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ISSUE 2  May 10, 2001

 

WHEAT RUSTS IN SOUTHERN PLAINS DEVELOPING SLOWLY

Wheat leaf rust is developing very slowly in the southern US. The USDA Cereal Rust Bulletin, dated May 2, states that the level of leaf rust is the lowest seen in many years, and that "the southern wheat growing area will provide reduced amounts of leaf rust inoculum for the northern wheat growing area." Wheat stripe rust in Texas also has slowed in development because of the onset of hot, dry weather in that region.

 

FUNGICIDES FOR EARLY SEASON TAN SPOT CONTROL

Wet weather and saturated soils may lead to some early season tan spot infections in emerged wheat. Wheat crops most likely to have this infection are those planted back into last year’s wheat ground.

Fungicides may be used to suppress early season tan spot, and often they are applied with a herbicide when the crop is in the 3-5 leaf stage (The NDSU Weed Control Guide has a table listing restrictions on tank mixes of herbicides with fungicides). Fungicides most likely to be used for early season tan spot include:

Fungicide Product

Chemistry

Rate for early season use1

Tilt

propiconazole

2 fl oz/acre

Dithane, ManexII, Manzate,
Penncozeb

mancozeb

1 lb /acre

Stratego2

propiconazole + trifloxystrobin

5 fl oz/acre

1 Rates given are half the full label rate; an early season use of Tilt or Stratego precludes the use of full label rate for later season leaf or head disease control.

2 Stratego is being marketed by Bayer Corp. for early leaf disease control, up through Feekes growth stage 8 (early flag leaf emergence); the full label rate is 10 fl oz/acre and the cost for a 10 fl oz/acre application will be around $10/acre.

 

SECTION 18 GRANTED FOR FOLICUR ON WHEAT AND BARLEY

A section 18 was granted in January for the use of Folicur on wheat and barley in North Dakota and Minnesota for the suppression of Fusarium head blight (scab). As in recent years, the section 18 allows a maximum of one application per season, and the full label rate is 4 fl oz/acre. Folicur may be applied up to the 50% heading stage and application may not be made within 30 days of harvest. Straw cut after harvest may be fed or used for bedding.

For optimum disease control, the lowest labeled rate of a spray surfactant should be tank-mixed with Folicur 3.6F. Our greenhouse and field studies with Folicur have shown that a non-ionic surfactant greatly improves the performance of Folicur for head scab control. Bayer recommends using 0.12% v/v of Induce surfactant.

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

 

DR. LUIS DEL RÍO HIRED FOR DRY BEAN PATHOLOGY POSITION

Dr. Luis del Río was hired to fill the dry bean pathology position in the Plant Pathology Department at NDSU. This position was vacated when Dr. Jim Venette moved into administration at NDSU. Dr. del Río arrived in March of 2001. He has a PhD degree in plant pathology from Iowa State University working on Sclerotinia stem rot of soybean and since then worked in a post doctorate position at the University of Wisconsin, also on Sclerotinia stem rot of soybean. In his work at Iowa State University Dr. del Río studied the effect of parasites that attack and destroy the sclerotia of Sclerotinia and he studied the effect of cropping systems on Sclerotinia survival while at the University of Wisconsin. This background is most welcome with the widespread Sclerotinia problems we have in North Dakota. Please join me in welcoming Luis del Río.

 

INTERCEPT BIOLOGICAL CONTROL PRODUCT REGISTERED FOR SCLEROTINIA

Intercept WG has been registered for reduction and/or control of Sclerotinia. Prior to registration it was known as Contans WG. It contains spores of Coniothyrium minitans, a fungus that attacks and destroys the sclerotia of the Sclerotinia fungus. Some trials by USDA pathologists at Fargo and Mandan were initiated last fall; others are planned for this fall.

Intercept WG can be incorporated in the upper 3 inches of soil for destruction of Sclerotinia sclerotia. It takes several months for complete destruction of sclerotia, which leaves some questions about the best time to apply: Fall application after fall tillage would provide adequate time for destruction of sclerotia in the upper 2 inches of soil. This would reduce the population of sclerotia capable of producing the mushroom structures (apothecia) that produce spores that infect canola and dry beans. However, the soil should not be disturbed after treatment, to avoid bringing untreated sclerotia to the soil surface. It may take some experimental trials before we learn the best way to use this product.

 

PREVICUR REGISTERED FOR POTATO

Previcur was registered for potato, to be used as a foliar application for control of late blight. Previcur contains propamocarb, one of the active ingredients in Tattoo C. It is to be applied in a tank mix with either chlorothalonil or mancozeb. Tattoo C will still be available this year; it contains propamocarb + chlorothalonil, and has provided excellent late blight control in NDSU trials.

 

GAVEL REGISTERED FOR POTATO

Gavel fungicide was recently registered for potato, to be used for control of late blight and early blight. Gavel contains zoxamide + mancozeb. Gavel has provided excellent late blight control in NDSU trials. Zoxamide is a new class of chemistry for late blight control and it has a different mode of action from other late blight products. With the number of new late blight products available, there are good opportunities for resistance management by alternation or rotation among various late blight products with differing chemistries and modes of action.

 

IMPORTANT WEB SITES

Several Web sites are of importance to producers of row and specialty crops. These include:

Sugarbeets:

American Crystal Sugar Company:  http://www.crystalsugar.com/agronomy/index.asp

Sugarbeet Research and Extension board of Minnesota and North Dakota (includes on-line all Sugarbeet Research and Extension Reports):  http://www.sbreb.org/

Canola:

Canola Council of Canada:  http://www.canola-council.org/

Northern Canola Growers Association:  http://www.northerncanola.com/

Dry Beans:

Northarvest Beans:  http://www.northarvestbean.org/

Sunflower:

http://www.sunflowernsa.com/

Pulse Crops:

lentil, chickpea, field pea, University of Saskatchewan:  

http://paridss.usask.ca/specialcrop/pulse_diseases/index.html

 

Soybean:

University of Wisconsin:  http://www.plantpath.wisc.edu/soyhealth/

Plant Diseases:

cereal, oilseed and pulse crops, Alberta Agriculture and food Development:  http://www.agric.gov.ab.ca/navigation/pests/plantdiseases/index.html

 

Art Lamey
Extension Plant Pathologist

alamey@ndsuext.nodak.edu


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