F. Adnan Akyuz, Ph.D.

Assistant Professor of Climatology

North Dakota State Climatologist

Southwest ND

Around the State

Isolated rain showers were reported by county agents in Mott and Amidon this morning which but did little to moisten the top soil. Rainfall totals at all NDAWN locations in southwest ND for the week indicated zero precipitation. Weather forecasters indicate there will be a good chances for rain over the next five days.  High winds gusting to 69 mph caused considerable movement of soil where crop residue from previous crops was insufficient to adequately cover the soil.  To date, alfalfa and grass appear to be most affected by dry conditions in far southwestern ND. Moisture conditions are better for areas north of I-94. Moisture was reported to four feet deep in crop fields and at least to three feet deep under sod in the Manning area.

Early planted spring wheat is at the two- to three-leaf stage while later planted wheat appears to be laying in dry soils in far south and west sections of southwest North Dakota. Spring wheat, barley and durum seeding is nearly complete in Bowman, Golden Valley, and Hettinger Counties with some producers interrupting the completion of seeding wheat and durum with corn planting. These producers will move back into seeding wheat and durum after the corn crop is in. Some early seeded canola in Bowman County froze and will be reseeded to another crop. Field pea emergence has been reported in Golden Valley County. Much of the corn in southwestern ND will likely be in the ground by the end of the week. Producers will be “racing” to get the remainder wheat and durum planted by the end of the week.

 In terms of pests continued reports of army cutworm damage continue to be received in Bowman County while wireworms have made their presence known in Golden Valley County and surrounding areas.

 A good rain this weekend will be appreciated.

Roger Ashley

Area Extension Specialist/Cropping Systems

THE NEVER ENDING DANDELION PROBLEM

The following is an edited version of information printed in an earlier Crop and Pest Report article by Dr. Jeff Stachler: As the number of tillage passes and depth of tillage decreases, dandelions become more prevalent in agricultural fields. 

Other reasons for increased dandelion populations include reduction of use of residual herbicides in Roundup Ready crops, creation of dandelion habitat along field borders where glyphosate or other non-selective, non-residual herbicides are applied, and maybe an increased prevalence of dandelions in road ditches/right-of-ways due to reduction in weed management of those areas.

Dandelion is a simple perennial, meaning a plant can survive for multiple years, but can’t spread vegetatively like quackgrass or Canada thistle, unless the root is cut into multiple sections during tillage operations.  The majority of movement or spread of dandelion is from seeds being blown by wind currents.  Seeds can easily travel greater than 100 feet.

The goal to managing dandelion is to stop seed production by controlling established plants and stopping the emergence or growth of seedling dandelion with the use of residual and/or postemergence herbicides.  The larger a dandelion plant is allowed to grow, the more difficult it is to control, especially with herbicides.  Established dandelions are almost always more effectively controlled in the fall than the spring, however applying herbicides in the fall in the Northern Plains is difficult.  Dandelion control with glyphosate and/or 2,4-D in the spring is erratic, including applications at high rates.  The following is results from a 2010 field research trial:
Glyphosate at 0.75 lbs ae/A = 36% control 40 days after application
Glyphosate at 2.25 lbs ae/A = 68% control at 40 days after application
Glyphosate at 0.75 lbs ae/A + 2,4-D ester at 1 pt/A = 45% control
Glyphosate at 0.75 lbs ae/A + Express SG at 0.5 oz/A + NIS + AMS = 90% control
Glyphosate at 0.75 lbs ae/A + Express SG at 0.5 oz/A + 2,4-De at 1 pt/A + AMS = 86 to 88% control
Liberty + Express at 0.5 oz/A + MSO at 1.25 pt/A + AMS = 86 to 88% control

Express must be applied 14 days prior to planting corn and soybean and can be applied immediately prior to planting wheat and barley.  Based upon the research above, an application of Express SG at 0.5 oz/A plus glyphosate at 1.125 to 1.5 lb ae/A plus NIS plus AMS applied 14 days prior to planting corn or soybean and just prior to planting wheat and barley should provide the most effective dandelion control.  Substituting a MSO based HSOC adjuvant for the NIS will enhance Express and possibly glyphosate.  The addition of 2,4-D ester at 0.5 lb ai/A to the above recommendation for corn and soybean should provide more consistent dandelion control, improve control of weeds difficult to control with glyphosate and Express, and allow glyphosate to be applied at 1.125 lb ae/A.

Few preemergence herbicides effectively control emerging dandelion but Valor, Lumax, and Verdict has shown to reduce dandelion populations in some studies.

Rich Zollinger

Extension Weed Specialist

WHERE DID MY PRE HERBICIDE GO?

 The condensed planting season may have diminished use of PRE herbicides. The high winds earlier this week may have moved soil particles from the dry soil surface. If PRE herbicides were applied some of the herbicide may have moved with soil particles. Reports from Stutsman County this week reported almost 0 visibility from dust storms. A good rain would keep the soil in place and those with crop residue on the soil surface from practicing zero-tillage may not have the soil movement compared to conventional tillage. It is impossible to predict how much of the PRE herbicide remains on the soil surface. Rain forecast later this week will activate remaining PRE herbicides. The warm temperatures will soon bring the first heavy flush of weeds and soon growers can determine the activity of PRE herbicides. If weeds do emerge through PRE herbicides then apply your POST herbicides to small weeds, especially to glyphosate resistant weeds as research has shown that glyphosate can control weeds that are less than 1 inch tall. Use full rates and the best adjuvant system with the herbicide mixtures.

Rich Zollinger

Extension Weed Specialist

Potato Seed Age Can Cause Irregular Emergence

Potato seed is aged in two ways, chronologically and physiologically. The chronological age is the number of days that have passed since the tubers were harvested. The physiological age refers to the internal age of the seed as affected by biochemical changes that take place within the tuber. Potato tubers age at a greater rate when grown in stressful environments such as temperature stress, moisture stress, fertility stress, disease pressure, when stored under fluctuating temperatures or warm temperatures, and are bruised.

Growing conditions last year included warmer than normal temperatures and less precipitation, which increased the bruising of potatoes during harvest. These stresses increased the physiological age of potato seed, or reduced the typical number of days of dormancy. Physiological old seed that was not properly stored is easily recognizable. It has sprouts, sprout tubers or second growth, and/or it can be soft or dehydrated. Planting seed with these symptomologies can result in missing plants, slow emergence, multiple stems, and a non-uniform stand in the field. This ultimately will affect yield and tuber size distribution. To ensure uniform emergence, use certified potato seed that do not exhibit long sprouts or sprout tubers.

Physiologically old seed potato tubers exhibit sprouting and sprout tubers or second growth.

 Andy Robinson

Assistant Professor, Extension Potato Agronomist

CORN EMERGENCE

 Only 18% of the corn acreage was planted in North Dakota as reported by NASS on Tuesday. This is well behind the long term average of 43% for the same period. Nevertheless, conditions in most of the state are currently nearly ideal for planting. If current conditions continue, the outlook is good for most of the corn to be planted by the last planting date. Warm days and strong winds have been drying the surface rapidly. Planting into moisture in soils that have been tilled is becoming a bit of a challenge. Normally we recommend planting corn 1.5 to 2 inches deep. In dry soils planting deeper than 2 inches may be needed. Soil temperatures have warmed up nicely with soils in parts of the state already above 70 degrees. This will help hasten emergence of recently planted corn. Corn requires soil temperatures above 50 degrees before it will begin to grow and an accumulation of about 120 growing degree days before it emerges. GDD accumulations during this recent hot weather have approached 20 GDDs per day, so emergence could occur in less than a week if this warm weather continues. Rain is predicted for later this week, which is needed to help germination in fields that are dry. However, a pounding rain can cause crusting, particularly in soils with a high silt content and those that have been heavily work and have little fresh organic matter.

Another concern for corn planted just before the cold period last weekend is cold temperature injury. When the dry seed imbibes cold water (some refer to this as it first drink of water) imbibitional injury may result (this can also happen to soybeans). Temperatures below 50 degrees can be harmful, with colder soils (and therefore colder water that the seed imbibes) being more problematic than those approaching 50 degrees. Cell membranes in the seed can rupture at low temperatures, causing cell contents to leak, providing a good source of food for pathogens.  In addition to poor stands, cold injury may cause the mesocotyl to corkscrew or the coleoptile and true leaves to emerge from side of coleoptile. Plants that develop from these seedlings may be stunted and have distorted leaves and may also develop more slowly than normal plants.  This can result in unevenness in the growth stages of plants within the field.  Anything that impacts plant stands and evenness of emergence and/or plant size has the potential to negatively impact yields. A cold rain heavy rain after planting seems to increase the chances of imbibitional injury probably because it overwhelms the ability of the soil to warm the water before it reaches the seed. Hopefully, soils did not cool too quickly last weekend so that the risk of imbibitional injury to early planted corn was minimal.

Joel Ransom

Extension Agronomist for Cereal Crops

Canola

Canola is a major oil crop in the northern Great Plains. In 2012, 1,450,000 acres of canola were harvested in North Dakota with an average yield of 1,420 pounds per acre. North Dakota accounted for approximately 83 percent of the canola acreage harvested in the United States. Selecting the right canola hybrid is one of the most important management decisions a producer can make.

The 2012 canola hybrid trial data from all NDSU Research Extension Centers can be found at this link: 2012 canola trial. The agronomic data presented in the hybrid trial report are from replicated research plots using experimental designs that enable the use of statistical analysis. The LSD (Least Significant Difference) numbers beneath the columns in tables are derived from the statistical analyses and only apply to the numbers in the column in which they appear. If the difference between two hybrids exceeds the LSD value, it means that with 95 percent probability (0.05 level) or 90 percent probability (0.10 level), the higher-yielding hybrid has a significant yield advantage. If the difference between two hybrids is less than the LSD value, then the hybrid yields are considered similar.

It is best to view yield averages of several years rather than using only one year’s data as a determining factor in selecting a hybrid. In addition, consider other agronomic characteristics, such as disease resistance, maturity, lodging score and oil content of the seed.

Canola has similar moisture requirements as cereal grains and can be grown on a wide range of soil types.  It is best suited to clay-loam soils that do not crust. Canola can be grown in a no-till or conventional tillage cropping system.  Avoid excessive tillage in the spring to prevent drying out the seedbed. Canola can be planted with a variety of seeding equipment. However, it is important to have good depth control. The optimum depth to seed canola is ½ to 1 inch.  Seeding depth should not exceed an inch with small seeded canola varieties.

The minimum soil temperature for germination is 38 F. Soil temperature will determine how long it will take from planting to emergence.  If soil temperatures average in the low 40’s after planting, canola will take 17 to 21 days to emerge.  If temperatures average in the low 50’s, canola will take approximately 10 days to emerge.

 If possible canola should be planted prior to planting cereal grains.  To maximize yield canola should be planted early May. Planting date research indicates that delayed planting may result in significant yield reductions especially if the canola flowering occurs during hot summer days. 

Seeding rate/plant population research studies indicate that planting 14 pure live seeds per square foot should establish an optimum stand of 8 to 12 plants square foot.  Four plants per square foot are considered a minimum stand for canola. In low populations the plants will have a thicker main stem and many branches which may increase the chance for uneven ripening of the crop and challenges during harvest.

Canola hybrids are tested at various Research Extension Centers

In this case at Minot

Hans Kandel

Extension Agronomist Broadleaf Crops

UPDATE ON ALFALFA WEEVIL

                Using the Degree Day Model for alfalfa weevil, we can expect adult alfalfa weevil emergence around 250-300 DD (see NDAWN map below).  The southern and western regions of North Dakota are around 100 accumulated DDs. So, we estimate that adult alfalfa weevils will start emerging in 7 – 10 days depending on the weather in those regions.

                To calculate the degree day units for alfalfa weevil development (Table 1), go to the NDAWN website at http://ndawn.ndsu.nodak.edu/.  Go to “Applications”, select “Insect Degree Days”, choose “Maps”, March 1is the default start date, select 48 F as the base temperature, and click “Submit” to generate the map.  You can also generate accumulated degree day tables for individual weather data recording stations.

Table 1.  Approximate degree day (DD) requirements for alfalfa weevil development using 48ºF as the base developmental temperature.

When and How to Scout

Scouting should begin immediately after egg hatch, and fields should be scouted weekly up through the first cutting.  Fields should be scouted in an “M” pattern or by selecting random sites within the field, with a minimum of five sampling sites per field.  Larger fields should have more sampling sites.  Be sure your sampling pattern is representative of the entire field – don’t scout only along the edges or in small areas. 

For sampling, you will need a sharp pruning shears, a white 5-gallon bucket, a hand lens, a yardstick for measuring plant height, and pencil, paper and a calculator.  At each sampling site within the field, select a minimum of 30 plants and cut them off at the base.  Invert the cut plants into the 5-gallon pail and vigorously beat the plants in the pail to dislodge the larvae.  First instar larvae feeding in rolled leaf tips won’t dislodge easily, so be sure to examine leaf tips for larvae.  Count and record 1) the number of plants sampled, 2) the total number of larvae counted, 3) estimate and record percent feeding damage (defoliation), and 4) the height of the alfalfa at the sampling sites.  Repeat this procedure for all sampling sites within the field.  When finished, total up the number of larvae sampled and divide by the total number of plants sampled to calculate an average number of larvae per plant for the entire field.  Also, calculate percent feeding damage and plant height averages for the field.

We do not recommend the use of sweep nets for sampling, because results are often highly variable and inaccurate.  Sweep nets can be used to determine the presence/absence of alfalfa weevil adults and larvae in a field at or prior to typical egg hatch (300 DD).

Economic Threshold and Management Decisions

Several factors must be considered when making alfalfa weevil management decisions.  Plant height, estimated yield, crop market value, management costs and plant injury based on the number of larvae per stem must be considered.  Studies conducted in Kentucky, Nebraska, New York and Utah have demonstrated that the level of plant damage per insect varies with geographic area.  No detailed research on alfalfa weevil damage has been conducted in North Dakota.  The following economic threshold table is based on third and fourth instar larvae damage levels observed in a two-year study conducted in Nebraska in 1990 and 1991 (Peterson et al. 1993, Agronomy Journal 85: 595-601), and has been adapted for North Dakota.  Threshold numbers are the average number of larvae sampled in the field using the 30-stem sampling method described above.  These economic thresholds apply prior to the first cutting only.

After the first cutting has been harvested, be sure to scout for larvae where the windrows were located.  Larvae that escaped the first cutting tend to move under the windrows for shelter, and will feed in these locations. Check regrowth for larval feeding. If 8 or more larvae per square foot are found or re-growth is delayed due to feeding, treatment is recommended.

Table 1.  Recommended economic thresholds for third and fourth instar larvae of alfalfa weevil for North Dakota prior to the first cutting.

When the decision has been made that insecticidal control is needed, some considerations must be made.  Pay particular attention to the pre-harvest (PHI) and pre-grazing (PGI) intervals.  The decision on which product to use should be based on when you intend to cut or graze the crop.  Also, it is important to note that products that have a long PHI do not necessarily have long residual insect control activity.  For example, chlorpyrifos (an organophosphate) applied at greater than 1 pint per acre has a PHI/PGI of 21days, but residual activity can realistically be expected for 5 to 7 days.  Zeta-cypermethrin (a pyrethroid) applied at either the low or high rate has a PHI/PHI of 3 days, yet should provide 7 to 10 days of residual control activity.

                Another important consideration is pollinator safety.  Most insecticide labels now carry ‘bee language’ such as ‘do not apply when crop is in bloom’ or ‘do not apply when bees are actively foraging’.  When treating, be sure to observe pollinator safety.  Only apply insecticides early in the morning and late in the evening when bees are not present.

                For insecticides registered for use in alfalfa in North Dakota for control of alfalfa weevil, please seen the 2013 North Dakota Field Crop Insect Management Guide.  Trade names are given as examples only, and do not imply endorsement of one product over another nor discrimination against any product by the North Dakota State University Extension Service.  BE SURE TO READ, UNDERSTAND AND FOLLOW ALL LABEL DIRECTIONS AND PRECAUTIONS.

Janet Knodel & Patrick Beauzay

Extension Entomologist & Research Specialist

Alfalfa Weevil Emergence Delayed

Alfalfa weevil was very damaging in North Dakota last year due to its early emergence and the drought stressed alfalfa.  The early emergence may have been due to eggs, which successfully overwintered during the mild winter of 2011/12, and as a result they hatched into larvae which started feeding on foliage earlier than normal.  However, in North Dakota alfalfa weevils typically overwinter as adults in sheltered areas and any eggs laid in the late summer or fall will die.  Since we had a very cold winter 2012/13, entomologists do not expect alfalfa weevil eggs to have successfully overwintered in North Dakota this year.  So, the degree day model for alfalfa weevil development should be accurate for predicting adult emergence, since it assumes no overwintering egg survival. 

                To calculate the degree day units for alfalfa weevil development (Table 1), go to the NDAWN website at http://ndawn.ndsu.nodak.edu/.  Go to “Applications”, select “Insect Degree Days”, choose “Maps”, enter March 1 as the start date, select 48 F as the base temperature, and click “Submit” to generate the map.  You can also generate accumulated degree day tables for individual weather data recording stations.

Table 1.  Approximate degree day (DD) requirements for alfalfa weevil development using 48ºF as the base developmental temperature.

Right now, we are not close to adult alfalfa weevil emergence prior to 300 DD (see NDAWN map below).  Most regions of North Dakota is only at <50 accumulated DDs! It’s probably going to be the 3^rd or 4^th week of May before adult alfalfa weevils start emerging.

It is important to integrate the degree day model into your alfalfa weevil management program.  Accumulated degree days will give you a window of when to scout, when damage might occur, and when control action might be necessary.  Scouting should begin immediately before egg hatch (≈300 DD), and fields should be scouted weekly up through the first cutting.  Stay tuned for more information on scouting and economic thresholds as we get closer to 300 DD.

Janet Knodel

Extension Entomologist

janet.knodel@ndsu.edu

F. Adnan Akyuz, Ph.D.

Assistant Professor of Climatology

North Dakota State Climatologist

http://www.ndsu.edu/ndsco/