In this issue
§ Soybean aphid update
§ Slugs and millipedes like the rain
§ EPA approves a new type of refuge for a Bt crop
§ Timely postemergence herbicide applications in soybean can increase profits
§ Tips for maximizing glyphosate activity in glyphosate-resistant soybeans
§ Replanting other crops after a sugarbeet stand is lost
§
§ Corn fields help clean up and protect the environment
§ Potato disease extension bulletins
§ Pesticide residue testing available
§ Regional reports
§ Weather
Christina DiFonzo, Entomology
Aphid suction traps have been running in
In soybeans, soybean aphids are reported in fields
throughout
To follow aphid reports on a web-based map, visit www.sbrusa.net.
Christina DiFonzo, Entomology
With the recent rains, slugs are common in some fields (view photo). Slugs feed on cotyledons, stems and leaves of emerging plants by scraping the leaf surface. With heavy damage, leaves take on a tattered appearance. Wet conditions favor slug populations, thus no-and reduced till fields with residue are at greater risk for slug feeding, especially if plants are emerging and growing slowly. Slugs are hidden during the day, but silvery slime trails may visible. To check for slugs, move residue aside during the day or walk fields at night. Another trick is to put something flat (like old shingles) out in the field overnight, by daybreak, slugs often accumulate on the underside. Seed treatments do not control slugs. Baits containing metaldehyde are very effective, but expensive. Drying conditions and good crop growth are the best solution to a slug problem.
Phil Kaatz from
Christina DiFonzo, Entomology
A few people contacted me to ask about a recent EPA decision to allow a “natural” refuge for resistance management in Bt cotton. Because there may be some confusion about how this relates to Bt corn, here are some details of the story.
Bollgard II is a stacked, transgenic cotton that produces two different Bt toxins, Cry2Ab2 and Cry1Ac. These Bt toxins control two important cotton pests, bollworm and tobacco budworm. In the past, producers using Bollgard II cotton were required to plant a certain percentage of acres to non-Bt cotton to manage insect resistance. In “government-speak,” this type of man-made refuge is called a “structured” refuge. Most of you are familiar with structured refuges, because they are also required when you plant Bt corn for European corn borer or corn rootworm control.
The Bollgard II cotton situation is a bit different from Bt
corn. Since Bollgard II produces two Bt toxins, its efficacy (kill off pest
caterpillars) is very high. If a caterpillar survives one Bt toxin, it is
presumably killed by the other toxin. The assumption is that the chance of
producing a resistant moth is extremely low, less than for transgenic cottons
producing only a single Bt toxin. Also, bollworm and budworm have many
alternate host plants, other crops as well as weeds. The assumption is that
caterpillars growing on the other hosts are not exposed to Bt, thus the alternate
crops and weeds act as a “natural” refuge for susceptible insects. Based on the
high efficacy and alternate hosts, Monsanto petitioned EPA to drop the
structured refuge requirement in favor of a natural refuge. EPA approved this
change for Bollgard II cotton planted from east
What does this mean for Bt corn refuges? Nothing. The
“natural” refuge only applies to one type of cotton planted in the eastern
Christy Sprague
Crop & Soil Sciences
Early season weed competition may be one of the biggest contributors to unseen yield losses in soybean. Appropriately timing postemergence herbicide applications is critical to preserving crop yields. Several studies have shown that delaying postemergence weed control strategies can substantially reduce crop yield. This has become more of a concern with the large number of glyphosate-resistant crop acres that rely on postemergence applications of glyphosate for weed control. We are not saying that postemergence herbicide application timings are not important in non-glyphosate-resistant crops, but herbicides generally used in these crops are most effective on small weeds. Therefore, growers that are growing non-glyphosate-resistant crops are probably already making postemergence herbicide applications early. If they are not, it is important to also follow the outlined guidelines for postemergence herbicide applications.
In glyphosate-resistant soybeans, there is the temptation to
delay postemergence glyphosate applications until all of the weeds have
emerged. Delaying these applications can rob soybeans of this maximum yield
potential. As mentioned before, research throughout the Midwest and
Over a four-year period, MSU conducted research to study the effect of glyphosate application timing and row spacing on corn and soybean yield loss from weed competition. This research showed that in at least one of the years that this research was conducted, if weeds were allowed to reach 6-inches in height before control, yield was reduced in narrow row soybeans and 30-inch row corn. Depending on when this yield loss occurred, soybean yield was reduced from 2.5 to 5.5 bushel/acre/day. This starts to add up when you consider the economics. Considering these crop loss estimates, delaying herbicide applications three days would cost you any where from $56.25 to $123.75/acre in soybeans ($7.50 new crop soybean.) Waiting to make postemergence herbicide applications can cost you money. Therefore, it is important to follow the recommendations to avoid yield losses due to early season weed competition.
Weeds should be controlled in:
§ 7.5 and 15-inch row soybean before weeds exceed 4-inches.
§ 30-inch row soybean before weeds exceed 6-inches.
Christy Sprague
Crop & Soil Sciences
Postemergence herbicide applications for weed control in soybeans are quickly approaching. The hot weather has both weeds and soybeans actively growing. With these approaching applications, there are several things that should be considered to maximize weed control with glyphosate in Roundup Ready soybeans. Following these guidelines can help reduce the risk of glyphosate failures, as well as reduce the chances of lower soybean yields due to weed competition.
There are over 30 different glyphosate products that growers
in
Another difference in glyphosate products is whether a surfactant needs to be added to the spray solution or if the formulated glyphosate product has a built-in adjuvant package. Products like Roundup WeatherMax, Touchdown Total and several others have built-in adjuvant systems. Even though all of these products have a built-in adjuvant system there can and many times are differences in the type of surfactant formulated in the product. These differences may equate to differences in weed control under extreme conditions. However, under most conditions there are no differences between these products especially when they are used at the correct rates, at the appropriate application timings. For products where the addition of a surfactant is recommended, add a high quality non-ionic surfactant at 0.25 to 1.0 percent v/v. Table 10 also includes information on whether the addition of a surfactant is recommended for a particular glyphosate product.
View Table 10 at http://www.ipm.msu.edu/cat07field/pdf/6-7Table10Weed.pdf
Ammonium sulfate (AMS) should always be added to all glyphosate products. We recommend adding dry spray grade AMS at 17 lbs/100 gal. or the equivalent of 17 lbs/100 gal. of liquid AMS products. The addition of AMS minimizes the negative effect of hard water on glyphosate activity and is important for velvetleaf control, regardless of water quality.
Applying the appropriate glyphosate rate in glyphosate-resistant soybeans is important for consistent weed control. Proper glyphosate rates should be based on weed type, weed size and spray volume. In most cases the appropriate rate to use for weed control in glyphosate-resistant soybean is 0.75 lbs a.e./A of glyphosate. This rate will effectively control several annual weed species between 2 and 8 inches tall. However, if weeds become larger or if harder to control species such as common lambsquarters or giant ragweed are present, increase the glyphosate rate to 1.1 lbs a.e./A or 1.5 lbs a.e./A to adequately control these weed species. In addition, by matching the appropriate glyphosate rate to the correct weed size you reduce your chances of weed control failures under extreme conditions.
Glyphosate application timing is everything! It is important to make timely glyphosate applications to minimize the chances of soybean yield loss due to early-season weed competition and to maximize weed control. As presented in an earlier article of today’s Field CAT Alert the optimum time for glyphosate applications is when weeds are 4 inches tall in narrow-row (7.5 and 15 inches) soybeans and 6 inches tall in wide-row (30 inches) soybeans. Controlling weeds at these times reduces the chances for soybean yield loss, as well as reduces the risk of weed control failures of larger weed that may be under stressful conditions (drought, stem-boring insects, coverage issue, etc.).
Windy conditions in the narrow application windows that we see this time of year make the use of drift reducing nozzles or drift reducing agents almost a necessity to reduce or prevent off-site particle drift. When using these technologies it is important to know their limitations. Using these technologies without the proper spray pressure and spray volumes can lead to reduced weed control with glyphosate. To maintain effectiveness with these technologies, make sure to follow manufacturer’s recommendations on pressure and volume, apply the appropriate glyphosate rate for the target species, and always check for a uniform spray pattern. Combinations of some of these technologies can reduce spray coverage that may result in reduced weed control. Following these guidelines, particularly checking the spray pattern, can help determine if the weeds are receiving an adequate dose of the herbicide for weed control.
Following these guidelines will help maximize glyphosate performance and reduce the risk of soybean yield loss due to weeds in the 2007 season.
Christy Sprague
Crop & Soil Sciences
Standing water or other issues such as herbicide carryover from previous crops can often times lead to bare areas in a sugarbeet field. In these abandoned areas, one question that grower’s often have, “Is what can be replanted in these areas?”, particularly where herbicide applications have been made for weed control in sugarbeets. What can be replanted depends on what herbicides have been applied. Here are some factors to consider for each of the herbicides that are typically used for weed control in sugarbeets.
Nortron (PRE). The
Nortron label states, “….do not plant crops other than sugarbeets or ryegrass
in treated land in the same season.” This can be a problem if sugarbeets can’t
be replanted. In
Pyramin (PRE). Pyramin is another herbicide that is typically applied PRE in a band. The Pyramin label reads, “Do not plant other crops in the treated band.” Again, similar to Nortron, planting the replant crop between the treated bands may reduce the chances of injury to the replant crop.
Betamix or Progress. Betamix has very little residual activity. The only rotational restriction that is listed on the label is not to rotate to cereal grain crops for 120 days. Progress has the same restriction listed on the label. However, with Progress there is a reduced rate of ethofumesate (same active ingredient as Nortron) in this formulation, so keep this in mind when choosing a replant crop.
UpBeet. All crops, other than corn, can be planted 14 days after an UpBeet application. For corn, there is a 21-day recrop restriction.
Stinger. Stinger is the herbicide, that is the most restrictive of the herbicides used in micro-rate applications. The crop rotation interval for applying Stinger and planting soybeans or dry edible beans is 10.5 months. The rotation interval increases to 18 months if soil organic matter is less than 2 percent and there is less than 15 inches of precipitation in the 10 months following the application. Stinger degradation is dependent on several factors: application rate, soil texture, temperature and moisture. The half life of Stinger is 30 to 90 days depending on these factors. Stinger degradation from microbes is greatest in warm-moist soils. Therefore, if 2 fl oz/A of Stinger is applied on May 1, 1 oz/A will be remaining on June 1 if soils are warm and moist. Because of the sensitivity of soybeans and dry beans to Stinger the question of replanting one of these crops in areas of sugar beet fields can be tricky. There is a high risk of bean injury and reduced yields in areas of abandoned sugar beet fields where Stinger was applied. The risk can somewhat be reduced by:
§ Planting dry beans in mid- to late- June.
§ Low rates of Stinger (1 to 2 fl oz/A) applied April or early May.
§ High soil moisture and temperature.
§ Low organic matter.
§ Tillage to dilute the remaining residues.
However, taking all of these factors into consideration does not guarantee a healthy bean crop.
Christy Sprague
Crop & Soil Sciences
Want to sharpen your diagnostic skills and stay on top of
the latest information in production agriculture? If so, we have the perfect
opportunity for you. We would like to invite you to attend the fifth annual
Participants will have the opportunity to hone their field decision-making and problem-solving skills as they interact with MSU Extension Specialists in small groups while participating in hands-on field activities.
This year’s
Approval is pending for RUP credits and continuing education units for certified crop advisors (CCA).
The $125 registration fee is due July 2. Participation is limited to the first 150 paid registrations. More information can be found at www.msuweeds.com or call 517-355-0271, ext. 1112 or e-mail misiak@msu.edu. A brochure with the registration form is enclosed in this issue and can be found at: 6-7DiagnosticSchoolBrochure.pdf
Kurt Thelen
Crop & Soil Sciences
Reports of climate change, global warming and greenhouse gas
emissions have been all over the news lately. What does this have to do with
agriculture? After many decades of being pointed to as a source of
environmental issues, field crop agriculture is being looked to as one of the
solutions to global climate change. The basis for this environmental
remediation affect is corn’s and other crops’ tremendous potential to remove
carbon dioxide (CO2), a major greenhouse gas, from the atmosphere. In
fact,
How much carbon dioxide does an acre of
When used as a renewable fuel source such as ethanol, corn
also displaces petroleum-based gasoline, a significant contributor of carbon
dioxide to the atmosphere. Each gallon of gasoline burned emits 19.4 lb. of
carbon dioxide (5.3 lb of C) to the atmosphere. In fact, the USEPA estimates
that the average car in the
Finally, in addition to the atmospheric environmental advantage of carbon sequestration, there are land-based environmental/agronomic benefits as well. Increased carbon levels in the soil provide better water infiltration, enhance nutrient cycling, help alleviate compaction and reduce surface run off.
To learn more about carbon credit trading, visit the Michigan Conservation and Climate Initiative web page at http://www.michiganclimate.org/
Phill Wharton
& Willie Kirk
Plant Pathology
Seven new high
resolution potato diseases extension bulletins are now available for purchase at
http://www.emdc.msue.msu.edu/ for
$1.50 each. The new group of publications includes the recent potato late
blight bulletin and bulletins on early blight, pink rot, Fusarium dry rot, Rhizoctonia
diseases, potato common scab, white mold and seed piece management. For more
information, call 517-353-6740. You can also download these bulletins from this
web page http://www.potatodiseases.org/extensionpubs.html
as PDF files from our late blight website.
Also at http://lateblight.org daily updates of potato
late blight risk are available for all the Michigan Automated Weather Network
sites in
Steven Gower
Diagnostic Services
Last summer, a
Besides the obvious chlorosis, distortion and browning of the leaves followed by defoliation, there was a spot at the base of each tree that was barren of grass and weeds for several months. I suggested we analyze soil collected near the base of these trees for the presence of residual contaminants capable of causing the observed injury. Unfortunately for the trees, tebuthiuron was detected in the soil at 2.3 ppm. (view photos)
Tebuthiuron (Spike) is a soil-applied herbicide for woody plant control in fencerows, utility right-of-ways, pipelines, pastures, rangelands and other non-cropland areas. Tebuthiuron controls unwanted trees, shrubs and vines after sufficient rainfall has occurred to move the product into the root zone.
In addition to diagnosing plant pathogens, nematodes and insect-related pests, all plant samples submitted to MSU Diagnostic Services – the multi-disciplinary plant health and pest diagnostic facility on campus – are visually inspected for pesticide injury. If warranted, samples can be tested for the presence of pesticide residue using appropriate analytical instruments and techniques.
We urge that clients interested in pesticide residue testing contact the laboratory before collecting and submitting samples. Samples should be collected immediately if pesticide injury is suspected. Collect samples according to visual pesticide expression, as some herbicides affect new plant growth, while others may only affect older growth. Collect enough plant tissue to fill a quart-size plastic bag; collect enough soil to fill a pint-size plastic bag. In general, samples should be frozen immediately and kept frozen until arrival at the laboratory.
Plant samples are visually inspected for pesticide injury for $20. Samples can be tested for pesticide residue on an individual basis or, if available, in multi-pesticide screens. Fees may vary depending upon number of samples, clientele location and numerous other special circumstances. Fees for individual pesticide residue screens are generally $90, $100 and $125 in water, tissue and soil, respectively. Fees for multi-pesticide residue screens are generally $125, $150 and $175 in water, tissue and soil, respectively. Questions regarding pesticide injury or pesticide residue testing should be directed to Steven Gower by phone at 517-432-9693 or by email at sgower@msu.edu.
Ned Birkey
It has been
warm, wet and muggy for the past two weekends. A couple of days at or near 90ºF
last week is again forecast for today. Some areas received four or more inches
of rain, plus high winds over the weekend. A localized and heavy hailstorm hit
southwest
Alfalfa is being cut as farmers “guestimate” the weather and forecasts for rain. Uncut hay quality continues to deteriorate, and high winds over the weekend have blown over some standing hay. Highly managed fields with good re-growth have been sprayed for alfalfa weevil.
Corn is variable in growth depending upon the soil compaction, soils, nitrogen received and rainfall amounts. Many fields had standing water this past week, though plants were above the water and most of the water was gone within 48 hours. Some fields are at V7 and nice and green with even stands, while others are irregular, with shorter and yellow corn. Black cutworms at the 5th and 6th instar have been found in second year corn. European corn borer moths are flying with low numbers found in traps in Wayne, Washtenaw and Lenawee counties this week.
Soybeans are starting off slowly, with bean leaf
beetle feeding. Some fields have had too much rain and will have replanted
areas. The soybean aphid/ rust sentinel plot in
Wheat looks good considering the hot and humid weather. Fields here are past flowering with Septoria, leaf rust, Cephalosporium stripe and powdery mildew diseases present, though no Fusarium head scab is noted yet. Most fields have good yield potential that will rely on favorable weather from now till harvest.
Soil nitrate samples will go to MSU this next Wednesday for later planted corn.
Bruce MacKellar
Rainfall over the weekend was highly variable in the southwest region, with totals ranging from less than an inch to over 2.5 inches in some locations. We have been on a temperature rollercoaster this week with cold night temperatures and pleasant daytime highs following the influx of dry air behind the cold front that passed through the region on the evening of Sunday, June 2. Hot weather returns today with temperatures expected in the 90’s today. Wind conditions are expected to be strong in advance of a strong cold front approaching from the west. There is potential for severe weather this evening and Friday.
Corn has taken advantage of the warmer conditions, which are about a full week ahead of where we were last year, to push growth into the 7-8 leaf collar stage on the earliest planted fields. Some fields have had rescue post emergence sprays applied to clean up weed escapes, mostly grasses. We are applying sidedress nitrogen in most of the earlier planted fields. The one trouble spot seems to be the fields planted to Roundup Ready corn. Weeds have been growing very rapidly, and with the wet and high wind conditions, we have had limited opportunities to get glyphosate on fields. I expect to see some fields exhibiting yield losses where the weeds have grown to heights where competition will occur. We also are beginning to see some crabgrass in the mix on grass escapes. This tends to present us with more of a challenge because there are limited options to control crabgrass in non-Roundup Ready fields.
Seed corn planting is beginning to come to a close. We have had some fields that were delayed as seed was slow in coming in from the off-shore “grow out” areas. Early planted seed corn is looking good at this point. Flaming is being used on the male rows on some fields to extend the period of pollen shed to improve pollination. Many of the same weed escapes that we see in commercial corn is also occurring in seed corn. We are seeing a pickup in the numbers of European corn borer moth flight in the area. We have not seen a large moth flight yet.
Early planted soybeans
are developing the second tri-foliate, many later planted fields are now at the
unifoliate stage. Bean leaf beetle feeding signs can be found, but remain below
threshold on fields that I have scounted. Many of the earlier planted fields
have been emerged now for five weeks or more. Some of these fields have been
sprayed. Keep an eye on the size of the weeds in soybeans and treat before
competition is a problem, or the weeds will get to a size where they are going
to be hard to control. Producers should also begin to see cysts on early
planted soybean fields that have extremely high levels of SCN in their fields. Watch
for uneven patterns of growth. The St. Joseph County SCN Resistant – RR soybean
trial featuring 12 varieties was established in late May south of Nottawa. We
have found our first soybean aphids in soybeans in southwest
Alfalfa harvest
has been significantly slowed by persistent rain in the forecast over the last
couple of weeks. Be sure to watch for alfalfa weevils in the early re-growth. Also,
potato leafhoppers are back into
Wheat continues
to look to have good yield potential in the region. While we did have rainy
conditions during a portion of the flowering window, at least a portion of the
time was dry. We will be looking during the next couple of weeks for the
development of bleached heads, denoting infection from Fusarium head blight. We
also need to keep an eye out for armyworms, especially along the border areas
because some fields in
The St. Joseph County IPM Breakfast Meetings are being held
on June 13, June 20, and July 5 and July 12 this year at the St. Joseph County
MSU Extension office, 7:00 AM-9:00 AM. Cost is $7, which includes a catered in breakfast.
Our guest speaker next week will be Dr. Greg Shaner,
Fred Springborn
A gentle rain fell for most of the day Sunday June 2 leaving
1.0 to 1.5 inches of rain across much of
Wheat is well into flowering in most fields. Much of the crop was flowering over the weekend. Powdery mildew is advancing up the plant in fields of susceptible varieties as well as some irrigated fields of moderately susceptible varieties.
Oats are progressing well with few insect disease problems at this time.
The 2006 corn
harvest is now complete as of the June 5. Every year there seems to always be
that last field standing. This is earlier than most years. In the 2007 crop,
corn growth ranges from V1 to V8 with the majority in the range of V4 to V6.
Some fields have emerged unevenly due to soil moisture variability. European
corn borer trap catches are picking up with an average of 19 moths per trap at
out
Soybean planting is progressing with 95 percent or more of the crop in the ground with several fields emerged with growth up to V2.
Dry bean planting has begun with 10 percent of the crop planted and fewer acres anticipated this year. With dryer weather in the coming week, we anticipate rapid progress in planting.
Alfalfa harvest is underway with nearly 50 percent of the crop harvested. Alfalfa weevil is still active in some fields. Harvested fields need to be monitored for feeding on re-growth. Potato leafhopper is around and scouting for this pest should begin.
Volunteer potatoes continue to be an issue.
Paul Gross
The most often used phrase for last week’s rains is “a million dollar rain.” The amount varied from 1.5 to 3.0 inches across the region. With most crops being planted and some needing this rain to emerge, this rain came at just the right time. While the rain was timely for growing crops, hay harvest has slowed and farmers trying to bale hay are not getting any drying days.
The corn crop is doing very well with this week’s rain. We have corn that is knee high and most of the stands are very good. Nitrogen applications are being made as well as herbicide applications. We are seeing very few problems at this time.
Soybeans are nearly all planted with just a few fields left that will be planted this week. Most stands will be adequate for optimum yields. The rains this week is just what was needed to help emergence on the fields that were planted in less that desirable conditions.
Field activities include herbicide applications.
Wheat has nearly completed flowering. The crop generally looks good. We are seeing powdery mildew and septoria. Fungicide applications were made last week to protect the crop from head scab. The timing was about right with the rains this week. There have been reports of a few armyworm found. Fields should be scouted for army worm.
Alfalfa harvest has been slowed by this week’s rain. Harvest is about 50 percent complete with most farmers calling yields average to below average. Alfalfa weevil numbers are over threshold in fields that have not been harvested. Potato leafhoppers have been found in some of the re-growth.
Oats are doing very well, and the stands are excellent. Alfalfa seedings in these fields are growing well. Herbicide applications are being made.
Dry bean planting is just getting started. We expect planting to go full speed ahead when field conditions allow.
Sugar beet fields are doing quite well and stands are generally good. The crop is enjoying the rains and favorable weather.
Mark Seamon
Wide swings of temperatures between the 40’s and the 80’s have been seen in the past week. Rainfall of about one inch fell in most of the area on Monday. This was followed by a full day of cool temperatures, which slowed drying.
In alfalfa, some hay has been harvested as conditions allowed, but much is waiting for a few days of good weather to cut.
Sugar beets are growing quickly. Many fields look very good with others struggling to add growth.
The wheat crop is variable with some fields well beyond flowering and others just now flowering. Fungicide applications to protect against Fusarium head blight are still possible in delayed fields, but most are beyond a labeled application. The rainfall and slow drying of this past week have encouraged Fusarium infection.
Corn growth is active with the tallest corn about 18 inches tall. Weed control and sidedress nitrogen applications are being made in most areas. Remember that yield can be affected with weeds over 4 inches in height. Early planted corn that has not been sidedressed yet is starting to show some yellowing.
In soybeans, most fields have emerged nicely with the most advanced fields having one trifoliate. Stands look good. Soybean aphids have arrived with low populations. Slugs have been found reducing stands in the southern Thumb.
In dry beans, planting has slowed due to rainfall, but soil moisture conditions should be very good when planting resumes.
Jeff
Andresen
Agricultural Meteorology
Geography
An area of low pressure located in the northern Great Plains
will rapidly intensify and move to central Ontario by late Friday, June 8. A
warm front associated with this system will move from southwest to northeast
across
Following the passage of the front, high pressure is expected to move in for the weekend, leading to fair, dry and seasonably warm conditions Saturday and Sunday and likely into early next week as well. Temperatures will fall back to near or slightly below normal levels early in the weekend, warming to near normal levels by Monday of next week. Highs by Sunday will generally range from the low 70's north to the low 80's north with lows in the 50's to low 60's. Rainfall will be possible once again by the middle of next week.
Further ahead, medium range forecast guidance is consistent
in calling for the formation of an upper air troughing feature across western
sections of the