Crop & Pest Report - All
How To Submit Samples To The Plant Diagnostic Lab
The NDSU Plant Diagnostic lab is open to the public. To support two technicians and to be able to purchase supplies and maintain equipment, a small fee applies to processing and diagnosing samples. Services and fees are available online at www.ag.ndsu.edu/pdl. In general, the lab stays busy through the winter months processing samples related to seed health testing and working on long-term projects, with routine samples beginning to pick up in the spring. Typical spring samples include evergreens, turf, and winter wheat. This summer, the lab will be short a technician as the assistant diagnostician, Jesse Ostrander, also fulfills the role of seed health technician until a new applicant can be chosen to fill that position (the position is expected to be filled by late summer 2014), but it is anticipated that the turnaround time for samples including virus testing and nematode screening should remain at about 36-48 hours from the time the sample is received. Routine diagnosis can vary from > 1 week to 2 weeks out depending on the sample.
When submitting a sample to the Plant Diagnostic Lab, please be sure to include the contact information of the submitter and list any other entity who you would like to receive a copy of the report or the invoice. It is also important to provide as much information about the sample being submitted as possible. To facilitate this process, a lab form is available at www.ag.ndsu.edu/pdl. The form can be filled out by hand or online, and a complete form should be sent in with each sample. Final reports of diagnoses are mailed along with invoices. Reports can be emailed if an email address is provided. Pre-payment is not required.
Plant Problem Diagnosis: For crops and herbaceous ornamental plants, try to send several affected plants showing a range of symptoms. Dead plants are rarely informative and we ask that you instead send a representation of a healthy plant, a plant in decline, and a severely affected plant. Try to send in the entire plant, including the roots, whenever possible as above-ground symptoms can be related to a problem with the lower stem or roots. This information also applies to turf, the difference being that you would collect a sample from a healthy portion of the lawn and a portion in decline. Photos showing the distribution of the symptoms in a landscape are also useful.
For woody species (trees and shrubs), images may be needed in order to determine the best sampling strategy. To prevent a decline in sample quality, wrap the foliage in DRY paper towels before placing the entire sample in a plastic bag. For all samples, shipping earlier in the week is best (Monday through Wednesday). Pack the sample so that the leaves cannot come into contact with soil (if included). Store the sample in a cool space such as a refrigerator or in a cooler with ice until it can be shipped. Samples from out of state must be double bagged and sent in a sturdy box.
Identification requests – weeds/plants, insects, fungi/molds: For plant identification, whole plants are usually needed, and the flowering stage is extremely helpful. For insect identification, small insects may be sent in vials of 70% alcohol. Larger insects, such as moths, should be packed in cotton placed in a sturdy box to avoid crushing. If submitting an insect pest of plants, please include a sample of the host plant if possible. For fungus/mold identification, whole mushrooms should be wrapped in dry paper towels and packed in a sturdy box to avoid crushing; household mold samples usually consist of discolored paper from sheetrock or shavings of affected wood trim. These should be placed in a small resealable plastic bag. Tape mounts, using crystal clear scotch tape and placing it over an affected area, lifting, and attaching to wax paper, can also be submitted.
NDSU Plant Diagnostician
NDSU Assistant Plant Diagnostician
Plant Diagnostic Lab 2013 Highlights
In 2013, the NDSU Plant Diagnostic Lab processed over 2,330 samples. Samples were divided into the following five categories: Reasearch - 14%, routine diagnosis - 25%, phytosanitary - 26%, seed health - 28%, and survey samples - 7%. In the category of routine diagnosis, 35% of the samples were submitted by NDSU Extension agents and Extension research specialists. Common problems that were diagnosed for samples in the routine diagnosis category included stigmina needle blight of spruce, viruses of small grains, soybean cyst nematode, and environemntal stress-related problems (such as drought, salts, root compaction). Details can be found in the NDSU Plant Diagnostic Lab Annual Report, online at www.ag.ndsu.edu/pdl/periodic-reports.
NDSU Plant Diagnostician
NDSU Assistant Plant Diagnostician
Many weeds are much easier to control through soil-applied herbicides rather than relying only on POST herbicides – namely kochia and lambsquarters. Many soil–applied herbicides control these and many others at germination. Seed-bed preparation in conventional tillage usually kills emerged weeds but larger weeds may survive the tillage operation especially on uneven ground. No-till systems require multiple chemicals for early pre-plant burndown applications. Glyphosate is usually the main component in the herbicide mixture but kochia and lambquarters biotypes in North Dakota have shown varying level of resistance/tolerance to glyphosate. Surviving plants after the first glyphosate application will continue to grow and will certainly be harder to control with increasing size. There are few effective POST herbicides in most broadleaf crops and many are “contact” herbicides that only control small weeds. Using soil-applied herbicides is a simple and easy solution to many hard-to-control weed problems.
1. Start clean at planting
2. Use effective foundation/soil-applied herbicides
3. Dead weeds don’t make seed!
Extension Weed Specialist
Management of Dandelion and Key Weeds in No-Tillage Soybean
Despite cold soil temperatures which has delayed dandelion emergence, managing dandelion in no-tillage soybean will be an issue again this season. Some have inquired about the use of Sharpen. Sharpen or Verdict may kill new seedlings but only burn dandelion leaves of perennial forms of dandelion (plants > 1 year of age) and plants will likely recover later. If a no-tillage soybean field has dandelion, an effective herbicide treatment is glyphosate at 1.125 to 1.5 pounds acid equivalent per acre (lb ae/A) plus 2,4-D ester at 1 pt/A plus Express SG at 0.5 oz/A plus MSO or HSMOC adjuvant at 1.5 pt/A at seven days prior to planting. If glyphosate-resistant horseweed/marestail, kochia, or common ragweed is present in addition to dandelion, the addition of Sharpen at 1.5 fl oz/A or Verdict at 7.5 fl oz/A should improve the control of horseweed, common ragweed, and kochia and provide additional residual control compared to Sharpen at 1 fl oz/A or Verdict at 5 fl oz/A. If Sharpen or Verdict is added to the tank-mixture at the high-end use rates mentioned above then soybean planting must be delayed until 14 days after application for all soils having > 2.0% organic matter and finer than a course soil texture. The addition of sulfentrazone (Spartan) products with the glyphosate, 2,4-D ester, and Express will improve control of glyphosate-resistant kochia present at the time of application and improve residual control compared to Sharpen, but it will not assist in the control of horseweed, common ragweed, and may likely reduce dandelion control. The addition of MSO or HSMOC adjuvant to the sulfentrazone, glyphosate, 2,4-D, and Express SG combination should enhance control of emerged kochia, but likely none of the other glyphosate-resistant weeds. When applying Sharpen, Verdict, or products containing sulfentrazone in a burndown application, the water volume should be greater than 15 gallons per acre, utilize medium-sized spray droplets and reduce travel speeds to maximize spray coverage.
Extension Weed Specialist
Weed Control in Sugarbeet
Are sugarbeet growers compromising yield due to delayed planting? Many of you might be familiar with the elegant tables that project corn yield against planting date. Historic data indicates yield is greatest when corn is planted the last week in April in North Dakota. Does the same logic apply to sugarbeet? Maybe…. Or maybe not. Historic data from American Crystal Sugar suggests that yield is greatest when sugarbeet are planted by April 25th. However, 2013 was a high yielding year and many acres of sugarbeet were planted during the second half of May. Remind yourself that the economically important part of a sugarbeet is its tap root and not seed yield. The literature states climate after planting, particularly rainfall and accumulation of heat units will dictate yield and sugar content. Equally important is successful stand establishment. Plant when soil moisture conditions permit excellent stand establishment.
Start clean. Sugarbeet does not compete well with weeds that germinate and emerged within eight weeks of planting. Schweizer & Dexter, 1987 found that early season competition can reduce sugarbeet yield by 26 to 100%. There are reports that kochia has already emerged in fields. If kochia is glyphosate resistant, then control postemergence is difficult if not impossible, especially if not killed during seed bed preparation. Kochia not only germinates early but can germinate in successive flushes through June. Growers with kochia, resistant waterhemp or other small seeded broadleaf weeds should consider using soil residual herbicides to complement their postemergence programs. A program we like and one we will evaluate in 2014 is ethofumesate (Nortron) plus Dual applied preemergence at 2 pints + 0.5 pints per acre.
Soil temperatures; sugarbeet and weed emergence. While it may not seem like it, soil temperatures certainly will increase in May. This means the time interval between sugarbeet and weed seed germination and emergence will decrease. Sugarbeet germinates and emerges between 7 to 12 days when soil temperatures are between 52 and 60 °F but emerges in only 5 to 7 days when temperatures are between 60 and 72 °F. You can be sure weeds will emerge even quicker! Be sure your sprayer is calibrated and there is product on-hand to control weeds when they are less than two inches tall.
Extension Sugarbeet Agronomist
NDSU & University of Minnesota
Salinity is rearing its ugly head this spring as a result of a relatively high water table from all the rain last fall, limited flushing of salts as a result of low snow cover/melting and high evaporation from fall tillage and lack of soil residue since most of it blew across fields this winter. A high water table brings the water that carries the salts closer to the surface, less snow cover means less flushing of salts in the spring and high evaporation drives a process called capillary action that moves the water from the water table up towards the surface. Additionally, with as much soil erosion as there was this winter, the soluble salts below the surface now have less soil to move up through to reach the rooting zone of crops.
Tillage seems like a good option to make a salt-affected, “white” soil turn “black” again and get rid of the problem. But, this practice actually accelerates salt movement towards the surface by increasing evaporation while the water table remains constant. When we talk about actively managing salinity, we often say, “dry the soils down.” To do this, you need to reduce evaporation and lower the water table.
Two things I recommend you do this spring:
- Collect soil samples – you need to “get your number” so you have a starting point to develop a long-term management plan. Do this from a saline area that you are concerned about and also a productive area from your field. Keep the samples separate and send them off to a soil testing lab to be run for Electrical Conductivity (aka Soluble Salts). You cannot begin to effectively manage an area until you know what your salt levels are. And having a comparison from a salt-affected area versus a highly productive area will help you understand what good and bad salt levels are.
- Avoid tilling saline areas – this is something you can do even without “getting your number”. Tilling increases evaporation and will bring more salts to the surface. Chances are good that nothing is growing in those saline areas anyways, so you can plant directly into them without the tillage. I have had conversations with a few producers who are doing this and it is working well for them.
Do these two things in the short-term and then work on developing a long-term plan.
NDSU Extension Soil Health Specialist
Few Tips to Manage Root Rots in Field Peas
There were serious incidences of field pea root rots in the north central and the north western regions of North Dakota last year. Root rots can attack the field peas at various growth stages; in seedlings we see seed decay, damping off, root rot, and seedling blight. Whereas, in mature plants we see stunting, gradual yellowing of plants (the yellowing is seen in patches associated with water logged areas), lodging, reduced crop uniformity due to premature senescence and finally yield losses.
Prevalent fungal pathogens that cause field pea root rots in North Dakota:
Fusarium solani, F. avenaceum, F. oxysporum, Aphanomyces euteiches, Rhizoctonia solani, and Pythium sps.
Root rot pathogen incidence largely dependent on the soil temperature in a season as well as on the rainfall received. For instance; if we receive higher than normal rainfall early in growing season we tend to see more root rot severity in field peas.
Pythium is more of a problem in cool (64° to 75°F) wet soils. Pythium causes root rots at early stages and a watery, soft decay of older plants in wet soils at an optimum temperature of 64° to 75°F. However, Rhizoctonia solani will damage peas at relatively low soil temperatures (65°F) but is most aggressive under warmer conditions (76° to 86°F).
Aphanomyces root rot is most damaging when soil temperatures are between 72° and 82°F, along with excessive soil moisture.
Fusarium root rot is devastating at soil temperatures of 79° to 82°F and at moderate soil moistures. There were over eight Fusarium species have been identified in North Dakota causing root rots in field peas. The most frequent is F. solani, followed by F. avenaceum and F. oxysporum.
Field peas planted in soil infected with both Fusarium and Pythium are more severely attacked than plants infected with only one pathogen at any soil temperature or moisture level. Often it’s difficult to determine which pathogen is causing root rots in advanced stages and there are instances of plants have been attacked by several pathogens together. When the plants are attacked with complex of organisms the yield losses are very high.
There is no completely satisfactory control for the root-rot diseases of field pea once the causal fungus or fungi is/are introduced and becomes prevalent in the soil.
Figure 1 courtesy:
Treatment and Preventative tips:
Control measures for all root rots are the same. The best control against these root rot diseases is to maintain cultural practices that will give the field peas a good steady growth rate, along with avoidance of over-fertilizing and mechanical damage to roots and stems.
- Avoid soil compaction, choose well-drained fields.
- Avoid overcrowding and deep planting.
- No commercial cultivars of peas have root-rot resistance. Planting cultivars that perform well in North Dakota may reduce the amount of stress-related loss.
- Planting cultivars that are adapted for your growing region may reduce stresses.
- Refer to Regional Variety Trials for cultivars best suited to your area.
- Ensure application of Rhizobium inoculant – good for pea growth, and can boost disease resistance.
- Balance soil fertility levels based on a soil test.
- Using high quality seed and treating the seed is the best way to manage early root rots. There are many registered seed treatments available for control of seed decay, damping off, root rot, and seedling blight. Use treated seed with an approved seed treatment fungicide for Rhizoctonia and Fusarium control, such as Maxim 4FS; a second fungicide for Pythium control, such as Apron XL LS and the Rhizobium inoculant for nitrogen fixation. Check the compatibility of fungicides with Rhizobium before treating. Refer to the 2014 North Dakota Field Crop Plant Disease Management Guide for more seed treatment options.
- For the root rots which occur in the later stages, the use of fungicide has no effect as the products are not carried to the roots, and by the time symptoms are noticed, it is too late.
- Avoid herbicides that may cause plant stress and cause root rot symptoms to become more severe.
- Crop rotation reduces the inoculum build-up of root rots. So growers must either avoid planting in fields with a history of the disease or switch to growing non-host crops until pathogen numbers drop to acceptable levels. If you had severe root rot problems in the past, it is better to follow a crop rotation of (based on the research done in Canadian Provinces): Small grains / Canola or flax or lentils / small grains / field pea.
Area Extension Specialist/Crop Protection
NCREC, Minot, ND-58701
One hundred years ago, on May 8, 1914, President Woodrow Wilson signed the Smith-Lever Act of 1914 into law. The ‘Agricultural Extension Act’ was passed to provide federal funding for land-grant institutions to conduct educational programs to disseminate useful and practical information on subjects relating to agriculture and home economics through cooperative extension efforts with states and counties. The legislation authorized cooperative extension work between the state land grant colleges/universities and the United States Department of Agriculture (National Institute of Food and Agriculture). Initially, the states provided matching fund, but over time, local governments or counties/parishes (or several counties in regional systems) also contributed to funding. In 2014, all states have a land grant college/university with an Extension Service comprised of on- and off-campus educators who are responsible for ‘taking the university to the people’. Extension’s educational program use research based information from land-grant universities, agricultural experiment stations, and the United States Department of Agriculture to help people improve their lives.
In North Dakota, the North Dakota State University is the Land Grant University responsible for Extension Education. North Dakota has extension educators in 52 county offices and the Fort Berthold reservation as well as on the main campus in Fargo. The main purpose of NDSU Extension Service is to create learning partnerships that help adults and youth enhance their lives and communities. In 2013, extension educators had 951,677 face-to-face or direct interactions with North Dakotans (with a population of 699,677). No wonder North Dakota is ranked number one for over 10 agricultural crops with the happiest populace! With 100 years of experience, we are well endowed to chart the journey for another century during which we can further improve the quality of lives of our fellow citizens on a sustainable planet.
Extension Sugarbeet Specialist NDSU & University of Minnesota
Small Grain Disease Forecasting Site
Almost all NDAWN locations have had continuous days of weather favorable for tan spot infection in the past week. Similarly, IPM scout have reported relatively high incidence (Figure 1) but low severity (Figure 2) of the disease. Reports from Extension specialists across the state indicate that most spring wheat fields are in the 3 to 5 leaf stage, or early tillering - perfect growth stages for early season application of fungicide if needed, based on presence of tan spot symptoms and crop rotation history.
Winter wheat fields are generally in the jointing to seven-leaf stage of development. Disease pressure, other than for tan spot, has been low in winter wheat, with no reports of stripe rust yet. Winter wheat is at least several weeks away from concern about possible Fusarium head blight development. The disease forecasting site currently indicates a high risk of Fusarium head blight in parts of the state, but these risk maps are based only on weather conditions. We don’t have any crop yet in the flowering stage, the time of infection in wheat.
An electronic version of the 2013 Field Crop Fungicide Guide is available.
Professor Emeritus, Cereal Crops
Extension Plant Pathologist, Broad-leaf Crops
The most-common disease pests of apples are fireblight, apple scab and black rot canker. Black rot canker has been the most common issue, and the rest of this article will cover this disease and the associated problem known as frogeye leaf spot. For more information about fireblight and apple scab, see the NDSU Extension publication “Insect and Disease Management Guide for Woody Plants in North Dakota” (http://www.ag.ndsu.edu/pubs/plantsci/trees/f1192w.htm).Black rot is a canker disease caused by the fungus (Botryosphaeria obtusa). When the fungus infects stems or branches, it causes cankers which tend to grow more quickly along the length of the branch, compared to going around the branch. A canker will typically be sunken, have darkened bark, and have small bumps that are the fruiting bodies of the fungus. As the canker develops and expands around the branches, the leaves on the girdled branches will turn bright yellow and fall to the ground, even in the middle of summer (Figure 1). As the canker continues to develop, entire branches or stems will be girdled and killed. Infections can also occur in the outer bark, which is dead. Outer bark infections are not sunken and cause no damage, but contain fungal fruiting bodies that can serve as a source of spores that cause new infections. Infections in the outer bark can develop into cankers if the tree is wounded or stressed.
The fungus also causes a leaf disease called frogeye leaf spot (Figure 2). Frogeye leaf spots are typically chocolate brown with a dark ring around the edge of the spot, and the margin of the spot is sharply defined. The infections on leaves typically occur early in the season and take place during cool, wet weather. If there are several leaf spots, or if leaf spots occur near the leaf petiole, the leaf will turn yellow and drop.
New infections on branches and stems occur through wounds – pruning cuts, hail damage, or tissue damaged during the previous winter. While old infections cannot be cured, there are several steps that we can take to prevent new infections or slow development of cankers. Avoiding stress to the tree allows the tree to resist initial canker infection and expansion of existing cankers. Be careful to not wound the tree with mowers or weed trimmers and minimize the use of herbicides – both regular herbicides and those used in weed-and-feed formulations with fertilizer – within the dripline of the tree. If the cankers are confined to a manageable level, branches with cankers should be pruned out, several inches below the most basal portion of the canker. Do not leave branch stubs that can serve as an entry point for the fungus. Pruning apple trees is best accomplished during the dormant season to minimize chances of infection by fireblight. If apple trees are pruned during the growing season, applying streptomycin or a copper-based fungicide will help reduce the risk of fireblight infection. If branches are broken during a windstorm or if bark is damaged by hail, treating the wounds with a copper-based fungicide will help reduce the risk of infection by both black rot and fireblight. Pruning of outer bark infections is not practical because they are usually too numerous and are not yet causing damage; instead, outer bark infections are best taken as an indication that care should be taken to avoid wounds and stress to the tree. If the fruit load is very heavy, consider thinning out the number of fruits to about one apple per six inches of branch.
Joe Zeleznik - Extension Forester
Jim Walla - Forest Pathologist