NDSU Crop and Pest Report
Plant Pathology


ISSUE 6  June 6, 2002

 

IPM FIELD SURVEY, MAY 31

NDSU IPM field scouts completed their first full week of scouting last week and disease pressure generally was very low or absent in small grains. Scouts reported dry conditions and slow crop emergence in many areas. In other areas with a little more soil moisture, the wheat crop looked good, with only minor frost and wind damage.

Spring wheat and barley ranged from the 1 leaf stage to the tillering stage, while winter wheat was in the 5 /12 to 6 leaf stage. The scouts also surveyed for grasshoppers at all field stops and for flea beetles in canola.

 

SMALL GRAIN DISEASE FORECASTING SYSTEM

The NDSU small grains disease forecasting system is now up and running on the web. The new web page is on-line at:

http://www.ag.ndsu.nodak.edu/cropdisease/

If an individual does not have access to the internet or is away from their computer, the information can be accessed via telephone at:  1-888-248-7357, or 231-6601 if in the Fargo calling area.

The forecasting system has expanded to additional NDAWN sites, with a total of 47 sites. Fusarium spores will be counted at 21 sites, with Carrington and Kenmare, ND and Sabin, MN being additions sites for 2002.

The forecasting system provides information on whether favorable infection periods occurred within the previous 13 days for the diseases tan spot, Stagonospora (Septoria) blotch, and leaf rust, at the specific NDAWN location chosen. Additional information about the rainfall, RH, temperature and wet periods of the last 13 days also is given. For the 21 sites with spore sampling, spore counts of Fusarium are included, and a spore map will be provided.

To get the above information, a user of this web site clicks on an NDAWN location and clicks on a growth stage for the crop. At the flowering growth stage option, forecasting models for predicting Fusarium head blight severity (scab) also are provided. The scab forecasting models are based on work done in Ohio and have not been completely validated for ND, but will provide some useful information on potential risk of the disease.

All of this information, in turn, can lead to more informed decision making about fungicide use. The following is an example of what the tabular information on the web page looks like for the Fargo NDAWN site on June 2:

Small Grain Disease forecasting models: Infection periods of tan spot, Stagonspora (Septoria) blotch and leaf rust

Interpretation: Yes = infection likely, No = infection unlikely. First, select the date when 50% of the flag-2 (or flag-1) leaves had disease symptoms. Then, consider a fungicide when 6-8 infection periods ("Yes" days) have accumulated.

Fargo NDAWN site

Model

6/1

5/31

5/30

5/29

5/28

Tan spot

No

No

No

Yes

Yes

Blotch

No

No

No

Yes

No

Leaf rust

No

No

No

No

No

The NDSU Small Grains Disease Forecasting System has been developed by Dr. Len Francl and his crew in the Dept. of Plant Pathology at NDSU. Maintaining sites and the spore sampling is a large cooperative effort among the Dept. of Plant Pathology, John Enz in NDSUís Soil Science Dept., the NDSU Research Extension Centers, Jochum Wiersma at the Univ. of Minnesota, Crookston, and various area and county extension agents, as well.

Support for these NDAWN sites and the forecasting and spore sampling efforts comes from many sources, including, but not limited to, SBARE, the ND Wheat Commission and the U. S. Scab Initiative.

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

 

POTATO DISEASE HOT LINE BACK AGAIN

The potato disease hot line is back and running as of May 31. The hot line, which provides forecasts and control recommendations for late blight, early blight, and other potato disease and insect information, will be updated each Monday, Wednesday, and Friday until mid-September. The hot line (Bravo/Quadris Blightline) is sponsored by Syngenta Crop Protection and is provided through Drs. Neil Gudmestad and Gary Secor of the NDSU Plant Pathology Department. The telephone number to call is: 1-800-482-7286. The information is also available online at:

 http://www.ndsu.nodak.edu./instruct/gudmesta/lateblight/

In addition to the recommendations available by phone or on the web, a new late blight forecasting website in cooperation with Dr. John Enz, NDSU and the North Dakota Agriculture Network (NDAWN) has been added. This new user-friendly website shows the status of late blight and early blight forecasts throughout ND at a glance with a series of color maps. The maps are generated using weather information from NDAWN stations across the state. The maps display information on late blight severity values, late blight favorable day values, and early blight p-values for the past two days and season-long accumulation. That website is:

http://ndawn.ndsu.nodak.edu/application/potatoes.html

As of June 3, no late blight severity values, and only minimal p-values have accumulated. Growers should destroy overwintering sources of late blight inoculum, cull piles and early volunteers, to prevent early infection.

 

NEW SOYBEAN HEALTH WEBSITE

A new website has been developed by the Plant Health Initiative, which was founded by the North Central Soybean Research Program, that provides information on soybean disease and insect problems. There are several good pictures and fact sheets of soybean diseases and pests on their website, which is located at:

http://www.planthealth.info/

Carl Bradley
Extension Plant Pathologist
cbradley@ndsuext.nodak.edu

 

SPRAY DRIFT TESTING AND OTHER SERVICES FROM THE PLANT DIAGNOSTIC LAB

This year, as in the past year, the Plant Diagnostic Lab is offering limited herbicide injury testing services. The lab is not set up, with either the personnel or equipment, to offer a full compliment of herbicide injury testing services (see Pg 112 of the 2002 ND Weed Control Guide or contact the lab for more extensive testing services), but we have partnered with a lab in the Plant Sciences department to offer some frequently requested services with high impact. These include plant tissue testing for exposure to glyphosate (RoundUp and others) and soil testing for imazethapyr (Pursuit). Most Pursuit soil testing has been done prior to planting but if you have need of the service and require sampling information, please call (701.231.7854) or email the lab, or visit the website (www.ag.ndsu.nodak.edu/diaglab). If you are interested in Round Up tests, samples should be taken (optimally) within 3 weeks of the time of application or exposure. Pull 4-5 symptomatic plants (or more), keep refrigerated (or at least out of the sun and cool), and do not seal them in plastic. Also pull 4-5 plants from an area that does not appear to have been exposed for comparative purposes. Include information on all pesticide applications made to the symptomatic area or field as well as all known applications made to surrounding areas. Planting date and recent weather condition data is also helpful. These and all samples should be mailed to:

NDSU Plant Diagnostic Lab
Walster 306
Box 5012
Fargo, ND 58105

The lab continues to look for ways to expand our service capabilities to meet the plant health needs of the citizens of the state. This year we will begin to add Phytophthora race testing for Phytophthora root rot of soybeans. The differential set used to check these samples is being established this year so for this year, race data will not be available until mid-fall. In the future, we should be able to provide this information within a few weeks of sample submission. Stay tuned for more details on Phytophthora root rot on soybeans and sampling techniques.

Cheryl Biller
NDSU Plant Diagnostic Lab
diaglab@ndsuext.nodak.edu


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