no. 8 july 3, 2008 - ag.ndsu.edu€¦ · adult flea beetles can be collected with sweep nets. after...

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No. 8 July 3, 2008

Inside this Issue...Scout for Leafy Spurge Flea Beetles . . . . . . . . . . . . . . . 1Wheat Midge Risk Forecast Low and Emergence Delayed . . . 1Wheat Stem Sawfly Emerging . . . . . . . . . . . . . . . . . . . . . . . . . 3Canola Insect Trapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Variable Corn Emergence – 2008 . . . . . . . . . . . . . . . . . . . . . . 3Iron Chlorosis Deficiency in Soybeans . . . . . . . . . . . . . . . . . . 4Most Recent NDSU IPM Small Grain Survey Results . . . . . . . 5Preharvest Intervals for Small Grain Fungicides . . . . . . . . . . . 6Fertilizer Use 2007 and a Look to the Future . . . . . . . . . . . . . . 6Does Glyphosate Price Matter? . . . . . . . . . . . . . . . . . . . . . . . . 7Is a Residual Needed with Post Corn Herbicides? . . . . . . . . . . 8Update from the NDSU Plant Diagnostic Lab . . . . . . . . . . . . . 8Around the State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Weather . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

SCOUT FOR LEAFY SPURGE FLEA BEETLESLeafy spurge flea beetles (Aphthona species - see

photograph) are an effective means of controlling thenoxious weed leafy spurge in North Dakota.

This group of flea beetles is host-specific to the leafyspurge plant, which makes them an ideal biologicalcontrol choice. The southern half of North Dakota hasaccumulated over 1,000 growing degree day (GDD) andscouting should begin for adult leafy spurge flea beetles.Flea beetles should be collected between 1,200 and the1,600 (see following map) using the sunflower GDD onNDAWN.

Adult flea beetles can be collected with sweep nets. Afterlate July, flea beetles begin to lay eggs and should not bemoved. The flea beetle typically take three to five years toestablish and impact leafy spurge infestations.

New publications from South Dakota State Universityoffer tips on using flea beetles to help control leafyspurge. SDSU Extension Extra 8161, “Managing LeafySpurge Flea Beetle Releases in South Dakota," isavailable online in PDF format at agbiopubs.sdstate.edu/articles/ExEx8161.pdf. SDSUExtension Extra 8162, “Leafy Spurge Flea BeetleCollection Recommendations,” is online atagbiopubs.sdstate.edu/articles/ExEx8162.pdf

WHEAT MIDGE RISK FORECAST LOW ANDEMERGENCE DELAYED

For the wheat midge risk forecast in 2008, NDSUExtension agents collected a total of 1,910 soil coresamples from 191 fields in 20 counties during the fall of2007. Lower levels of overwintering wheat midge larvaewere observed in the 2007 soil survey than previous years(see 2007 Wheat Midge Larval Survey ND map).

Brown-legged spurge flea beetle, Apthona lacertosa(Rosenhauer). (Photo courtesy USDA APHIS PPQ Archive)

North Dakota State University CROP & PEST REPORT July 3, 2008

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Wheat midge populations ranged from zero to 678 midgelarvae per square meter, with most of the state having lessthan 200 midge larvae per square meter. Approximately56 percent of the soil samples were positive for wheatmidge larvae, with an average of 107 larvae per squaremeter. In 2008, areas with more than 500 midge larvae persquare meter in Cavalier and Towner counties decreasedfrom the previous year. A small, new pocket, with morethan 500 midge larvae per square meter was discovered inDivide County in northwestern North Dakota. There arealso several small pockets of lower numbers of 201 to 500midge larvae per square meter in central Divide, south-central Burke, west-central Renville, east-centralMountrail, central Ward, northern Benson, eastern Eddy,northern Ramsey Counties and a larger pocket in centralCavalier County. Areas with more than 200 midgelarvae per square meter should be scouted todetermine if economic population levels exist inwheat/durum fields in the susceptible crop stage –heading to early flowering. No 2007 soil samplescollected had more than 1,200 midge larvae per squaremeter, which is considered a high-risk for infestation in2008.

The parasitism rate of the tiny parasitic wasp,Macroglenes penetrans (see photograph), has doubledfrom an average parasitism rate of 8 percent in 2007 to 16percent in 2008 (see 2007 Wheat Midge Larval Survey -% Parasitism ND map). This wasp lives inside wheatmidge larvae and eggs, and will emerge the followingspring. It kills the developing wheat midge larva. Theparasitism rate typically ranges from 0 percent to 100percent each year, with higher rates occurring in areaswhere midge populations have been high the past fewyears. Counties with parasitism rates of more than 50percent include Burke, Mountrail, Ward, McHenry,McLean and Bottineau counties.

The wheat midge soil survey is supported by theNorth Dakota Wheat Commission.

A degree day (DD) model using daily temperatures tocalculate DD accumulation allows for more accurateprediction of local adult emergence. Events for the midgepopulation (degree day base = 40 F) are listed in the tablebelow.

DD Biological Event450 Midge breaks the larval cocoon and

moves close to soil surface to form thepupal cocoon.

1300 10% of the females will have emerged.1475 About 50% of the females will have

emerged.1600 About 90% of the females will have

emerged.

Typically, wheat midge is emerging during the first weekof July in the northern counties of North Dakota.However, this year the DDs are behind normal and onlynear 1,000 DD in the northern tier (see Wheat Midge DDmap). Wheat midge DD maps for North Dakota areavailable on the NDAWN website:

http://ndawn.ndsu.nodak.edu/wheat-midgedd-form.html

Parasitoid, Macroglenes penetrans, of wheat midge(photo courtesy Saskatoon Res. Centre, Canada)


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WHEAT STEM SAWFLY EMERGINGField reports indicate that adult wheat stem sawfly has

begun to emerge in southwestern North Dakota. Highnumbers of adult sawflies have been collected using sweepnets in spring wheat fields at Hettinger, Scranton, Regent,and Mott. The sex ratio is 2:1 (male to female) sawflies.Adults are small, black wasps with three yellow bandsaround the abdomen (see photograph). Males emerge earlierthan females. Adults live only 7-10 days. They are inactiveinsects that spend most of their time resting with headsdown on grass stems. Females prefer to lay eggs in wheatthat has not reached the jointing stage (stem elongation).Plants in the boot stage are not preferred for egg laying.Currently, there are no monitoring methods or economicthresholds that have been established for adult wheat stemsawfly.

These is one generation of wheat stem sawfly per year.Female sawflies deposit eggs into the elongating stems ofhost plants (wheat, rye, triticale, barley) in early summer.The developing larvae feed and move up and down thelength of the stem interfering with water and nutrient flowto the developing grain head. As the wheat plant matures,and usually prior to harvest, the larva moves down to thebase of the stem and chews a notch around the inside of thestem. Feeding injury causes reduced yield and quality ofgrain (lower protein and kernel weight), and lodgingproblems.

How can I control wheat stem sawfly? Currently, thereare no insecticide recommendations for control for wheatstem sawfly. The best control strategies include seedingsolid-stemmed varieties that are resistant to wheat stemsawfly or planting alternative non-host crops. Swathinginfested wheat at 40% kernel moisture will help save stemsbefore they are cut by sawfly and lodging losses. NDSU isconducting research on wheat stem sawfly in 2008 on:

- different monitoring methods, - control with insecticide seed treatments or foliar

insecticide sprays; and - evaluation of solid-stemmed varieties for host plant

resistance.

CANOLA INSECT TRAPPINGAll trap counts for bertha armyworm and

diamondback moth have been low so far this year. Like somany other insect pests that overwinter in North Dakota,emergence of bertha armyworm has been delayed due tocool spring temperatures. The migration risk forecast foradult diamondback moths is also low. Maps on trappingresults will be posted on the NDSU Extension IPMSurvey website. Click on “Canola Trap Network.”

http://www.ag.ndsu.nodak.edu/aginfo/ndipm/index.htm

Janet J. KnodelExtension [email protected]

VARIABLE CORN EMERGENCE – 2008I have observed abnormally high levels of variability

in the plant height of corn this spring. Much of thisvariability is related to differences in plant emergencetiming. No doubt the cooler than normal temperatures thisMay were partly to blame for the magnitude of thisproblem. Variability in plant size is especiallypronounced in fields with poorly incorporated residuesfrom the previous crop. Plant height differences were alsoaccentuated this year by the excessive wet conditions ofearly June. Plants that emerged later seem to have lessaccess to plant nutrients because of smaller root mass,further stunting their growth. Of the common cropsgrown in North Dakota, corn is probably the mostresponsive to stand uniformity. Corn can compensate forsome reductions in plant populations associated with poorseedling emergence or from poor seed drop. On the otherhand, corn is quite sensitive to unevenness in plantemergence and plant height. Plants that are significantlysmaller than their neighbors will be shaded and oftenstruggle to form a cob. They will, nevertheless, stillcompete for light, water, and nutrients with their largerneighbors (unlike a skip). In a real sense, they becomevery expensive weeds that are not practical to control.

Adult wheat stem sawfly


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What is the expected yield loss associated with unevencorn emergence/height?

Yield losses associated with late emerging or shortplants can be impacted by a number of factors includingdifferences in size, the hybrid grown, and the percentageof the plants that emerge late (or that are significantlysmaller than their neighbor). Recent research reportedyield losses of between 4 and 23% depending on thepercent of the plants that emerged late and the length inthe delay in emergence of the late emerges. The greatestlosses when emergence delays are one week occur when50% of the plant emerge late. The longer the delay (mostresearch looked at delays of up to 3 weeks) the greater theyield losses. See a recent article by Elmore andAbendroth (http://www.ipm.iastate.edu/ipm/icm/2006/6-12/cornheight.html) for additional details on relevantresearch findings. Some data suggest that hybrids maydiffer in their ability to compensate for stand unevenness,though there is no definitive research to elucidatecharacteristics that impart greater yield stability in suchhybrids.

Can Unevenness in Emergence Be Managed?Differences in the temperature and moisture that

surround the seed and seeding depth are probably themain factors impacting the timing of seedling emergence. Though we cannot alter the weather, we can to someextent alter the micro-environment in which the seed isplace. The following are practices may improve standuniformity:• Seeding depth. Soil temperature changes with soil

depth. Similarly soil moisture content may vary withsoil depth. Improving the uniformity of seedingdepth can be one of the most important practices forimproving uniformity in emergence.

• Crop residue. Though crop residue protects the soil,excessive residue can induce variability in soiltemperature and soil moisture. The impact of cropresidue on emergence uniformity is amplified in earlysprings that are unusually cold, like this year. Whenplanting into soils with residue, using a trash whipperto reduce the amount of residue directly above theseed row may help.

• Soil-seed contact. Adjust packer wheels and seedopeners so that there is good soil-seed contact whenplanting.

• Minimize tillage. Avoid excessive tillage that maydry out or compact the seedbed or predispose the soilsurface to crusting after planting.

Joel RansomExtension Agronomist for Cereal Crops

[email protected]

IRON CHLOROSIS DEFICIENCY IN SOYBEANSIron is essential for plant growth. Plants can develop

iron deficiency chlorosis deficiency (IDC) symptoms inthe plant tissues, especially newly formed leaves, wheniron in the plant is insufficient to meet the requirements.IDC will show up as unusual yellowing of the leaves inbetween the veins of the leaf. The veins may remaingreen. Iron is needed in the production of chlorophyll; thelack of leaf color is due to the failure of the chlorophyll todevelop normally. Affected leaves turn brown andeventually the tissue dies resulting in weak and stuntedplants.

Usually IDC is due to non-absorption rather than alack of iron in the soil. A high soil pH (>7) can causeother elements to interfere with the absorption of iron.IDC is a common yield reducing soybean plant conditionwhen crops are grown on high pH calcareous soilsespecially when salt levels are elevated. Althoughsoybeans may grow out of the chlorosis, yields can bereduced or in severe cases the soybean plant may die.

VarietyThe most important management practice is selecting

chlorosis tolerant soybean varieties. The websitehttp://www.soilsci.ndsu.nodak.edu/yellowsoybeans/ provides IDC scores for many soybean varieties grown inthe region. The rating scale used by NDSU is:

1 = no chlorosis, plants normal and green; 2 = a slight yellowing, no differentiation between veinal

and interveinal areas on the leaf; 3 = interveinal chlorosis (leaf veins green but interveinal

areas yellow), but no indication of stunting of growthor necrosis (death) of leaf tissue;

4 = interveinal chlorosis with reduced growth or somenecrosis of leaf tissue;

5 = very severe chlorosis, plants with stunted growth, andyoungest leaves and growing point necrotic, or entireplants dead.

Chlorosis severity differs from year to year, and it isimpossible to give exact recommendations as to whatlevel of chlorosis resistance is appropriate for a specificfield. In general, the more severe the chlorosis symptomsoccur in a field, the higher level of variety resistanceshould be selected. In Figure 1, the higher IDC scores(more severe chlorosis symptoms) within each year gavelower yield regardless of the different yield potential foreach growing season.


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DiagnosisDifferent plant stresses can cause yellowing and

produce chlorotic symptoms. Yellowing can be a result ofwet soils, insufficient nitrogen, insects, soybean cystnematode, root rot, or herbicide injury. Note that true irondeficiency has yellowing between the leaf veins but greenveins.

Carbonates and salts are two important factorsaffecting potential for iron chlorosis. Carbonates are afixed soil property, but salts can be reduced with tiledrainage. Soil pH alone is not a good indicator ofpotential iron chlorosis, however knowing the carbonateand salt level can help growers choose soybeanproduction fields.

Other management aspects• If soybean plants are closer together (higher seeding

rate) the plants seem to benefit one another and lesssevere IDC is observed.

• Cultivation of the crop may alleviate chlorosis as thesoil is loosened and aerated. Working the ground maydry out the top of the soil and help during wet yearsto warm up the soil.

• Use of iron seed treatment may help the crop to staygreen. Foliar applications or in-furrow application ofiron containing fertilizers has resulted in variableresponses and can help to eliminate or reduce IDCsymptoms; however iron applications are usuallyexpensive.

• Crop injury, when conventional herbicides are used,may increase IDC symptoms on already stressedbeans.

• Nitrogen fertilizer interferes with iron uptake andmay aggravate IDC symptoms.

Hans KandelExtension Agronomist, broadleaf crops

[email protected]

MOST RECENT NDSU IPM SMALL GRAINSURVEY RESULTS

The NDSU IPM field scouts surveyed 117 wheatfields and 25 barley fields last week. Field scouts are alsolooking at row crops for aphids and diseases now. Aphidcounts in small grains remain quite low, with a few aphidsobserved in 6% of scouted fields.

Tan spot continues to be the predominate diseaseobserved in wheat, but 11 fields showed symptoms of leafrust last week, five were winter wheat fields and six werespring wheat fields. The greatest leaf rust severity (25%)was observed in winter wheat in the south central region. Septoria leaf blotch, bacterial leaf stripe, black chaff,loose smut, and powdery mildew also were observedoccasionally in wheat. In barley, fungal leaf spots are theonly diseases observed at this point.

Figure 1. Source: R.J. Goos

Soybean cotyledon and unifoliate leaves are green.First trifoliate is yellow with green veins.


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PREHARVEST INTERVALS FOR SMALL GRAINFUNGICIDES

A recent temporary embargo of some Kansas wheatoccurred because the fields had been treated with Quiltfungicide beyond the appropriate preharvest interval(PHI) for that product (45 days). The followingpreharvest intervals are indicated on our currentlyregistered small grain fungicides:

Product PHIHeadline* Feekes 10.5 (~ 40 days PHI)Quadris 45 daysCaramba 30 daysFolicur** 30 daysProline 30 days wheat, 32 days barleyTilt** 40 daysQuilt 45 daysStratego 35 days

* Headline is the only product that doesn’t specify numberof days in their PHI. Feekes 10.5 is approximately 40days before harvest in ND, depending on air temperatures. Hot temperatures push the crop to flowering, Feekes10.51, more quickly. ** Additional tebuconazoles such as Orius, etc., oradditional propiconazoles, such as Propimax, etc., haveND state supplemental labels that specify the same PHIsas the original registered products.

Products recommended by NDSU for heading orflowering application for Fusarium head blightsuppression all have 30 day PHIs in wheat (32 days forProline in barley), a duration that should allow ample timein ND for maturity before swathing or harvest. Producersand applicators need to take heed of these PHIs, as whathappened in Kansas is a very strong reminder that labelsare the law and must be followed.

Marcia McMullenNDSU Extension Plant Pathologist

[email protected]

FERTILIZER USE 2007 AND A LOOK TO THEFUTURE

Product1995 1998 2002 2004 2005 2006 2007

-1,000 tons sold -NH3 350 367 296 309 322 278 387Urea 295 319 416 522 501 487 520AMS 7 25 46 45 51 42 60

11-52-0 123 184 252 320 336 356 43918-46-0 222 176 123 113 95 49 320-0-60 45 50 49 44 40 39 57Elem S 1 3 3 4 7 2 810-34-0 14 24 24 44 40 39 57Total N 502 531 517 590 594 537 656

Total P2O5 184 201 210 243 243 232 273Total K2O 43 34 33 38 37 35 44

Total S 3 8 13 13 20 13 23

In 2007, corn acres increased in ND and soybeanacres decreased. The result was a dramatic increase intotal N, P and K used. A wetter spring and signs of sulfurdeficiency probably contributed to the increase in S. Notmany years ago, most S applications were to canola, butrecently S deficiencies have been present in many fields,so general use for small grains and corn has been moreregular. Soil test K levels continue to decline as moresoybeans and corn are raised and K is removed at a muchfaster rate than our small grain rotations of the past. As Ncosts increased, the percentage of total N as ammoniaincreased for the first time in many years. I expect thattrend to continue through the first half of this year at least.Notice that MAP and DAP positions in use havedramatically changed since 1995. The phosphate minesources that could easily make DAP have been depleted.The industry has changed its position, at least in theNorthern Plains, to a MAP market. A concern to me is therecent increase in use of elemental S. The work byresearchers in North Dakota and Canadian Provinces haverepeatedly shown that elemental S is not nearly asefficient in supplying S as soluble sulfate forms such asammonium sulfate. I fear that industry pressures onstorage space and rate of S with seed issues is driving thispoor agronomic practice. Hopefully, grower pressures anda change in industry marketing will reverse this trend. Theuse of 10-34-0 is expanding as new planters discontinuedry fertilizer boxes in favor of pumps and liquids. Notethat use more than doubled in five years. Part of ourproblems with obtaining 10-34-0 this spring is likely thatthe demand was much higher in 2008 than even 2007.


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If you are wondering where the demand for additionalfertilizer is coming from, a small part of the reason is righthere in North Dakota. In the last ten years, N demand hasincreased over 20%, P demand by about 50%, and Sdemand over 700%. Extrapolate that increased demandover the US and then add into that mix China and otheremerging economies, and the pressures on supply aregreat.

Anhydrous ammonia is now somewhere near 70cents/lb N. Urea is about 80 cents, and 28% about 90cents. If anything will open doors for cheaper product it isthese prices; not now, but in the future. Costs for naturalgas are up, but these gas prices only support ammoniaprices of 25-30 cents/lb N, not the current shortage pricestructure. I would encourage fall application in areas thatdo not have a problem with spring denitrification orleaching, but if a grower needs to wait until spring toapply, wait for deals. They won’t happen until later in thefall. Right now there is tremendous pressure on suppliesdue to Midwest rains, with the accompanyingdenitrification and leaching issues. The central corn beltusually has a significant amount of side-dressed N, andthis was delayed in many areas and is now increasingpressure on dwindling ammonia and 28% supplies. Inaddition, still more growers will need to apply even moreN if preplant or fall N was applied due to N losses. Supplywill dictate price until late fall. If crop prices remain nearthe current levels, expect high prices through next year.Take your banker to dinner.

Dave FranzenNDSU Extension Soil Specialist

[email protected]

DOES GLYPHOSATE PRICE MATTER?Glyphosate has been the herbicide of choice for weed

control for a decade and for good reason. It controlsweeds well without injuring soybeans and its price keptdropping, which made the choice easier. However, thetrend of low priced glyphosate changed in 2008.Glyphosate prices have spiked because of reducedglyphosate supplies and increased demand.

Does this change how glyphosate is used insoybeans? Glyphosate will still be the backbone for mostcorn and soybean weed control programs, but the higherprice may have a couple consequences. First, some peoplemay be tempted to reduce glyphosate rates, which maylead to poor control if the weeds are too large whensprayed. Some people also suggest that reduced rates may

contribute to a shift towards more tolerant weeds.Regardless of price, apply the glyphosate rate that isappropriate for the weed species and size in fields. Avoidthe temptation of reducing rates below those needed foreffective control just to save costs.

The second consequence of higher glyphosate pricesis that it may open the door for some other herbicideoptions. Consider the preemergence (PRE) herbicides.The cost of several PRE herbicides that are recommendedas foundation treatments in Roundup Ready soybeans maybe similar to the current cost of glyphosate. “Foundationtreatments” often refer to PRE herbicides that are appliedat lower rates to provide early season weed suppression.They can help to control weeds that might be tougher tocontrol with glyphosate alone or provide early seasonweed suppression so that glyphosate can be applied closerto soybean canopy closure. As a result, more consistentand higher levels of weed control are typical (based onuniversity test results). Adding a PRE herbicide alsobrings another herbicide mode of action into the weedmanagement program, which may reduce the selectionpressure for glyphosate-resistant weeds.

Conditions where 2 glyphosate applications may berequired:

• 30-inch row soybeans• Weeds with extended emergence (ie waterhemp,

common ragweed)• Tough to control weeds (See page 107 in the ND

Weed Control Guide)

Standard 2 pass glyphosate* = $12 + $12 = $24/APRE herbicide* and POST glyphosate = $12 + $12 = $24/A*Actual costs will vary depending on herbicide and rate,but can be very similar.

Most of the foundation herbicide programs have beenpromoted to improve broadleaf weed control and many ofthe common options are listed below. Some otherherbicides provide effective control of a mix of broadleafand grass weeds while others are primarily effective ongrass weeds. Glyphosate is only one of many items with arapidly changing price. The prices of crops, fertilizers,seed, fuel, and land are all in flux and it may be temptingto cut costs. However, remember that the goal of a weedmanagement program is to protect yield. The old sayingabout being penny wise and pound foolish certainlyapplies to weed management. Herbicides are a wiseinvestment. This investment may now include more thanjust glyphosate. The price increase of glyphosate shouldmake us consider if other herbicide options have a fit insoybean systems and provide benefits to improve overallweed management.


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IS A RESIDUAL NEEDED WITH POST CORNHERBICIDES?

I have received a few calls about the need for residualactivity with postemergence herbicide applications. I’mgoing to focus on grass weeds, which were the basis for thecalls. Of course, every situation differs. In some areas,weeds had emerged before it rained to fully activatepreemergence herbicides. These fields may still get somebenefit from the preemergence herbicides, but the escapesstill need to be controlled. Other fields that are being treatedentirely postemergence may have a greater need for residualactivity as there was no residual herbicide in the system yet.

Let’s consider a crop planted on May 1 for an example.We would typically like to have 8 weeks of residual weedcontrol provided by a preemergence herbicide. By that time(July 1), the corn should be canopied and shading out mostweeds emerging during the rest of the season. Plus, weedgermination is also greatly diminished by that time of thesummer. If we are making a postemergence application onJune 1, we normally don’t need 8 weeks of residual activityanymore. Rather, about 4 weeks of residual activity shouldget us to the same July 1st date. With the cool weather thismay be pushed back. We can get that residual activity twodifferent ways. One way is to get the residual activity fromthe postemergence herbicide. The postemergence grassherbicides differ in the amount of residual activity that theyprovide. Under conditions where a rain is received a coupledays after application, which would activate their residual, Iwould rank the herbicides in the following general order:glyphosate (no residual), Liberty (< 1 week), Option (about1 week), Accent and Stout (1-2 weeks), Steadfast andResolve (2-3 weeks). Of course, these estimates will varyon the weed species, their density, rainfall, etc. and shouldbe used as a relative guide. So, some of these herbicides canprovide some residual and may be sufficient especially ifcleaning up escapes from a poorly activated preemergenceherbicide. Others would benefit from additional residualactivity.

A second way to get residual activity is to add apreemergence herbicide to the tank mix. A full rate is notneeded anymore since 4 weeks have passed since plantingin this example. A half rate should be adequate in manycases at this point in the season. Using a half rate alsomakes the addition of a residual herbicide more palatablewhen considering the cost. Herbicides to consider includethose in the acetanilide family (i.e. Dual, Harness, Outlook,etc.) and Prowl. These herbicides do not havepostemergence activity on grasses, but can provide thedesired residual activity. Their benefit would be mostobvious with herbicides like glyphosate and Liberty.

A wide range of field situations and needs certainlyexist in corn fields across the area. However, if the timepoint in the season (the time between planting and canopy)and some basic principles are considered, appropriatedecisions on the need and benefits of residual grassherbicides can be made.

Rich ZollingerExtension Weed Specialist

[email protected]

UPDATE FROM THE NDSU PLANT DIAGNOSTICLAB

The tables below summarize samples received andprocessed by the NDSU Plant Diagnostic Lab for the pastweek (June 25 through July 1, 2008).

Table 1. Number of Sample Submissions by Category.Sample Category # of samplesField crops 19Woody ornamental -Deciduous 11Seed health/Phytosanitary 23Woody ornamental - Evergreen 3Perennial 1Total 57

Table 2. Diagnoses by state, county, and host.State-County

Host Diagnosis

KS-Grove

Field Pea (Pisum sativum)

Foliar bacterial disease(Pseudomonas sp.)

KS-Unknown

Field Pea (Pisum sativum)

Foliar bacterial disease(Pseudomonas sp.)

MN-Polk

Sugar beet (Beta vulgaris altissima)

Fusarium root rot(Fusarium sp.)

MN-Polk


Rhizoctonia root rot(Rhizoctonia solani)

ND-Barnes

Corn (Zea mays)

Bacterial leaf spot(Pseudomonas sp.)

ND-Bottineau

Sunflower (Helianthus sp.)

Herbicide carryoversuspected

ND-Cass

Blue spruce (Picea pungens)

Stigmina needle blight(Stigmina lautii)

ND-Cass



ND-Cass



ND-Cass

Durum wheat (Triticum turgidum)

Fusarium root rot(Fusarium sp.)

ND-Cass


Common root rot(Bipolaris sorokiniana)

ND-Cass


Pythium root rot(Pythium sp.)

ND-Cass

Elm (Ulmus species)

Squirrel damage

ND-Cass

Silver maple Mechanical damage


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Table 2. Diagnoses by state, county, and host (continued).State-County

Host Diagnosis

ND-Foster

Elm (Ulmus species)

Scale insects (Orderhomoptera)

ND-Foster

Elm (Ulmus species)

Woolly elm aphid(Eriosoma americanum)

ND-GrandForks

Apple (Malus domestica)

Plant bugs (FamilyMiridae)

ND-Griggs

Potato (Solanum tuberosum)

Herbicide injury

ND-Griggs

Potato (Solanum tuberosum)

Herbicide injury

ND-Cass

Corn (Zea mays)

Herbicide injury

ND-McLean


Unknown abioticdisorder

ND-Morton

Wheat (Triticum species)

Drought stress damage

ND-Morton

Wheat (Triticum species)

Herbicide injury

ND-Mountrail

Scotch Pine (Pinus sylvestris)

Drought stress damage

ND-Mountrail

Spruce (Picea species)

Root injury

ND-Ramsey

Green Ash (Fraxinus pennsylvanicalanceolata)

Ash anthracnose(Gloeosporium aridum)

ND-Steele

Dry Bean (Phaseoulus vulgaris)

Herbicide injury

ND-Towner

Watermelon (Citrullus lanatus)

Heat canker

ND-Traill

Soybean (Glycine max)

Insufficient sample

ND-Walsh


Girdled branch

ND-Walsh


Frost injury (earlyseason)

ND-Walsh

Siberian elm (Ulmus pumila)

Spring cankerworm(Paleacrita vernata)

ND-Walsh


Herbicide injury

ND-Wells

Linden (Tilia sp.)

Eriophyid mites(Family Eriophyidae)

SD-Dewey

Choke cherry (Prunus virginiana)

Herbicide injury

Kasia KinzerNDSU Plant Diagnostician

[email protected]

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

South-Central ND

During the past week (June 25 to July 1), the regionreceived rain ranging from less than 0.1 inch at Edgeley,Linton, Streeter and Wishek to over an inch at Carringtonand McHenry, based on NDAWN (North DakotaAgricultural Weather Network). Additional rain generallywould be welcome in the region.

Crop growth continues to accelerate with warm weather.Barley is headed and spring wheat is in boot to floweringstages. Much of the region’s corn will be ‘knee high’ onJuly 4. Corn planted on May 1 at Carrington is at about600 growing degree day (gdd) units and Oakes at 725 gddunits as of July 1, with both sites continuing to be behind80 to 100 gdd units compared to the 5-year average. Soybean is in the 2-trifoliate stage or beyond and willsoon start flowering. Sunflower is rapidly growing.

Initial POST herbicide application is near completion inrow crops. Wheat foliar diseases are present but continueto be at low incidence. Farmers are making decisions onfungicide application for control of spring wheat leafspotdisease and suppression of Fusarium head blight (scab).Currently, scab risk is low but the continued threat ofleafspot disease, along with good yield and commodityprices, appear to favor application of foliar fungicide.Small grain aphids have been detected by the south-central ND IPM scout, while soybean aphids have yet tobe found.

Greg EndresArea Extension Specialist/Cropping Systems

NDSU Carrington Research Extension [email protected]


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F. Adnan Akyüz, Ph.D.Assistant Professor of Climatology

North Dakota State Climatologisthttp://www.ndsu.edu/ndsco/

Non-Profit Org.U.S. Postage

PaidPermit No. 818

Fargo, N.D.

North Dakota State UniversityCROP & PEST REPORTExtension EntomologyHultz Hall 202Fargo, ND 58105-5346

Sam Markell, Co-EditorPlant Pathology231-8866 phone231-7851 fax

Janet Knodel, Co-EditorEntomology231-7582 phone231-8557 fax

Plant Sciences231-7972 phone231-8474 fax

Soils231-8881 phone231-7861 fax

Weeds231-7972 phone231-8474 fax

Ag Engineering231-7261 phone231-1008 fax

Helping You Put Knowledge To WorkThe information given herein is for educational purposes only. References to a commercial product or trade name is made with theunderstanding that no discrimination is intended and no endorsement by the North Dakota Extension Service is implied.

NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and the U.S. Department of Agriculturecooperating. 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, sex, handicap, age, Vietnam era veteransstatus, or sexual orientation; and are an equal opportunity employer.This publication will be made available in alternative formats for people with disabilities upon request (701) 231-7881.

NDSU Crop and Pest Report http://www.ag.ndsu.nodak.edu/aginfo/entomology/ndsucpr/index.htm

no. 8 july 3, 2008 - ag.ndsu.edu€¦ · adult flea beetles can be collected with sweep nets. after...

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