cq perspectives jan 2010

8/4/2019 CQ Perspectives Jan 2010

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OFFICIAL PUBLICATION OF CROP QUEST AGRONOMIC SERVICES, INC

C r o p Q u e s t P e r s p e c t i v e s

Volume 20 Issue 1 January 201

Continued on Page 3

How do you know when weeds areresistant to a particular family of

herbicides?Poor timing of herbicide application, nozzles

clogging, operator error in application, evena bounce or two here and there with the sprayrig all are among hundreds of viable reasonsweeds survive herbicide application.

Herbicide resistance starts with one plant.Through random chance, that numbers in mil-lions-to-one odds, a gene is turned the wrongway or a crease forms in the gene wall and aplant becomes tolerant to a herbicide. That plantproduces seed and new weeds. Herbicides kill offthe competition and the herbicide tolerant weedis left with an ideal environment to grow.

Its not an overnight occurrence, but in amatter of three or four growing seasons, that onesolitary resistant weed can turn a productive,protable eld into a nightmare for a grower.The rst key to managing herbicide resistance isrecognition.

Roundup, or glyphosate, resistance is thebiggest name in the herbicide resistance game,but its far from the only material plagued withresistance problems.

In southern Illinois, pigweeds and water hempare resistant to four distinct herbicide modes ofaction: ALS-inhibitors, glyphosate, PPO-inhibi-tors and triazines.

In Missouri we only have triple-stackedweeds, states Kevin Bradley, University of Mis-souri Weed Scientist. He adds that the occurrenceof resistance to glyphosate, PPO-inhibitor, andALS-inhibitor herbicides in one weed is still rarethroughout the Plains. However, the implicationsare dire for farmers, if this level of resistancespreads rapidly through corn/soybean-producingareas of the country.

According to Bradley the biggest economicthreat to growers is dealing with glyphosateresistant pigweed. Crop Quest Agronomists areseeing an increase in possible glyphosate resis-

tance in two of the common pigweed species,Palmer amaranth and water hemp, across the

High Plains.Phil Westra, a weed scientist at Colorado

State University says the outlook for herbicideresistant pigweed is not good. He has uncovereda fourth mechanism for glyphosate resistancethat could further challenge growers to developgood resistance avoidance programs.

Westras research team has found a new mech-anism in which the plant dramatically increasesthe number of copies of a gene critical forglyphosate to work. The glyphosate moleculesattach to the protein produced by these genes andessentially prevent the weed from being affectedby the glyphosate.

A typical plant will have two copies of thegene. In a glyphosate-resistant plant we have

NEW DISCOVERY INCREASESTHE IMPORTANCE OF

HERBICIDE RESISTANCEMANAGEMENT

Up to now scientists have workedwith herbicide resistance developmentfrom three technical perspectives:

uAltered target site in which thereis mutation for a certain enzymein a gene. This is the classicmechanism for ALS-inhibitorsand sulfonylureas.

vAltered translocation pattern inwhich the plant sends the herbi-cide to areas of the plant whereit cant hurt the plant. This isa typical method of develop-ment for horseweed resistance toglyphosate.

wMetabolism in which an enzymein the plant breaks down the her-bicide. This has not been docu-

mented in the U.S., but is com-mon in other parts of the world.


2/4C r o p Q u e s t P e r s p e c t i v e s w w w . c r o p q u e s t . c o

What a differencea year can make. Last

year, we were looking atsky high fertilizer prices, and

availability was on everyonesmind. Cropping plans were made

based on getting by with the lowest amount offertilizer. In a lot of cases, the decision was made to

limit the amount of phosphate and potassium fertilizer and allow thecrop to use some of the residual soil fertility. This was a good decisionfor the economic situation we were facing.

Today, we have fertilizer prices that are one-third of last years. Thisprovides an opportunity to not only return to normal fertility practicesbut also to catch up on elds that were limited in the past. Phosphateand potash are two nutrients that can be built up in the soil by ap-plying more than the amount needed by the crop. The soil can holdthese nutrients in reserve for future use. Nitrogen is a mobile nutrient

and cant be stockpiled in the soil for the future as losses will occurthrough leeching.

The decision of how much fertilizer to apply is both an agronomand economic one. A soil test is the best way to determine the fertilevel of the eld. Armed with the information from the soil test, aplan can be made for the amount and type of fertilizer to apply. Theconomics of the recommendation can then be weighed. To determthe nal amount of fertilizer to apply, you will need to decide if yowant to fertilize for the next crop only or to build up the nutrient le

for the future.The method of application should also be considered. Banding o

fertilizer, either on the surface or injected in the soil, limits the surfarea of soil contact and keeps it available for the crop. Because thefertilizer is not being tied up in the soil as eas-ily, banding is often thought to be a moreefcient way to apply the fertilizer. Thisefciency can be used to our advantageto stretch our fertilizer dollars byreducing the amount of fertilizer tobe applied in tough times. However,if banding a lower amount of fertil-izer than the crop is removing fora number of years, the soil fertility

level will decline.Many factors must be consideredwhen developing a fertilizer recommen-dation. Soil sampling is the rst step, andyour Crop Quest agronomist will assist you indeveloping the best fertilizer plan for your operation.

PREPARING SEED BEDS

IN WET SOILSOver a good portion of our trade area,

we have dealt with wet soil conditionsduring the fall and early winter months.Harvest delays were very frustrating toall of us. These wet soils have left manyelds with serious harvest track prob-

lems. Fall fertilizing has been delayed oris non existent.Once we get a chance to get back into these

elds, the tillage window is going to get pretty

short. This could affect what tillage operations can be done priorto planting. It may also affect our fertilizer program, and whatproducts are applied. Strip tillage has become very popular thelast few years, and anhydrous ammonia is a popular nitrogenchoice for this operation. If the anhydrous is applied too close toplanting, we can see salt injury to the crop. You might need toconsider substituting anhydrous for a liquid nitrogen fertilizer.

There is also a tendency to deep rip ground that has beencompacted by harvest equipment. Deep ripping works quite wellin drier soils where we see good fracturing of the compactedlayer. On the other hand, deep ripping wet soils can be counter

productive. We can actually seal the ground off worse by tryinto rip wet soils. If ripping is delayed until spring, we lose thebenet of the freeze/thaw effect. Fall ripping allows time forcold temperatures to freeze and thaw the large clods, which mlows the ground further. It does take soil moisture for this effeto occur. Since we already have wet soils, we should benet frthis freezing and thawing effect even without ripping. It will bimportant to evaluate the ground prior to ripping to make surwe will achieve the desired results. It is also important to distguish between packed equipment tracks and a true compactio

layer. There may be a need to just smooth out the tracks withless aggressive equipment instead of automatically assumingthat the eld needs to be deep ripped.

Crop Quest Agronomists can help you decide what type of tage needs to be done this spring. For many elds, we may haveto break the normal pattern of no tilling or minimum tilling aeld for a year to get the eld back into shape.

For most of us, we are always glad to see abundant precipitation. We just need to adjust to the conditions. It also bodes wefor the prospects of starting the new year in good shape, andhaving a good crop in the coming year!

Ulysses, Kan.

By: Dwight KoopsRegional Vice President

St. John, Kan.

By: Jim GleasonRegional Vice President

Opportunity to Enhance Soil Fertility


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New Discovery ... Continued from Page 1

When customers hire a Crop Quest agrono-mist, they know they are hiring much more

than just a crop scout. Because we con-sult in such a dynamic industry, a broadunderstanding of the many factors that

may contribute to our customers successis imperative. Our agronomists continueto go through a variety of professional de-

velopment initiatives to ensure they havethe most current agricultural information

available when making recommendations.Topics for Professional Development continue

to become more diverse as new technology is adapt-ed and more research is conducted.

It is our job to share this information directly with you- our customers. Therefore, we attempt to write inter-esting, thought-provoking and relevant articles in thisnewsletter.

The previous edition of the Crop Quest Perspectives hadan article on the Erratic Nature of Climate Changefeaturing Jerry Hateld, one of our Full Staff Meetingskeynote speakers. Because of this article, we recently hada client call in saying he wasnt happy about Crop Questpromoting global warming. To clarify this misunder-standing, the article was not promoting global warmingas it was not even mentioned. I realize some people jumpto concluding global warming when they see phrases likeclimate change, but climate change happens whether we

are warming, cooling, or just in a short weather cycle.The whole purpose of this article was to point out the

facts. We are seeing more erratic weather conditions,and this calls for different management practices. JerryHateld has a lot of experience and data regarding climate

change and the impact it can have on cropping conditions.As agronomists, we need to understand the changes that

are occurring and the impact they may have on croppingsystems. Being aware of how these climatic changes canaffect insect cycles, diseases, and plant tolerance to droughor wet conditions will aid us in making the best recom-mendations possible for our customers. Awareness willhelp alert us to changes that need to be made to lessen theimpact of these erratic changes on a farmers crop.

I am less concerned with if we are in a global warmingcycle, a global cooling cycle or whatever cycle makes thenext headline. I really doubt that man has much of an ef-fect on such a long-term cycle; the climatic scientists caneven agree on that topic.

Crop production is what our agronomists are con-cerned about and anything that may have an impact onyield is important for us to understand.

If you have suggestions or topics you would like to seecovered in this newsletter, please feel free to submit yourideas to our headquarter ofce at 620-225-2233 or viaemail at [email protected]. You can also nd uson Facebook. Thank you for your business; you areappreciated!

found up to 160 copies ofthe gene that produces theenzyme to which glyphosateattaches, Westra explains.

The pigweed plantpumps out these genecopies, which in effectdilutes glyphosate to thepoint of being ineffectivein controlling these weedpests. When glyphosateis sprayed on one of theseresistant plants, some of themolecules are tied up, but

plenty more are around andnot affected by the herbi-cide, Westra explains.

This occurrence ofgene amplication as aherbicide resistance mecha-nism in a naturally occur-

ring weed population is particularly signicant because it couldthreaten the sustainable use of glyphosate-resistant crop technol-ogy, Westra contends.

The molecular trait in pigweed is passed along via pollen. Pollencan easily move 300 to 400 feet in a cropping season. Westra saysthis explains why growers usually see a pigweed or two sticking upin a eld one year and the next year have an oval-shaped clump of

weeds that may be 20 to 30 feet across.This type of mechanism for spread of Palmer amaranth is not

good news for farmers, but it is critical in understanding howherbicide resistance spreads and accentuates the need to avoid theproblem by alternating herbicides with different modes of action.

If a high percentage of pigweed, either Palmer amaranth or itsclose cousin water hemp proves to have tolerance to glyphosatevia the gene amplication mechanism discovered by the ColoradoState University researchers, the options for growers become morlimited. And, the need for a herbicide resistance plan for each crobecomes more critical.

A side effect of the new discovery is the development of a highaccurate, fast test method for glyphosate resistance. Though notcommercially available, USDA Researcher Dale Shaner has deve

oped an assay test that can be done on leaf samples and providesa denitive answer to whether a plant is glyphosate resistant in acouple of days.

As for now the best test for glyphosate resistance is to have asmany eyes as possible looking for plants that are not controlledby the herbicide. Having a crop consultant, armed with a croppinghistory of the eld and the knowledge of what resistant plants loolike in the eld is likely the best scenario for detecting glyphosateresistance.

Putting together a workable, both from a production and aneconomic perspective, herbicide resistance plan is a good insurancpolicy against what is sure to continue to be a serious productionproblem for farmers.

Member, National Allianceof Independent Crop

Consultants, CPCC-ICertied

By: Ron OHanlonPresident

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cq perspectives jan 2010

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