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Frost Damage in Small Grains and Corn (05/21/15)

Air temperatures recently dipped below freezing in much of North Dakota. Since most of the small grains had been planted and emerged and some of the corn, there is concern about the type of damage this cold weather may have caused.

Frost Damage in Small Grains and Corn

Air temperatures recently dipped below freezing in much of North Dakota. Since most of the small grains had been planted and emerged and some of the corn, there is concern about the type of damage this cold weather may have caused. Temperature below freezing certainly have the potential to damage emerging crops. Nevertheless, the amount of damage is influenced by crop tolerance, growth stage, moisture content of the soil, duration of the sub-freezing temperature, location in the field, and environmental conditions before the occurrence of the sub-freezing temperature.

Factors affecting frost damage

Crop - Cereal crops are generally considered to be frost tolerant early in their growth cycle. There is considerable variation for tolerance between crops, however. In general terms for the cereals grown in ND (and provided they are at the same stage of development), tolerance to freezing temperatures can be ranked in the following order: winter rye (most tolerant to frost) > winter wheat > oats > barley > wheat > corn (least tolerant).

Growth stage - One reason that cereals tolerate frost early in the season relative to broadleaf crops, is that their growing points remain below the surface of the soil for several weeks after emergence and are therefore protected from the extremes in the temperature of the air above. In small grains the growing point extends above the soil’s surface at about the six leaf stage or just prior to jointing and in corn at about the five leaf stage. Fortunately, all of the spring sown cereals in the state were still relatively young and their growing points were below the soil’s surface during the recent cold weather. Some winter wheat, however, has jointed and is potentially more susceptible to frost damage than its spring sown counterpart.

I would recommend that you carefully inspect growing points in your winter wheat if you had temperatures below 25 degrees for any extended period of time as the growing point is more susceptible to damage than leaf tissue during jointing. A damaged growing point will appear brownish or water soaked. A dead leaf may appear in the whorl if the growing point has been damaged. Prolonged (or very low) sub-freezing temperatures can kill growing points of cereal crops even if they are below the surface of the soil. Corn is the most sensitive and temperatures of less than 28 degrees can be lethal.

Environmental factors - Temperatures change more slowly in wetter soils than in dryer soils. Therefore, there is more risk of low temperatures killing plants if your soils are also dry. Plants are capable of hardening themselves against freezing and plants that had previously been exposed to near freezing temperatures are more likely to tolerate lower sub-freezing temperatures than those that have not. Most of the cereal crops were probably at least partially hardened before the arrival of the coldest weather last week. This may provide an additional level of protection. Cold air is heavier than warm air, so cold air will flow towards the lowest parts of your field, making frost damage more severe in these areas. When assessing frost damage, I would suggest that you visit the lowest spots of your farm first.

Inspecting for damage - Foliage that has been damaged by frost will initially appear yellow and within a few days turn black usually towards the tips of the leaf first. If the growing point was not damaged, after 3 to 5 days of reasonably warm weather, new growth should appear from the whorl. If this occurs, then you can be assured that the growing point was not killed. Loss of leaf tissue at this early stage will have little if any effect on yield. For corn that has not yet emerged, I would suggest that you dig up a few seeds to check for germination and to see if the emerging seedling is viable. Seeds that had not germinated will not be adversely affected, but emerging seedlings could be killed if soil temperatures were very cold, though generally they are thought to be quite tolerant to cold temperatures.

Joel Ransom

Extension Agronomist for Cereal Crops

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Canola and Frost Damage (05/21/15)

During the middle of May 2015, early morning frost occurred in many parts of North Dakota. The temperature at which freezing injury may take place in canola varies with the growth stage of the plant, soil moisture content, and the length of time the temperature is below freezing.

Canola and Frost Damage

During the middle of May 2015, early morning frost occurred in many parts of North Dakota. The temperature at which freezing injury may take place in canola varies with the growth stage of the plant, soil moisture content, and the length of time the temperature is below freezing.  Early seeded canola, after several days of near freezing temperatures, may undergo a gradual hardening process that will allow the plants to withstand freezing temperatures without serious damage. 

Frost damage occurs to the small canola plant when ice crystals form within the leaf or stem tissue or when the plant actually freezes, which will cause cell walls to rupture.  A severe drop in temperature which only lasts a very short time, may not damage canola plants; while a light frost of several degrees below freezing that lasts all night may cause severe damage.

Canola seedlings will usually recover from a light spring frost that does not damage the growing point of the plant.  If a heavy frost does blacken the leaves, no action should be taken for at least 4 to 7 days.  The extent of injury can be determined in a week or less following the frost.  If there is any green color at the growing point in the center of the frozen leaf rosette, the plant will recover and yields will most likely be higher than if the field is re-seeded.

In evaluating frosted seedling fields, consider the percentage of plants killed and the percentage recovered.  The surviving plants should be evenly distributed in a field. Even if two-thirds of the seedlings in a reasonable stand are frost killed, the field will usually produce more when left than if re-seeded.  The surviving plants will take advantage of the reduced competition for light, moisture and nutrients, and grow larger, producing more branches, pods and seeds per pod, thereby compensating for the lost plants.  The surviving plants may require five to eight days longer to mature; but a re-seeded crop will require an even longer period to reach maturity.

Hans Kandel

Extension Agronomist Broadleaf Crops

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Good Bug Corner (05/21/15)

This week’s featured group is beneficial wasps (also called parasitoids) that attack and kill eggs and immature stages of many insect pests. Parasitoids are described as tiny wasps in the insect order Hymenoptera and include many different families (Braconidae and Ichneumonidae, for example).

Good Bug Corner

This week’s featured group is beneficial waspsent.jk.6.mp (also called parasitoids) that attack and kill eggs and immature stages of many insect pests. Parasitoids are described as tiny wasps in the insect order Hymenoptera and include many different families (Braconidae and Ichneumonidae, for example). A good example of a successful parasitoid in North Dakota is Macroglenes penetrans that parasitized the eggs and larvae of wheat midge. As part of the annual wheat midge soil survey, we also assess the parasitism rate on wheat midge. The parasitism rate for 2014 ranged from 0 to 100 percent in some fields with an average of 11 percent parasitism. Although the parasitic wasp - wheat midge populations are cyclic, M. penetrans plays an important role in keeping wheat midge controlled naturally. We need to continue to conserve parasitic wasp populations when possible by spraying insecticides only when pest populations are at economic threshold levels, and avoiding any late insecticide applications to minimize the negative impacts on the parasitic wasps that are active at that time.

Many parasitoids are available commercially for release into fields or gardens, and can be obtained from distributors of beneficial insects. A good example of a parasitoid that has been commercially reared and released in sweet/field corn fields for biocontrol of European corn borer is Trichogramma species. This tiny wasp is only 1 mm long! It has been used for biological control of many leaf-feeding caterpillars including armyworms, squash borers, cankerworms, alfalfa caterpillars, cutworms, cabbage loopers, and other pests.

Thanks to the North Dakota Wheat Commission for supporting the wheat midge soil survey.

Janet J. Knodel

Extension Entomologist

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Watch Out for these Invasive Insect Pests (05/21/15)

Since the cold temperatures have slowed insect pest activity this past week, I thought this would be a good opportunity to update you on the status of a few invasive insect pests of field crops. Please look for these invasive insect pests when you are out scouting fields or around your home.

Watch Out for these Invasive Insect Pests

Since the cold temperatures have slowed insect pest activity this past week, I thought this would be a good opportunity to update you on the status of a few invasive insect pests of field crops. Please look for these invasive insect pests when you are out scouting fields or around your home. Send any suspect specimens to me for confirmation. Thank you for your help in finding these invasive insect pests.

 Brown Marmorated Stinkent.jk.1.bmsb Bug (BMSB) – The BMSB is getting closer to North Dakota. It has been detected in 42 states since its introduction in 2001 into the United States. The closest neighboring states with BMSB are Minnesota, Iowa and Nebraska. It has a wide host range infesting fruits, vegetables, and field crops (soybean, dry bean, field corn). If it is not being a problem damaging crops, this stink bugs invade houses in the fall, similar to boxelder bugs! You can identify it by its large size (3/4 inch), mottled brown appearance, and alternating light and dark band on the antenna and abdominal edges. Feeding injury symptoms appear as necrotic spots that look like a lesion on leaves, fruits, or pods. It is becoming a major pest of corn and soybean in the eastern United States.

 Sipha maydis – A new ent.jk.2.sipha mayisspecies of aphid, Sipha maydis, was discovered feeding on grain crops in western Colorado in 2015. Sipha maydis is native to Europe, Asia, the Middle East and northern Africa and was introduced into the United States in 2007. It was first found in California in 2007, Georgia in 2012, New Mexico in 2014 and Colorado in 2015. Sipha maydis can be identified as a black aphid with numerous white hairs covering the abdomen and short cornicles. The ESA accepted common name will be the “hedgehog grain aphid.” It feeds on a wide range of grasses including oats, wheat and barley. Symptoms of feeding injury includes chlorosis of leaves at feeding sites of colonies. The scientific literature on S. maydis is limited; however, it indicates that it is a vector of barley yellow dwarf virus and cucumber mosaic virus.

Japanese Beetle - The Japanese ent.jk.3.jap.beetle.adultbeetle, Popillia japonica, belongs to the insect family Scarabaeidae. The adult Japanese beetle is oval-shaped and approximately ½ inch long and ¼ inch wide. The head and thorax are metallic green, and the wing covers are typically coppery-purple bordered with green. You can identify it from other beetles by the five patches of white hairs protrude from each side of the abdomen. It is a highly destructive plant pest that feeds on more than 300 host plants, including field crops (especially corn and soybeans), ornamental trees and shrubs, garden flowers and vegetables, and turf (lawns, pastures and golf courses). Adult beetles defoliate the leaves and some of the preferred host plants are rose, apple, black cherry, cherry, flowering crabapple, plum, grapes, hollyhock, blackberry, raspberry, linden, elm and buckeye. Grubs are found primarily in the root zones of grasses where they feed on the roots. Grubs are about 1 inch long when mature, C-shaped and creamy white with a brown head capsule. White grubs are identified using the pattern of hairs (rasters) that form a V just below the anal slit on the end of the abdomen.

Japanese beetle is found in our neighboring states:  Minnesota, South Dakota and Montana. It first was detected in North Dakota in 2001 in Bismarck, but it did not become established. In 2012-2014, the Japanese beetle was detected at several locations in North Dakota, including Bismarck, Fargo, Grand Forks, Minot, Oakes, Taylor, West Fargo and rural Foster County. Upon investigation, the source of the infestation was identified as infested nursery stock that was shipped into North Dakota. At this time, whether any Japanese beetle will become established in North Dakota is unknown. To determine if it is present in North Dakota, the North Dakota Department of Agriculture (NDDA) has organized a pheromone trap survey using a total of 1900 traps or about 25 traps per county of North Dakota. If you are interested in volunteering for the NDDA Japanese beetle survey, please go to the North Dakota Department of Agriculture website to sign up.

Once established, it can be a difficult and expensive insect pest to control. Control costs for Japanese beetle are estimated at approximately $450 million each year in the United States. Please see the NDSU Extension Service factsheet E1631 Integrated Pest Management of Japanese Beetle in North Dakota for more information.

Swede Midge – The swede midge, Contarinia nasturtii, ent.jk.5.sm adultwas introduced in the United States in 2004 in New York, and has spread westward in Canada (Manitoba, Saskatchewan, and Nova Scotia). This tiny mosquito-like midge infest plants in the family Brassicaceae, such as canola, mustard, cabbage, cauliflower and several Brassica weeds (wild mustard). The adult is a small, brown fly about 1.5-2 mm and is difficult to distinguish from other midges except by a trained entomologist. Damage symptoms appear as abnormal growth, puckered leaves, distorted growing points, or leaves and flowers with gall formations. Symptoms are difficult to distinguish from herbicide injury, heat or cold stress; however, tiny white larvae (3-4 mm when mature) should be found inside the plant tissues. Due to the recent detection of swede midge in a pheromone trap in canola near Winkler (Manitoba) in 2014, NDSU Extension Service will be running 13 trap sites in Pembina, Cavalier and Towner Counties in northeast North Dakota. Any positive results will be posted in future issues of the Crop & Pest Report. Thank you to the Northern Canola Growers Association for support of the swede midge trapping network.ent.jk.4.sml

 

 

 

 

 

 

 

 

 

 

 

Janet J. Knodel

Extension Entomologist

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Fertilizer with the Seed (5/11/17)

The restrictions on fertilizer rate that can be relatively safe to apply with the seed are based on a combination of salt and urea injury hazard. Both can reduce seed germination when fertilizer is applied with the seed.

Fertilizer with the Seed

The restrictions on fertilizer rate that can be relatively safe to apply with the seed are based on a combination of salt and urea injury hazard. Both can reduce seed germination when fertilizer is applied with the seed. The table values meant to guide growers are based on pounds N + K2O in the blend. The tables for small grains can be found in circular SF1751 on my website under extension publications. Tables for use in canola and other crops can also be found on my website under the specific crop. The rate is also based in solid-seeded crops on row spacing and the tool that may or may not spread the fertilizer over a band area within the soil at seeding depth. These circulars are free to download and readily accessible to read even with a smart-phone.

My webpage extension publication link is https://www.ndsu.edu/soils/personnel/faculty/dr_david_franzen/extension_publications/

Dave Franzen

NDSU Extension Soil Specialist

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Soybean Cyst Nematode Distribution in North Dakota (5/11/17)

Since 2013, over 2,200 soil-samples have been submitted as part of a state-wide survey for Soybean Cyst Nematode (SCN).

Soybean Cyst Nematode Distribution in North Dakota

Since 2013, over 2,200 soil-samples have been submitted as part of a state-wide survey for Soybean Cyst Nematode (SCN). The program is funded by the North Dakota Soybean Council and operated by the North Dakota Extension Service. Approximately 1/3 of these samples have been positive and approximately ½ of those have been higher than a ‘low level’ (gray boxes). Positives have occurred primarily in the Southeastern part of the state, but SCN is clearly being detected in other locations. However, growers should be aware that some of these results are likely to be false positives.

Several very important points about the results are below.

1) How egg counts are determined?

Data points are nematode egg counts, presented as eggs/100cc of soil (100cc of soil is roughly 3-4 ounces). Egg counts are determined by extracting eggs from the soil and visually counting eggs through a microscope.

2) Low egg counts could be false positives.                                                                                         

It is nearly impossible to differentiate SCN eggs from the eggs of other closely related nematode species. Consequently, a soil sample positive for low egg counts (gray boxes) could be reflective of other nematodes in the soil, and doesn't necessarily mean the sample positive for SCN eggs. To a lesser degree, some green triangles could be false positives too, as the range goes from 201-2,000. I am suspicious of the two green triangles in Ward and Mercer counties – they were both on the low end of the green range.

3) Zeroes could be false negatives.

During the extraction process nematode eggs can be lost, which may result in a false positives. Additionally, SCN is notoriously patchy in a field and may be missed in the sampling process.

4) What level causes yield loss?

Under favorable conditions (which include high pH, lighter soil, a warm and dry growing season) yield loss can begin to occur at any egg level. This is primarily because SCN can undergo 2-3 life cycles in a single growing season, and with each cyst producing 100-200 eggs, egg counts can increase very quickly and quite dramatically. We believe that when numbers are 10,000 or greater (yellow boxes and red pentagons) even resistant varieties will experience significant yield loss.

markell.1

Sampling in 2017.

The North Dakota Soybean Council will be funding this sampling program again in 2017. Up to 2,000 sample bags will be available at County Extension offices beginning in mid-August (sampling at the end of the growing season is the best time to detect SCN). We will provide more information on the sampling program, detecting and managing SCN as the season progress.

We thank the North Dakota Soybean Council for funding this program, the many Extension agents who operate the program, Agivse for sample processing, and all the growers and agriculture professionals who submitted samples.

markell.2

 

Sam Markell

Extension Plant Pathologist, Broad-leaf Crops

 &

 Guiping Yan

Plant Nematologist


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Canola Early Season Growth Stages (5/11/17)

Understanding the growth and development of a canola plant helps the producer make more effective management decisions.

Canola Early Season Growth Stages

Understanding the growth and development of a canola plant helps the producer make more effective management decisions. Early season canola growth is characterized by the germination process and two main vegetative growth stages. The length of each growth stage is influenced by temperature, moisture, light, nutrients and hybrid. Growth stages of canola can be estimated based on accumulative canola growing degree days, with a base temperature of 41oF. The model predicts that the seedling will be established at about 256 accumulated canola GDD’s. The canola growth stage can be estimated using the North Dakota Agricultural Weather Network at https://ndawn.ndsu.nodak.edu/canola-growing-degree-days.html. Selecting a specific nearby weather station and entering the canola planting date will provide a local estimate of the canola growth stage.

Pre-emergence (Germination)

The germination process involves water absorption, swelling, splitting of the seed coat and emergence of the root tip. Cotyledons are pushed through the soil surface by an active hypocotyl. Germination typically takes from four to 10 days, depending on soil temperature and moisture, seed soil contact and planting depth. During this stage, canola is susceptible to many soil-borne pathogens.

Seedling

Once emerged, the cotyledons open and supply the new seedling with nourishment. At this stage, the seedling still is vulnerable to soil-borne pathogens and very susceptible to flea beetle injury. The growing point of canola is between the two cotyledons. The exposed growing point is susceptible to spring frosts, wind-blown soil particles, insects and hail damage. Canola is a very poor competitor with weeds, and good stand establishment is very important.

Rosette

The first true leaves develop four to eight days after emergence. The plant quickly establishes a rosette with older leaves at the base increasing in size and smaller, younger leaves developing in the center. During this time, the stem length remains basically unchanged although its thickness increases. The rosette stage is characterized by an increase in leaf area index. Rapid and abundant leaf growth captures more sunlight and produces more food for the plant, thus producing more dry matter per day and increasing yield potential. A rapidly developing canola canopy encourages root growth, reduces soil moisture evaporation and shades weeds.

 Hans Kandel

Extension Agronomist Broadleaf Crops

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