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Issue
1 - May 2, 2007 Sign up for the SWROC Crop Production list serve IPM Stuff Classics Corn
Planting Depth - 3/5/99 SWROC Pages: Home Page Other Cropping Newsletters: Minnesota Crop eNews - Regional Newsletters Minnesota Fruit and Vegetable IPM News The Bulletin - Other States IPM Newsletters
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If you receive these newsletters as forwards and would like to be on the mailing list subscribe at: http://mailman.cfans.umn.edu/mailman/listinfo/cropproduction or send a request to Molly Werner. You get what you pay for. This is a free newsletter.
To keep up to date on all the
crop weather details during the growing season see: http://swroc.cfans.umn.edu/Weather/weather.htm.
The past week was extremely windy with minimal precipitation. For the
month of May we are currently at average precipitation. We are slightly
above average Growing Degree Days(GDDs) or Growing Degree Units (GDUs)
http://swroc.cfans.umn.edu/Weather/Y2007/Weekly_Reports/may15-21.pdf.
Has it been too hot and windy for you? Some corn thinks
so too. Most corn looks good and is 2- 4 collar. There is some early planted five collar corn out there. At 5 leaves, corn has developed an ear and tassel. The growing point is above ground and can more easily be killed by hail or frost. The pictures to the right is from the "Crop Growth and Development & Management Information for Replace Decisions" publication by L.L. Hardman and J.L. Gunsolus.
My euphoric optimism in the previous issue is waning a bit. Weed control is urgently needed in a few fields but has been delayed because of wind. Read the herbicide label for growth stage restrictions for herbicides.
Some areas are in need of moisture. Odd corn growth, or lack thereof, has been sporadically reported across southern Minnesota. Fritz Brietenbach looked at a field of rather shallow planted corn with dead radicals and nubbed seminal roots. Jay Zielske called about a corn field where plants were falling over, had little or no nodal root development and a pinched area on the mesocotyl. Tim Moline reported corn leafing out below the soil surface but no crust.
Injury from herbicide or fertilizer close to the seed, poor seed quality or genetic based early season vigor problems and environment are all possibilities. At first glance there does not appear to be a common thread. Let's work through this a bit. Although we cannot completely rule out other factors, hot dry soils near the surface are suspects in all cases. High winds may have forced the issue in the last two. Hot dry soils are not favorable for root development.
In the first example, soil moisture conditions were very low. With shallow planted corn, early root development would be exposed to extremes in temperature and moisture. Injury from seed placed fertilizer under dry conditions can cause similar injury but placement was not in the row.
In the second example, wind working on emerged corn can weaken and injure portions of the mesocotyl below ground. Loose soil would increase risk. Combine this injury with slow nodal root development above and you have a vertically challenged corn seedling.
In the final example, soil disturbance from high winds could rupture the coleoptile as it neared the surface. The result is leaf unfurling below ground.
Circumstantial evidence points to a strong environmental component in the three examples presented above.
On the other hand, areas with higher rainfall (near Lamberton for example), have had portions of corn fields succumb to crusting or drowning. Most of these trouble areas have been replanted. Nightlife
at Lamberton and Fulda
2007 insect flights in Minnesota will be tracked at Bill Hutchison's VegEdge website: http://www.vegedge.umn.edu/moth.htm. This site is updated weekly on Wednesdays and has a lot of good information including a good newsletter dealing with vegetable IPM. Based on degree day models 1st generation European corn borer moths should begin flying at 375 Degree Days (DD) base 50F. Lamberton has accumulated 340 DD as of 5/21/07. We usually catch our first corn borer with a day or two of the peony blooms opening. Both 375 DD and peony bloom should happen by Memorial Day weekend around here.
If you spend a lot of time outside, you run across many insect species. While checking winter rye, I came across a lady beetle species I had not seen in SW MN before.
The Large parenthesis lady beetle, Hippodamia glacialis, is a North American native. It shares the convergent white lines on the top of the thorax with the Convergent lady beetle and the parenthesis markings on the elytra with the Parenthesis lady beetle, two other members of the genus. Hippodamia glacialis is much larger than H. convergens or H. parenthesis. For all you livestock types, it is not a vigorous hybrid of the two smaller, more common species.
If you are willing to stoop
to picture book taxonomy, the Lady
beetles of Ontario site maintained by the University of Guelph has
some great photos and descriptions for budding Coleopterists.
Alfalfa - Alfalfa is cut or ready to be cut. Alfalfa weevil larvae are relatively abundant this year. I have not seen or heard of any fields at economic threshold. After cutting I would watch re-growth in fields where alfalfa weevil larvae were numerous. Dry weather increases the chance for problems. If green-up is delayed by larval feeding (fields will have a frosted appearance) an insecticide may be warranted. The University of Nebraska has a good publication. Yield loss calculators for 1st crop and re-growth are included at: http://www.ianrpubs.unl.edu/epublic/pages/index.jsp?what=publicationD&publicationId=556
Small grains - Spring wheat and oats are well advanced in tillering. It is important to pay close attention to growth stage restrictions with herbicides if they have not yet been applied. Dry windy weather has kept the crop relatively free of leaf diseases. In this part of the world, I'd focus on late season foliar disease and scab at heading.
For a listing of fungicides registered for Fusarium head blight (Scab) and a forecast model, see http://nwroc.umn.edu/Cropping_Issues/2007/Issue1/05_16_07_no_2.htm. This is a very professionally done regional newsletter from Northwest MN.
Corn - Insect problems are relatively minor so far this year. Some white grub infestations have been reported from the LeSeuer and Sibley county areas. Seed treated with a neonicitinoid seed insecticide (e.g. Cruiser or Poncho) is a good investment when replanting into white grub problems.
Soybeans - Bean leaf beetles (BLB) are active. At this point, infestations appear lower than 2006. The cold snap in April may have had a negative effect on overwintering BLB breaking diapause. However, I would still watch early planted fields over the next week as windy weather may have delayed the movement of overwintered beetles into soybean. Seed and food grade fields require more attention for BLB. The concern is bean pod mottle virus which is transmitted by BLB. Although a bit more bean pod mottle virus was observed in Southwest MN during 2006 than previous years, levels were quite low. Fifty percent defoliation is a rarely reached economic threshold for overwintered BLB in general commodity soybean production.
Soybean aphid - Will
this be a bad aphid year? I would not get too exited about this insect
for a couple of weeks. In spite of the large number of aphids observed
last fall, I have not observed any soybean aphid on buckthorn at Lamberton
this spring. They have been observed in good numbers on buckthorn at Rosemount
and SE MN. Crop production events in SW MN Thursday, July 12 - SWROC Summer field Day
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The
cool and especially the windy nights have led to some very low moth captures
at Lamberton and Fulda. You know nights have been windy when even the
May/June beetle captures are low this time of year. A low number of armyworm
adults moving in from the south were the only other pest species captured.
The black light traps are set up to look for pest species but manage to
capture all sorts of nocturnal insect travelers. The variety makes looking
through the masses of insect cadavers interesting to entomologists, both
amateur and professional. The night of May 10th brought a fairly uncommon
Abbots' sphinx visitor to Lamberton's trap. We have quite a few species
of the Sphingidae (sphinx or hawk moth family) in SW Minnesota. The larvae
of Abbot's sphinx feed on grapes. 