Volume 8, No. 6, August 2005

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Index


Dear Reader,

Virginia's growing season has really been a mixed bag this year. I've seen some of the best looking crops that I've ever seen in one area just to find severe drought-stricken ones a couple of miles down the road. A few miles (or counties) further, I'd see flooded fields. It seemed the typical thunderstorm pattern was here to stay. Last weeks heat broke that pattern somewhat, but the afternoon thunderstorms persisted.

Extreme heat doesn't really benefit any crop, but it seems to hurt soybean the most. I'm seeing flowers and pods abort, probably because of the heat, where there's no drought stress. But, it's still early in the season and we could still have a good crop

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Soybean Rust Update

Soybean rust seems content to stay to the south of Virginia. So far, it remains in Florida, Georgia, Alabama, and Mississippi. Some models have predicted soybean rust spore movement up the Atlantic coast and even into Virginia. I will remind you that these are just models, yet to be thoroughly validated. Yes, rust spores have been found in Kentucky and Tennessee. But, these have not been confirmed as soybean rust spores. Plus, the number was very low. We too have spore traps set up in Virginia; we have not detected any rust spores.

So, why hasn't rust taken the country by storm? I think the answer to this question lies in the fact that the amount of rust in the U.S. is still very low. You'll hear the words incidence, severity, and source strength. Incidence is basically the percent of the leaves (or crop) infected with the disease. Severity is how severe the infection is on a leaf or plant. It's my understanding that even where rust has been detected, the incidence and severity of it is very low. Scouts are finding it only on a few leaves per plant and not over the entire field or kudzu patch. This relates to the source strength, which is the ability to produce a large number of spores. The source strength in most confirmed areas is very low. It basically is a probability game. Once the incidence and source strength increases, the probability that a large number of spores will survive transport into new areas increases.

Will we see rust in Virginia this year? Probably. But, barring any tropical system moving the spores right into Virginia, I think we might just avoid spraying for rust on our full-season soybeans. What about double-crop beans? That's another issue.

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Stay Up-To-Date on Soybean Rust with the Virginia Tech Website and Hotline

Elizabeth Bush, Research Associate working with Dr. Erik Stromberg in the Plant Pathology, Physiology, and Weed Science department, has created an excellent web page on soybean rust. It can be found at http://www.ppws.vt.edu/ipm/soybeanrust/index.htm. This web site is updated at least twice per week and lists Virginia recommendations and the latest forecast and tracking information. You'll also find a wealth of other information concerning soybean rust.

In addition to the website, we've created a phone hotline at the Tidewater AREC. Currently, we're updating this on Tuesday and Friday afternoon. You can access this hotline at 757-657-6450 ext. 103.

I would suggest that you access these sources of information often since rust can move very fast and the scenario could rapidly change.

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Frogeye Leaf Spot: Should We Expect a Repeat of Last Year?

Most foliar soybean diseases are not much of a concern. There are exceptions. Soybean rust is the big one. Other foliar diseases that could reduce yield include aerial blight, Cercospora blight, and frogeye leaf spot. We have never seen aerial blight in Virginia and Cercospora blight is only common during a wet August and September and its potential for reducing yield is questionable. On the other hand, frogeye leaf spot has potential for significant yield losses in Virginia.

2004 could be remembered as the year of frogeye leaf spot on Virginia soybeans. In some areas, it was so bad, that by late in the growing season, defoliation was occurring in some locations. Significant yield losses occurred in some fields. Should we expect the same this year? It's hard to say, but we have not been seeing as much as we saw at this point last year. By July of last year, frogeye was one of the most common leaf diseases on samples being brought in by our soybean aphid and rust scout. However, this year, we've only detected the disease on a couple of samples. And on these samples, the severity was not bad; there were only a spot or two. These observations in combination with less favorable weather conditions lead me to say that no, it won't be as bad as it was last year. Still, we shouldn't take chances.

Frogeye leaf spot, sometimes called Cercospora leaf spot, is caused by the organism Cercospora sojina (not the same species that causes Cercospora blight and purple seed stain). The disease occurs everywhere soybean is grown, but is most destructive during warm and humid conditions. The fungus can survive from year to year on infected soybean residue and infected seeds. Although yield losses could be up to 30% with susceptible varieties, we have generally managed this disease with rotation, resistant varieties, and pathogen-free seed.

Last year, in nearly all cases of heavy infection (see photo below), the soybeans were second- or third-year soybeans (no rotation). The varieties used had little or no resistance to frogeye leaf spot. In some cases, these were public varieties where the seed was saved from last year and probably infected. When you combine the above with a wet year like 2004, it's no wonder that we saw such a problem. Clearly, in some fields, a fungicide would have been beneficial.

So, how do you know if you need to apply a fungicide to control the disease this year? Unfortunately, there are no good thresholds. If you're not rotating, using saved seed from an infected field last year, and/or are growing a susceptible variety, you're a good candidate. Generally, if you're seeing 5 to 10 spots per leaf and weather conditions are right for further development and you have a susceptible variety, then you should consider a fungicide.

On the next page is a list of soybean varieties with good or moderate resistance to frogeye leaf spot. If you are planting one of these varieties, I would not suspect that you'd have a problem. But, if you are, you should scout your field regularly then re-evaluate the need for a fungicide. This list may not be complete, so check with your seed representative for more information.

Virginia Soybean Varieties with
Resistance to Frogeye Leaf Spot
Asgrow A5427 USG 5002T
Asgrow AG4801 USG 5601T
Asgrow AG5402 USG 7423nRR
Asgrow AG5701 USG 7443nRR
D&PL DP5414RR USG 7482nRR
Delta King DK5366RR USG 7489RR
Garst 4612RR/N USG 7563nRR
Garst 5012RR/N USG 7582nRR
Pioneer 94B73 Vigoro V42N3RR
Pioneer 94M40 Vigoro V45N4RS
Pioneer 94M41 Vigoro V53N5RS
  Vigoro V58N3RR

Virginia Soybean Varieties with
Moderate Resistance to Frogeye Leaf Spot
Asgrow AG3905 Delta King DK5465RR
Asgrow AG4102 Delta King DK5961RR
Asgrow AG4201 Garst D484RR/N
Asgrow AG4403 Hytest HTS4915RR
Asgrow AG4502 Pioneer 9492
Asgrow AG4902 Pioneer 94M90
Asgrow AG4903 S.States RT4230N
Asgrow AG5301 S.States RT4981N
Asgrow AG5501 S.States RT4810N
Asgrow AG5603 S.States RT4502N
Asgrow AG5605 S.States RT5130N
Asgrow AG5903 S.States RT5450N
Asgrow AG5905 S.States RT5540N
D&PL DP3861RR S.States RT5730N
D&PL DP4331RR S.States RT5930N
D&PL DP4546RR USG 510nRR
D&PL DP4724RR USG 570nRR
D&PL DP5110S USG 7404nRR
D&PL DP5634RR USG 7440nRR
D&PL DP5644RR USG 7473nRR
D&PL DP5806RR USG 7478nRR
D&PL DP5915RR USG 7484nRR
Dekalb DKB38-52 USG 7514nRR
Dekalb DKB40-51 USG 7524nRR
Dekalb DKB44-51 USG 7547 RR
Dekalb DKB46-51 USG 7553nRS
Dekalb DKB51-51 USG 7562nRR
Dekalb DKB58-51 Vigoro V40N3RR
Delta King DK4461RR Vigoro V48N5RR
Delta King DK4763RR Vigoro V50N5RR
Delta King DK4868RR Vigoro V55N5RR
Delta King DK4967RR Vigoro V562NRR

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Quadris or Headline for Better "Plant Health"

Fungicide manufacturers have been recently touting the "plant health" benefits of strobilurin fungicides, specifically Quadris from Syngenta and Headline from BASF. Supposedly the plant health benefits include increased growth and efficiency, increased tolerance to stress, and late season foliar disease control. Of these benefits, I think the last is probably the most important. While there may be some evidence that these fungicides do have some physiological benefit to the plant, this evidence has yet to be reviewed and documented with accepted scientific methods. Until that occurs, I think that we can only communicate the disease control merits.

With that said, we do have data from last year that showed significant yield increases from Quadris alone or Quadris + Warrior insecticide. In six replicated experiments, county agents and I showed an average yield increase of 3.0 bushels per acre from a Quadris + Warrior application. Five of the six experiments significantly increased yield. The yield increase ranged from 2.6 to 4.2 bushels. In split-field experiments, Quadris + Warrior increased yields in 7 of the 8 fields for an average yield increase of 3.7 bushels per acre.

But, which product, the fungicide or insecticide, contributed to these yield increases. To answer this question, I conducted an experiment comparing an unsprayed control, Quadris alone, Warrior alone, and Quadris + Warrior. We made these applications to either R4 (late pod) or R5 (early seed) stage soybeans. Quadris proved to be responsible for an average yield increase of 3.2 bushels. Warrior did not contribute to the yield increase. In addition, application stage did not significantly affect the yield response.

Due to these yield increases, many growers in Virginia will be making a strobilurin fungicide application between the R3 (early pod) and R5 (early seed) development stages. But, before the trigger is pulled, one needs to consider a few things.

First, last year was perfect for development of many foliar diseases. Although we did not evaluate disease incidence or severity in the above-mentioned experiment, several foliar diseases were visually present, although not in high amounts. Disease control was likely the primary reason for the yield increases. But, I could be wrong. We are conducting the same experiments this year. With two years of data, I can be more confident in any recommendation.

Secondly, I cannot recommend adding an insecticide with the fungicide if the insect pest is not above threshold levels. Applying insecticide just to insure control of a pest that may or may not be there is very bad pest management. One sure way to flare corn earworm or other insect pest problems is to apply an insecticide a week or so ahead of the major moth flight. The only thing you can be sure to kill is the beneficial insect population, which can hold pests in check. Therefore, do not include an insecticide with a fungicide application unless the target insect pest is present and above threshold.

I'm not overly excited about fungicide applications to improve "plant health." I believe fungicides are valuable for disease control. But, let's not treat for something that's not there.

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Soybean Fungicides in Virginia

P. M. Phipps, Plant Pathologist

Fully Registered Fungicides (Sec. 3, FIFRA): Products with a single active ingredient:

  1. Chlorothalonil (Bravo, Echo): Protectant for common foliar diseases
  2. Azoxystrobin (Quadris): Protectant for common foliar diseases and rust
  3. Pyraclostrobin (Headline): Protectant for common foliar diseases and rust

Emergency/Crisis Registrations (Sec. 18, FIFRA): User must possess label at time of application

Products with a single active ingredient:

  1. Tebuconazole (Folicur): Curative/protectant for soybean rust
  2. Tetraconazole (Domark): Curative/protectant for soybean rust
  3. Propiconazole (Tilt, Propimax, Bumper): Curative/protectant for soybean rust
  4. Myclobutanil (Laredo): Curative/protectant for soybean rust

Products with two active ingredients:

Use Patterns for Control of Common Diseases and Soybean Rust:

Resistance management: Solo applications of strobilurin fungicides (Quadris and Headline) are limited to one spray per season. Applications of triazole fungicides (Tebuconazole, Tetraconazole, Propiconazole, Myclobutanil) are limited to two sprays per season. Pre-mixes of a strobilurin with a triazole aid in resistance management as well as combine preventative and curative modes of action for disease control

Examples of Spray Programs: The most effective period for disease control and maximizing the yield is likely when soybeans are between stages R2 (Full flowering) or R5 (Seed 1/8 in. long in pods at 1 of 4 upper nodes on the main stem). Sprays prior to flowering or after pods have full green seeds are not likely to be profitable)

Common disease present, and risk of rust is LOW
Bravo720 or Echo 720 20 fl oz/A
Quadris 2.08SC 6.2 fl oz/A
Headline 250EC 6 fl oz/A

Rust not detected in region, but the risk for an outbreak of soybean rust in area is HIGH
Quadris 2.08SC 6.2 fl oz/A (protectant only)
Headline 2.08SC 6.2 fl oz/A (protectant only)
Folicur 3.6F 4 fl oz/A (curative/protectant)
Laredo 2EC 7 fl oz/A (curative/protectant)
Domark 230ME 5 fl oz/A (curative/protectant)

Rust detected in region, and if present, must not exceed more than 10% of lower canopy
Folicur 3.6F 4 fl oz/A (curative/protectant)
Laredo 2EC 7 fl oz/A (curative/protectant)
Domark 230ME 5 fl oz/A (curative/protectant)
Quilt 1,66EC 14 fl oz/A (curative/protectant)
Headline SBR 7.8 fl oz/A (curative/protectant)

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Application Equipment for Effective Control of Soybean Foliar Diseases

Bobby Grisso, Extension Ag Engineer and David Holshouser, Extension Soybean Spec.

We addressed the issue of selective the proper application equipment for controlling soybean rust a few issues ago. However, in light of the questions that I continue to receive, I feel that that information needs to be restated. Remember, an effective job of controlling soybean foliar diseases is directly related to properly applying the fungicide.

The single most important factor affecting prevention of disease is complete coverage of the plant with fungicide. Fortunately, we have the technology; however, you might incur expenses with adaptation to the current application equipment.

First, remember the 5 major principles that result in satisfactory and economic control of the problem: 1) Positive identification of the disease, 2) Correct pesticide, 3) Selection of the right equipment, particularly the right type and size of nozzle, 4) Timely application, and 5) making sure the accuracy of equipment to confirm correct application amounts based on label recommendations.

First and probably most important, apply 15 to 20 gallons per acre of spray solution. Just as important, select the nozzles and pressures that will result in fine to medium droplets (200 to 300 microns). Pressure is not the key. Too high of pressure will just create fine and very fine droplets that are prone to drift.

Nozzles producing cone pattern are not recommended for foliar soybean diseases, especially soybean rust. The flat-fan pattern nozzles are still the best choice as long as the droplets from these nozzles are categorized as fine to medium. Check the nozzle catalog to find out at what pressure the nozzle you picked should be operated for it to produce fine to medium quality spray. A flat-fan nozzle set up with two spray patterns seems to provide a better coverage of plants with fully developed canopies. This is mainly due to being able to double the gallons per acre while still maintaining the desired droplet size. Research has also shown that hitting the target from two different angles, with one forward and one backward spray pattern, provides a more effective coverage than spraying with just one spray pattern shooting down. Several nozzle manufacturers have either the nozzles that provide a twin spray pattern from one tip, or special fittings/caps that allow the producers to place two nozzles in the same cap, one pointed forward, and the other one pointed backward.

Here are some recommendations to help achieve the best coverage and control when spraying for soybean rust.

On the following pages are some tables that can assist you with nozzle, travel speed, and pressure selection. Note that the tables are only for a single-nozzle setup. If you use two nozzles, your output will double and allow you to increase your speed of application. These tables can also be downloaded as an Excel spreadsheet at the Virginia Soybean Rust website: http://www.ppws.vt.edu/ipm/soybeanrust/index.htm. With the spreadsheet, you can manipulate your gallons per acre, nozzle spacing, and speed to fit your needs. Remember, droplet size is very important, so you should maintain your pressure in the manufacturers' suggested range. To download the spreadsheet, just click on Nozzle Selection Guide (Excel document) under the Fungicide & Equipment section found under the Links at the right-hand portion of the page.

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Soybean Insect Update

Ames Herbert, Extension Entomologist

Our annual corn earworm survey is underway. Although only four counties are completed, so far populations seem to be very small compared with last year. Southampton Co. (data provided by Wes Alexander, VCE Agent, Southampton Co.) reported that only 25 percent of ears surveyed were infested (compared with 41 percent in 2004), Suffolk (data provided by my staff) had 17 percent infested (compared with 85 percent in 2004), Westmoreland Co. (data provided by Sam Johnson, VCE Agent, Westmoreland Co.) reported only 7 percent infested (compared with 13 percent in 2004), and Richmond Co. (data provided by Sam Johnson) reported about 4 percent. It also appears that the major moth flight will be later than normal. Blacklight trap catches are still low, although we have seen a slight increase over the last three nights. Even the sweet corn in our area seems to have escaped much earworm pressure. We will post more information as it becomes available, but early predictions (always a dangerous thing to do with insects) are that we may be looking at an overall light pressure year.

More good news Ð we still have not detected soybean aphids in our multi-county survey. It may just be too hot for them. We may see an increase as we move into August and September. The later they show up, the less likely they will have any impact on yield Again, we will continue posting updates as we gather new information.

Table 8.1. Nozzles and the corresponding pressure and travel speed ranges to achieve "Medium" droplets at a 20" nozzle spacing and 20 GPA.
Spacing= 20 Pressure Speed Range for MEDIUM Droplet
GPA= 20 Range (psi) Speed (mph) 
  GPM Low High Low High input psi
XR8002 0.2 15 30 1.8 2.6 2.0 18.1
XR11002 0.2 15 20 1.8 2.1 2.0 18.1
TP8002 0.2 30 35 2.6 2.8 2.7 33.1
DG8002 0.2 30 60 2.6 3.6 3.0 40.8
DG11002 0.2 30 60 2.6 3.6 3.0 40.8
TT11002 0.2 30 80 2.6 4.2 4.0 72.6
XR8003 0.3 15 50 2.7 5.0 4.0 32.2
XR11003 0.3 15 25 2.7 3.5 3.0 18.1
TP8003 0.3 30 50 3.9 5.0 4.0 32.2
DG8003 0.3 35 60 4.2 5.5 5.0 50.4
DG11003 0.3 35 60 4.2 5.5 5.0 50.4
TT11003 0.3 50 90 5.0 6.7 6.0 72.6
TJ60-6503 0.3 30 35 3.9 4.2 4.0 32.2
XR8004 0.4 25 60 4.7 7.3 6.0 40.8
XR11004 0.4 15 40 3.6 5.9 6.0 40.8
TP8004 0.4 30 60 5.1 7.3 6.0 40.8
TP11004 0.4 30 40 5.1 5.9 6.0 40.8
DG8004 0.4 50 60 6.6 7.3 7.0 55.5
DG11004 0.4 40 60 5.9 7.3 7.0 55.5
TT11004 0.4 70 90 7.9 8.9 8.0 72.6
TJ60-6504 0.4 30 50 5.1 6.6 6.0 40.8
TJ60-8004 0.4 30 35 5.1 5.6 5.5 34.3
XR8005 0.5 40 60 7.4 9.1 8.0 46.4
XR11005 0.5 15 50 4.5 8.3 8.0 46.4
TP8005 0.5 35 60 6.9 9.1 8.0 46.4
TP11005 0.5 30 50 6.4 8.3 8.0 46.4
DG8005 0.5 50 60 8.3 9.1 9.0 58.8
DG11005 0.5 50 60 8.3 9.1 9.0 58.8
TT11005 0.5 80 90 10.5 11.1 11.0 87.8
XR11006 0.6 25 60 7.0 10.9 8.0 32.2
TP11006 0.6 30 60 7.7 10.9 8.0 32.2
TT11006 0.6 80 90 12.6 13.4 13.0 85.2
TJ60-6508 0.6 30 60 7.7 10.9 8.0 32.2
TJ60-8008 0.6 30 60 7.7 10.9 8.0 32.2
TJ60-11008 0.6 30 40 7.7 8.9 8.0 32.2
XR11008 0.8 50 60 13.3 14.5 6.0 10.2
TP11008 0.8 50 60 13.3 14.5 14.0 55.5
TT11008 0.8 80 90 16.8 17.8 17.0 81.9
TJ60-6508 0.8 50 60 13.3 14.5 14.0 55.5
TJ60-8008 0.8 35 60 11.1 14.5 14.0 55.5
TJ60-11008 0.8 30 60 10.3 14.5 14.0 55.5
TJ60-8010 1.0 50 60 16.6 18.2 18.0 58.8
TJ60-11010 1.0 30 60 12.9 18.2 16.0 46.4

Table 8.2. Nozzles and the corresponding pressure and travel speed ranges to achieve "Medium" droplets at a 20" nozzle spacing and 15 GPA.
Spacing= 20 Pressure Speed Range for MEDIUM Droplet
GPA= 15 Range (psi) Speed (mph)  
  GPM Low High Low High input psi
XR8002 0.2 15 30 2.4 3.4 3.0 23.0
XR11002 0.2 15 20 2.4 2.8 2.5 15.9
TP8002 0.2 30 35 3.4 3.7 3.5 31.2
DG8002 0.2 30 60 3.4 4.8 4.0 40.8
DG11002 0.2 30 60 3.4 4.8 4.0 40.8
TT11002 0.2 30 80 3.4 5.6 5.0 63.8
XR8003 0.3 15 50 3.6 6.6 6.0 40.8
XR11003 0.3 15 25 3.6 4.7 4.5 23.0
TP8003 0.3 30 50 5.1 6.6 6.0 40.8
DG8003 0.3 35 60 5.6 7.3 7.0 55.5
DG11003 0.3 35 60 5.6 7.3 7.0 55.5
TT11003 0.3 50 90 6.6 8.9 8.0 72.6
TJ60-6503 0.3 30 35 5.1 5.6 5.5 34.3
XR8004 0.4 25 60 6.3 9.7 9.0 51.7
XR11004 0.4 15 40 4.8 7.9 7.0 31.2
TP8004 0.4 30 60 6.9 9.7 9.0 51.7
TP11004 0.4 30 40 6.9 7.9 8.0 40.8
DG8004 0.4 50 60 8.9 9.7 9.0 51.7
DG11004 0.4 40 60 7.9 9.7 9.0 51.7
TT11004 0.4 70 90 10.5 11.9 11.0 77.2
TJ60-6504 0.4 30 50 6.9 8.9 8.0 40.8
TJ60-8004 0.4 30 35 6.9 7.4 7.0 31.2
XR8005 0.5 40 60 9.9 12.1 12.0 58.8
XR11005 0.5 15 50 6.1 11.1 11.0 49.4
TP8005 0.5 35 60 9.3 12.1 12.0 58.8
TP11005 0.5 30 50 8.6 11.1 11.0 49.4
DG8005 0.5 50 60 11.1 12.1 12.0 58.8
DG11005 0.5 50 60 11.1 12.1 12.0 58.8
TT11005 0.5 80 90 14.0 14.9 15.0 91.8
XR11006 0.6 25 60 9.4 14.5 14.0 55.5
TP11006 0.6 30 60 10.3 14.5 14.0 55.5
TT11006 0.6 80 90 16.8 17.8 17.0 81.9
TJ60-6508 0.6 30 60 10.3 14.5 14.0 55.5
TJ60-8008 0.6 30 60 10.3 14.5 14.0 55.5
TJ60-11008 0.6 30 40 10.3 11.9 12.0 40.8
XR11008 0.8 50 60 17.7 19.4 19.0 57.6
TP11008 0.8 50 60 17.7 19.4 19.0 57.6
TT11008 0.8 80 90 22.4 23.8 23.0 84.3
TJ60-6508 0.8 50 60 17.7 19.4 19.0 57.6
TJ60-8008 0.8 35 60 14.8 19.4 19.0 57.6
TJ60-11008 0.8 30 60 13.7 19.4 19.0 57.6
TJ60-8010 1.0 50 60 22.1 24.2 24.0 58.8
TJ60-11010 1.0 30 60 17.1 24.2 24.0 58.8

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2005 Virginia Corn & Soybean Ag Expo

Thursday, Aug. 11

This year the Virginia Ag Expo will be held at Montross on the Historic Northern Neck. The location is Windsor Farm home of our hosts, Ferdie Fax and Bonnie Chandler. Windsor Farm has been farmed by the Chandler family since its purchase in 1843. Mr. Chandler's name is a familiar name on the lists of yield contest winners on a state and national level with several different crops. The theme is very appropriate for an area so rich in history, "Today's Agriculture on the Historic Northern Neck". The Ag Expo is the largest field day event held annually in the Commonwealth of Virginia and is an educational, marketing and social event that farmers look forward to every year.

There will be corn and soybean exhibit plots along with field demos of a guidance system, sprayer nozzle demos for rust control and GreenSeeker, an on-the-go variable rate fertilizer application system. Companies will be displaying the latest products and services they have to offer to the agricultural community. Local businesses and associations will be showcasing the diversity of agriculture on the Historic Northern Neck.

There will be a traditional Bar-B-Que with all the trimmings and beverage. Lunch tickets are $5.00 in advance with a limited number available on the day of the Ag Expo for $7.00. Look for registration information in the mail coming soon or contact your local Virginia Cooperative Extension Office.

The Virginia Ag Expo is a joint project of the Virginia Corn Growers Association, the Virginia Soybean Association and the Virginia Cooperative Extension Service.

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Soybean Development Stages Explained

If nothing else, soybean rust will make us learn our soybean development stages. I get confused looks when I talk about V and R stages. To alleviate some of this confusion, I've listing the most important reproductive (R) stages. These are important because these are the stages that the soybean plant needs the most protection. Once the crop reaches the R6 stage, fungicide applications can pretty much cease.

R1 = One open flower at any node on the main stem. The date of occurrence will depend on planting date and maturity group. Our full-season group 4 soybeans flower in early- to mid-July; full-season group 5 soybeans flower in late July.

R2 = Open flower at one of two uppermost nodes on the main stem with a fully developed leaf. This stage occurs about 3 to 5 days after R1 and will last about 10 days.

R3 = Pod 3/16" long at one of the four uppermost nodes on the main stem with a fully developed leaf and lasts about 10 days. Full-season group 4 soybeans enter this stage in late July; full-season group 5 soybeans enter this stage in August.

R4 = Pod 3/4" long at one of the four uppermost nodes on the main stem with a fully developed leaf and lasts about 10 days.

R5 = Seed beginning to develop in a pod in one of the four uppermost nodes on the main stem. This stage lasts about two weeks.

R6 = Pod containing a green seed that fills the pod cavity at one of the four uppermost nodes on the main stem. Soybeans remain in this stage for about 3 weeks


Sincerely,

David L. Holshouser


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