Traill County Ag Alert Newsletter
July 24, 2008
|
Issue #12 July 24, 2008 |
RAINFALL & GROWING DEGREE DAYS (GDD)
Location Mayville Hillsboro Galesburg
Corn GDD
1073
1087 1075
Compared to 2007 -243
-233 -232
5 Year Average -133
-121 -148
Wheat GDD
2366
2374 2380
Compared to 2007 -357
-353 -326
5 Year Average -219
-212 -148
Rainfall since June 1 6.26 inches 7.79 inches 7.71 inches
I have been asked to clarify GDD for corn and wheat and the following is the explanation given on the NDSU NDAWN site.
Corn: For most plants, phenological development is strongly related to the accumulation of heat or temperature units above a threshold or base temperature below which little growth occurs. This lower threshold temperature varies with plant species. Scientists have determined the lower base temperature for corn is 50 °F (10 °C). In some plants there is also an upper threshold temperature, above which conditions are stressful to the plants. The upper limit for corn is 86 °F (30 °C). Although temperature is the most important factor controlling the rate of plant development, other factors such as water and light availability and daylight length may modify its effects.
Corn growing degree days (GDD) are calculated by subtracting the plant's lower base or threshold temperature of 50 °F (10 °C) from the average daily air temperature in °F or °C. Average daily air temperature is calculated by averaging the daily maximum and minimum air temperatures measured in any 24-hour period. All daily NDAWN data are based on a midnight to midnight (Central Standard Time) 24-hour calendar day.
Wheat: Growing degree days (GDD) and are calculated by subtracting the lower threshold temperature from the average daily air temperature. Although the lower growth limit for wheat is about 42 °F, Bauer found better correlation in the GDD predictions by defining the lower threshold temperature as 32 °F (0 °C). Average daily air temperature is calculated by averaging the daily maximum and minimum air temperatures. Thus, Daily GDD (°F) = ((Daily Max Temp °F + Daily Min. Temperature °F) / 2) - 32 °F.
PLOT TOUR FOCUSSING ON
RAGWEED CONTROL - AUGUST 5 - MAYVILLE
A field tour to look at possible Glyphosate-resistant Common Ragweed is set
for August 5 near Mayville. “This site is highly suspected of having glyphosate-resistant
common ragweed,” says Jeff Stachler, North Dakota State University and
University of Minnesota Extension Service Sugarbeet Specialist. “If true, this
would be the first confirmation of a glyphosate-resistant weed species in the
state.”
Glyphosate is an herbicide that provides broad-spectrum weed control with excellent crop safety in glyphosate-resistant crops. It is used considerably in no-tillage cropping systems. Glyphosate is good at controlling many weed species, has no soil activity (allowing for flexible crop rotations), and has low environmental and human health risks.
Stachler is conducting research to determine the level of glyphosate resistance and how important timing of glyphosate applications will be in maximizing activity and control. A second study of Stachler’s focuses on how to control common ragweed in sugarbeets.
Rich Zollinger, NDSU Extension Service Weed Specialist, is working with Stachler and focusing on herbicide programs to control common ragweed in soybeans and dry beans.
The tour will begin at 9:30 a.m. and last approximately two hours. To get to the field, take Exit 111 off Interstate 29. Go four miles west on North Dakota Highway 200. Turn north and go 2.5 miles on County Road 10 (158th Avenue). The research plot is in a wheat field on the east side of the road. Parking will only be available along the side of the road.
In case of inclement weather, the tour will be canceled or postponed. If inclement weather does occur, contact Stachler at 701-231-8131, Mohamed Khan at 701-231-8596 or Kendall Nichols at 701-636-5665.
BANDED SUNFLOWER MOTH EGG
LAYING UNDERWAY
Eggs of banded sunflower moth have been found on R3 stage sunflower fields.
Fields should be scouted now for egg laying activity, especially R3 sunflower
fields. R3 sunflowers are when the head is formed but has not opened.
Timing of Treatments. The best sunflower plant stage to treat is the
R5.1 growth stage, or when pollen shed is just beginning. At this stage
most banded sunflower moth eggs have hatched and larvae are beginning to feed on
florets. Larvae will be exposed on the head and are susceptible to the
insecticide treatment. On older plants where the seeds have formed, larvae begin
feeding in the seeds or underneath the florets, and are protected from the
insecticide. By then, much of the feeding damage already has occurred.
Insecticides labeled for Sunflower head feeding insects.
Active Ingredient
Trade Name Product/Acre PHI
Beta-cyfluthrin
Baythroid XL 2.0-2.8 fl oz 30 Days
Carbofuran Furadan 4F 1
pt 28 days
Chlorpyrifos Lorsban 4F 1-1.5
pt 42 days
Warhawk 1-1.5 pt 42 days
Yuma 4E 1-1.5 pt 42 days
Clorpyrifos +
gamma-cyhalothrin Cobalt 19-38 fl
oz 45 days
cyfluthrin Tombstone 2.0-2.8 fl
oz 45 days
Tombstone Helios 2.0-2.8 fl
oz 45 days
Deltamethrin Delta Gold 1.0-1.5 fl
oz 21 days
Esfenvalerate Asana XL 5.8-9.6 fl
oz 28 days
Gamma-cyhalothrin Proaxis
2.56-3.84 fl oz 45 days
Lambda-cyhalothrin Lambda-Cy 2.56-3.84 fl oz 45
days
Taiga Z
2.56-3.84 fl oz 45 days
Warrior 2.56-3.84 fl
oz 45 days
Zeta-cypermethrin Mustang Max 2.24-4 fl oz
30 days
PHI= Pre-harvest Interval
All listed insecticides are classified at Restricted Use Pesticides
WHITE MOLD IN BEANS
White mold is a common problem on edible beans, and can be found in many
soybean fields as well. Yield loss from white mold is possible in either crop,
but white mold is more frequently a problem for edible beans. The disease begins
when spores germinate on senescing flower petals, and infection progresses into
the stem. An infected stem will take on a dried bone color and may be shredded.
Sometimes a white fuzzy mold appears (where white mold gets its name), and small
black survival structures are produced (sclerotia). Because the infection begins
on the senescing flower petals, the most important time to assess disease risk
is at early bloom.
The highest risk for white mold occurs when a few environmental factors come together as follows.
Soil saturation. The disease cycle begins when the survival structure of the fungus (sclerotia) germinates and produces a small mushroom-like structure (apothecia) full of spores. These spores are then dispersed, and can land on the senescing flower petals which can result in disease. For this to happen, researchers have estimated that the soil must be saturated for about 10-14 days.
Canopy wetness. Once spores are on the petals, a saturated canopy for a prolonged period of time (day or more) is necessary for the disease process to begin. Rainfall and heavy dews during flowering increase risk of infection.
Temperature. When it gets hot, white mold is less of a problem. Temperatures above 85 F will inhibit apothecia formation and disease development. If you believe you may be at high risk numerous fungicides are available. Application timing is important, an application during the early bloom stage is recommended. For further information, consult the 2008 North Dakota Field Crop Fungicide Guide (PP-622), available at: http://www.ag.ndsu.nodak.edu/extplantpath/fungicide.html
NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating, Duane Hauck, Director, Fargo, North Dakota. Distributed in furtherance of Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, sex, handicap, age, Vietnam era veteran status, or sexual orientation; and are an equal opportunity employer.
Go to Traill County Agriculture Program Page
Traill County Extension Office
P.O. Box 730
Hillsboro, ND 58045
701-636-5665 or toll-free1-877-843-6383
Contact us at: NDSU.Traill.Extension@ndsu.edu