September 21, 2006
In this issue
§ Final issue for 2006
§ Evaluate corn N management with stalk nitrate test
§ Glyphosate injury on potatoes
§ New
Ag weather station installed:
§ Regional reports
§ Weather news: Will harvest be delayed?
This issue concludes
our publishing season for the 2006 Field
Crop CAT Alert newsletter. We welcome your suggestions for topics you’d
like us to cover in 2007. We also are interested in your ideas to improve our
publication and web site (http://www.ipm.msu.edu/field-cat.htm).
Let us know about
any annoying glitches or helpful improvements. Please send your comments to catalert@msu.edu or mail them to: Joy Landis, MSU IPM Program, B18 National
Food Safety & Toxicology Bldg.,
Thank you – Joy N. Landis, editor.
As corn grain has or soon will reach black layer, corn
growers should consider using the stalk
nitrate test to evaluate their nitrogen management program. Even though the stalk nitrate test is
post-mortem (end-of-season) it can be useful for long-term adjustment of N
management practices. The nitrate N concentration in the lower portion of the
corn stalk at the time grain black layer is formed is a good indicator of the
nitrogen status the crop experienced throughout the growing season. When used
over a number of years, the stalk nitrate test can help identify N efficient
fields and/or management systems, thus enabling fine tuning of N inputs.
The optimum time is one to three weeks after black layer has formed in 80% of the corn kernels. Cut an 8-inch segment of the stalk between 6 and 14 inches above the ground, from 15 stalks within the area of interest. Remove any portions of leaves that may remain attached. Splitting the stalk segments will facilitate drying. Refrigerate the stalk segments if the sample cannot be sent or delivered to a test lab within 1 day. Do not use plastic bags as this will prevent drying and may cause spoilage. The testing lab will oven dry and grind the stalks prior to analysis. This service is provided by the MSU Soil and Plant Nutrient Lab and various private labs. The fee at the MSU Lab is $12 per sample.
As corn approaches maturity, plants stressed for N will move
nitrate from the lower cornstalk to the ear resulting in a low stalk nitrate
concentration. When corn plants have sufficient N or more than sufficient N for
maximum yield, nitrate accumulates in the corn stalk. Extensive studies done by
Purdue and Iowa State universities have shown the usefulness of this test in
distinguishing between sufficient and excess N situations. With the high cost
of fertilizer N, elimination of excess N use improves the net return and
provides a positive environmental situation. Interpretation guidelines are
presented in Table 1. Stalk nitrate values from nitrogen rate studies (3 years)
at
|
Excessive |
> 2000 ppm. |
Excessive N available to the crop, or some other production factor limited crop growth and yield |
|
Optimum |
450 to 2000 ppm (Purdue) |
Grain yield was not limited by amount of N available to the crop. |
|
|
700 to 2000 ppm (ISU) |
|
|
Marginal |
250 to 700 ppm (ISU) |
Nitrogen supply may have limited yield |
|
Low |
< 450 ppm (Purdue) |
N was likely yield limiting during the growing season, especially < 250. |
|
|
< 250 ppm (ISU) |
Both sets of studies show that a stalk nitrate N
concentration above 2000 ppm is indicative of excessive nitrogen having been
available to the corn crop. Quite often this is associated with the application
of animal manure, but may also be related to over application of fertilizer N. In
the Purdue studies maximum yields were associated with stalk nitrate N
concentrations above 450 ppm.
Potato plants submitted to MSU Diagnostic Services contained chlorosis followed by necrosis of the newest leaves with the older leaves being normal. In addition to first turning yellow, the newest leaves contained a proliferation of buds and small leaflets. (view image)
The symptoms observed were characteristic of glyphosate injury, and tank contamination was suspected. Therefore, the potato tissue was analyzed for the presence of glyphosate and its metabolite. Glyphosate was detected in the tissue at 0.47 ppm.
Late last week a new
agricultural weather station was added to the statewide network maintained by
our Agricultural Weather Office at MSU. This station is in
The addition of the
weather station in
Information from
this station can be accessed at www.enviroweather.msu.edu
It has been cool and wet for most days over the past two weeks.
Alfalfa is hard to put up with shorter and cooler days. Some farmers are struggling to get the third cutting finished. Potato leafhoppers have not been a problem in this cool weather.
Corn is mostly mature, though I have not seen any
harvested as grain. There are fields with dry stalks and ears hanging down, so
some fields could be harvested any time. Will yields top the 163-bushel county
average of last year? I checked the last European corn borer trap yesterday,
which had 15 moths. The corn earworm trap had 83 moths, so the sweet corn
farmer at this location will continue to spray as he still has sweet corn
coming on. The MSU Corn Variety Trial in
Soybean harvest has begun with one combine running
yesterday and two other fields finished. Many soybean fields have turned yellow
very quickly, within the past week, and are dropping leaves fast. I do not
recall ever seeing fields change color so quickly, although there still are
some completely green fields with green leaves top to bottom. The MSU Soybean
Variety Trial in
Wheat planting will begin on or before October 1, slightly ahead of normal, especially with some soybeans coming off fields earlier than normal. Some farmers intentionally plant early soybeans just to get some early wheat planted. Wheat acreage should be high again this year, depending upon the fall weather, as some farmers have sold 2007 and 2008 wheat, “pulling the trigger” during some high prices last February.
The fall harvest season is coming early without a killing
frost. The ethanol plant near Blissfield (
Scattered light rains have slowed fieldwork this past week. One and a half to 2 inches of rain fell in the early portion of last week. Other rain events have been more in the nature of a few hundreths of an inch to a few tenths. High temperatures over the past two weeks have been in the range of mid-50s to mid-70s. Low temperatures have been in the 50s and 40s.
Corn is drying down. Moisture samples hand-harvested in central
Dry bean harvest is 30 to 35% complete. Rains have
slowed harvest considerably. Yields have been very good so far with reports of
dryland light red kidney bean yields of 18-19 cwt. per acre.
Soybeans are turning. Many fields have lost their
leaves and harvest will begin soon.
Wheat planting has begun as has planting of winter
rye.
An area of low
pressure organizing over the Rocky Mountain region will move through the Great
Lakes region Saturday (September 23), leading to a wet upcoming weekend in
Michigan. Rain will overspread the state from southwest to northeast during the
day Friday and continue overnight into Saturday. The threat of rain will
continue Saturday into early Sunday with some thunderstorms possible across
southern sections of the
Medium range
forecast guidance is consistent in calling for an upper air troughing feature
forecast across the central
The official NOAA
Climate Prediction Center 6-10 day
and 8-14 day outlooks (covering September
26-30 and September 28 through October 4) both call for below normal mean
temperatures and above normal precipitation state- and region-wide. Unfortunately,
this forecast strongly suggests more upcoming delays in harvest and fall
fieldwork activities with relatively low grain dry down rates.
The first frost or
freezing temperatures of the season, which have already occurred in northern
sections of the state, would also be a possibility in central and southern
sections of the state. Climatological normal maximum temperatures during the
last week of September range from the upper 60s north to the low 70s south with
low temperatures ranging from the low to mid-50s. Normal weekly precipitation
totals range from about 0.75 inches in eastern sections of the state to just
less than 1.0 inch in extreme western sections of both