ISSUE 5 May 31, 2001
GOOD BYE (NOT REALLY)
This is my last Crop and Pest Report before retirement. But it is not good bye, because after retirement I will work as a half time coordinator (consultant) for a Sclerotinia project on canola. This project was initiated and funded in Minnesota with thanks to Senator Gramsí support, and will embrace research and extension in both Minnesota and North Dakota. From time to time I may have information to provide relative to this project that can be shared through this publication.
It has been an honor and a pleasure serving the agricultural community of North Dakota. I also wish to state what a pleasure it has been to work with the various commodity groups, the agribusiness community and with my colleagues in Extension in Fargo and across the state. I wish to thank my administration for their support over the years; you have made my job easy, as I only had to deal with the technical matters of my job.
Extension Plant Pathologist
INITIAL REPORTS FROM SMALL GRAIN SCOUTING
Field scouting of wheat in Ransom, Sargent, Cass, and Richland counties on May 24 and 25th by Matthew Gregoire indicated very little disease present and no detectable insect pressure. Winter wheat fields surveyed were in the advanced tillering to advanced jointing stage. Tan spot was detected in two of these fields. Only a trace amount was found in a winter wheat field planted into barley stubble, but a field planted into wheat stubble had considerable tan spot on the lower leaves. All of the spring wheat fields surveyed were in the one to three leaf stage; no disease was observed in these young spring wheat fields and none were planted into wheat stubble.
Field scouting by Jeanna Jambor in Dunn, Stark, Hettinger, and Golden Valley counties from May 21-May 24 indicated virtually no disease, with only one wheat field having a trace amount of spot blotch. Wheat, oat, and barley crops surveyed by Jeanna were in the one to three leaf stage. She did note wireworm damage in six of thirteen fields surveyed. Other field scouts began actively scouting this week.
PROPER USE OF FUNGICIDES FOR EARLY SEASON TAN SPOT CONTROL
Recent rains across the state may trigger tan spot outbreaks in wheat fields planted into wheat stubble. Crops will need to be sprayed for weeds soon, and if tan spot is showing up, producers may want to use a Ĺ rate of fungicide for tan spot control. Fungicides available for this use were described in the second Crop and Pest Report (May 10). This information can be accessed at:
If fungicides are going to be tank mixed with herbicide, applicators should observe all directions for use, use rates, precautions, and limitations which appear on the tank mix product (herbicide) label. Also, a jar test will tell if the products are mixable or physically compatible. When these fungicides are mixed with a herbicide, the herbicide acts as an adjuvant, and additional adjuvants for the fungicide are not recommended with this use.
Extension Plant Pathologist
SCLEROTINIA RISK MAP FOR CANOLA
A risk map for Sclerotinia stem rot of canola has been in operation for some time in the Prairie Provinces of Canada. It has been a dream to provide this risk map for North Dakota and northwestern Minnesota. I have shared this dream with Dr. Gary Platford, retired plant pathologist from Manitoba Agriculture, Barry Coleman, Northern Canola Growers Association and Beth Nelson, Minnesota Canola Council. Funding from BASF, the Northern Canola Growers checkoff and a federal grant to the Minnesota Canola Council is being used to support development of a Sclerotinia Risk Map for North Dakota and northwestern Minnesota. Data is being exported to Winnipeg where the risk map is being developed in the same manner as the one used in Canada.
Initiating a Sclerotinia Risk Map has required a team approach involving every county agent and area specialist in North Dakota as well as county educators in northwestern Minnesota. It also involved assistance from Bruce Seelig, NDSU water quality specialist, John Enz, NDSU climatologist in charge of the North Dakota Agricultural Weather Network (NDAWN) and Dave LeGare, Minnesota Canola Project. Support from Barry Coleman and Gary Platford has been critical to project initiation. I canít begin to list all of the other persons in Manitoba who have been involved in this project, but key persons have included Gary Platford, Guy Ash (my constant contact) who is agrometeorologist with the Canadian Wheat Board, Jennifer Lamb with GEOMET Technologies, and Rick Raddatz with Environment Canada. Hope I got all of these right!
Thanks to all for their help in making this possible. Preliminary testing of the Risk Map begins next week.
PREVICUR AND TATTOO C
In Crop and Pest Report No. 2 (May 10, 2001) I stated that Previcur was registered for potato. I also indicated that Tattoo C would still be available this year. I was mistaken: Previcur will be available but Tattoo C will not be available. Thanks to Dean Maruska of Aventis for clarifying this to me.
Extension Plant Pathologist
When applied appropriately and in time, herbicides provide necessary relief from weed pressure; however, when they are misapplied, the results can be costly. The NDSU Plant Diagnostic Lab offers a diagnosis, based on visual assessment, for many types of potential herbicide injury. We can also provide plant tissue tests for RoundUp and soil tests for Pursuit residue. In the case of RoundUp misapplication, it is important to take samples within 2-3 weeks of the time the herbicide was sprayed. Symptoms are generally visible within 7-10 days, so regular scouting is necessary to detect potential problems in time to get optimal test results. Include a plant of the same species and growth stage that has not been exposed to the herbicide as well as the plant or plants that were potentially exposed to RoundUp. Results will be more definitive with a "control" sample at the same maturity level as the plant species in question.
When assessing soil residues for Pursuit, it is useful to know the field history. It is also useful to know pH variation across the field since the herbicide is broken down more slowly in areas where pH is lower. If you do have some field history, concentrate the samples from the area of the field that is of concern, particularly areas of low pH. If an accurate field history is not available, the soil sample submitted should be representative of the whole field. Soil plugs from 0-6" should be pulled from all across the field, including high spots, low spots, corners, and field entrances. Thoroughly mix the soil plugs.
There are two methods of Pursuit soil testing we can perform. If the Pursuit application was within the past 2.5-3 years, then a standard HPLC test will generally provide useful results. If the application was potentially made 3 or more years ago, then a more specific LCMS test should be done. A standard HPLC test costs $150.00 and the more specific testing method costs $300.00. While it may be tempting to try to get by with the less expensive testing method, this test is not sensitive enough to detect the very low levels of chemical residue that can damage sugarbeets, and that may be present 3 years after the herbicide application.
If you have any questions about how to take a sample or what kind of testing is available and should be performed, feel free to call or email the lab.