NDSU Crop and Pest Report
Plant Pathology


ISSUE 2   May 13, 2004

WHEAT GROWING DEGREE DAYS

The North Dakota Agricultural Weather Network (NDAWN) is an excellent resource for information on weather and growing degree days (GDD) for a number of crops. The tools provided by this web site can help with pesticide decisions.

For wheat, the GDD information can be used for determining date of emergence and current growth stage. Current leaf stage provides information, for ecample, on when herbicides are needed and when the crop is too advanced for certain herbicides. If frost or wind damage causes loss of leaves, the GDD information provided by NDAWN would allow correct leaf staging in absence of some leaves. Correct growth staging also is important for fungicide decisions.

The NDAWN web site has several options on examining wheat GDD. The following steps provide some examples:

1. Access the NDAWN web site at:

http://ndawn.ndsu.nodak.edu/index.html

2. On left side of map, click on: "Applications"

3. Under wheat: click on: Degree Days Growth Stages

4. You then can chose the options of:

a) Detailed table for particular NDAWN station:

Choose station, planting date and end date and submit, and get a table that provides GDD accumulation for each day in the time frame specified for that station

b) Statewide Map of Degree Days:

The following is map showing accumulated growing degree days(AGDD) if the planting date was 4/10/04 and the end date was 5/10/04:

Degree days map

Note: This map is colored and takes some time to upload. Be patient.

c) Map of Growth Stages for accumulated GDD:

The following is a map of Haun leaf stages for a planting date of 4/10/04 and the end date was 5/10/04.

Leaf stage image

d) Summary Table for any Station at up to 10 different planting dates:

The following is an example of AGDD and leaf stagefor various planting dates for the Fargo Station at various planting dates

Planting date

Wheat AGDD

Estimated Haun leaf stage

4/05/04

544

3.0

4/07/04

504

2.8

4/10/04

492

2.7

4/15/04

422

2.2

4/20/04

338

1.6

4/25/04

273

1.2

4/28/04

219

0.8

5/02/04

174

0.5

5/05/04

112

0.0

5/08/04

49

0.0

 

EARLY SEASON WHEAT FUNGICIDE USE

Next week’s Crop and Pest Report will contain detailed information about use of early season fungicides on wheat, but the above table indicates there may be some wheat in the state in the 5-leaf stage before that report comes out. The five-leaf stage is generally the most appropriate timing for early season fungicide use. Some winter wheat in the southern counties also may be in the five leaf stage, as well. Recent rains may activate sporulation of the tan spot fungus.

Marcia McMullen
Extension Plant Pathologist
mmcmulle@ndsu.nodak.edu

 

FOLICUR AVAILABLE FOR USE ON SUNFLOWER FOR 2004 GROWING SEASON

A section 18 emergency exemption request for use of Folicur for protection of sunflower against rust was recently approved by the EPA. The exemption, which expires September 5, 2004, allows Folicur to be applied to sunflower at a maximum of 4 fl. oz per acre with a maximum of two applications. A 30 day pre-harvest interval must be observed as well as a 120 day rotational crop restriction on crops not currently listed on the label.

 

PROTECT SOYBEAN SEED AGAINST SEED AND SEEDLING BLIGHT

The cool, wet weather the state is experiencing is providing a conducive environment for Pythium seed and seedling blight. Pythium, which is a fungus-like plant pathogen, can rot seed and cause blight and damping-off of young soybean seedlings. Unprotected seeds are at the greatest risk. Two fungicide seed treatments that protect against Pythium infection are metalaxyl (Allegiance, Gustafson) or Apron XL (mefenoxam, Syngenta). Use of a seed treatment that contains a mixture of one of these products along with another broad-spectrum fungicide, such as ApronMaxx RTA (Syngenta), Warden RTA (Agriliance), or SoyGard (Gustafson) is recommended to help ensure good stands.

Other factors to consider when to use fungicide seed treatments on soybean seed include:

Cropping history: To reduce the inoculum levels of root rot pathogens, rotation with small grains or corn is necessary. However, if planting soybean after a broadleaf crop (especially soybean or dry bean), seed treatment with a fungicide may be required.

Tillage practice: In fields where reduced tillage practices are used, soil takes longer to warm up and dry out. This cool and moist environment is conducive for seed and seedling blight.

Seed quality: Most seed quality problems can be avoided by purchasing quality-assured or certified seed; however, bin-run seed can harbor several seedborne pathogens that can cause seed rot.

Inoculants: Older seed treatments such as captan and PCNB may harm Bradyrhizobia inoculants, and should be avoided if inoculating. No matter what seed treatment product is used, always allow the fungicide to completely dry before using inoculants, and inoculate as close to planting time as possible. Use of granular inoculants may help avoid any antagonism with seed treatments.

Carl Bradley
Extension Plant Pathologist
carl.bradley@ndsu.nodak.edu

 

NEW PLANT PEST DIAGNOSTICIAN

I am replacing Cheryl Biller as Plant Diagnostician in the NDSU Plant Diagnostics Lab, as of May 10. My first name is pronounced "Kasha" – the ‘si’ becomes ‘sh’. During the transition period, we at the lab will do our very best to ensure that timely and reliable results are provided without disruption. As a reminder, please refer to the following instructions for submitting and mailing samples:

For plant samples: Collect as much of the living plant as possible. If possible, several plants should be sent. Wrap mushrooms, roots, fruits, and other soft, fleshy samples in newspaper and place them in a sturdy box. Most other samples can be placed in a bag (plastic is okay as long as it is not sealed). Fold the bag over loosely, making sure it is not sealed tightly. Avoid adding moist paper towels – they can cause the sample to decompose rapidly. If possible, place several leaves of the sample flat in a paper envelope, with the remaining sample in the bag.

For insects: Send small specimens in a vial of alcohol. Insects should never be sent in an envelope, and live insects should never be mailed. Pack larger insects, such as moths, in cotton in sturdy boxes.

Mail Samples to:
NDSU Plant Pest Diagnostic Lab
206 Waldron Hall
Box 5012
Fargo ND 58105

Samples will usually reach Fargo in one day from anywhere in North Dakota.

Cheryl Biller will continue to provide excellent service in her role as independent crop consultant with her new company, Plant Pro Inc, based in Fargo.

Please feel free to drop in on the Plant Diagnostics Lab, 206 Waldron, whenever you are on or near NDSU campus.

Kasia Kinzer
Plant Pest Diagnostician
diaglab@ndsu.noak.edu


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