ISSUE 5    June 2, 2005

SECTION 18 GRANTED FOR FOLICUR FOR WHEAT AND BARLEY

The ND Dept. of Agriculture announced on May 27th that EPA granted a Section 18 Specific Exemption for the use of Folicur (tebuconazole) fungicide for the control of Fusarium head blight (scab) in wheat and barley. A maximum of 2 million acres of wheat and 250,000 acres of barley in ND may be treated this year with Folicur.

For barley, Folicur may be applied up through full head emergence (Feekes 10.5) and for wheat, Folicur may be applied up through the beginning of flowering (Feekes 10.51).

Both Section 18 labels state that application may not be made within 30 days of harvest. The maximum use rate of Folicur is 4 fl oz/acre.

Please see the labels for specific information about use of adjuvants and spray volumes. The labels for these uses must be in possession of the user at the time of pesticide application. These wheat and barley labels will be posted at the ND Dept. of Ag. Web site http://www.agdepartment.com/Programs/Plant/Section18Exemptions.html  

and the Pesticide Certification and Training web site http://www.ag.ndsu.nodak.edu/aginfo/pesticid/LabelPage.htm

 

NDSU IPM SURVEY BEGINS

NDSU’s summer IPM survey began last week. Field scouts went through a training session with NDSU extension area and state specialists and representatives from the ND Dept. of Ag. on May 24th at the Carrington Research and Extension Center. The field scouts will be examining fields of wheat, barley, canola, sunflower and soybean for major disease and insect pests in 2005. The information they gather will be provided on a timely basis to producers and crop advisors in the weekly NDSU Crop and Pest Report and via the Agdakota listserve and county ag alerts. Field scouts for 2005, and their local coordinators are:

Scout

Coordinator

Location

Clara Presser

Greg Endres

Carrington REC

Josh Seekins

Roger Ashley

Dickinson REC

Wes Messmer

Roger Ashley

Dickinson REC

Dan Liane

Terry Gregoire

Devils Lake Area Office

Ryan Davis

Jan Knodel

North Central REC

Drew Erdman

Jan Knodel

North Central REC

Kelsey Steenblock

Marcia McMullen, Carl Bradley

NDSU, Fargo

 

IPM SURVEY DETECTS WHEAT LEAF RUST AND TAN SPOT, MAY 24-27

The survey scouts examined 131 wheat fields during the week of May 24-27th and found tan spot in 37.4% of these, with severities generally low but in some cases as high as 22%. Highest severities were observed in winter wheat. Wheat was identified as the previous crop in all fields with high incidences and severities of tan spot. Most fields with no detection of tan spot were previously planted to soybean, sunflower or potato.

Wheat leaf rust was detected the last week of May by Clara Presser, in LaMoure, Burleigh and Dickey counties. On May 31, Clara found wheat leaf rust in Eddy county, and Kelsey Steenblock found wheat leaf rust and stripe rust in Cass county, in spring wheat. Incidences of both rusts were generally low and severities were a trace amount.

Marcia McMullen
Extension Plant Pathologist
marcia.mcmullen@ndsu.edu

 

CROP INSURANCE ISSUES FOR SOYBEAN RUST COVERAGE

If soybean rust makes its way to North Dakota, soybean growers with crop insurance need to know what to do to be covered for losses. According to the USDA - Risk Management Agency (RMA), covered losses must be naturally occurring and farmers must follow good farming recommendations of agricultural experts such as extension agents and certified crop consultants. Farmers need to document advice received and the actions taken. Failure to purchase and apply recommended fungicides because of the costs is not an insurable cause of loss. For more information regarding crop insurance issues for soybean rust coverage go to:

http://www.rma.usda.gov/news/soybeanrust/

To track the spread of soybean rust in the U.S. and to see regional management recommendations, go to:

http://www.sbrusa.net/

 

PHYTOPHTHORA ROOT ROT: RESISTANT VARIETIES AND RACES

Phytophthora root rot is a soilborne disease of soybean that can cause pre- and post-emergence damping off as well as root rot. Two types of resistance to Phytophthora root rot are available in soybean varieties: single-gene resistance and partial resistance (a.k.a. field resistance, tolerance).

Single-gene resistance is available in many soybean varieties. With this type of resistance, soybean varieties will contain a specific gene for resistance, known as Rps genes. Rps genes commonly found in soybean varieties available to North Dakota growers are Rps 1a, 1c, 1k, and 6. These genes control specific races of the Phytophthora pathogen. Dr. Berlin Nelson (NDSU Plant Pathologist) recently conducted a Phytophthora survey to determine the prevalent races in North Dakota. The results of this survey indicate that race 4 is the most prevalent and race 3 is the second most commonly found race. Over ten races were observed in all. The Rps 1a and 1c genes are not able to give protection against both of the most common races 3 and 4, whereas the Rps 1k and 6 genes are able to provide protection against both of these races. Some of the races found were also able to cause disease on varieties with the Rps 1k or 6 genes; however, these races were found at a very low level. To slow down the development of new races in a field, it is recommended to not use varieties with the same resistance gene in a particular field year after year. Rotating among varieties that contain different effective resistant genes may slow down the development of new races in a field.

Partial resistance is available in a few soybean varieties. This type of resistance does not provide complete control, but it will work across all races of the pathogen. Partial resistance is usually indicated in seed catalogs as a numbered rating on a scale and is also referred to as field resistance or tolerance. Results of trials conducted in Ohio indicated that using partially resistant varieties in combination with fungicide seed treatments provided good control of the disease.

Carl Bradley
Extension Plant Pathologist
carl.bradley@ndsu.edu

 

OPTIMUM PLANT POPULATION FOR HIGH SUGARBEET YIELD AND QUALITY

Sugarbeet growers are currently busy controlling weeds when conditions are favorable. Should warm weather conditions prevail during the growing season, the potential is high for another good sugarbeet crop.

What is one practice growers can employ to increase their chances of an economical sugarbeet crop? Have a high plant population. Research has shown that maximum recoverable sucrose correlates well with high plant populations. In 2003 and 2004, research was done at North Dakota State University and the University of Minnesota that showed that a plant population of 175 plants per 100 foot of 22 inch wide rows at the 6-leaf stage was ideal for maximum recoverable sucrose per acre. It is important that the plants be evenly spaced within the rows. Growers should take their planters to the annual ‘planter test stand clinics’ to ensure they are calibrated to deliver the stand desired.

What happens if growers have lower plant populations, say 100 to 125 plants per 100 foot of row? The roots tend to be somewhat larger but there is generally a reduction in yield, and sucrose concentration decreases resulting in higher processing costs. In addition, lower plant populations will mean that it will take longer for the canopy to completely cover the soil resulting in a more costly weed control program.

What happens if growers have too high a plant population, say 225 plants per 100 foot of row? Plant populations above 200 plants per 100 foot of row results in too much competition among the plants and consequently smaller sugarbeet roots and lower recoverable sucrose per acre compared to plant populations of 175 plants per 100 foot of row. Defoliation becomes more difficult at high populations. Plant populations of 225 plants per 100 foot of row result in diminishing returns. Sugarbeet fields with 225 plants per 100 foot of row should be thinned to about 175 plants per 100 foot of row.

Remember, we reap what we sow. Plan to have a good plant pop. of 175 plants evenly spaced per 100 foot of row so that we can reap a sweet 2005 sugarbeet crop.

 

GENETICALLY MODIFIED SUGAR CANE APPROVED FOR TESTING IN BRAZIL

Brazil’s National Technical Committee on Biosafety (CTNBio) approved field testing for Brazil’s first genetically-modified sugar cane variety. The new variety is resistant to the sugar cane mosaic virus. It is expected that the new variety could be available to farmers in 2007 (F.O.Licht’s International Sugar and Sweetener Report, Vol 137:12). The use of genetically-modified sugar cane could pave the way for acceptance of genetically-modified sugarbeet.

Mohamed Khan
Extension Sugarbeet Specialist
701-231-8596
mkhan@ndsuext.nodak.edu

 

COOL, WET SPRING FAVORS SEVERAL COMMON TREE DISEASES IN ND

The following section on Ash Anthracnose is an article that first appeared in the May 29, 2003 issue of Crop and Pest Report. The information is repeated here because it is relevant.

LEAF DROP ON GREEN ASH DUE TO ASH ANTHRACNOSE

Green ash trees are losing their leaves.The seemingly healthy leaflets just drop off the trees. Ash leaves are "compound leaves", composed of (mostly) seven to nine leaflets arranged along a stalk or "rachis." In this condition, individual leaflets separate from the rachis and drop, but the leaflets appear a normal healthy green color and don't show browning or yellowing. Close examination may reveal a few tiny spots discolored brown or purple. These spots are especially noticeable on the rachis where leaflets have dropped.


Extreme leaf drop caused by Ash Anthracnose.
Picture taken in Grand Forks, ND, in June.
Bob Stack Photo.

This leaf drop condition is caused by a fungus disease, ash anthracnose, sometimes in combination with feeding by sucking insects.

The cool, showery weather of the past several weeks favors infection by the anthracnose fungus. The cool temperatures also slow the development of the ash leaves, giving the fungus a longer time to infect. Once leaves start to fall, it is too late for any fungicide sprays to be effective because infection has already taken place.

If you see this happening to your tree, the first thing to remember is DON'T PANIC! While unsightly and worrisome, a single defoliation by anthracnose will not permanently damage the tree. When warmer weather comes, the tree will make new leaves to replace those lost. Ash anthracnose is not a new disease; it has been recognized in the midwestern states for more than 100 years. Ash anthracnose is one of many tree diseases know to occur in periodic "boom and bust" cycles -- years when it is severe followed by years when it is rare. During the early and mid 1980s, for example, anthracnose was very common in ND, especially in the Red River valley. During that time, several studies were done at NDSU to better understand the disease and how it develops.

What to do about the problem: As mentioned, a single year of anthracnose, even if it causes severe leaf drop, will likely not permanently harm a tree. For the current season, rake up and destroy (burn, bury or compost) leaves to reduce the disease carryover. Prune-out cankered branches and remove twiggy growth to promote air movement within the crown. Fertilize trees in spring to promote vigorous growth.

If your tree(s) see repeated anthracnose damage in successive years, a preventive fungicide treatment may help. These need to be carefully timed to the bud break of the tree to be effective. A fungicide containing the active ingredient chlorothalonil can be used. Contact your county agent or the NDSU Plant Diagnostic Lab (701-231-7854) for current recommendations.

More information about ash anthracnose is available in the NDSU extension circular #PP697 "Deciduous Tree Diseases" available at: http://www.ext.nodak.edu/extpubs/plantsci/hortcrop/pp697-2.htm 

Kasia Kinzer, with NDSU Plant Diagnostic Lab, adds that ash anthracnose has been prevalent for most of the past few years, so protecting smaller trees with the fungicide applications described above may be beneficial in 2006-2007 if those trees have suffered defoliation due to ash anthracnose in 3 out of 5 consecutive years. For this year, if you missed the critical timing recommended for the first fungicide application, some studies suggest that a late fungicide application may benefit affected trees by reducing late-season infections.

For most trees, applying fertilizer and watering sufficiently to encourage vigorous re-growth of defoliated trees may be the only ‘treatments’ required for this disease. You can read more about this and other diseases of trees at the following web site:

http://www.ext.nodak.edu/extpubs/plantsci/trees/f1192w.htm

Robert Stack
Research Plant Pathologist

 

OAK ANTHRACNOSE

Another unsightly disease which is favored by our recent cool, wet weather is Oak Anthracnose. The fungus that causes this disease is almost always present, but environmental factors determine the severity of the disease. This explains why you might notice this disease one year and not the next. The three phases of this disease include twig blight, shoot blight, and leaf blight. On an evening stroll a research plant pathologist, Dr. Jim Walla, noticed a tree with the leaf blight phase, where leaves were distorted and partially killed at the tips or along the veins. As with ash anthracnose, spring application of fertilizer and watering the affected tree appropriately will promote vigorous re-growth.

To manage this disease culturally, rake up leaves and remove or destroy them in the fall, and prune out dead and dying branches, to reduce inoculum sources that can infect new growth the following spring.

Although this disease does not permanently harm established, vigorous trees, new transplants or trees that have suffered several consecutive years of defoliation will benefit from one or more applications of a protectant fungicide. As with ash anthracnose, the first application should begin at bud break to protect new growth.

The following link has more information on oak anthracnose:

http://www.ext.nodak.edu/extpubs/plantsci/hortcrop/pp697-3.htm

 

RHIZOSPHAERA NEEDLE CAST OF SPRUCE

This disease has been observed on several spruce samples evaluated by the lab this year. The Colorado spruce is especially susceptible to this disease, caused by a fungus, Rhizosphaera kalkhoffii. Rhizosphaera needle cast often begins in the lower part of a tree, killing interior needles. The buds on the limb usually remain viable, and in more dramatic cases, the buds are accompanied by only 1-3 years’ worth of needles on a limb. Severe cases of the disease can lead to death of lower limbs, if left unchecked. Infected needles may be a purplish-brown color. Black fruiting bodies of the fungus can usually be observed with a 10x hand lens, and these fruiting bodies cause the normally white stomates along an infected needle to appear black. Sometimes, needles that are suspected to be infected must be incubated in a moist chamber for a day or two to force the fruiting bodies to emerge.

Cultural practices that can reduce disease severity include promoting better aeration within the tree canopy. This may involve selective pruning within a tree or, more dramatically, the selective removal of closely planted, unthrifty trees. Planting spruces too close together should be avoided. Fungicides are effective, but timing is absolutely critical to protect the newly developing buds, and two applications in each of 2 consecutive years are required for the fungicide to be effective. The first application should occur shortly after bud break, when needles are 50% elongated (usually in early June), and the second application should be made when needles have reached their full length (about 3-4 weeks later). These two applications must be repeated the following year.

The links below have more information on needle diseases of spruce:

http://www.ext.nodak.edu/extpubs/plantsci/trees/pp789-1.htm

http://www.ext.nodak.edu/extpubs/plantsci/trees/pp1276w.htm

Kasia Kinzer
NDSU Plant Diagnostic Lab
diaglab@ndsuext.nodak.edu


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