections. These are being offered to reduce the number of people that we have in face-to-face meetings. There is no limit on the number of people that can participate in a virtual training event.
If you are not able to participate in virtual training sessions, we are still going to offer in-person trainings. Please see the dates and locations in the chart. At in-person training events, attendees will be required to sit 6 feet apart and wear face masks. These are guidelines to keep everyone safe while in-person. We will only be allowed to have 25 people present during in-person trainings. Again, you must pre-register to attend either virtual or in-person trainings, even if you registered earlier for an event that was postponed. If you are not able to attend a virtual or in-person training, LDAF does allow for recertification by re-testing in each certification category.
Virtual trainings are a privilege that we have been granted for this season and we would like to respect this opportunity. Please plan to interact and participate during both the virtual and the in-person trainings.
Be sure to pick the date or dates that works best for you. Registration can be found at: https://store.lsuagcenter.com/c-3-eventsservices.aspx
If your organization is not able to pay online with a credit card please contact the LSU AgCenter Pesticide Safety Education Program to receive a registration form. The website is: www.lsuagcenter.com/pesticide
If you previously paid a registration fee earlier this year for an event that was postponed due to the COVID-19 shutdown, please complete the registration form attached, and check the box that indicates that you already paid. Then select the event that you intend to attend.
Virtual training will be done live, in an online format through Microsoft Teams. Applicators that are planning to participate in recertification programs virtually will have to pre-register, must have an email address and access to the internet. The day prior to the training you will receive an email with the meeting invite and instructions.
Be sure to have your certification card number to assist LDAF with proper identification for recertification credit.
Both virtual and in-person trainings will be monitored by the Louisiana Department of Agriculture and Forestry staff. Throughout the virtual training there will be quiz questions that you will be required to answer in order to ensure that participants are engaged during the training. Questions will only cover the material presented.
For more information or for questions, please email email@example.com or call 318-427-2697 or 225-578-6998.
|Corn, cotton, grain sorghum||Agronomic||Dan Fromme||318-880-8079|
|Grain sorghum||Agronomic||Dan Fromme||318-880-8079|
|Pathology||Cotton, grain sorghum, soybeans||Boyd Padgett||318-614-4354|
|Pathology||Corn, cotton, grain sorghum, soybeans, wheat||Trey Price||318-235-9805|
|Entomology||Corn, cotton, grain sorghum, soybeans, wheat||Sebe Brown||318-498-1283|
|Weed science||Corn, cotton, grain sorghum, soybeans||Daniel Stephenson||318-308-7225|
|Irrigation||Corn, cotton, grain sorghum, soybeans||Stacia Davis Conger||904-891-1103|
|Ag economics||Cotton, feed grains, soybeans||Kurt Guidry||225-578-3282|
|Precision ag||Agronomic||Luciano Shiratsuchi||225-578-2110|
||Corn, cotton, grain sorghum, soybeans||Rasel Parvej||479-387-2988|