July 24, 2008
In this issue
§ Western bean cutworm alert
§ Armyworm also in northwest Michigan
§ Looking for a few “good killers”
§ Corn and soybean fungicide: To spray or not to spray –that is the question
§ Agricultural field sanitation requirements in Michigan
§ Regional reports
§ Weather
Next issue August 7
Christina DiFonzo, Entomology
§ Western bean cutworm egg laying and hatch are confirmed.
§
Scout now
(starting the week of July 21), particularly in northwest
§
Some fields in northwest
§ Populations are very variable from field-to-field.
§ Application timing, based on scouting is critical for caterpillar control.
Western bean cutworm trapping with milk jug pheromone traps
began several weeks ago. Moths have been caught throughout the state. In
general, the number of moths per trap is one to two, but hot spots, for
example,
Scouting for eggs and larvae begins when moths are detected,
concentrating particularly on the weeks of peak catch. That is now, especially in northwest
Eggs are laid in the upper canopy on the top three to four leaves. Eggs may even be on the leaf wrapped around the tassel. The eggs are on the upper leaf surface –on upright leaves, they are on the leaf surface facing into the tassel.
Eggs are round, not flat and shingle-like, like corn borer
egg masses, laid in in groups of a few to 200. The average sized mass I’ve seen
was smaller than
The tiny larvae emerge and sit on the egg mass, then crawl up the plant to the tassel. As second and third instars they move back down to the silks, then as larger larvae into the ear. Insecticide applications must be timed close to egg hatch and when small larvae are exposed on the tassel and leaf surface.
The threshold for treatment is five percent of plants with
egg masses or small larvae. Many bulletins and my MSU Insect Guide E-1582
give a threshold of eight percent. However, in discussions this winter with my
colleague Tom Hunt from the
Insecticides include pyrethoids such as Warrior, ProAxis, Pounce/Ambush, Mustang, Capture, Baythroid, Asana and Lorsban. More critical than product is timing to kill exposed caterpillars.
A special alert to people managing sweet corn. Growers tend to have consecutive planting dates of sweet corn, which makes it likely that one or more of the plantings will be attractive to western bean cutworm. Beth Bishop in the MSU Vegetable Program has developed a recommendation for sweet corn. Check the Vegetable CAT alert for her thoughts.
Dry beans are particularly attractive to western bean cutworm if neighboring corn fields have already tasseled.
Less information is available for managing western bean cutworms on dry beans, and it is harder to scout for eggs on the plants. Eggs are laid on the underside of dry bean leaves and may be easily missed.
On the plus side, if you are trapping, the trap can be used to time spray treatments on dry beans. Moth numbers are accumulated over time until peak flight. This requires checking traps regularly to detect the peak.
If the accumulated catch is between 700 and 1000 moths, damage risk to beans is moderate and beans must be scouted closely. Check fields for larvae and larval feeding 10 to 20 days after the peak, and spray if pod feeding is found. If the catch exceeds 1000 moths by the peak, the risk is high for damage in dry bean and an insecticide application is most likely needed 10 to 20 days after peak flight. So far, we are considerably under the 700-1000 per trap required to treat dry beans.
|
County |
WBC number per trap |
|||
|
|
Week ending |
|||
|
|
July 4 |
July 11 |
July 18 |
July 25 |
|
Allegan |
0 |
0 |
4 |
1 |
|
Cass |
0 |
0 |
0 |
5 |
|
Grand Traverse |
0 |
2 |
0 |
3 |
|
Ingham |
0 |
1 |
14 |
1 |
|
|
0 |
0 |
3 |
0 |
|
|
0 |
0 |
9 |
11 |
|
Mecosta |
0 |
0 |
7 |
14 |
|
Montcalm |
1 |
4 |
4 |
17 |
|
Oceana |
0 |
0 |
67 |
126 |
|
Osceola |
1 |
2 |
0 |
21 |
|
St. Joe |
0 |
0 |
11 |
0 |
Christina DiFonzo
Entomology
For those of you in the northwest part of the state, I have
received multiple reports of armyworm in both corn and alfalfa fields, and
visited a big infestation personally in
Confounding the management situation is that caterpillars, at least in the field I visited, ranged in size from about 0.75 to 1.5 inches on the same plant. While it is probably too late to control the biggest larvae, plants may be infested with larvae of multiple sizes. In corn, scout and count smaller larvae (under 1.5 inches), using this threshold for treatment: 75 percent of plant with one or more larvae.
Be sure to unroll whorls when scouting, as larvae hide out during the day. Many products are registered for control and aimed down into a whorl, they will be quite effective. If the problem is confined to field edges or larvae are moving in from a nearby field, consider a border spray to save time and money. However, some of the corn is reported as five or more feet tall, making it difficult to treat unless a high clearance ground rig or aircraft is available.
In forages, the threshold is four or more per foot of row. Cutting will help to kill larvae in place of spraying.
If you cannot or do
not treat, armyworm larvae are attacked by parasitic flies and a pathogen. I
saw signs of both in
Diane Brown-Rytlewski
Plant Pathology
Can you help us with our search for soybean killers? We need to collect isolates of the fungus that causes Soybean Sudden Death Syndrome (SDS) from grower fields for a research study funded by the Michigan Soybean Promotion Committee. The first part of the project is to collect plants with symptoms of SDS from grower fields.
We’d like to sample at least 10 grower fields with symptoms
of SDS. After the plants are collected we will be culturing symptomatic plant
tissue to recover the pathogen. Isolates of the pathogen will be tested to
determine their level of pathogenicity. We need to find isolates that are “good
killers” for the second part of the study. Next year, we will be inoculating a
field with the SDS pathogen and planting soybean varieties that have been bred
for resistance to SDS to see how well they perform in
Soybean Sudden Death Syndrome symptoms usually appear in late July - August. Leaves develop yellow spots that merge to form yellow patches between veins. As the disease progresses, the leaf tissue between the veins turns brown, and the leaves stay green. Leaves may fall off, leaving the leaf petiole still attached. SDS usually occurs in patches where there is compacted or poorly drained soil, and may be associated with soybean cyst nematode. A fact sheet about SDS with color photos of symptoms can be found at http://www.ipm.msu.edu/fieldcrops.htm/pdf/7-24SDS.pdf
If you know of a field with symptoms of SDS, please contact
your
Diane Brown-Rytlewski
Plant Pathology
High market prices for both corn and soybeans this year are once again tempting growers to consider applying fungicides in the absence of disease. Whether or not a yield increase will result continues to be a topic of many lunch counter discussions, and among plant pathologists.
Fungicides are routinely applied in seed corn fields where
there may be little resistance to disease. In a multi-state study where
fungicides were applied to field corn, results ranged from instances of yield
decrease, to no differences from untreated controls and some instances of
increased yield. In the absence of threshold levels of disease, no consistent
pattern emerged that that could help predict when applying a fungicide would
result in a yield increase. Yields were found to increase with fungicide
application where gray leaf spot (Cercospora
zeae-maydis) was present at levels above economic thresholds. Gray leaf
spot does not occur on a widespread, annual basis in
Timing of fungicide application is important in corn. When certain fungicides were applied during the critical period one to two weeks prior to tasseling, particularly in combination with another pesticide or adjuvant, abnormal ear development (“beer can ears”) resulted in significant loss of yield. The cost of fungicides and application needs to be considered to determine whether there will be an economic return from a fungicide application. Run-down resulting from ground application needs to be figured into the equation as well.
In soybeans, there has also been considerable work done to evaluate foliar fungicide applications, partly as a result of looking at fungicides to control soybean rust. Data has been compiled to summarize the results of foliar fungicide application to soybeans across a wide range of soybean varieties and growing conditions in multiple states across multiple years. Again, results ranged from instances of yield decrease, to no differences from untreated controls and some instances of increased yield. In the absence of threshold levels of disease, no consistent pattern emerged that that could help predict when applying a fungicide would result in a yield increase.
Most soybean diseases that foliar fungicides are designed to
control do not reach economic levels in
White mold is another disease of soybean that can cause
economic losses, but foliar fungicides do not control it. Frogeye leaf spot (Cercospora sojina) can cause economic
losses in susceptible varieties that have shown significant responses to foliar
fungicides. Frogeye leaf spot has been more of a problem in states further
south, but has occurred in scattered fields in
If you do decide to invest in a fungicide application to your corn or soybeans, why not set up a fair evaluation in your field to see whether or not you realized any benefit? Here are some guidelines for setting up check strips and an evaluation in your field. (From the C.O.R.N. OSU newsletter July 7, 2007, So You Are Trying Fungicides On Corn And Soybeans, How To Evaluate If They Are Worth The Cost? - Anne Dorrance, Pierce Paul, Dennis Mills)
1) Know what the variety or hybrid is. For both corn and soybeans only the moderately susceptible and highly susceptible hybrids and varieties have demonstrated yield impacts in fungicide applications.
2) Have more than one check strip, wider than your combine, and space them across the field. Three should be plenty but two is not enough.
3) In your comparisons, do not include the parts of the field where you have weed escapes or along tree lines, these areas are going to yield less anyway, so this is false data whether it was treated or not. Make sure other variables such as soil types, soil fertility variations and pest issues are not biasing your field experiment.
4) Approximately three weeks after applications, walk some of the strips. For corn, look at the ear leaf, determine what percent leaf area has got lesions in the treated vs. non-treated. Is gray leaf spot, anthracnose, or northern leaf blight present? For soybeans – look at the upper canopy for frogeye or downy mildew and on the lower canopy look at how much brown spot is present.
5) Take averages. When you do harvest your fields, take several strips, both untreated and treated. Then take the average of the untreated strips and compare that average to the treated. Fields are not uniform and with our stand issues and unevenness across many fields this year, there is going to be even more variability.
Vera Bitsch
Agricultural, Food, and Resource Economics,
The Michigan Occupational Safety and Health Administration (MIOSHA) has updated enforcement procedures for field sanitation standards in 2008. Inspections may be based on complaints or referrals, as well as, programmed inspections, which are conducted by MIOSHA personnel as time permits where they see hand-labor operations in the field.
Clean and safe potable water must be readily accessible to all employees. Heat-related illness can be reduced or prevented by drinking enough water and taking other precautions, including suitable clothing. Farm workers experience the highest risk of heat-related illness of all occupations.
Where 11 or more employees have worked on any day during the last 12 months, the water must also be suitably cool for the temperature conditions and dispensed by single-use cups or by fountains.
Toilet and hand washing facilities must be provided whenever work time plus transportation time to and from the field exceeds three hours. One toilet and hand washing facility shall be provided for each 20 employees or fraction thereof. The facilities shall be located together and as close as practical to the work location.
For small operations, where the 11 or more employees rule does not apply, the facilities must be either provided as above or available to employees by using employer furnished transportation.
Employees must be given reasonable opportunity to use these facilities. Toilets shall be ventilated and screened, have self-closing doors lockable from the inside, and constructed to ensure privacy. Toilets shall be operational and include an adequate supply of toilet paper. Hand washing facilities must have an adequate supply of potable water, soap, and single-use towels.
All facilities must be maintained in clean and sanitary conditions and waste shall be disposed in a sanitary manner. Where the 11 or more employees rule does apply, employers must inform all employees about the importance of good hygiene practices to minimize adverse health effects.
More information is available at www.michigan.gov/miosha,
and by calling the MIOSHA General Industry Safety and Health Division at
517-322-1831 or the district supervisor at 616-447-2650. Free consultation and
compliance assistance is available through the MIOSHA Consultation Education
and Training Division (CET) by calling the
To read Dr. Bitsch’s complete newsletter go to her website
at http://www.msu.edu/user/bitsch.
Under “News” click on “Agricultural Field Sanitation” or click on “Agricultural
Labor Issues in
Ned Birkey
Weather has been hot and humid, cool, wet and dry. Parts of southeast Michigan have had over eight inches of rain in July with up to seven inches coming at one time on July 2. Fortunately, no widespread damaging winds or hail, though some storms had high winds. What a difference a year makes, as we were generally hot and very dry until Thursday, July 26 last year, then received up to 12 inches of rain through August. Farmers hope the weather does not change to hot and dry now.
Alfalfa harvest is being done between the rains. It has been difficult to get the first and second cuttings removed. Quality is spotty because of the rain, but the quantity of hay is very good. Last year’s second cutting was negligible due to the dry conditions. There have not been large potato leafhopper numbers and there is enough moisture that plants are not severely stressed.
Barley has been harvested with generally good yields. Acreage is creeping up and probably will again this fall.
Corn generally looks very good with most fields at the R1 silking stage. Some fields with low areas have lost corn plants due to excessive rains. European corn borer and corn earworm traps have low numbers, which should quickly increase with the second generation. Some corn is lodging due to shallow roots and storms with high winds.
Oats are headed and turning with harvest perhaps next week. This has been a good weather year for oats.
Soybeans are on-the-ropes with all the rain. Plants are at the R2 full flowering stage. Many fields have yellow areas; some low areas have lost plants due to rain. Commercial pesticide applicators are busy applying post emerge herbicides, fungicides and foliar fertilizers. Western bean cutworm and western corn rootworm traps are out. Japanese beetle numbers are not as high as last year. Lots of double crop soybeans have been planted through last week. There is enough moisture for germination. Our STARS fungicide/insecticide plots are going in this week and next.
Wheat is 99 percent harvested, which has been a struggle. Yields and test weights are down, with a premium being paid this week for wheat delivered to a terminal elevator with a 60.6 pound test weight.
Is Fall coming early? The Lions open their pre-season games in two weeks! Farmers here are optimistic about corn yields, but are throwing everything but the kitchen sink at soybeans.
The Center for Excellence Field Day in
Bruce MacKellar
The southwest region has had two very different types of
weeks since the last report. Last week, conditions became much warmer and drier
over the lower tiers of counties, with scattered thunderstorms developing over
the northern and central portion of southwest
Our average heat accumulation is around 25-27 base 50 growing degree days per day at this point in the season.
At this point, most of the commercial corn continues to look very good. Pollination has been completed on some of the earliest fields, but many fields are pollinating right now across the lower tiers of counties. We did have some drought stress and high temperatures as the plants were heading into pollination last week, so there may be some impact on yields on sandier fields. The crop is approaching maximum water usage during the next two to three weeks, with evapotranspiration rates ranging from 0.25 – 0.28-inches per day under hot and dry conditions during this period.
We have seen western corn rootworm adults, but their levels seem to be fairly low so far this year. Japanese beetles have been emerged for a couple of weeks, so it still may be worthwhile to look for evidence of silk clipping in your fields during pollination. The goal on most commercial corn is to keep at least half an inch of viable silk from the tip of the ear until pollination is completed (silks brown or not turgid).
Western bean cutworms have been on the increase in
European corn borer moth activity should be on the upswing
by the next Field CAT Alert report. It takes approximately
1000 GDD’s from first moth flight in the spring to for the first generation
larvae to reach pupation, and second generation adults emerge at about 1200 GDD’s
from first moth flight. In central
Detasseling is nearing completion on the earliest planted seed corn, but we will have an extended
season this year as the later plantings are approximately knee high at this
time. Leaf rust is easy to find, with lots of pustules on lower leaves, and
some moving up the plant towards the ear leaf. We may be seeing the early signs
of northern corn leaf blight on a few fields as well. Be careful when applying
fungicides to seed corn before the ear is developed to understand what your
seed corn agronomists and crop protection company reps are saying about adding
other materials such as adjuvents, insecticides or foliar fertilizers into a
tank mix. In some instances, tank mix partners that would be acceptable in
later fungicide applications may have the potential to cause damage to
sensitive in-breds with some fungicide products. Western bean cutworm moth flight
has been relatively small, but steady in
The early planted soybeans are at R1 to R2, and are growing rapidly. We did see some drought and heat stress on soybeans last week. Soybeans are increasing in their water demand at this point in the season, with evapotranspriation rates ranging from about 0.18 – 0.22-inches per day under hot and dry conditions for the most advanced fields.
We have seen some increased incidence of root and stem
diseases in a few soybean fields in
I would encourage growers to monitor their fields for the development of Sudden Death Syndrome (SDS) in portions of these fields because of the wet conditions this spring and the correlation between SCN and SDS.
Soybean aphid numbers have remained low, but there has been a small increase in the number of winged aphids (alates) I have seen. Japanese beetle defoliation appears to be down somewhat this year, but bean leaf beetle feeding seems to be higher than in the past several years. Overall, the crop continues to look good, and perhaps has shown better growth in the last few weeks where heavy rainfall early cause uneven stands.
Deer damage continues to be a significant. I counted an average of five to six deer browsing in each soybean field on my way home one evening at dusk.
In alfalfa, producers are putting up second and third cutting hay this week. The forecast is showing good opportunities to put up after this weekend for the next couple of weeks. Potato leafhopper numbers are high and increasing in the southwest, so be prepared to treat re-growth alfalfa to protect the small plants.
Most wheat producers that I talked to were pretty satisfied with their wheat yields, although we won’t be setting any major records in the lower tier of southwest region. The straw has been coming off fields very quickly to make way for second crop snap beans and cucumbers. Some second crop soybeans have been planted on earlier harvested irrigated fields as well.
Oats are
beginning to turn. Yield potential continues to look good, with the first
harvest a week or so away.
Fred Springborn and Roger Peacock
Rains have been scattered and fairly light over the past two
weeks in much of the area, a few locations received heavy rains of more than an
inch. High temperatures have been in the upper 70s to low 80s.
Crop report
Alfalfa harvest of the second cutting is winding down. Potato leafhoppers are present in many fields at relatively low levels.
Wheat harvest is underway with generally good yields and test weights reported. Less than half of the crop is harvested due to light rain showers. Minimal damage from sprouting has been reported thus far.
Oat harvest will begin very soon.
Corn is
pollinating in many fields. Some irrigated fields are just past pollination.
Dryland fields are quite variable due to soil moisture and early season issues.
European corn borer trap counts remain quite low. Western bean cutworm has been
detected in
Soybeans are flowering. Very low levels of soybean aphid have been observed; natural predators seem to be keeping the pest well under control.
Dry beans are blooming. The bulk of the crop has gotten off to a good start. The early planted fields are suffering from root rot problems, especially those that are in a tight rotation.
Paul Gross
There has been lots of variability in rainfall over the past
two weeks. Some parts of the region received about an inch, while others
recorded six inches with scattered hail. There was a small strip of hail in
southern
Wheat harvest is in full swing as the weather permits. Most farmers are harvesting wheat at higher moisture than they would like in order to avoid sprout issues that have caused problems in the past. There is very little head scab reported at this time. Most growers are very pleased with yield and test weight. Some have reported fields yielding in the three digits.
The corn crop is
progressing nicely. Some are beginning to pollinate while others are just
beginning to tassel. Most are optimistic about yield potential. There are no
serious problems at this time. There have been no western bean cutworm moth
catches in the
Soybeans are in full bloom with some in R-1. Most stands are looking good. Some of the stands that were having problems early are starting to improve. Soybean aphids have been found in most fields, but at very low levels. Continue to scout for this and other insect pests.
Harvest of second cutting alfalfa is progressing between rains. Farmers that chop have completed harvest. Those making dry hay are finding it a challenge. Most are reporting very good yields. Potato leafhoppers are over threshold in some fields. Farmers are advised to scout the re-growth for this pest. Populations are high at this time.
Oats and barley are turning and harvest could begin next week in some areas. Stands look good and yield potential is there.
Dry beans are doing pretty well. The crop seems to be average with some problems with excess rains in some areas. Leafhopper numbers are high.
Sugar beets are looking very good. It looks like we could have a very good crop.
Bob Battel
The weather has been humid, warm and wet over most of the area. During the past two weeks, rain has ranged from about one inch to 2.75 inches.
Wheat harvest has
been stop and go. Rain and poor drying conditions have really slowed harvest,
and there is concern about sprout. Wheat is probably less than half harvested
in
Alfalfa second cut is for the most part completed, and had very good yields, better than first cut. With all the moisture, the third cut is looking very good.
Corn started tasselling the middle of last week. Pollination is underway. It looks like there will be a very good corn crop. The western bean cut worm trap I have near Pigeon had one moth trapped on July 23. There was also a report of trapping in the Sanilac trap.
Soybeans are flowering, and early planted soybeans are setting pods. Soybean aphid activity has been extremely low, with most fields showing no aphid activity. There is some light Mexican bean beetle activity, but biological control agents are also present. Nothing seems to be over threshold.
Early planted dry bean fields are beginning to flower. Many areas of dry beans are drowned out.
Oats are beginning to turn, and it looks like a good crop.
The rains have really helped sugar beets, and it looks like a very good crop. Growers have been spraying for rhizoctonia and cercospora leaf spot.
Jeff
Andresen
Agricultural Meteorology
Geography
A large area of high pressure over the Great Lakes region Thursday morning (July 24) will result in another one to two days of fair and dry weather in Michigan before the passage of a frontal system which will bring the next chance for showers and thunderstorms to the state. The best chances for rainfall with this system will be Friday evening through Saturday morning, and across northern areas of the state. At this point, widespread rainfall is not expected with this system, with only scattered 0.25-inch totals where rainfall occurs, many areas of the state will remain dry.
High temperatures Friday and Saturday should range from the mid-70s far north to the mid-80s south with lows from the upper 50s into the mid-60s. Slightly cooler temperatures are expected by the end of the weekend and early next week, with highs from the low 70s north to the low 80s south and lows from the mid-50south to low 60s far south. High pressure is forecast to dominate weather across the region early next week, with fair and dry conditions expected. Rainfall should be possible again by the middle of next week.
In the medium range period, forecast guidance suggests upper
air troughs across northwestern and northeastern sections of the