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Western Flower Thrips Photo courtesy of UC IPM and Jack Kelly Clark

Early Season Thrips Management Strategies in Cotton

Early Season Thrips Management Strategies in Cotton published on No Comments on Early Season Thrips Management Strategies in Cotton

By Sebe Brown, Dr. David Kerns, Dr. Rogers Leonard – LSU AgCenter Entomologists

Thrips are annual pests of cotton in Louisiana. Damage by these insects cause stunted growth, delayed plant maturity and plant death under heavy infestations.  Cotton is most susceptible to thrips from emergence to the 4 true leaf stage.  Once cotton has reached the 4 true leaf stage, root differentiation has increased, terminal bud growth is accelerated and plants become less susceptible to injury.

The most common thrips found in Louisiana cotton are tobacco thrips, eastern flower thrips, onion thrips and western flower thrips.  These insects overwinter on a variety of weed hosts.  Planting seasons with windy conditions can have considerable influence on the severity of thrips populations in early cotton.  Thrips are typically weak flyers and wind helps to distribute infestations across fields.

Cotton seedlings that experience cool, wet soils develop very slowly and remain susceptible to thrips injury much longer than cotton planted in a warmer, more optimum, environment.  This year has been very warm and wet with considerable alternate hosts around cotton fields to produce sources of thrips infestations.  With the loss of Temik for the 2012 growing season, insecticide seed treatments (ISTs) and over-sprays will be critically important for controlling thrips on seedling cotton.

Cotton seed comes with a variety of seed treatment options that may either be purchased through a seed company or applied by a dealer downstream.  Outlined below are a few of my thoughts with regards to insecticide seed treatment packages on cotton seed.

Dow’s Phytogen seed comes with a base package of thiamethoxam (Cruiser), with Avicta Complete Cotton available upon request.  Avicta Complete Cotton includes Cruiser for the IST, multiple fungicides and abamectin for nematode control.  Information on Phytogen seed treatment options can be found here.

http://www.dowagro.com/phytogen/varieties/seed_treatments.htm

Monsanto’s Deltapine cotton seed comes with a combination of products that fall within the Acceleron treatment umbrella. The base package in cotton includes imidacloprid (Gaucho) and several fungicides.  However there are several options within the Accereleron brand.  Be sure that your seed is treated with what was ordered.  These options are upgrades to Avicta Duo Cotton with Cruiser for insect control, several fungicides for disease control and abamectin for nematodes.  Beware: the Acceleron seed treatment label in other crops may contain other products.  More information on Acceleron seed treatment options can be found here.

https://www.acceleronsts.com/Cotton/Pages/Cotton.aspx

Bayer’s Stoneville/Fibermax cotton seed comes with a base package that includes Gaucho for insect control and thiodicarb for nematodes that falls under the Aeris treatment umbrella.  Producers also have the option to upgrade to Poncho/Votivo with clothianidin (Poncho) for insects and Bacillus firmus (Votivo) for nematodes. More information on Aeris seed treatment options can be found here.

http://www.bayercropscience.us/products/seed-treatments/aeris/

Western Flower Thrips Photo courtesy of UC IPM and Jack Kelly Clark
Western Flower Thrips Photo courtesy of UC IPM and Jack Kelly Clark

Another option is to buy the minimum insecticide treatment available, and have a dealer apply additional insecticides downstream after the seed is purchased.

IST’s offer limited early season protection from thrips. Effective residual efficacy usually offers 10-14 days of control after plants emerge. Unsatisfactory residual control can occur with these treatments and cotton should be frequently scouted for thrips until the four leaf stage and when cotton plants are actively growing.

During 2011, western flower thrips were a problem in many Louisiana cotton fields. Western flower thrips can be difficult to control with standard applications of acephate, dimethoate, bidrin, etc.  Producers also risk flaring spider mites and cotton aphids with repeated applications of broad-spectrum insecticides. Recent research conducted by the LSU AgCenter demonstrated satisfactory control of a complex of species including western flower thrips with Tracer and Radiant at 2 and 7 days after treatment.

The use of a nonionic surfactant with these insecticides can help increase efficacy against thrips. Rescue applications of foliar insecticides should be applied early in cotton development with applications at the 1-2 true leaf stage yielding significantly greater lint per acre than treatments applied at the 3-4 true leaf stage.  Do not wait for thrips treatment in an attempt to time an overtop herbicide application.

Insecticide seed treatment options get producers off to a good start when it comes to insect pest management in cotton. However, these treatments should not be relied upon for sole control of all early season pests. IST’s are one of the best management practices (BMP’s) recommended by the LSU AgCenter for cotton IPM.

For more information concerning insect pest management, contact your local LSU AgCenter parish agent, LSU AgCenter specialist, or Louisiana independent agricultural consultant.

Thrips-injured cotton. Photo: LSU AgCenter
Thrips-injured cotton. Photo: LSU AgCenter
Cotton without thrips injury. Photo: LSU AgCenter
Cotton without thrips injury. Photo: LSU AgCenterThrips-injured cotton. Photo: LSU AgCenter

Wheat Insect Update

Wheat Insect Update published on No Comments on Wheat Insect Update

by Sebe Brown, Extension Entomologist

All, I have been seeing more instances of true armyworms infesting wheat in the North Louisiana.  These include wheat plots at St. Joe and Winnsboro at various stages of growth.  Our threshold for armyworms is 5 worms per square foot with foliage loss occurring. If armyworms reach the flag leaf and the wheat has not headed an application should be made.  I have also encountered varying levels of stink bugs (primarily rice stink bug) in wheat. Populations of stink bugs have to be high for damage to occur and our threshold is 10% infested wheat heads in the milk stage and 25% infested heads in the soft dough stage.  Stink bug numbers  will usually be higher around the edges of a field with numbers falling off as you walk further toward the middle. This means you may reach threshold around the edges of a field, but may also be well below threshold 100 feet in.  Applications of pyrethroids can control both of these pests.

Rice stink bug  photo courtesy of Gus Lorenz

Armyworm larvae on wheat heads photo courtesy of Robert Bellm, University of Illinois Extension

 

 

Rice insecticide seed treatment considerations for 2012

Rice insecticide seed treatment considerations for 2012 published on No Comments on Rice insecticide seed treatment considerations for 2012

by Natalie Hummel

You can link to Dr. Natalie Hummel’s weblog by going to: http://louisianariceinsects.wordpress.com/

This article was originally published in Louisiana Farm and Ranch, February 2012. I’m reposting it here for your information. This is an important article to read as growers are making their decision about insecticide seed treatments in rice for the 2012 season.

Authors: Natalie Hummel, Associate Professor and Assistant to the Director & Mike Stout, Professor

We have had quite a few inquiries about using a combination of seed treatments, neonicotinoid and Dermacor X-100, in rice. While this practice is legal, using more than one seed treatment is not a practice that we encourage in most circumstances because it results in more insecticide use in rice production than may be necessary.

The rice industry is considering one of these combinations of seed treatments: 1) Dermacor X-100 and CruiserMaxx or 2) Dermacor X-100 and NipsitINSIDE. Typically, a combination of seed treatments is only being considered when planting rice at low seeding rates, primarily because of concerns about the lack of efficacy of CruiserMaxx and NipsitINSIDE at hybrid seeding rates (25 lbs/acre or less) that we have observed in our rice water weevil demonstration trials and small plot trials. The second scenario is where Dermacor X-100 is being used for rice water weevil management and there is a history of stand reduction because of a sporadic pest infestation, usually chinch bugs or armyworms. Combining seed treatments provides a benefit of protecting the crop from injury by some primary and sporadic crop pests.

As the rice industry moves toward a more sustainable crop production profile, the LSU AgCenter strongly encourages rice producers to be good stewards of these insecticide seed treatments. Stewardship of these seed treatments means avoiding the use of insecticides not needed in the crop. For this reason, we discourage the widespread use of a combination of insecticide seed treatments in rice. We instead encourage the person making the seed treatment decision to consider the spectrum of pests that each insecticide can control, the seeding rate, and the history of crop pests in that field.

It is important to remember that each of the seed treatments controls a different group of insects. Dermacor X-100 belongs to a class of insecticides called anthranilic diamides, which target a specific receptor in the muscle of the insect. Dermacor X-100 is registered to control rice water weevil larvae, borers (Mexican rice borer, Rice stalk borer, Sugarcane borer), armyworms and colaspis (2ee registration for suppression). CruiserMaxx and NipsitINSIDE are both neonicotinoid insecticides that affect the nervous system of target insects. CruiserMaxx is labeled to control rice water weevils (larvae and adults), chinch bugs, colaspis and thrips. NipsitINSIDE is labeled to control rice water weevils and colaspis. We do not have data to support the ability of CruiserMaxx or NipsitINSIDE to control chinch bugs, colaspis or thrips in Louisiana, but we anticipate that they will control these pests based on observations from other crops and from rice in other parts of the world. As you study these seed treatments, you can see how a combination of these products can control most of the insects that attack rice in Louisiana. This is part of the reason why there is an inclination toward using a combination of treatments.

Here are criteria for you to consider as you make your seed treatment decision. The first is the seeding rate. This needs to be considered because neonicotinoids don’t always provide good control of rice water weevils at low seeding rates. Dermacor X-100 does provide control of rice water weevils at all seeding rates, but it will not control chinch bugs or thrips. According to the chemical manufacturers, neonicotinoids do control other early season pests including chinch bugs, thrips and colaspis. Another challenge at low seeding rates is that the plant stand is thin and is less tolerant to any insects that reduce the stand by killing seedlings. Insects that can reduce the plant stand count include armyworms, chinch bugs, colaspis and thrips. Borers can infest fields after the plant is at the green ring growth stage and reduce yields by causing deadhearts and whiteheads. Remember that if you put out a combination of seed treatments for a sporadic pest and that pest doesn’t infest your field, then you didn’t need to use a combination of seed treatments. We have data that indicate that rice water weevils infest more than 90% of rice fields in Louisiana. This justifies the use of a seed treatment to control rice water weevils as part of a good IPM program. That is not the case for many of our sporadic pests (armyworms, chinch bugs, colaspis, borers, etc.), which rarely occur at levels that justify treatment. Also, keep in mind that we rarely recommend an insecticide treatment for thrips in rice; usually the damage is not severe enough to require an insecticide.

Here are a couple of situations where a combination of seed treatments may be a good management decision. If you are planting rice at a low seeding rate and you anticipate that you will have an infestation of chinch bugs that would justify a pyrethroid treatment, then a combination of seed treatments would be a good option. In this situation, you would be using Dermacor X-100 to control rice water weevils, borers and armyworms and adding a neonicotinoid to control chinch bugs or thrips. Also, if you are planting rice at conventional seeding rates and you are using a neonicotinoid seed treatment to control rice water weevils and colaspis, but you typically have problems with armyworms or borers, then you may want to apply Dermacor X-100 to your seed.

There is one more thing to consider as you make your seed treatment decisions for the 2012 season. The EPA recently approved a Section 24C (special local need) registration for use of Dermacor X-100 in water-seeded rice. If you are interested in this option, a certified seed treater can provide more information. Remember that you CANNOT use the other seed treatments (CruiserMaxx or NipsitINSIDE) in water-seeded rice. The use of CruiserMaxx and NipsitINSIDE in water-seeded rice is illegal and will not provide control of the target pests.

If you have any questions about the seed treatment options registered for use in rice, please contact your local County Agent, or Natalie Hummel (nhummel@agcenter.lsu.edu) for more information.

 

Influence of Nitrogen Fertilizer Rate, Source, and Time of Application on Improving N Efficiency: Silt Loam

Influence of Nitrogen Fertilizer Rate, Source, and Time of Application on Improving N Efficiency: Silt Loam published on No Comments on Influence of Nitrogen Fertilizer Rate, Source, and Time of Application on Improving N Efficiency: Silt Loam

H.J. “Rick” Mascagni, Jr. and Brenda Tubana

Introduction

            Nitrogen (N) fertilization is a critical cultural practice required for producing maximum corn yield. Many factors, including soil type and crop management systems, determine optimum N rates. Nitrogen is typically knifed-in soon after the crop has emerged and an adequate stand established. Growers often times split N fertilizer applications as part of their management system or, in some cases, due to uncontrollable factors such as excessive or lack of rainfall, may produce soil conditions conducive to N fertilizer loss through denitrification and/or inefficient plant N uptake.  If N is topdressed with a fertilizer containing urea losses may occur due to volatization, which depends to a large extent on climatic and soil factors. If irrigated or rainfall occurs (0.5 inch or greater) within about three days, the fertilize is incorporated and no or minimal volatization losses will occur  Sometimes N applications are delayed or omitted due to inclement weather, while at other times, growers apply the recommended N rate for an expected yield potential. However, as the crop develops yield potential may be higher than expected and additional N may be required. In each of the above situations the question arises, how late can N fertilizer be applied and be effective? The fertilizer N source is also an important component of an effective fertility program. Products are also available such as urease inhibitors (i.e., Agrotain) that minimize urea volatization losses for 7 to 10 days. The objective of this trial was to evaluate N applications, N sources, and an urease inhibitor at different growth stages on a Mississippi River silt loam.

 Procedures

            A field experiment was conducted in 2011 on Commerce silt loam at the Northeast Research Station near St. Joseph to evaluate the influence of N rate, timing, and fertilizer source on corn yield and N fertilizer use efficiency (NFUE). Early-season N rates were injected at about the 3-leaf growth stage (April 16) as 30-0-0-2 solution (UAN) at N rates of 0, 120, 150, 180, and 210 lb N/acre. Urea, with and without Agrotain (3 qts/ton urea), was also hand-broadcast at the rate of 120 lb N/acre at the 3-leaf growth stage. For the early-season N rate of 120 lb/acre using 30-0-0-2, supplemental N rates of 30 and 60 lb/acre were applied at about the 12-leaf (May 23) and early-silk growth stages (June 7). Urea, with and without Agrotain, was hand-broadcast  and 30-0-0-2, with and without Agrotain, was hand-dribbled (to simulate a dribble application) at the 12-leaf and early-silk applications. There were a total of 23 treatments (see Table 2). REV® 28HR20 was planted on March 24 at 32,000 seed/acre. Cotton was the previous crop and all LSU AgCenter recommended cultural practices were followed.

             The experimental design was a randomized complete block with four replications. Grain yield, yield components, plant N, seed N, NFUE, and remote sensing data were determined. Grain yield was determined by machine harvest from the two middle rows of four-row plots and reported at 15.5% moisture. Yield components, seed weight (g/100 seed) and ear size (seed/ear) were also determined from the two middle rows.  Ear-leaf samples were collected at the early- silk growth stage to determine the influence of treatments on the N status of the plant. Seed samples were also collected at harvest. Total N was determined in the plant tissue and harvested seed by the LSU AgCenter’s Soil and Plant Testing Lab. Seed-N uptake (lb N/acre) was calculated by multiplying seed-N concentration by grain yield. NFUE was calculated using the following formula: (seed-N uptake for a given N rate – seed-N uptake for the no-N control) / N rate.   Remote sensing data using a SPAD meter were also determined at the 3- and 12-leaf growth stages. Statistical analyses were performed using the GLM procedure of SAS using a probability level of 0.10.

 Results and Discussion

            Rainfall was extremely low in May with a only a total of 4.9 inches in May and June in this dryland trial (Table 1). However, overall yields were extremely good averaging over 150 bu/acre (Table 2).

             At early-season, urea, urea + Agrotain, and UAN were compared at the 120 lb N/acre rate. Yield response had the following rank: UAN = urea + Agrotain > urea (Table 2). Evidently, there was some N loss due to volatization for the urea fertilizer. There was a 10 day interval between application and the first rainfall event. For the late N applications at the 12-leaf growth stage and early silk, both the 30 and 60 lb N/acre rates increased yields across sources. Yields tended to be a little higher for the early silk compared to 12-leaf applications. There were 11 and 2 day intervals between application and rainfall for the 12-leaf and early-silk applications, respectively. There was a yield response to urea + Agrotain for the 30 lb N/acre late application at the 12-leaf growth stage. When comparing equivalent N rates applied either once early season or split between early season and 12 leaf or early-silk growth stages, yields were similar. The treatment influence on kernel weight and ear size (kernel number) are shown in Table 2.

 Plant and seed N data are presented in Table 3. Leaf N, seed N, seed N uptake, and NFUE had the following rank for the early-season N treatments: UAN>urea+Agrotain>urea. Similar to yield responses, there were only small differences between the 12-leaf and early-silk late N applications for each N trait. Nitrogen fertilizer use efficiency (NFUE) was extremely high, ranging from 0.36 to 0.78 (Table 3). There were no differences in NFUE between the single and split applications, when comparing equivalent N rates. SPAD readings reflected treatment effects similar to yield responses (Table 4).

 

Table 1. Rainfall in St. Joseph, 2011.

Month

Rainfall

 

inches

 

 

March

8.3

April

3.0

May

0.9

June

4.0

July

4.4

August

1.3

 

Table 2. Influence of N fertility treatments on corn yield and yield components on Commerce silt loam, 2011.

 

 

 

N rate

 

 

 

 

 

 

 

ESN1 rate

ESN

source2

 

12-leaf

Early silk

Late N

source

Total N

applied

 

Yield

 

Ears

Kernel

weight

 

Kernels

lb/a

 

———lb/a——

 

lb/a

bu/a

no/a

g/100

no/ear

 

 

 

 

 

 

 

 

 

 

0

0

39.6

31,390

31.7

124

120

Urea

120

116.7

32,700

32.0

293

120

Urea + Ag

120

141.9

32,700

33.4

329

120

UAN

120

145.8

33,350

34.4

365

 

 

 

 

 

 

 

 

 

 

120

UAN

30

Urea

150

160.7

33,350

34.7

327

120

UAN

30

Urea+Ag

150

169.4

32,700

34.1

386

120

UAN

30

UAN

150

165.8

30,740

34.7

423

120

UAN

30

UAN+Ag

150

165.6

32,700

36.0

385

Average

 

 

 

 

165.4

32,370

34.9

380

 

 

 

 

 

 

 

 

 

 

120

UAN

60

Urea

180

170.0

32,050

35.2

386

120

UAN

60

Urea+Ag

180

176.8

34,010

36.2

397

120

UAN

60

UAN

180

160.3

33,350

35.2

357

120

UAN

60

UAN+Ag

180

166.2

32,700

35.1

378

Average

 

 

 

 

168.3

33,030

35.4

380

 

 

 

 

 

 

 

 

 

 

120

UAN

30

Urea

150

168.5

34,660

35.1

361

120

UAN

30

Urea+Ag

150

151.8

33,350

34.9

368

120

UAN

30

UAN

150

168.7

32,700

35.7

389

120

UAN

30

UAN+Ag

150

168.0

33,350

34.3

386

Average

 

 

 

 

164.3

33,520

35.0

376

 

 

 

 

 

 

 

 

 

 

120

UAN

60

Urea

180

177.0

32,700

35.6

403

120

UAN

60

Urea+Ag

180

172.8

34,010

34.4

383

120

UAN

60

UAN

180

166.5

33,350

34.1

381

120

UAN

60

UAN+Ag

180

170.0

32,700

35.1

393

Average

 

 

 

 

171.6

33,190

34.8

390

 

 

 

 

 

 

 

 

 

 

150

UAN

150

166.2

34,010

34.3

374

180

UAN

180

169.8

30,740

33.9

432

210

UAN

210

178.8

34,010

36.7

380

 

 

 

 

 

 

 

 

 

 

LSD (0.10):

 

 

 

 

14.7

NS3

2.7

53

                                                 

1ESN, early-season N injected at about 3-leaf growth stage.

2Ag = Agrotain; UAN = 30-0-0-2;

3NS = Non-significant at the 0.10 probability level

 

Table 3. Influence of N fertility treatments on N nutrition of corn on Commerce silt loam, 2011.

 

 

 

N rate

 

 

 

 

 

 

ESN1 rate

ESN

source2

 

12-leaf

Early silk

Late N

source

Total N

applied

 

Leaf N

 

Seed N

Seed N

uptake

 

NFUE3

lb/a

 

———lb/a——

 

lb/a

%

%

lb N/a

 

 

 

 

 

 

 

 

 

 

 

0

0

1.18

1.28

39.7

120

Urea

120

1.57

1.22

82.0

0.36

120

Urea + Ag

120

1.86

1.38

107.9

0.57

120

UAN

120

2.24

1.43

133.0

0.78

 

 

 

 

 

 

 

 

 

 

120

UAN

30

Urea

150

2.30

1.40

116.9

0.52

120

UAN

30

Urea+Ag

150

2.23

1.43

135.0

0.64

120

UAN

30

UAN

150

2.26

1.44

141.7

0.68

120

UAN

30

UAN+Ag

150

2.32

1.45

143.5

0.69

Average

 

 

 

 

2.28

1.43

134.3

0.63

 

 

 

 

 

 

 

 

 

 

120

UAN

60

Urea

180

2.32

1.50

142.4

0.57

120

UAN

60

Urea+Ag

180

2.27

1.55

166.4

0.71

120

UAN

60

UAN

180

2.15

1.50

138.1

0.55

120

UAN

60

UAN+Ag

180

2.36

1.52

145.4

0.59

Average

 

 

 

 

2.28

1.52

148.1

0.61

 
 

 

 

 

 

 

 

 

 

 

 
120

UAN

30

Urea

150

1.40

135.0

0.64

 
120

UAN

30

Urea+Ag

150

1.44

136.1

0.64

 
120

UAN

30

UAN

150

1.48

146.9

0.72

 
120

UAN

30

UAN+Ag

150

1.48

143.7

0.70

 
Average

 

 

 

 

1.45

140.4

0.68

 
 

 

 

 

 

 

 

 

 

 

 
120

UAN

60

Urea

180

1.47

151.7

0.63

 
120

UAN

60

Urea+Ag

180

1.53

149.8

0.61

 
120

UAN

60

UAN

180

1.47

139.1

0.56

 
120

UAN

60

UAN+Ag

180

1.45

142.4

0.58

 
Average

 

 

 

 

1.48

145.8

0.60

 
 

 

 

 

 

 

 

 

 

 

 
150

UAN

150

2.28

1.45

139.3

0.67

 
180

UAN

180

2.50

1.49

146.9

0.60

 
210

UAN

210

2.48

1.48

154.4

0.55

 
 

 

 

 

 

 

 

 

 

 

 
LSD (0.10):

 

 

 

 

 

0.16

0.10

21.7

0.14

 
                                                   

1ESN, early-season N injected at about 3-leaf growth stage.

2Ag = Agrotain; UAN = 30-0-0-2;

3NFUE = N fertilizer use efficiency

Table 4. Influence of N fertility treatments on SPAD readings taken early season and at 12-leaf growth stage on Commerce silt loam, 2011.

 

 

 

N Fertilizer Source

 

 

 N rate1

 

Total N

 

Urea

Urea + Agrotain

 

UAN2

UAN + Agrotain

 

Average

lb/acre   ———————————SPAD Readings ————————————-
 

 

 

 

 

 

 

 

 

 

Early-Season N Application

 

 

 

 

 

 

 

 

120

120

38.5

44.0

46.9

43.1

150

150

48.5

48.5

180

180

51.1

51.1

210

210

52.4

52.4

 

 

 

 

 

 

 

 

 

 

     12-leaf Growth Stage N Application

 

 

 

 

 

 

30

150

49.2

46.4

50.0

50.4

49.0

60

180

50.1

52.2

48.4

51.2

50.5

Average

 

49.7

49.3

49.2

50.8

 

 

 

 

 

 

 

 

LSD (0.10):

 

 

 

3.8

 

 

                   

1N rate applied early-season (3-leaf) and 12-leaf growth stage

2UAN = 30-0-0-2 fertilize solution

 

Influence of Nitrogen Fertilizer Rate, Source, and Time of Application on Improving N Efficiency: Clay

Influence of Nitrogen Fertilizer Rate, Source, and Time of Application on Improving N Efficiency: Clay published on No Comments on Influence of Nitrogen Fertilizer Rate, Source, and Time of Application on Improving N Efficiency: Clay

 H.J. “Rick” Mascagni, Jr. and Brenda Tubana

Introduction

            Nitrogen (N) fertilization is a critical cultural practice required for producing maximum corn yield. Many factors, including soil type and crop management systems, determine optimum N rates. Nitrogen is typically knifed-in soon after the crop has emerged and an adequate stand established. Growers often times split N fertilizer applications as part of their management system or, in some cases, due to uncontrollable factors such as excessive or lack of rainfall, may produce soil conditions conducive to N fertilizer loss through denitrification and/or inefficient plant N uptake.  If N is topdressed with a fertilizer containing urea losses may occur due to volatization, which depends to a large extent on climatic and soil factors. If irrigated or rainfall occurs (0.5 inch or greater) within about three days, the fertilize is incorporated and no or minimal volatization losses will occur  Sometimes N applications are delayed or omitted due to inclement weather, while at other times, growers apply the recommended N rate for an expected yield potential. However, as the crop develops yield potential may be higher than expected and additional N may be required. In each of the above situations the question arises, how late can N fertilizer be applied and be effective? The N fertilizer source is also an important component of an effective fertility program. Products are also available such as urease inhibitors (i.e., Agrotain) that minimize urea volatization losses for 7 to 10 days. The objective of this trial was to evaluate N applications, N sources, and an urease inhibitor at different growth stages on a Mississippi River clay soil.

 Procedures

            A field experiment was conducted in 2011 on Sharkey clay at the Northeast Research Station near St. Joseph to evaluate the influence of N rate, timing, and fertilizer source on corn yield and N fertilizer use efficiency (NFUE). Early-season N rates were injected at about the four-leaf growth stage (April 15) as 30-0-0-2 solution (UAN) at N rates of 0, 150, 210, and 240 lb/acre. Urea,with and without Agrotain (3 qts/ton urea), was also hand-broadcast at the rate of 150 lb N/acre at the four-leaf growth stage. For the early-season N rate of 150 lb/acre using 30-0-0-2, a supplemental N rate of 60 lb/acre was applied at about the 12-leaf (May 22) and early-silk growth stages (June 2). Urea was hand-broadcast and UAN was hand-dribbled (to simulate a dribble application) at the 12-leaf and early-silk applications. There were a total of 10 treatments (see Table 2). Pioneer 31P42 was planted on March 23 at 32,000 seed/acre. The trial was furrow irrigated. Cotton was the previous crop and all LSU AgCenter recommended cultural practices were followed.

             The experimental design was a randomized complete block with five replications. Grain yield, yield components, plant N, seed N, NFUE, and remote sensing data were determined. Grain yield was determined by machine harvest from the two middle rows of four-row plots and reported at 15.5% moisture. Yield components, ears/acre, kernel weight (g/100 seed), and ear size (kernels/ear) were also determined from the two middle rows.  Ear-leaf samples were collected at the early-silk growth stage to determine the influence of treatments on the N status of the plant. Seed samples were also collected at harvest. Total N was determined in the plant tissue and harvested seed by the LSU AgCenter’s Soil and Plant Testing Lab. Seed-N uptake (lb N/acre) was calculated by multiplying seed-N concentration by grain yield. NFUE was calculated using the following formula: (seed-N uptake for a given N rate – seed-N uptake for the no-N control) / N rate.   Remote sensing data using a SPAD meter were also determined at the 4- and 12-leaf growth stages. Statistical analyses were performed using the GLM procedure of SAS using a probability level of 0.10.

 Results and Discussion

            Rainfall only totaled 4.9 inches in May and June (Table 1). Furrow irrigations were applied on May 22 and June 2. Across treatments, yields ranged from 15.9 (control) to 197.5 bu/acre (Table 2).

             At early season, urea, urea + Agrotain, and UAN were compared at the 150 lb N/ace rate. Yield responses to treatments had the following rank: UAN > urea + Agrotain > urea (Table 2). There was a 11 day interval between application and rainfall. The late application of 60 lb N/acre increased yields similarly for both the 12-leaf and early-silk applications. There was little difference in yield between sources. Kernel weight was slightly higher for the late compared to early-season applications. When comparing equivalent N rates applied either once early season or split between early season and 12 leaf or early-silk growth stages, yields were similar.

 

Leaf and seed N data are presented in Table 3. Leaf N, seed N, seed N uptake, and NFUE responses to early-season N treatments were highest for UAN compared to urea + Agrotain and urea. There were small differences between the 12-leaf and early-silk N applications for each N trait evaluated. When comparing equivalent N rates, there were small differences between single and split applications for any N trait. Nitrogen fertilizer use efficiency (NFUE) was extremely high, ranging from 0.46 to 0.68. The highest NFUE value occurred for the 150 lb N/a UAN treatment applied early season. SPAD readings reflected trends similar to the yield response (Table 4).

 

Table 1. Rainfall in St. Joseph, 2011.

Month

Rainfall

 

inches

 

 

March

8.3

April

3.0

May

0.9

June

4.0

July

4.4

August

1.3

 

Table 2. Influence of N fertility treatments on corn yield and yield components on Sharkey clay, 2011.

 

 

 

N rate

 

 

 

 

 

 

 

ESN1 rate

ESN

source2

 

12-leaf

Early silk

Late N

source

Total N

applied

 

Yield

 

Ears

Kernel

weight

 

Kernels

lb/a

 

———lb/a——

 

lb/a

bu/a

no/a

g/100

no/ear

 

 

 

 

 

 

 

 

 

 

0

0

15.9

33,350

30.4

42

150

Urea

150

114.3

32,700

33.9

270

150

Urea + Ag

150

124.8

32,050

33.4

295

150

UAN

150

164.8

28,780

36.6

414

 

 

 

 

 

 

 

 

 

 

150

UAN

60

Urea

210

187.8

28,780

37.2

441

150

UAN

60

UAN

210

184.4

30,080

38.2

416

Average

 

 

 

 

 

186.1

29,430

37.7

429

 

 

 

 

 

 

 

 

 

 

150

UAN

60

Urea

210

191.1

28,780

37.2

446

150

UAN

60

UAN

210

186.1

34,010

37.6

402

Average

 

 

 

 

 

188.6

31,400

37.4

424

 

 

 

 

 

 

 

 

 

 

210

UAN

210

183.9

32,050

37.6

400

240

UAN

240

197.5

33,350

34.8

471

 

 

 

 

 

 

 

 

 

 

LSD (0.10):

 

 

 

 

 

10.9

NS3

NS

80

                                         

1ESN, early-season N injected at about 4-leaf growth stage.

2Ag = Agrotain; UAN = 30-0-0-2;

3NS = Non-significant at the 0.10 probability level

Table 3. Influence of N fertility treatments on N nutrition on Sharkey clay, 2011.

 

 

 

N rate

 

 

 

 

 

 

 

ESN1 rate

ESN

source2

 

12-leaf

Early silk

Late N

source

Total N

applied

 

Leaf N

 

Seed N

Seed N

uptake

 

NFUE3

lb/a

 

———lb/a——

 

lb/a

%

%

lb N/a

 

 

 

 

 

 

 

 

 

 

 

0

0

0.98

1.29

11.5

150

Urea

150

1.47

1.24

79.8

0.46

150

Urea + Ag

150

1.60

1.20

84.1

0.48

150

UAN

150

2.50

1.23

114.1

0.68

 

 

 

 

 

 

 

 

 

 

150

UAN

60

Urea

210

2.60

1.27

133.7

0.58

150

UAN

60

UAN

210

2.60

1.32

136.0

0.59

Average

 

 

 

 

 

2.60

1.30

134.9

0.59

 

 

 

 

 

 

 

 

 

 

150

UAN

60

Urea

210

1.31

140.3

0.62

150

UAN

60

UAN

210

1.34

139.5

0.61

Average

 

 

 

 

 

1.33

139.9

0.62

 

 

 

 

 

 

 

 

 

 

210

UAN

210

2.57

1.30

134.3

0.59

240

UAN

240

2.65

1.36

149.9

0.58

 

 

 

 

 

 

 

 

 

 

LSD (0.10):

 

 

 

 

 

0.17

0.05

9.1

0.05

                                         

1ESN, early-season N injected at about 4-leaf growth stage.

2Ag = Agrotain; UAN = 30-0-0-2;

3NFUE = N fertilizer use efficiency

Table 4. Influence of N fertility treatments on SPAD readings at the early season and

12-leaf growth stages on Sharkey clay, 2011.

 

 

 

N Fertilizer Source

 

N rate1

Total N

Urea

Urea + Agrotain

UAN

lb/a

lb/a

———————–SPAD readings—————————
              

 

 

 

 

 

 

 

Early-Season N Application

 

150

150

39.6

40.3

54.6

210

210

 

 

59.1

240

240

 

 

56.1

 

 

 

 

 

 

 

 

 

 

 

 

 

12-leaf Growth Stage N Application

 

60

210

54.2

 

56.7

 

 

 

 

 

LSD (0.10):

 

 

3.8

 

                     

 

Nematode Ratings of the Highest Yielding Soybean Varieties for 2012

Nematode Ratings of the Highest Yielding Soybean Varieties for 2012 published on No Comments on Nematode Ratings of the Highest Yielding Soybean Varieties for 2012

Charles Overstreet, Extension Nematologist

Highest yielding cultivars in Group III and Early Group IV Soybean Varieties

Soybean Variety

Soybean Cyst Nematode

Reniform Nematode

Root-knot Nematode

Delta Grow 4460RR

R 3

NA

S

Pioneer 93Y92

R 3, MR 14

NA

NA

Progeny 3911RY

S

S

S

Progeny 4211

R 3, MR 5, 14

S

S

Rev 44R22Tm

S

NA

S

S42-T4 Brand

R 3

S

S

S44-D5 Brand

R 3,  MR 14

NA

NA

 Highest Yielding Group IV Late Soybean Varieties

Soybean Variety

Soybean Cyst Nematode

Reniform Nematode

Root-knot Nematode

Armor 55 R 22

R 3, MR 14

NA

NA

Armor X1210

S

S

S

Armor X1211

S

S

S

Asgrow 4832

R 3

S

S

Asgrow 4932

R 3

S

S

Delta Grow 4670 R2Y

S

S

S

Delta Grow 4875 R2Y

R 3, MR 14

S

S

Delta Grow 4975 RR

MR 5

NA

S

Dyna-Gro 31RY45

R 3, MR 14

S

S

GoSoy 4810 LL

R 3

NA

NA

HBK R4829

MR 3

NA

S

HBK R4924

R 3, MR 14

S

S

HBK RY4721

R 3, MR 14

S

S

Miami 949LL

R 3

NA

NA

Morsoy 4707

R 3

S

S

Morsoy Xtra 46X29

NA

S

S

Morsoy Xtra 46X71

R 3

S

S

Pioneer 94Y70

R 3, MS 14

NA

S

Pioneer 94Y80

R 3, MS 14

NA

S

Pioneer 94Y82

R 3, MR 14

NA

S

Progeny 4510RY

S

NA

S

Progeny 4611RY

R 3, MR 14

S

S

Progeny 4710RY

S

NA

S

Progeny 4750RR

MR 3

NA

S

Progeny 4807RR

R 3

NA

S

Progeny 4811RY

R 3, MR 14

S

S

Progeny 4906RR

S

NA

S

Progeny 4911RY

S

S

MR

Soybean Variety

Soybean Cyst Nematode

Reniform Nematode

Root-knot Nematode

Progeny 4928LL

MR 3

NA

NA

REV @46R73TM

NA

S

S

REV @47R53TM

NA

S

S

REV @48R10TM

R 3

NA

S

REV @48R21TM

NA

S

S

REV @48R22

NA

NA

S

REV @48R33TM

NA

S

S

REV @49R10TM

NA

NA

S

REV @49R11TM

R 3

NA

S

REV @49R22TM

NA

NA

S

REV @49R43TM

NA

S

S

S08-14087 RR

R 3, MS 14

S

S

S08-17361

R 3, MS 14

NA

NA

Schillinger 457.RCP

R 3, MS 14

NA

S

Schillinger 458.RCS

MR 3

NA

S

Schillinger 478.RCS

MR 3, MS 14

NA

S

Schillinger 495.RC

MR 3, MS 14

NA

S

Highest Yielding Group V Soybean Varieties

Soybean Variety

Soybean Cyst Nematode

Reniform Nematode

Root-knot Nematode

AGS 568 RR

S

NA

MR

AGS 5911 LL

NA

NA

NA

AGS 597 RR

S

NA

S

Armor DK5363

MR 3

NA

S

Armor X1213

S

S

S

Armor X1215

S

S

S

Asgrow 5232

R 3

S

S

Asgrow 5332

R 3

S

S

Asgrow 5632

R 3

S

S

Delta Grow 5110R2Y EX

MR 5

S

MR

Delta Grow 5545RR

S

S

MS

Delta Grow 5555RR

R 1, 3, 5, 9

NA

S

Delta Grow 5625R2Y

S

S

S

Dyna-Gro 32RY55

R 3, MR 14

S

R

Dyna-Gro 35F55

R 1, 3

NA

S

Dyna-Gro 35P53

MR 2

NA

S

Dyna-Gro 37RY52

R 3, MR 14

NA

S

Dyna-Gro 39RY57

R 3

NA

R

GoSoy 5111 LL

R 3

NA

NA

HBK R5529

MR 1, R 2

NA

S

HBK RY5121

R 3

S

S

Soybean Variety

Soybean Cyst Nematode

Reniform Nematode

Root-knot Nematode

HBK RY5421

NA

S

S

HBK RY5521

NA

NA

S

Morsoy 5168

NA

S

S

Osage

S

NA

MS

Pioneer 95Y01

R 3, MR 14

NA

S

Pioneer 95Y10

R 3, MR 14

NA

NA

Pioneer 95Y20

NA

NA

NA

Pioneer 95Y31

R 3, MR 14

NA

S

Pioneer 95Y50

NA

NA

S

Pioneer 95Y70

NA

NA

S

Progeny 5111RY

R 3

S

MR

Progeny 5330RR

R 1, MR 2

NA

MR

Progeny 5610RY

R 3, MR 14

NA

R

Progeny 5655RY

S

S

S

Progeny 5711RY

R 3

S

S

Progeny 5811RY

S

S

S

Progeny 5960LL

NA

NA

MR

REV @51R53TM

S

S

S

REV @56R63TM

MS 3

S

MS

S54-V4 Brand

R 3

NA

S

USG 75Z98

S

NA

NA

 Letter designations for nematode reaction are: S = susceptible, MS= moderately susceptible, MR= moderately resistant, R= Resistant, and NA= no information available. All information in this table was provided by the seed companies or the University of Arkansas variety testing program at http://www.arkansasvarietytesting.com/crop/data/5.

 Soybean cyst nematode (SCN) continues to be a very minor nematode pest in our state. Currently, selection of a variety based on this nematode is not very important. None of the varieties on our list have any resistance against the reniform nematode which is found in 60% or more of our soybean fields. A few varieties have some level of resistance against the root-knot nematode.

Corn Insecticide Seed Treatment Options

Corn Insecticide Seed Treatment Options published on No Comments on Corn Insecticide Seed Treatment Options

Sebe Brown, Extension Entomologist

 Selecting corn seed treatments can be a challenging and expensive undertaking faced by many producers across Louisiana.  Corn seed treatments target three spectrums of pests: nematodes, fungal seedling diseases and insects.  This article will address insecticide seed treatment options available for corn.

Insecticide seed treatments are usually the main component of a seed treatment package.  Most corn seed available today comes with a base package that includes a fungicide and insecticide.  The insecticide options for seed treatments include Poncho (clothianidin), Cruiser/Cruiser Extreme (thiamethoxam) and Gaucho (Imidacloprid).  All three of these products are neonicotinoid chemistries.  Cruiser and Poncho at the 250 (.25 mg AI/seed) rate are the most common base options available for corn.  These insecticides are a good foundation; however, do not expect these treatments to give you extended protection from all below ground pests. If sugarcane beetles have been a problem in the past, Cruiser at the 250 or 500 rate will not provide adequate control; consider using Poncho at the 500 rate with 1250 providing better protection.  None of these products provide adequate control of cutworms.  Each company offers treatments that provide differing levels of early season insect protection, outlined below are some options available to producers with regards to insecticide seed treatments.

Pioneer’s base insecticide seed treatment package consists of Cruiser 250 with Poncho/Votivo 1250 available upon request.  Votivo is a biological agent that protects against nematodes.

Monsanto’s products including corn, soybeans and cotton fall under the Acceleron treatment umbrella.  Dekalb corn seed comes standard with Poncho 250.  Producers also have the option to upgrade to Poncho/Votivo, with Poncho applied at the 500 rate.

Agrisure, Golden Harvest and Garst have a base package with a fungicide and Cruiser 250.  Avicta complete corn is also available; this includes Cruiser 500, fungicide, and nematode protection.

Another option is to buy the minimum insecticide treatment available, and have a dealer treat the seed downstream.

Avipel was re-issued a section 18 for field and sweet corn seed in Louisiana.  The exemption is effective from February 24, 2012 through February 24, 2013.  Avipel can only be applied at the dealer and is used as a humane bird repellent.

It is important to note that below ground Bt traits available for western corn rootworm will not work on our strain of root worm in Louisiana.  Look at using in-furrow applications of Counter (organophosphate) or Force (pyrethroid) to help keep rootworms under control.  If an ALS herbicide was used in burndown applications or is anticipated, organophosphate insecticides should not be used.

Insecticide seed treatments are a valuable tool that allows producers a head start on early season protection from a variety of pests.  Minimizing damage below ground will help get this year’s corn crop off to a promising start.

Current Weather Conditions May Affect Burndown Strategies

Current Weather Conditions May Affect Burndown Strategies published on No Comments on Current Weather Conditions May Affect Burndown Strategies

From: Daniel Stephenson, Ph.D (Weed Scientist), Sebe Brown (Extension Entomologist) and John Kruse, Ph.D. (Cotton and Feedgrain Specialist)

Historically, many corn producers in Louisiana desire to plant corn in February. LSU AgCenter weed scientists and entomologists suggest burndown applications occur 4 to 6 weeks prior to planting to prevent competition from weeds and to remove vegetation that may be infested with insect pests – collectively known as “breaking the green bridge”.

Fields intended for corn should have already received a burndown application; however, weather conditions during January and early February may have prevented herbicide applications. As an example, 14.5 inches of rain were recorded at the Dean Lee Research and Extension Center in Alexandria since January 1.

The wet fields prevented ground application of burndown herbicides. Also, there were only a few days since January 1 that an airplane was able to make these applications due to wind conditions. As a consequence, Louisiana producers may be faced with weedy fields that are intended for corn.

A failure to “start clean” can greatly influence corn yields. Data have shown that corn determines its leaf orientation very soon after emergence. Leaf orientation perpendicular to the planted row is desired for maximum light interception, which influences growth and yield potential. If a spiking corn plant perceives any competition from an adjacent winter weed, the leaf orientation will be altered, thus potentially reducing that corn plant’s ability to intercept enough light for maximum yield. Therefore, planting into a weed-free field is very important.

Focus on Weed Control

Traditionally, a burndown application of glyphosate plus 2,4-D has been the standard protocol. This treatment usually provides good to excellent control of many winter/spring annual weeds common in Louisiana fields.

When applied 4 to 6 weeks prior to planting, a producer has time to evaluate the efficacy of glyphosate plus 2,4-D and decide if an additional herbicide treatment is needed prior to planting. If a producer is prevented from applying the burndown application in a timely manner, then weed competition and insect pressure may be an issue for emerging corn. Henbit in particular may be a refuge for cutworms and spider mites.

If a field scheduled for corn has received a burndown application, then these fields need to be evaluated to determine if corn will be planted into a “clean” field.

If the weather has prevented a burndown application and a producer intends to plant corn within the next few weeks, several factors must be considered.

The first issue is the 2,4-D plant-back restriction, which is 7 days for corn. If you are within this window, then you should not apply 2,4-D, to prevent herbicide injury to the corn. Second, maximum efficacy of glyphosate will not be observed until 21 to 28 days after application, so glyphosate applied 7 to 10 days before planting may not provide acceptable weed control and may allow insect populations to survive.

If a producer is within 7 to 14 days of planting corn, he/she should consider the following burndown treatments:

  • Gramoxone SL at 1.5 qt/A plus atrazine at 1 lb ai/A plus 0.25% v/v nonionic surfactant.
  • Gramoxone SL at 1 qt/A plus Leadoff at 1.5 oz/A plus 0.25% v/v nonionic surfactant.

Gramoxone SL will provide control of existing weeds, but coverage is essential. Therefore, a minimum of 12 gallons of water per acre and flat-fan nozzles should be utilized to maximize coverage. Also, Gramoxone SL efficacy can be increased when the air temperature is high and cloud cover is minimal.

Atrazine or Leadoff will assist Gramoxone SL with control by providing residual activity on winter/spring weeds during the first few weeks after corn emergence – if beds are not disturbed at planting. However, if an organophosphate insecticide will be applied in-furrow when planting corn, then Leadoff cannot be applied or injury will occur.

Focus on Insect Control

At-plant bands or post-emergence pyrethroid applications can be used to control cutworms; however, the infestation needs to be detected early to minimize stand loss. Moist soils will help incorporate the application to improve efficacy on any cutworms that may be located below the surface.

Foliar insecticide applications can be applied in bands behind the planter in reduced tillage fields. At planting soil insecticides such as Lorsban 15G can be t-banded with corn to help control cutworms pre-emergence. Lorsban should not be planted in furrow due to possible phytotoxicity. It is important to note that the use of ALS inhibiting herbicides with organophosphates such as Counter and Lorsban have the ability to cause significant crop injury.

If producers used Leadoff in their burn down strategy then Counter should not be used at all, to prevent any negative effects between the two chemicals. Lorsban has greater crop safety than Counter when used in conjunction with ALS inhibiting herbicides.

Force 3G can also be used at plant to help protect against cutworms. Force 3G is a pyrethroid insecticide and the ALS interaction is not a factor. Counter is not effective for control of cutworms but useful for rootworms.

Planting corn into a weed-free field is a must to maximize yield. Regardless of when you apply a burndown treatment, a producer must strive to “start clean”.

Wheat: Cold Weather Means Risk

Wheat: Cold Weather Means Risk published on No Comments on Wheat: Cold Weather Means Risk

We are forecast to finally have some real winter over the next few days. Unfortunately, much of our wheat has already moved on to spring. Temperatures in Baton Rouge are forecast to reach 28–30 ˚F Saturday night. In Monroe (along I-20 in north Louisiana) temperatures are forecast to reach 22-24 ˚F, 18 ˚F at Greenville, MS, and 16 ˚F at El Dorado, AR.

The forecast has been in a state of flux over the past couple of days and it is hard to know what will really happen. I am pretty confident that we will have some freeze damage to wheat this weekend but it is difficult to predict how much. The good news is that it is still very early in the growing season, wheat has lots of time to recover, and wheat is a very resilient crop.

Wheat that is not jointed will not suffer anything more than superficial leaf burn at 20 ˚F. Our wheat has been growing very rapidly and there are lots of tender leaves that will have the tips burned, but this should not impact yield. Prior to jointing wheat is very tolerant of cold weather and damage is infrequent and superficial. Wheat becomes much more vulnerable to freeze damage as it progresses from first node to flowering. Hopefully we will have a cool February and not have to address that issue. There is really not much that can be done at this point. The chart below (borrowed from http://www.ksre.ksu.edu/library/crpsl2/c646.pdf)

shows the relationship between growth stage, temperature, and freeze damage. The months that correspond to the growth stages are appropriate for Kansas, not Louisiana. The growth stages are valid, except that tillering occurs all winter in Louisiana.

*** CLICK ON IMAGE TO ENLARGE ***

 

*** CLICK ON TABLE TO ENLARGE ***

 

Wheat that has jointed (Feeke’s GS 6) will start to sustain significant damage around 24-26 ˚F. This damage can manifest in several ways. Stems can freeze on one side which weakens stems and can result in lodging at heading and poor grain fill due to inability to supply the developing head with adequate water and nutrients; or stems can completely freeze at the soft growing point resulting in loss of that tiller.

The link below is a good summary of spring freeze damage symptoms in wheat from our friends at Mississippi State. . http://msucares.com/crops/wheat/faq7_damage.html

The amount of damage on tillered wheat will depend on temperature and duration of exposure. I suspect that most of the wheat in Louisiana will only sustain superficial damage. I do know that there are some fields that have one and maybe even two nodes showing and these will be hurt. It normally takes a couple of days after a freeze before symptoms are easily apparent. This comes in the form of dead and dying tissue; lodging and discolored tillers; and a distinct odor of rotting tissue. Again, we won’t know the extent of damage until early next week and there is still a lot of time for the plants to form new tillers and make a near-normal yield. I’m sure the internet will be abuzz with freeze damage discussions next week

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