Crop & Pest Report

Accessibility


Crop & Pest Report - All

| Share

Scout for Spider Mites in Beans (08/16/18)

It is not surprising to see spider mites showing up in soybeans and dry beans with the hot dry weather.

Scout for Spider Mites in Beans

It is not surprising to see spider mites showing up in soybeans and dry beans with the hot dry weather. Mites are small and magnification is required to see them. A quick sampling procedure to determine whether mites are present is to hold a piece of white paper below leaves, then beat them to dislodge the mites. The mites appear as tiny dust specks; however, they will move after being knocked off the leaf. Another method is to pull plants and examine the undersides of the leaves for mites and webbing. Begin from the bottom of plants and move upwards into the canopy. Feeding damage by mites first appears as small yellow spots (stippling). As feeding activity increases, leaves become yellow, bronzed or brown, and eventually shed from the plant. Be sure to scout during full pod (R4) through beginning seed (R5) stages since these crop stages are the most important contributors to soybean yield. Mite infestations typically are first noted near field edges. Soybeans are susceptible to spider mite feeding injury up through R6 crop stage. Cooler temperature and any moisture (or rain) could help slow the mite problem.

Spider Mite Threshold: There is no specific threshold that has been developed for two-spotted spider mite in dry beans or soybeans. Treatment is advised when heavy stippling on lower leaves with some stippling progressing into middle canopy. Mites may be present in middle canopy with scattered colonies in upper canopy. Leaf yellowing is common on lower leaves.

Pest Management: Insecticides registered for spider mites management in dry bean and soybean are listed in the 2018 North Dakota Field Crop Insect Management Guide E1143.

The only pyrethroid that will control spider mites is the active ingredient bifenthrin (Tundra, Sniper, Brigade, Fanfare, Bifenture, etc.) in dry beans and soybeans. Other pyrethroids, such as lambda-cyhalothrin (Warrior, Silencer, etc.), they will cause spider mites to flare up and then you will need to spray again with an organophosphate (OP) insecticide.

Two active ingredients of OP insecticides for control of spider mites are chlorpyrifos and dimethoate. However, chlorpyrifos (Lorsban and generics) is NOT registered for foliar application in dry bean. However, chlorpyrifos is labeled for spider mites in soybeans. Chlorpyrifos resistant spider mites were detected in NW MN, so be sure to re-scout field after application to be sure it worked. Dimethoate will control spider mites in dry beans and soybeans, but has a shorter residual than bifenthrin. We think it’s realistic to expect about a 7 to 10 day residual from bifenthrin (if it is hot, residual may be decreased), a 4 to 7 day residual from chlorpyrifos, and a 3 to 5 day residual from dimethoate. It is extremely important to scout and monitor for recurring spider mite populations after spraying. Check your fields five days after treatment and again at regular intervals to make sure your insecticide is holding. If newly hatched spider mites are observed after 5 days, a second treatment may be necessary with a different insecticide mode of action. For example, if you use bifenthrin (pyrethroid) for the first application, use a non-pyrethroid product, such as dimethoate or chlorpyrifos (OP), for the second application. Agri-Mek SC (active ingredient abamectin) is also registered for spider mite control in soybeans and dry beans.

Complete coverage is important for spider mite control. Use high water volumes 15-20 GPA via ground and 3-5 GPA via air, and high pressure to penetrate foliage (40 psi).

Check out the NDSU Extension YouTube video on pest management of two-spotted spider mites in soybeans. Early detection of leaf injury symptoms, such as stippling and leaf discoloration, is important to prevent crop damage from spider mites and facilitate rescue treatments. Proper scouting techniques, action thresholds and pesticide selection for managing spider mites are discussed.

knodel.3

Janet J. Knodel

Extension Entomologist

| Share

Grasshoppers on the Move! (08/16/18)

Grasshoppers have been increasing in parts of North Dakota (see IPM map) and infestations are reported in field edges of soybeans, sunflowers and field corn.

Grasshoppers on the Move!

Grasshoppers have been increasing in parts of North Dakota (see IPM map) and infestations are reported in field edges of soybeans, sunflowers and field corn. The recent hot, dry weather favors higher populations of grasshoppers and can lead to hot spots or even localized outbreaks. As cereal grains are dried down and harvested, producers should be aware of grasshopper movements into row crops. According to the USDA NASS North Dakota Crop, Livestock & Weather Report of August 13th, cereal grain harvest progressed with barley at 52% harvested, oats at 41% harvested, spring wheat at 29% harvested, and durum wheat at 9% harvested.

Now is a good time to scout row crops for grasshopper infestation. Early detection is critical for preventing yield loss. Grasshopper damage usually starts in field margins and move into fields. Grasshoppers feed on leaves/pods/kernels, which can be completely destroyed. An economic level of adult grasshoppers is 21-40 per square yard in field margins and 8-14 per square yard in the interior of field.

knodel.1

knodel.2


Janet J. Knodel

Extension Entomologist


| Share

Pigweed Identification using Flowering Structure (08/16/18)

Pigweed (Amaranthus species) are in full flower. I thought it might be a good idea to refresh weed identification skills based on characteristics of the flowering structure.

Pigweed Identification using Flowering Structure

Pigweed (Amaranthus species) are in full flower. I thought it might be a good idea to refresh weed identification skills based on characteristics of the flowering structure.

Redroot pigweed. Flowering structure is highly branched with male and female flowers on the same plant. Branches of flowering structure usual are very compact, usually less than 2-inches long and thicker than a pencil. Redroot pigweed is very common across Minnesota and North Dakota.

 

Powell amaranth.

Flowering structure is branched, but less than redroot pigweed. Branches of the flowering structure are usually 4 to 8 inches long and thicker than a pencil. Male and female flowers are on the same plant. At first glance, Powell amaranth will remind you of those pictures of Palmer amaranth from other states. Powell amaranth is common in North Dakota and northwest and north central Minnesota but less common in southern and west central Minnesota.

Waterhemp.

Flowering structure are open and located near the top of the plant and at the tips of branches. There are male and female waterhemp plants. Males shed pollen while females produce seed. Male plants tend to have a flowering structure with a dominant central branch while female plants are highly branched with branches of proportional size. Waterhemp is abundant in North Dakota, especially east of US281.

 Peters.3 4

Palmer amaranth.

Like waterhemp, each plant is either male or female. The male flowering structure feels soft and sheds pollen, while female flowering structure feels prickly and contains seed. The branches of Palmer amaranth are very long, often up to 24 inches in length. We currently have not identified Palmer amaranth in North Dakota

Peters.5

 

Tom Peters

 Extension Sugarbeet Agronomist

NDSU & U of MN

| Share

Red Sunflower Seed Weevil Increasing (08/02/18)

The USDA NASS reports that 54% of the sunflowers were blooming in North Dakota as of July 30th compared to only 31% last year (USDA NASS News Release).

Red Sunflower Seed Weevil Increasing

The USDA NASS reports that 54% of the sunflowers were blooming in North Dakota as of July 30th compared to only 31% last year (USDA NASS News Release).

Economic threshold levels of red sunflower seed weevils (RSSW) were present in blooming oilseed sunflowers in southeast ND (Cass County), and southwest ND near Dickinson (Stark County). Please send me your field reports including locality and numbers.

Scouting should continue until the economic threshold is reached or most plants have reached 70% pollen shed. At 70% pollen shed, plants are no longer susceptible for egg laying or significant damage. On older flowering plants (after R5.7), larvae of RSSW (and banded sunflower moth larvae) will be feeding inside the seeds and protected from the insecticide. By then, much of the feeding damage has already occurred and no foliar insecticide is recommended then.

knodel.2

 

Janet J. Knodel

Extension Entomologist

| Share

Protect Pollinators - Wise Insecticide Use (08/02/18)

Bees are in trouble in the United States and other areas of the world.

Protect Pollinators - Wise Insecticide Use

Bees are in trouble in the United States and other areas of the world. Native bee species are declining in numbers due to habitat loss, pesticides and other factors. Approximately one-fourth to one-third of European honey bee colonies in the U.S. die each year despite the best efforts of their attentive beekeepers.

An Integrated Pest Management (IPM) approach should be used to promote judicious use of pesticides for pest control only when needed and to implement scouting, use of economic thresholds and non-pesticide pest management strategies, such as cultural, biological control or host plant resistance.

Remember, most of our insecticide used in field crops are broad-spectrum insecticides. Any broad-spectrum insecticide can kill ‘all’ insects, including bees and natural enemies of the targeted insect pest. Choose the least hazardous formulation of an insecticide product for bee safety (Table 1).

Application is recommended in the late evening (after sunset) or when temperatures are below 55 F, when most bees are not actively foraging. Remember, some bees such as bumblebees forage in cooler temperatures (up to 50 F) and are actively foraging in the early morning, much longer than honeybees.

Use short-residual insecticides. If possible, ‘spot’ treat instead of broadcast spraying to minimize the area treated with insecticide, especially for edge insect pests, such as young grasshoppers that do not move very far from their egg hatching sites.

Remember to use all pesticides in a manner consistent with the label. Always read, understand and follow the pesticide’s label directions in regards to pollinator protection. Some pesticide labels require applicators to notify beekeepers 48 hours prior to applications to blooming crops (or if flowering weeds are present in fields).

Pesticides that have the honeybee hazard icon (on right) on the label indicate that this product is highly toxic to bees and specific application restrictions apply to protect pollinators. An example of an acutely toxic substance to bees is the active ingredient imidacloprid or chothianidin in the neonicotinoid insecticide group, IRAC 4A (systemic insecticides).

Finally, know and communicate with your local beekeepers if you need to spray flowering sunflowers or other flowering field crops for insect pests. Please PROTECT honeybee colonies by notifying beekeepers before an insecticide application (at least a 48 hours notice), so they can move or cover up their hives before the application.

To find beekeepers, see the North Dakota Bee Map on the North Dakota Department of Agriculture website. Zoom in on the area of interest to find names and contact information of local beekeepers. Please read our North Dakota Pollinator Protection Plan from the North Dakota Department of Agriculture.

A NDSU Extension YouTube video is available on Protect Bees from Pesticide Poisoning.

knodel.6 8

knodel.9

 

Janet J. Knodel

Extension Entomologist

| Share

Soybean Aphids Increasing Slowly (08/02/18)

Based on recent counts from southeastern ND, soybean aphids are slowly starting to increase.

Soybean Aphids Increasing Slowly

Based on recent counts from southeastern ND, soybean aphids are slowly starting to increase. A few fields that were scouted this week in Barnes and Cass Counties, had one or two plants with 100-150 soybean aphids per plant. The remaining plants were all very low, <10 aphids per plant. Therefore, we still have a ways to go to reach the Economic Threshold of an average of 250 aphids per plant with 80% of plants infested, and increasing aphid populations. The soybean crop ranges from R2 (full bloom) through R4 (full pod set) crop stages, so we are getting closer to the R6 (full seed set) crop stage where there is minimum impact on yield from soybean aphid feeding injury.

Continue to scout fields for soybean aphid populations and stay tuned for more reports. Maps are posted weekly on the NDSU IPM website.

knodel.5

Janet J. Knodel

Extension Entomologist

| Share

Summer Flea Beetles Feeding on Canola Pods (08/02/18)

The summer population of flea beetles has emerged in large numbers this year.

Summer Flea Beetles Feeding on Canola Pods

The summer population of flea beetles has emerged in large numbers this year. Flea beetles are being observed in maturing canola fields (North Central ND; Source: Brady Schmaltz, Arthur Companies), Brassicas crops being used as cover crops (i.e., radishes) and in backyard gardens. For canola, there is no established Economic Threshold for flea beetle feeding injury on pods. Flea beetle feeding injury on pods is usually most significant on late-planted canola and on the upper pods. Fortunately, the lower pods of canola are the primary pods that provide most of the canola yield. However, flea beetle feeding injury on pods can result in poor seed fill, premature pod drying, or pod shattering. If the canola is mature, pass the 5.2 growth stages (when seeds in lower pods have turned translucent to green), then yield will probably be less impacted by flea beetle feeding. In a flea beetle trapping study of freshly swathed canola, the number of flea beetles per trap decreased dramatically after 7-days of drying in swath. Flea beetles are mobile insects and fly around to find ‘greener’ canola fields (late-planted) for summer feeding.

Insecticides registered for flea beetle control with a short, 7 day Pre-Harvest Interval (PHI) include: Delta Gold (deltamethrin), Declare (Gamma-cyhalothrin), Warrior II and generics (lambda-cyhalothrin), and Mustang Maxx (zeta-cypermethrin). Insecticides that are labeled to control flea beetles on canola are listed in 2018 North Dakota Field Crop Insect Management Guide E-1143.

knodel.4

 

Janet J. Knodel

Extension Entomologist

| Share

Scout for Bertha Armyworm in Canola (08/02/18)

Mature bertha armyworm larvae were found feeding on the pods of canola in northcentral McHenry County (Source: Kristine Keller, Farmers Union Oil of Velva, Butte, Drake and Anamoose).

Scout for Bertha Armyworm in Canola

Mature bertha armyworm larvae were found feeding on the pods of canola in northcentral McHenry County (Source: Kristine Keller, Farmers Union Oil of Velva, Butte, Drake and Anamoose). Older larvae reach a length of ¾ to 1½ inch and are velvety brown to black with a yellowish band along each side of the body. As leaves dry, these larvae begin feeding on pods or flowers. The greatest risk of crop injury occurs in August as the worms are mature. Larvae chew holes in the pods, eat the seeds and cause premature shattering. Mature larvae eat approximately 85% of the plant materials consumed during their larval development. Larvae feed at night and often hide underneath leaf litter and clumps of soil during the day, which makes them difficult to see when scouting.

The Economic Thresholds is an average of 20 to 32 larvae per square yard with insecticide + application costs of $6.50 to $10 per acre, respectively. However, thresholds may need to be lowered if larvae are feeding on maturing pods at high population densities.

Fields above the economic threshold level should ideally be sprayed once the hatch is complete and when larvae are small about ½ inch. Apply a well-timed insecticide in early morning or late evening when larvae are actively feeding. High volumes of water should be used for good coverage of the dense canola canopy. Insecticides that are registered to control bertha armyworm on canola are listed in 2018 North Dakota Field Crop Insect Management Guide E-1143. When larvae are mature, 1½ inch long, they are close to the pupal stage, which is a non-feeding, resting stage. So, no insecticides are necessary this late in the insect’s development and the feeding damage is already done.

Please see the NDSU Extension publication on Bertha armyworm in Canola: Biology and Integrated Pest Management E1347 (revised) for more information.

knodel.3

 

Janet J. Knodel

Extension Entomologist

| Share

Good Bugs II Workshop (08/02/18)

Come learn about farming and integrating beneficial insects for natural pest control, a Conservation Biocontrol Short Course!

Good Bugs II Workshop

Come learn about farming and integrating beneficial insects for natural pest control, a Conservation Biocontrol Short Course! On Wednesday, August 15th, the course will be offered in Grand Forks County at the Larimore Dam Rec Area. Additionally, the course will be offered a second time at the Carrington Research Extension Center on Thursday, August 16th. Both offerings will start at 9 am at their respective locations.

knodel.1

Participants will learn about supporting beneficial insects that provide natural pest control during this full-day short course. Conservation biological control is a science-based pest management strategy that seeks to encourage beneficial insects back into cropping systems for natural pest control, ultimately rewarding farmers with economically-viable pest management systems. A representative from the Xerces Society will overview conservation biological control and beneficial predators and parasitoids that attack insect pests. Participants will learn how common farm practices can impact beneficial insects and how to assess and create farm habitat for beneficial insects. This workshop is sponsored by Conserving Natural Resources, Xerces Society, USDA Natural Resources Conservation Services, Soil and Wather Conservation Society and NDSU Extension.

 

Please register at: http://www.ndswcs.org/


Please note, there is a small fee for registration and it is limited to 50 per site. Lunch and snacks will be provided. If you have any questions, please contact Dr. Travis Prochaska via email Travis.Prochaska@ndsu.edu.

 

TJ Prochaska

Extension Cropping Systems Specialist

NDSU North Central Research Extension Center

| Share

Weather Forecast (08/02/18)

The August 2 through August 8, 2018 Weather Summary and Outlook

Temperatures were well below average at most of the North Dakota Agricultural Weather Network (NDAWN) stations during the period of July 25 through July 31, 2018 (Figure 1). With the second half of July mostly on the cool side, the month as a whole finished near or slightly below normal for temperatures. That was a noticable departure from what was recorded during both May and June as both of those months finished with above average temperatures.

ritchison.1

There were some widely scattered thunderstorms in the region this past week on a few days with most of the NDAWN station not recording much precipitation (Figure 2). In fact, several NDAWN recorded little or no precipitation from July 25 through July 31, 2018. South central and southeastern North Dakota into west central Minnesota recorded above average rainfall in July, but most of the rest of the area recorded below average rainfall during July.

ritchison.2

The past couple of weeks the temperatures have mostly been below average. The next couple of weeks will see temperatures recover back to average or even above average. There will be several cold fronts moving through with a day or two of cooler air, similar to what we experienced yesterday and what eastern North Dakota and western Minnesota are experiencing today (Thursday). Yet, overall a warmer period is expected for the first 10 days of August. The transitional periods from warmer to cooler will of course be our main thunderstorm opportunities.
This weekend and toward the middle of next week looks to be the best time periods for rainfall. This time of year, widespread rain events are less likely, meaning most of the rain we get in the near term will come from scattered or isolated thunderstorms. Therefore, typical of August, a trend toward drier conditions in many areas will be the trend for the first part of this month. The projected growing degree days (GDDs) Base 50°, 44° and 32° for the period of August 2 through August 8 is presented in Figure 3.

ritchison.3

Using May 5 as a planting date, the accumulated wheat growing degree days (Based 32°) through July 31, 2018 is presented in Figure 4. You can find your exact GDDs for your planting date(s) at: https://ndawn.ndsu.nodak.edu/wheat-growing-degree-days.html

ritchison.4

Using May 10 as a planting date, the corn accumulated growing degree days (Base 50°) through July 31, 2018 is presented in Figure 5. You can find your exact GDDs for your planting date(s) at: https://ndawn.ndsu.nodak.edu/corn-growing-degree-days.html

ritchison.5

 

Daryl Ritchison

Meteorologist

Interim Director of the North Dakota Agricultural Weather Network

Document Actions

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

USDA logo

Creative Commons License
Feel free to use and share this content, but please do so under the conditions of our Creative Commons license and our Rules for Use. Thanks.