ISSUE 4 May 28, 1998
The North Dakota Dept. of Agriculture announced on May 20,1998 that the EPA granted a request for a specific exemption (Section 18) for the use of Folicur fungicide for suppression of Fusarium head blight (scab) on wheat and barley. This exemption allows the rate of 4 fl. oz/acre of Folicur product to be applied to wheat or barley from Feekes growth stage 10.3 (50% heading) to Feekes growth stage 10.51 (flowering of wheat). The exemption allows a single ground application in a minimum of 10 gallons of water per acre, or a single aerial application in a minimum of 3 gallons of water per acre. A maximum of 220,000 acres of barley and 880,000 acres of wheat (including durum) may be treated in North Dakota under this specific exemption. A similar exemption was granted for 150,000 acres of barley and 500,000 acres of wheat in Minnesota.
The specific exemption request was made for Folicur for the purpose of suppressing scab. Folicur is a systemic product with a wide spectrum of activity against the rusts and fungal leaf spot organisms, as well.
Persons applying Folicur must have a copy of the label in their possession during application and dealers are required to keep sales records for Folicur. I do not have a 1998 label for Folicur yet, but the label should be available before the spraying window.
WHEAT DISEASE OBSERVATIONS
Two winter wheat fields in Cass Co. were in the Feekes growth stage 9 on May 21. Both fields had excellent winter survival and good stands. The field with the densest stand had powdery mildew infection on the bottom leaves and stems, not unusual for dense wheat stands trapping humidity in the lower canopy. Very little tan spot and no leaf rust was observed in these winter wheat fields that were planted into barley stubble. Spring wheat in Cass and Richland counties were in the 3-41/2 leaf stage on May 21. Wheat on wheat stubble had considerable tan spot infections on all but the newest leaf; wheat on barley or soybean stubble had virtually no leaf disease evident.
Some wheat fields with short rotations between wheat and or barley crops are showing symptoms of root rot infection, indicating early infection during the time soils were quite wet. In some cases infection is severe enough to cause dying out of plants in areas in the field.
Surveys of crop pests will be enhanced this year by the addition of
several field scouts who will be surveying wheat and other crops for diseases and insects.
Carrie Buttke, an NDSU Plant Protection major from Mayville, ND, will be working out of
Fargo and will be surveying much of the Southeast, East Central and Northeast tier of
counties for wheat diseases and insect pests, as well as helping with wheat fungicide
trials and helping Dr. Art Lamey with canola disease surveys.
Sarah Gehlar, a junior at NDSU from Ypsilanti, will be working with Jim Harbour, Crop Protection Specialist at Carrington, operating in the Central and South Central counties and conducting wheat disease and insect surveys. Shane Crawford, a senior at NDSU from Garrison, will be working with Janet Knodel, Crop Protection Specialist at Minot, operating in the North Central and Northwest counties to conduct disease and insect surveys. These survey efforts are supported in part by federal Integrated Pest Management (IPM) funding, and CAPS federal pest survey funds coordinated through Dave Nelson of the ND Dept. of Agriculture.
The National Sunflower Association established a web page at http://www.sunflowernsa.com. It contains news and daily updates, recent issues of The Sunflower magazine, buyers information, recipes, nutrition information, and a section entitled "Especially for Producers", with sections on crop statistics, a discussion group, producer primer and daily marketing news. The discussion group is a section where producers can ask questions and personnel with the National Sunflower Association (NSA), or other interested persons, can provide answers. A news section lists upcoming events including NSA board meetings, research meetings and research reporting sessions; NDSU Research Extension Center field days and other events.
Two weeks ago I suggested that root rots caused by water molds might become severe. Fortunately not many dry beans or soybeans were planted before the heavy rains in the eastern part of the state. In contrast, most sugarbeets were planted before the heavy rains. Dr. Al Cattanach, NDSU/UM sugarbeet specialist, reports that Aphanomyces is showing up in many fields, and that it is severe in some. He checked a field recently and concluded that it needed to be replanted due to severe Aphanomyces damage.
Is replanting necessary? Dr. Cattanach indicates that replanting should not be considered unless you expect less than 60 plants will survive in 100 feet of row. If a field is replanted, it would be advisable to plant it to an Aphanomyces tolerant hybrid with Tachigaren pelleted seed, if available. This is suggested because the chances of another Aphanomyces attack are high if more wet weather occurs after replanting.
How long does Tachigaren protect? Data from greenhouse trials by Dr. Carol Windels, University of Minnesota, Crookston, indicate that the 45 gram rate provides full protection for at least 3 weeks after planting with partial protection for at least another week, and the 75 gram rate provides full protection for at least 4 weeks after planting.
Some sugarbeets in the northern Red River Valley and in western North Dakota may start to close the rows by mid-June, according to Dr. Cattanach and reports from county and area agents. Monitoring for Cercospora should begin when rows close, which might be as early as mid-June in some fields, earlier than the previous two years in the Red River Valley. Producers may need to begin spraying earlier, too, depending on when Cercospora is observed and on weather conditions.
If grasshoppers are a problem when the Cercospora spraying season is underway, producers should remember that the label for Asana XL prohibits tank mixing with Super Tin. Asana XL has a vegetable oil base; this oil base may result in severe phytotoxicity when tank mixed with Super Tin. If Asana XL is to be tank mixed with a fungicide, use mancozeb.
Extension Plant Pathologist
No single crop or disease has been predominant this past week in the lab. There have been several calls regarding poor emergence, uneven stands and yellowing wheat. The samples submitted to the lab so far have had multiple problems. One of these problems is that the seed was planted too deep. The result is that the seed expends a great deal of energy growing up to get to the soil line where the crown develops. Fields where the deep seeding occurred sporadically generally show uneven stands. Depending on the vigor of the seed, poor emergence across the field can result as well. The two diseases so far observed in the lab this season are Tan spot and root rot. Tan spot is caused by a fungus called Pyrenophora tritici-repentis. Symptoms of the disease are brown flecks that can appear on both the upper and lower leaf surfaces during spring and summer. These tan-brown flecks may expand to oval shaped lesions, often with a yellow to white border. The lesions can coalesce to form fairly large, light tan areas with brownish spots throughout. Conidia (asexual spores) are formed in these large lesions, which can then be continuously dispersed by wind to reinfect other leaves or plants. Host debris (straw or wheat stubble) left in the field serves as the source of ascospores which are the primary inoculum, one stage in the life cycle of the organism that causes the initial infection for the current growing season. This means that wheat on wheat rotations are more likely to have a tan spot problem.
Several different tree species with an assortment of disorders have also been evaluated. Maple trees with yellowing leaves, a condition called iron chlorosis, has been observed. This is a problem of particular concern in the valley where the soils tend to be more alkaline. Soils with a higher pH, alkaline soils, bind iron so that it cant be as easily absorbed by plant roots. When a deficiency of iron occurs, the tree is unable to manufacture chlorophyll normally and the yellowing symptoms are the end result. Application of iron chelate, a form of iron that is not as readily bound up by molecules in the soil will reverse the yellow condition. Iron chelate may be applied as a spray treatment on the tree or injected directly into the roots.
Plant Pest Diagnostician
The 10th Sclerotinia Workshop will be held September 9 to 12, 1998 at the Holiday Inn, Fargo, ND. The meeting will begin with a social on Wednesday evening, then two days of meetings and discussions plus a field trip in the Red River Valley on Saturday. The meeting brings together pathologists and plant scientists from industry, government, extension and Universities. Students are encouraged to attend. The theme is biology and control of Sclerotinia ( S. sclerotiorum, S. minor, and S. trifoliorum). Presentations and discussions are usually grouped around specific topics such as biology, biotechnology, etiology, epidemiology, resistance, biocontrol, and chemical control. Discussions and mingling are emphasized in this meeting. Fridays sessions will cover the more applied aspects of control including chemical, biological, cultural, resistance, and screening. Crop consultants, extension agents, seed company researchers, and others with primary interest in applied research on Sclerotinia may find these sessions valuable. Although oral presentations will be accepted, the emphasis will be on poster and discussion sessions. A 1-2 page abstract will be required from each presenter. A proceedings of the meeting will be published and provided to each registered attendee.
Co-organizers are Tom Gulya, USDA, Northern Crop Science Lab (phone
701-239-1316; email- firstname.lastname@example.org.
gov ) and Berlin Nelson, Dept. Plant Pathology, North Dakota State University (phone 701-231-7057; email- email@example.com ). Registration forms and hotel information can be obtained from Stephanie Carlblom, Dept. Plant Pathology, phone 701-231-8363 (fax 701-231-7851) or email- firstname.lastname@example.org. There is a web site for this meeting: http://www.ndsu.nodak.edu/ndsu/news/1998/ 090998.sclerotinia_ppth.html
Berlin D. Nelson