NDSU Crop and Pest Report
Plant Pathology


ISSUE 1  May 2, 2002

 

PLEASE WELCOME CARL BRADLEY, EXTENSION PLANT PATHOLOGIST FOR BROADLEAF CROPS

Dr. Carl Bradley, Extension Plant Pathologist for broadleaf crops, started at NDSU on April 1. Carl received his PhD degree in Plant Pathology from the University of Illinois, working on soybean diseases. He grew up on a corn/soybean farm in southern Illinois, and worked full time as a research associate at the University of Illinois, while doing his graduate work. He joins the NDSU Extension Service after working one year as a PostDoctorate Fellow for the University of Idaho at the Kimberly Research Extension Center.

Carl has a 90% extension, 10% research appointment and will be responsible for disease management education for all broadleaf field crops. Please welcome Carl to North Dakota and the Extension Service, and be sure and call him with those disease questions on broadleaf crops!

 

SECTION 18 AND 24C FUNGICIDE LABELS FOR 2002

Section 18 Emergency Exemptions granted: EPA has approved the following North Dakota requests for Section 18 exemptions for fungicides for 2002:

* Folicur 3.6F: wheat and barley, for scab suppression (granted Nov. 21, 2001)

* Folicur 3.6F: sunflower, for leaf rust (granted Feb. 7, 2002)

* Eminent 125SL: sugarbeet, for Cercospora leaf spot (granted March 12, 2002)

* LSP seed treatment fungicide: Lentils, for seed-borne Ascochyta; both Gustafsonís and Mertects LSP (granted April 22, 2002).

The North Dakota Department of Agriculture also is seeking Section 18s for the following crops, but no action has yet been taken (April 30) by EPA:

* Tilt for control of rust in dry beans

* Quadris for Ascochyta control in chickpeas

* Quadris for Alternaria control in safflower

State SLN 24C labels: The North Dakota Dept. of Agriculture has granted 24C labels to PropiMax EC and to Stratego fungicides for wheat. The 24C labels will allow application of these fungicides to wheat up through Feekes growth stage 10.5 (full head emergence). The current federal label for both of these fungicides only allows application through Feekes 8, or early flag leaf emergence.

PropiMax is propiconazole fungicide, sold by Dow AgroSciences. Stratego is a combination of propiconazole + trifloxystrobin fungicides and is sold by Bayer Corp.

A supplemental 2 (ee) label was granted to PropiMax fungicide for early season control of leaf and glume blotch diseases in wheat, using a rate of 2-4 fl oz/acre/season.

Further information about special labels in North Dakota, along with links to PDF versions of the labels, can be found at the NDSU Extension Service Pesticide Programís web site:

 http://www.ag.ndsu.nodak.edu/aginfo/pesticid/pesticid.htm

 

PROLONGED EXPOSURE TO CERTAIN SMALL GRAIN SEED TREATMENTS

Recent cold temperatures may have halted planting of small grain seed already treated with fungicide and insecticide seed treatments. Generally, there are no problems expected for short-term storage of seed treated with a seed treatment as long as seed is stored in a cool, dry place.

Some seed treatment labels carry cautionary statements about minimizing the time between treating and planting of seed treated with combinations of both lindane insecticide and imazalil fungicide. Lindane and imazalil may shorten the sub-crown internode length under certain conditions. If seed has been exposed to these two chemicals for extended durations prior to seeding, growers should: pay close attention to seeding depth and stay close to the 1.5" recommendation; and they may want to slightly increase their seeding rate (Dr. Jochum Wiersma, University of Minnesota, Crookston, small grains specialist, recommends a 5% adjustment in seeding rate).

 

SMALL GRAIN CROP AND DISEASE DEVELOPMENT IN SOUTHERN PLAINS

Every year I look to southern plain states for disease development on cereal crops that may have a potential to impact our northern plains small grain crops, diseases including the cereal rusts and barley yellow dwarf. The most recent Cereal Rust Bulletin, published April 23, 2002 by the USDA/ARS Cereal Disease Lab in St. Paul, indicated:

* trace to 10% severities of wheat leaf rust observed in wheat fields in Texas and Oklahoma;

* wheat stripe rust at trace to severe levels in Texas;

* very low levels of wheat stem rust reported in wheat plots in Texas.

* barley leaf, stem, and stripe rusts at trace levels or have not been reported yet, while some hot spots of oat crown rust were reported in Texas.

Grain aphids were active in the fall in Kansas wheat fields, indicating a potential for spring activity and spread of the barley yellow dwarf virus, as reported by the April 4 edition of the KState Plant Disease Alert. Recent cool temperatures in Kansas have slowed any disease development. Also, the April 28 USDA-NASS report on winter wheat condition indicates that only 36% of the US winter wheat acreage is rated good to excellent at this time. In North Dakota, early reports around the state indicate good survival of winter wheat crops.

Marcia McMullen
Extension Plant Pathologist

mmcmulle@ndsuext.nodak.edu

 

SEED TREATMENT OF SOYBEANS

Treating soybean seeds may be a good defensive tool to use against seed and seedling diseases. Some factors that need to be evaluated before making the decision to treat or not to treat the seed include:

* Field history: If the field has a history of being poorly drained, or if root rot or poor stand establishment has been a problem in the past, then treating seed may help protect against seedling blight and ensure a better stand.

* Tillage practice: In reduced tillage conditions, soil may remain cold and wet longer than in conventional tillage. Cooler temperatures may slow the growth of soybean, making it susceptible to seedling diseases for a longer period of time. Seed treatments can provide protection against seedling blights under these adverse seed germination conditions.

* Certified vs. "bin-run" seed: Use of certified disease free seed is strongly recommended; however, if "bin-run" seed is to be used, then treating the seed may be beneficial in reducing the chance of spread of seed-borne diseases such as white mold and downy mildew.  If the decision to treat soybean seed is made, some additional factors should be considered:

* Use of inoculants: The seed treatments captan and PCNB have been shown to be antagonistic to the Bradyrhizobia bacteria used in inoculants; therefore, these seed treatments should be avoided if the seed will be treated with an inoculant.

* Flow of treated seed in planter: The flow of treated seed may be restricted in the planter, checking the seeding rate, adjusting the planter accordingly, and using graphite may be necessary to achieve the desired plant population with treated seed.

* Use a broad-spectrum seed treatment: Using a seed treatment that will provide control against a broad-spectrum of pathogens such as Fusarium, Phytophthora, Pythium, and Rhizoctonia is important. Recently labeled seed treatments for North Dakota that provide broad-spectrum control include Warden RTA from Agriliance (0.72% fludioxonil and 2.21% mefenoxam) which contains the same active ingredients as Apron Maxx RTA from Syngenta (0.73% fludioxonil and 1.10% mefenoxam), and SoyGard from Gustafson (15% azoxystrobin and 20% metalaxyl).

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

 

NDSU PLANT DIAGNOSTIC LAB

It seems odd to be talking about a new diagnostic season with night time temperatures still in the 30's. Despite the temperatures, the trees are starting to bud and the calendars tell us it is time to start planting. And so we begin another growing season in ND where our weather is rarely boring and often fodder for long conversation.

We are fortunate that personnel in the lab remain the same this summer - Mary will be back answering the phone, sending out responses, and generally helping keep the place organized, and Matt continues to do a great job keeping us up-to-date technologically as well as managing cultures and special testing.

Pricing and services remain largely the same this season as well. We get great administrative support for publications; however, technical and clerical support and lab operations are maintained solely on the basis of the fees generated from samples. We have added an additional service to the list of routine diagnoses, insect and plant identifications, and various other special tests - the lab is now offering mold species identification on home building materials. As a result of the flooding in 97 and subsequent years, university specialists were inundated with requests for mold information. In response, a joint project between Cass and Clay counties in Fargo and Moorhead, respectively, put together very comprehensive and user-friendly material to provide homeowners with answers to the myriad of questions that come about as the result of water damage in a home (see web site at http://www.homemoisture.org ). Part of the that response was to enlist the assistance of the diagnostic lab (based on our experience in identifying plant pathogens which, like most mold organisms, are primarily fungal). The role of the lab is to help homeowners and businesses find out if they have a mold problem, and if there is mold present, what it is. We are not able to identify every mold species out there, but we can identify or rule out those typically associated with health concerns, and the more commonly occurring species. The fee for this service is $30.00.

The lab is also working on a pilot project involving placement of microscopes and image capture equipment in several locations in the state. Using monies made available by the administration, 7 sites will get a stereo (dissecting) microscope, compound microscope, and digital camera that works on both scopes, in addition to training and resources to help xamine samples. The intent is that with the equipment, agents and specialists in these 7 locations will be able to send digital images in high enough resolution for disease diagnosis or identification to be made remotely. This will not be a magic bullet, and it will take some time to get working smoothly. But, it will be another tool for those people out in the state to use to make sound decisions based on useful information. The 7 locations that will have equipment include the Dickinson REC, North Central REC in Minot, Carrington REC, LaMoure county, Hettinger, Grand Forks county, and Devilís Lake REC. Personnel in neighboring counties are encouraged to utilize this equipment when it is convenient, and we hope to expand the number of sites equipped as money becomes available.

Questions, concerns, and requests for information on this or any other plant problems may be directed to the lab by one of the following three means: by phone - 701.231.7854, by email - diaglab@ndsuext.nodak.edu , or by visiting the website at:

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

Cheryl Biller
Diagnostician
diaglab@ndsuext.nodak.edu


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