September Soybean Newsletter
John Woodruff
UGA – Crop & Soil Science
Excessive Soybean Bloom/Pod Shed- The number one question being asked in August
is: “Is there still time to make a soybean crop? My soybeans have shed nearly all of the
flowers and small pods”. Soybeans, exposed to extended heat, soil moisture stress, and
sometimes, a late surge of vegetative growth, have shed more than usual amounts of
blooms and small pods. Some fields even by the third week of August had hardly any
pod set. The short answer to the question is yes. The site of soybean plants with bare
flower stalks is not pretty, but isn’t uncommon in mid August. What’s most important at
this point is to keep the soybean leaves healthy. In my 30+ years working with soybeans,
I have seen this situation often but have never seen a soybean yield failure for late
maturing varieties due to poor pod set in August if favorable weather conditions resumed
by September 1. Soybean plants develop a primary flower stalk at each node. In
addition, they have buds for two secondary flower stalks at each node. When favorable
weather conditions occur during R2 most pods are set on the primary flower stalk. But in
years like 2007 (when the heavy stresses during R2 causes the excessive bloom shed on
the primary flower stalk) the soybean plant can bloom a second and even a third time
if/when favorable weather returns. That’s exactly what’s happening right now in many
fields across GA. Remind growers that if they protect the soybeans from insects and
soybean rust (if needed), they still have a chance to make a pretty good soybean yield.
Start Plans Now for Profitable 2008 Soybeans- Nov 08 soybean futures are trading for
around $8.50/bu or about 50 percent above the last ten year average price, and wheat is
trading about 75 percent above the last ten year average. On paper there appears to be
good profit potential in double cropping wheat and soybeans. A lot of folks are now
asking questions about 2008 double crop soybeans. This is good because success starts
with a good plan. Encourage your growers to give attention to the following areas in
making plans for 2008 double crop soybeans.
1. Get a soil test for both wheat and soybeans. Request recommendations for both
the wheat and soybean crops. Take care of lime, phosphorus and potassium needs
this fall. Doing so this fall will allow for quick double crop soybean planting next
May-June without delay and yield penalty. If growers plan to bale the wheat
straw, make sure they know how much nutrient removal is involved, and that they
have a plan now to meet those needs.
2. Do necessary deep soil tillage this fall ahead of wheat planting. This can have
carryover benefit for 2008 soybeans if tram lines and field traffic control are set
up and maintained during wheat culture.
3. Plan for no-till, strip-till, or some means of reduced tillage for 2008 soybeans
following wheat. Strip tillage is usually the most successful way of planting
double crop soybeans. Yields will usually be improved 10-15 percent if the row
width can be reduced to 30 inches. I really like strip till soybeans. This cultural
method allows for in-row subsoiling. Most GA farmers have good planters for
strip tillage. As such, they tend to get much better soybean stands with this as
opposed to other no-till planting methods.
4. Start this fall lining up preferred double crop soybean varieties. Since soybean
acreage is expected to expand, preferred double crop soybean varieties will likely
be in short supply. Growers should be planning this fall which soybean varieties
will be best for 2008, and should be lining up seed supplies. 2007 UGA soybean
yield data should become available by late November.
5. Getting soybeans planted on time next May-June will require some luck with the
weather, but careful planning now can help with timely planting. Consider
planting some early maturing wheat if adapted and available. Spend needed time
this winter for maintenance and repairs to have combines, planters and other
equipment field ready come wheat harvest time. If soybeans have consistently
been planted after the optimum period, setting up wheat planting for relay
interplanting of soybeans next May could be a way to deal with this problem.
6. Encourage some forward 2008 soybean marketing/contracting now to take
advantage of current high market prices. As mentioned earlier, Nov 08 soybean
futures are trading at about 50% above the long term average price. Chances are
quite high that these prices won’t be this good next fall. I am not a marketing
expert, but my observation is that high prices serve the primary purpose of
attracting production but that they don’t remain high beyond a growing season
unless additional problems or markets develop. The situation is “we have an
opportunity to sell some 2008 soybeans now at a profitable price, let’s take
advantage of the opportunity while it is available”.
Georgia Soybean Update—Late August
John Woodruff
UGA – Crop & Soil Science
What a month this has been! The 2007 Georgia soybean crop has been exposed to
extremes of drought and heat. We have received numerous calls about soybeans shedding
flowers and small pods. In recent days, the heat has abated somewhat, and local rain
showers are occurring.
The good news is that we still have a chance to make a pretty good soybean crop.
Fields are greening up and blooming a second and/or third time following showers. My
guess is that about 30% of fields are in good to excellent condition, 50% in fair and 20%
in poor condition going into the final lap. We can still make a pretty good statewide crop,
but it’s going to take effort.
Insects (loopers, VBCs and stink bugs) are really starting to increase. Soybean
rust has been found at several South Georgia locations, and will likely spread if the
humid wet days continue.
Please encourage your growers not to give up on this crop. The soybeans across
the state are finally starting to set pods. Encourage growers to apply all needed
insecticide and fungicide treatments. Doing so will bring encouraging results if rains
continue through September.
Update on Soybean Rust Situation in Georgia
Bob Kemerait
UGA – Plant Pathology
This update is current as of 31 August 2007
Asian soybean rust has been confirmed at four locations located in three counties in
Georgia at this time.
1. Soybean rust is present in at least 1 commercial field and 1 private research farm
in Brooks County. We have yet to find it at other sites in the county, though it is
almost certainly there.
2. Soybean rust is present in at least one location in Tift County, a private research
farm near Chula. Note: We have not found soybean rust in any commercial
fields in Crisp or Turner Counties or in University field trials or sentinel plots in
Tift County. Again, low levels of the disease may be present in commercial fields
in the area, but we have not found them yet.
3. Soybean rust is present in very low levels in soybeans planted at the Attapulgus
Research and Education center in Decatur County.
Outside of Georgia, soybean rust has recently been found at low levels in soybean plots
in the panhandle region of Florida along the southwestern corner of Georgia.
Additionally, soybean rust is active in the south and southwestern portion of Alabama.
Current weather conditions across much of southern Georgia (slightly lower temperatures
and increased rainfall) will help to fuel the spread of soybean rust both by increasing the
movement of spores from field to field and by increasing the number of successful
infections of spores that land on foliage.
To date, development of soybean rust has been slow both within fields and across areas
of Georgia. I expect that the spread of soybean rust will increase now that 1) weather
conditions are more favorable and 2) much of our commercial soybean crop is entering
reproductive growth.
I am often asked by growers and agents to give them an estimate of the current risk to
soybean rust in their specific area. I believe that soybean growers across all of Georgia
are currently at some risk to Asian soybean rust, at least in the future, but the risk is much
higher in some areas and much lower in others.
1. Northwest Georgia: Current risk to soybean rust is LOW because of geographical
separation from current rust finds and because of extreme drought. Soybean
producers in this region should continue to monitor the spread of soybean rust in
southern Georgia and Alabama.
2. Northeastern Georgia: Current risk to soybean rust is LOW because of current
geographical separation from the disease. Soybean producers should continue to
carefully monitor spread of disease elsewhere in Georgia.
3. East Georgia: Current risk to soybean rust is MODERATE in this region of the
state. Soybean rust has not been detected in sentinel plots in Burke, Washington,
Appling, Laurens, or Ware Counties; however it is possible that rust could move
into the eastern region from southern Georgia in the near future. Soybean
producers in east Georgia should be ready to spray fungicides as rust begins to
move. The most conservative growers may apply fungicides at R3 (pod
development stage) growth stage as they put out other materials such as Dimilin
and boron. However, many growers will decide to wait to apply a fungicide until
the treat from rust is more immediate. Given the slow spread of the disease this
season, such a tactic should work well.
4. Southwestern Georgia: Current risk to soybean rust is VERY HIGH. Growers in
southwestern Georgia should assume that their crop has been showered with
soybean rust spores and that they should protect the crop with fungicides.
Although the disease is moving slowly, growers in this area should protect their
crop, at least by the R3 growth stage. I believe that producers in Seminole, Early,
Miller, Decatur, Grady, Thomas, Brooks, and Mitchell Counties are likely to have
some small level of rust in their fields.
5. South central Georgia: Current risk to soybean rust in HIGH. Growers in counties
such as Colquitt, Tift, Ben Hill, Cook, Turner, Crisp, Worth, and Berrien should
assume that rust may be in their area. Rust is also possible now, or in the near
future, in Calhoun, Sumter, and Terrell Counties. Growers in this region will
need to apply a fungicide during reproductive soybean growth, though they may
wish to wait until R3 or until rust is found to be in sentinel plots closer to their
fields. NOTE: Soybean rust has not yet been found in sentinel plots in Tift
County or in Sumter County, or at the SunBelt Expo in Moultrie.
Common Questions:
1. What fungicide do I spray? If you believe that you are spraying ahead of soybean
rust in your field, you can apply either protectant or curative fungicides
effectively. If you suspect that rust may be in your field, you should spray either
a curative triazole fungicide or a triazole/strobilurin mix.
2. How long do these fungicides last? Theoretically, a strobilurin such as Quadris or
Headline will remain active for up to 3 weeks; triazole fungicides for about 2
weeks. Of course this can vary.
3. When should I spray again? There is a slim profit margin in soybean production
and we don’t want to spray more than we have to spray. If it has been at least two
weeks since your last triazole spray and three weeks since your last strobilurin
spray, you should consider whether you need to spray again or not. If rust is not
moving much in the area, weather has been unfavorable for spread of rust, or you
are approaching R6 (full seed growth stage) you likely can wait a little while to
spray again or eliminate the second application. If rust is active and spreading,
you should likely spray again.
4. Two years ago, I sprayed my fields because you told me to and my neighbor
didn’t. He made every bit as good a yield as I did. Didn’t you waste my time and
money having me spray? Good question, but no, I didn’t waste your time or your
money. We are still learning much about soybean rust, though we know that it is
an important disease. Some commercial growers have improved their yields by
20 bu/A by spraying a fungicide. Fungicide sprays are, in my opinion, a very
good investment and insurance policy WHEN rust threatens. Of course, the final
decision on whether to spray or not rests with the grower.
Insect Update for Soybeans
Phillip Roberts
UGA - Entomology
Soybean Insect Update: Soybeans should be scouted for insect pests and damage at
least once per week (twice a week is preferred during periods of high insect activity or
critical stages of plant development) until the leaves begin to turn yellow and fall from
the plants. Pod-feeding (corn earworm and stink bugs) and foliage feeding insects
(soybean looper and velvetbean caterpillar) have been reported at threshold levels from
various areas. Proper scouting allows the producer to know if an insecticide application
is needed, and which insecticide is most appropriate for the complex of insect pests
infesting the field.
Pod Feeders: Corn earworm (CEW) infestations have exceeded threshold levels in some
fields. Most reports of CEW have been from east Georgia. Be sure to monitor pods for
CEW injury, shaking plants over a drop cloth and/or use of a sweep net will allow
populations to be estimated for determining the need to spray. Stink bugs appear to be
increasing in some areas. Southern green, brown, and green stink bugs are present in
fields. We are often asked about control of brown stink bug with pyrethroids. High rates
of pyrethroids provide increased control of brown stink bugs compared with low-medium
rates.
Foliage Feeders: Soybean looper and velvetbean caterpillar are two common foliage
feeders which infest soybeans. In fields which were treated with Dimilin, velvetbean
caterpillars and green cloverworms are generally controlled. However soybean looper
may still reach threshold levels. Tracer, Steward, Larvin, and Intrepid are potential
options for control of soybean looper. Multiple options exist for control of velvetbean
caterpillar (note that Steward is not recommended for control of velvetbean caterpillar).
See the Pest Management Handbook for thresholds and recommendations for individual
pests. Note that thresholds are lower during pod-fill as this is a critical stage of plant
development.