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Issue 1 - April 4, 2008

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Issue 1
April 4, 2008

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Table of Contents:

• Through the looking glass
• The Problem with Agriculture
• Corn on Corn Production
• Next Issue

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Through the looking glass - Comments on production agriculture with emphasis on the current state of pest management in the northern Corn Belt cropping system

I was not planning to write a newsletter during the 2008 season. A concerted academic, ag industry and regulatory approach to pest management has apparently beaten most common pest problems into submission. Further, new evidence suggests that long held assumptions on pest/crop interactions may not be valid.

Please read the following points with caution. The points presented below may or may not reflect your personal view of reality. They are filled with inaccurate correlations, half-truths and other malarkey extrapolated and refined from real-world political, marketing and sales efforts. The following discussion is not meant to imply that politics, marketing and sales are inherently evil.

Entomologists, and to a lesser extent, workers in other pest-based disciplines, are doing some soul searching. Peer group discussions as well as public displays of angst, center on the death of Integrated Pest Management (IPM) in commodity crops. The academic community is trying to determine if in fact, the philosophy has died, or is merely in a state of diapause or hibernation. Another hypothesis, which does not have widespread support, suggests that instead of extinction, IPM has become so highly evolved that it no longer resembles its primitive ancestor. IPM has long been held as an obvious truth with the entomological community. Understandably, any perception of IPM's potential demise is deeply troubling.

The symptoms of poor health for IPM began to appear at approximately the same time glyphosate tolerant crops were introduced. The first signs of stress amongst agriculturalists were observed in those individuals specializing in the previously many faceted discipline of weed management. However, the timing of IPM's perceived demise relative to the introduction of transgenic crops may be only corollary and not causative in nature. Most entomologists are currently too traumatized to perform a detailed analysis.

Unemployment fears among IPM practicing agriculturalist are intensified by the knowledge that reduced corn acreage will soon drive food prices to record highs and all available employment niches within the plant pathology discipline have already been occupied by weed science refugees.

I have been taking classes at the University of Minnesota since January and have had limited communication with the outside world. Nevertheless, through conversations with individuals involved with production agriculture, reading popular farming literature, and listening to the radio, I began to realize that there are some problems with the logic previously used for crop pest management. It is now apparent and appears common knowledge that:

1. Soybean aphids will still be a problem in 2008. Suction traps caught few aphids last fall and examination of buckthorn tends to indicate that egg populations going into the winter are low. Aphid populations, however, are irrelevant when managing soybeans. The most likely reason for the very low expected 2008 soybean aphid populations is obvious. With $10-$13 soybeans, treatment should begin at a very low level. When economic injury level calculations are made using more than $15/ bushel soybean prices; it should be easy to see why the economic threshold would trigger blanket spraying at 1 soybean aphid/county. Since it is impossible to sample an insect at this low density, a calendar based, season long aphid treatment schedule should be adopted. Previously discounted sub-250 aphid/plant soybean aphid thresholds may have been prophetic when viewed in an historical basis.
2. Soybean rust will never be a problem in Minnesota. Although this disease may never see a Minnesota soybean growing season, it has, arguably, caused more economic impact than all other soybean diseases combined. On the debit side is the cost (time) spent in meetings being scared about the potential problem (movie theatre attendance and rental of horror videos have declined since this disease was reported in South America). Initially, I was concerned about dollars wasted through needless fungicide applications but have since been proven wrong (see points 3-5). On the credit side, attendance at APS meetings has increased. Although the number of spores contained in a basidium remained a mystery, many agronomists learned how to spell Phakospora rapidly developed the ability to speak at length about plant pathogens. Perhaps the least recognized benefit of the soybean rust phobia was the rapid labeling of numerous fungicide compounds for soybean. This led directly to the discovery of the yield benefits of treating imaginary disease.
3. Transgenic crops and other forms of host plant resistance have solved our insect, weed, disease, and nematode problems long-term. This will allow producers to focus on management tasks that are really important and add to the bottom line. Formerly, great concern over the development of pest populations able to damage plant host resistant varieties caused some moderation in use of these traits. We now know that stacking similar genes/proteins within a plant eliminates the potential for pest resistance. In fact, it is so effective that refuge requirements could be dramatically lowered. Plant genome based insect and disease controls are obviously much less likely to create resistant pest problems. It is in the plant, after all, and there is no way for the insect or disease to escape death. If this theory fails in practice, industry has a lot of products on the shelf just waiting to be placed in the battle. For just this reason, resistance to a pest management product is welcomed by the pesticide industry; provided resistance develops the year after a product goes off patent.
4. Although point 3 makes crop protection chemicals obsolete, seed applied and post emerge applications of herbicide and particularly insecticide and fungicide can produce a plant vigor effect known by one of several trademarked terms. This effect is most commonly observed in the absence of disease or insects. More frequent pesticide applications increase the probability of seeing this type of response. We now know that timely application of these products can actually eliminate the adverse effects of bad variety selection, field preparation including tillage and fertilizer management, and all manner of poor agronomic practices. Scouting would unacceptably delay the speed with which pesticide recommendations could be made. Therefore, a calendar based spray program will be the only viable alternative. An unfortunate side effect could be an accelerated economic collapse due to a major reduction in sun screen, hand lens, identification guides and soil probe sales (Yes, soil fertility management is undergoing a similar renaissance). We can hope that the Federal Reserve and Congress are ready to react quickly with changes in monetary policy and a targeted stimulus package if increased sales of spray tips cannot compensate for reduced sales of crop scouting paraphernalia.
5. We have entered a new era. We now know that high commodity prices can change not only economic thresholds, they can actually change biology. As a result, high value crops suffer detectable yield loss at much lower levels than the same variety when prices are low. A breakthrough in our understanding of economic thresholds occurred when it was discovered that reducing the rate of a fungicide until application costs were equal to a very low expected yield benefit still provided the vigor effect mentioned previously. It is now possible to match a fungicide rate to any level of expected yield loss. The underlying principle might also apply to insecticide and herbicide applications but these have not been adequately tested. The issue is not if a pesticide application will pay; but whether aquifers, already stressed by ethanol production, can supply the increased need for spray carrier. Research is currently underway to determine whether or not a yield benefit can be obtained simply by purchasing a product or does an inconvenient pesticide application actually have to occur. Parallel discovery indicates that it is impossible to purchase too much insurance. Research, conducted mainly within the seed industry working on transgenics, indicates that pest induced yield loss, as a percentage of yield, is positively correlated with the yield potential of a field. These last two studies, when viewed as a whole; show that it is imperative that pests should be treated at lower levels in high yielding crops. Intuitively, a calendar based pest management program, with redundant pest controls is the most efficient option.

Hopefully you can see that the above are not good strategies. They are only partly if at all, grounded in reality, and a recipe for disaster. These strategies may lead to an earlier than desired retirement, perhaps on a wide scale, from production agriculture. They are presented to make a point. IPM principles are still valid. If you don't get the point we have the rest of the growing season to make it clearer.

The Problem with Agriculture

The document at http://www.cis.gsu.edu/~dstraub/Courses/Grandma.htm contains an analogy for all that is really wrong with agriculture and it's perception of reality. Perspectives of producers, industry, government and academia are equally represented. This document was presented during a statistics course to illustrate the dangers of bias, observational studies and misinterpretation of data. Please take some time to read this document carefully. I will discuss the findings of in the next IPM stuff issue. Dr. Adams groundbreaking 1990 treatise illustrates errors that occasionally occur in scientific publications. Those who interpret research findings for political reasons are especially prone to errors of this type. Examples are readily observed in both sides of climate change and bio-fuel debates. More germane to this discussion, some examples can be found in peer-reviewed pest management studies and examples are abundantly represented in marketing information. Finally, with a bit of introspection, the readers of this article should be able to find related problems in how they collect or interpret data. Over the course of the growing season, I'll try to explain the problems involved in collecting and understanding pest management data and the ever present threat of bias affecting both.

Knowledge is power. The pursuit of the truth has no end but knowledge combined with an understanding of the truth is freedom. Then again, being asked questions stresses and irritates some people and it's a lot easier to just do as you are told.

Corn on Corn Production

For those of you that haven't talked yourselves out of it yet, here is a check list put together a year ago. It seemed to have been more or less accurate. More importantly, it appears to do no harm.

U of M SWROC Winter Crops Day

February 7, 2007

B. Potter

• Primary tillage
  • No till corn on corn risky in our climate
  • The yield effects of between row residue less severe ( zone tillage) and may be correlated to width of tilled zone
  • Assuming full width tillage, residue sizing will ideally be done before or width with primary tillage.
  • Partially incorporated un sized residue can/will cause seed bed and planting issues
• Seedbed preparation
  • Sized residue to allow planting
  • Firm seedbed encourages consistent seeding depth
    • Late emerging corn plants do not contribute to yield
    • Field cultivators tend to lift residue. High corn residue fields may require changes in spring tillage
  • Till and plant when field conditions are good
  • Everything within reason and moderation
• Residue management
  • Much more residue following corn
  • Surface residue in the row is detrimental (cooler and wetter)
  • Shallow buried residue in the row can impact germination or early development
  • Good row cleaners needed
• Nitrogen management
  • N rates for corn on corn need to be higher than corn following beans
    • Greater N immobilization on large amounts of corn residue
  • Be ready with rescue application or plan for side dress - Don't overdo Popup N
  • Spring application (all or part) desirable
    • Increasingly so under higher rainfall conditions
• Hybrid selection
  • High yielding corn on corn hybrids are not always good corn on corn hybrids
  • Try to avoid planting the same hybrid(s) back to back
  • Defensive traits more important
    • Root and stalk scores
    • Early season growth
    • Drought tolerance
    • Leaf disease and stalk rots
• Pest management
  • Weeds
    • Watch for and manage species shifts -
  • Insect control
    • Corn rootworm and European Corn borer tend to be worse in continuous corn fields
    • Both insects can interact with stalk rots o An economic response to control not guaranteed
    • Continuous transgenic corn (ECB, CRW) will push insects to deal with the trait
  • Disease
    • Watch for early season foliar diseases
    • No evidence that prophylactic fungicides improve yield consistently

In the next issue: How yield loss really happens.

Bruce Potter 
IPM Specialist SW Minnesota
University of Minnesota Extension Service
Department of Entomology
University of Minnesota Southwest Research and Outreach Center
23669 130th Street
Lamberton, MN 56152
Ph:       507.752.5066
Fax:     507.752.5097
E-mail: bpotter@umn.edu
http://swroc.cfans.umn.edu/SWMNPEST/swmnpest.htm