Ramsey County

2008 SUNFLOWER SURVEY

            The National Sunflower Association is conducting and sponsoring the 2008 sunflower survey for this cropping season again. This survey assess the major pest problems including insect pests, birds, diseases, weeds and agronomic problems in sunflowers grown in the Great Plains (ND, SD, MN, KS, CO, Manitoba). Two new insect pests will be surveyed - sunflower bud moth (Suleima helianthana (Riley)),  and sunflower head maggot (Neotephritis finalis (Loew)). Many sunflower producers, seed companies, crop consultants, ... are concerned that these two insect pests are becoming more common and economically important causing an unknown yield loss. Larvae of both insects tunnel in the heads causing distorted heads (see photographs). Surveyors will be measuring the percent of plants that have distorted heads (or tunneling in the heads). In the past, entomologists claimed that injury caused by these insects are not economical; however, the recent increase in the percentage of head injured has many concerned. As a result, this survey data will help assess the impact of these insect pests in sunflower.

PLANTING WINTER WHEAT IN 2008

                In the parts of the state that were not ravaged by drought, winter wheat yields were good again this season.  If you are planning on planting winter wheat this fall, the following are a few suggestions:

~Planting date: The optimum planting date for the northern half of the state is September 1-15 and for the southern half September 15-30.  The last date that winter wheat can be planted will depend on the weather.  The seed must germinate in the fall so that the crop will be vernalized in the spring.  A larger plant will over winter better than a seedling or a sprouted seed. 

~Planting depth: Adequate moisture for establishing winter wheat is often a concern as the soil profile is usually depleted of moisture in the fall.  If there is little or no moisture in the soils surface, planting shallow (1 to 1.5 inches deep) and waiting for rain is recommended.

~Seeding rates: Generally a seeding rate of 900,000 to 1 million viable seed per acre is adequate.  Higher seeding rates may be appropriate if planting late or when planting into poor seedbeds.

~Plant in to crop residue: The best winter survival is achieved when winter wheat is no-till planted into standing crop residues that are able to catch and retain snow.  Planting winter wheat into a low residue crop such as soybean increases the risk of winter kill, so only the most winter hardy varieties should be grown (see data on winter survival in 2005/06 in the following table and at www.ag.ndsu.nodak.edu/aginfo/smgrains/WWsurvial.htm.

~Variety selection: In addition to agronomic characteristics such as plant height, yield, and disease and lodging resistance, also carefully consider the winter hardiness of a variety.  In many years there is a direct correlation between winter survival and yield.  Yield data from the 2008 season are being posted on the Small Grains Page http://www.ag.ndsu.edu/smgrains/.  Data from previous years’ trials are available at http://www.ag.ndsu.edu/variety/index.htm. .  Sources of certified winter wheat seed are ND State Seed Department or at the Small Grains Page. 

Joel Ransom
Extension Agronomist for Cereal Crop

RUST ON DRY BEANS APPEARINIG IN ND

                The appearance of rust on dry beans has been sporadic this year, but is severe in localized areas in the state.  Rust can cause yield loss when severe.

                Rust can be identified by small (about 1/8 inch) reddish-brown pustules on leaves.  Reddish-brown spores (urediniospores) are produced in the pustules, which can easily be rubbed off with your finger.  The ability to rub off spores distinguishes rust from other diseases such as bacterial blights. 

                Rust can progress quickly in fields when temperatures and moderate, and when heavy dews occur in the mornings.  As the season progresses, the rusty-colored spores in the pustules will be replaced by black spores (teliospores), which are hard to rub off.  Once the color change of the spores is apparent, disease progression will grind to a halt. 

                Fungicides can be used to manage rust, and several fungicides are available for rust control, including Folicur, which just received a Section 3 – Full registration for management of rust on beans.  The supplemental label is available at http://www.cdms.net/LDat/ld6AK031.pdf.  The supplemental label must be in your possession if a fungicide application is made.  Other fungicides can be found in the 2008 ND Field Crop Fungicide Guide (PP-622) available at

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

                If  fungicide application is something you’re considering, it is vital to keep a couple things in mind.  First, be certain your beans are infected with rust, and not something else.  We are observing lots of bacteria diseases throughout the state, which cannot be controlled with fungicides.  For more information about bacterial disease, including symptomatic pictures, please refer to my article in the last issue of the crop and pest report at http://www.ag.ndsu.nodak.edu/aginfo/entomology/ndsucpr.   Secondly, as the season progresses, the likelihood that new rust infections will cause yield loss decreases.  As the weather turns cooler rust will develop more slowly and eventually cease when teliospores are produced.  Additionally, as beans mature, rust is less detrimental to yield, and thus, fungicides are not economic.

 SOYBEAN APHIDS MOVING FIELD TO FIELD AND WHITE DWARFS PRESENT

            This past week there has been some calls about soybean aphid populations increasing and ‘white dwarf’ aphids in maturing R4 (full pod) to R5 (beginning seed) soybeans.  In mid to late August, soybean aphids typically move around from field to field as soybeans mature. It’s easy to find little white aphids called ‘White Dwarfs’.

                These are not baby aphids or diseased aphids. Many species of aphids do this in response to change, like hot temperatures, higher humidity, shorter day length, or change in plant nutritional quality. Be sure not to confuse them with the caste skins of aphids (see photograph) as they molt to the next growth stage.

                 These are living, feeding and reproducing soybean aphids and should be included in your total plant population counts when assessing economic levels of soybean aphids. Research from University of Minnesota indicates that white dwarf aphids (those typically on lower leaves) live half as long and their lifetime fecundity is reduced 70% compared to the ‘mountain dew’ colored soybean aphids (source: D. Ragsdale). Thus if the population is only comprised of white dwarf aphids, the economic injury level (population of aphids that cause a yield loss) would probably not be reached in 7 days. An economic threshold (population of aphids that triggers an insecticide) has not been established for plants with primarily white dwarfs, however, it is obviously higher than 250 aphids per plant.

                Soybean aphids will remain active until temperatures reach 45 degrees F, at which time they turn sexual and fly to their natural staging area (buckhorn) for the rest of the fall.

                Remember, to continue scouting soybean fields for aphids until R6 or full seed! No insecticide sprays are recommended in R6 or later R7 (beginning maturity) as there is little or no economic return from treating.

HARVESTING LOSS GUIDELINES

    What’s a good guide to determine the amount of any given crop loss in a field following harvest? There can be pre-harvest losses due to shattering, gathering losses at the combine header and also separation losses due to the threshing operation itself. In the chart below is an approximate loss guide to determine how much if any is being left in any given field. Usually crop harvest losses in the 2 to 3 percent loss range are tolerated.

    Kernels or seeds per pound and number per square foot to equal one unit loss per acre at harvest.

*These are average numbers from past seasons, and individual varieties or hybrids will vary among themselves as well as be influenced by environmental factors. 

NDSU Extension Service, North Dakota State University of Agriculture and  Applied Science, and U.S. Department of Agriculture cooperating.  Duane Hauck, Director, Fargo, North Dakota.  Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.  We offer our programs and facilities to all persons regardless of race, color, national origin, religion, sex, handicap, age.  Vietnam era veterans status, or sexual orientation; and are an equal opportunity employer.

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Devils Lake  ND  58301
701-662-7027
email - NDSU.Ramsey.Extension@ndsu.edu

Additional Information:
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