Agronomy Notes

June 3, 1999

Contents

SOYBEANS

Dr. Alan Blaine

As of mid-May, the crop report showed the Mississippi soybean crop 63 percent planted, the highest percentage ever for this time of year. Considering the spring weather Mississippi experienced, it is really amazing how much growers accomplished early.

This spring reemphasized the importance of applying burndown herbicides. In many fields we waited in hopes of being able to get in and perform some tillage early, but in many cases that opportunity never presented itself. Existing vegetation worked against growers as it required much more tillage once we were able to get in the fields.

Excessive tillage (which was needed to destroy large vegetation) caused many fields to dry faster than most felt possible. Although normally not a problem, this year should serve as a reminder about the benefits of early burndowns.

Regardless of your cropping plans, your foremost goal is to avoid a delay in planting. Delaying a burndown application or not using one at all sets up many fields for later planting; this was particularly true in the Hill area of Mississippi.

The concept of early planting has not really caught on in the Hills as in other areas, but it should. Higher yields have become more of a norm than chance; however, some producers have not even tried planting earlier. In any cropping system, your goal should be to avoid planting delays. This year a burndown program should have been a part of your plans.

Encourage producers to try this new concept. Many have nothing to lose but it will require a change in their ways of doing things for it to work. Just because you have always done something a certain way does not mean a better alternative is not available. Encourage producers to start small but at least give it a try.

One reason it is imperative to rethink current plans is a point made by Dr. Normie Buehring. He told me that in his 25-plus years at the Northeast Branch Experiment Station in Verona, he is in the best shape ever (crop wise) for this time of year. He accomplished this through the use of stale seedbeds and burndowns. The experiment station is in the center of northeast Mississippi, and there is no reason more of us cannot be in the position Normie is at Verona.

Several problems have surfaced that are worthy of attention. Several replanting situations have surfaced, and most are because the proper seed treatment was not used. If you have questions about the use of seed treatments, ask someone. Don't expose yourself to this potential problem, especially since we know how to control it.

Another problem becoming more widespread is grasshoppers. So far they have been mainly associated with no-till fields. Existing vegetation that was not controlled early has provided a food source for them until the crop emerged. Once this vegetation dies down, these insects will probably begin to feed on any green plants. There is not a good threshold for grasshoppers. It has been my experience that if you wait on 35 percent foliage loss, you will never reach it because of the rapid growth of the soybean crop this time of the year. This problem is a carryover from the dry year in 1998 and the recent mild winter.

Base your decisions to spray on numbers present. As grasshoppers grow larger, they become winged and may fly away, but that may not occur. We have already sprayed several fields based on large numbers and what happened last year. If producers take out this initial population, it may go a long way in helping control grasshoppers the rest of the season.

Several good options are available; the main factor is to look at your crop because this problem is erratic and not occurring in every field. Coverage is a major factor in weed and pest control. We looked at some 5-gallon versus 10-gallon work and there was no comparison, with the higher volume spraying providing almost 100 percent control versus 50 to 60 percent.

Many producers have called about tank mixing with Roundup. If morning glories are your major problem, .25 ounce of Classic added to Roundup is a good option. In the case of other weeds, base your decision on cost. In many instances, you are probably better off just increasing your Roundup rate.

This year has once again reminded us that the best laid plans often do not work out. Two things that come to mind are preemergence herbicides under Roundup Ready soybeans and timing of spraying.

I had someone tell me the other day, they just could not understand why anyone would use metribuzin under Roundup Ready soybeans. Well, I can think of one good reason, and it is called "teaweed." Roundup needs some help on some weeds, and teaweed is one weed not very difficult to control with a pre herbicide.

Another problem has been an ability to spray when needed. I am reluctant to admit it, but we have had to apply conventional herbicides on several Roundup Ready fields because of windy conditions. Given the amount of problems many have had spraying Roundup, pre herbicides will probably play a much bigger role in the future.

Encourage growers to give some thought to what herbicides they are applying. Contact materials need higher water volumes to work properly. Many of the control problems experienced could be solved by applying higher volumes of water to improve coverage. In the case of some herbicides, water is the cheapest thing you can buy.

CORN

Dr. Erick Larson

Be prepared for corn borersóFirst-generation corn borers were found again this year in the Delta during mid-May. The first generation seemed to occur about a 7 to 10 days earlier than last year. This could intensify potential problems because the second generation hatch, (likely in mid-June, 4 to 5 weeks after the first generation), may coincide closely with pollination. First- and second-generation corn borer feedings reduce yield potential mainly by stunting vegetative development and destroying stem tissue responsible for distributing water, nutrients, and energy within the plant.

Intensive field scouting is required to effectively and economically control corn borers, since insecticide contact is impossible once corn borers tunnel into the stalk or ear. However, corn borers hatch and feed on leaf tissue for up to 10 or 12 days before tunneling. During this time, they are susceptible to insecticide applications with optimum (around 80 percent) control normally accomplished by treatment coinciding with peak egg hatch. Egg masses are difficult to find, so use a hand lens and also search for evidence of leaf feeding and small larvae. Newly hatched larvae leave elongated, translucent windowpane and pinhole-feeding scars close to leaf collars within three leaves of the ear leaf. The treatment threshold for Southwestern corn borers is 25 percent of plants infested with either an egg mass or a worm. The treatment threshold for European corn borers is 50 percent of plants infested. Southwestern corn borer larvae are off-white colored and have prominent dark spots on their backs. European corn borer larvae are opaque to light-gray colored and have inconspicuous spots. Second- and third- generation corn borers normally favor later planted corn, if different growth stages are available.

Water stressóCorn is especially sensitive to water stress during a 4-week period following silking, which should occur this month for most of Mississippi's crop. During this period, seasonal water demands normally peak at around 1.75 inches per week; therefore, growers using irrigation should begin incrementally meeting crop demand before system capacity cannot replenish soil moisture, especially with center-pivot irrigation systems.

Chinch bugsóSeveral reports of severe chinch bug damage occurred during the last week of May. The chinch bugs were generally damaging corn and grain sorghum planted during May. Chinch bugs often migrate from native grass ditches or borders adjacent to fields. Grain sorghum is highly favored by chinch bugs, so scout fields thoroughly, especially during warm, dry weather conditions.

Weed controlóThe major weeds competing with corn are present now. Thorough scouting may reveal morning glory, broadleaf signalgrass, or johnsongrass problems that can be suppressed by applying various timely layby treatments. Although control options become limited the taller corn grows, scouting may also provide insight into future problems. Diagnoses of weed history is important for future crops because corn weed problems can usually be more effectively and economically addressed with preemergence rather than postemergence treatments.

SOIL AND NUTRIENT MANAGEMENT

Dr. Larry Oldham

Many reports show that Delta farmers are being advised to add 5 to 6 tons of dolomitic limestone to adjust the soil magnesium level to a better "ratio" for plant growth. I recently read a recommendation in an otherwise reputable magazine that some soils may require 10 to 20 tons of calcitic lime to adjust soil calcium contents to maintain a better ratio. I have also heard reports of adding large amounts of ammonium sulfate to achieve better ratios in the soil.

The 20-ton calcitic rate was recommended for southern Mississippi. A few weeks ago, lime was about $28 per ton in the greater Hattiesburg area; therefore, 20 tons would cost $560 per acre. A 10-acre field would require 200 tons, totaling some $5,600. Would any agronomic response be cost-effective? I don't think so.

The fact is that no ideal cation ratio exists for soils used for growing crops. Bizarre recommendations can hurt your balance sheet, and, furthermore, devastate the yield potential of the soil through nutrient imbalances, but these DO NOT equal a poor nutrient ratio.

There is no substitute for a well-founded fertility-management program based on good, reliable, and repeatable science. Anecdotal evidence is only as good as the current price of a cup of coffee.

SUSTAINABLE CROP PRODUCTION: IS BIOTECHNOLOGY INCLUDED?

Dr. Malcolm Broome

Agriculture in the United States has long had the reputation of being the envy of the world. Much of this is directly attributed to our public and private research institutions. Our food supply is the key to security. New ideas and technology have given the American farmer a competitive advantage.

Biotechnology will, or has the potential, to completely change agriculture as it is known today. Already producers have soybeans resistant to specific herbicides, cotton repelling caterpillars, and corn with high oil content, borer resistance, and herbicide resistance. Crops in the future can be made tolerant to colder temperatures or conditions of varying soil types, both of which could expand the growing regions of the crop. New modifications in vegetables to improve nutrition, or possibly even developing compounds to be used for improved human health, are on the edge of reality. These new technologies also offer a cost savings to the farmer in the form of less purchased inputs, less time (labor) per acre, improved soil tilth, and less runoff or drift. At the same time, these new technologies are benefitting the public by enhancing the environment and quality of the food and fiber produced. By using less pesticides, fertilizer, water, and other resources, the sustainability of agriculture will be greatly increased.

Biotechnology, however, is not without risk from the standpoint of how new products react in the farmer's fields under real world conditions, not just in the laboratory. Also there are concerns as consumers encounter these new foods that are genetically engineered for assurances of safety. The scientific community must be in agreement that a product deemed safe is just that. People can then choose to buy or not, but it will be their choices. Good science should be used along with an active, educational effort to create consumer understanding. Scientists and farmers want to develop and produce crops free of harm to consumers and the environment. Safe must mean safe. Farmers, who live in this same environment, are also consumers and have the same desires for safe products.

Farmers surveyed by "Farm Progress" Magazine report in addition to farming more acres, they are looking at new technology for their businesses. Agriculture, the most important industry of the United States, must remain strong. Biotechnology will provide improved conditions for humans worldwide, and a lot of these improvements will be necessary if the U.S. farmer is to continue to be competitive with other countries. Remaining competitive and the other factors mentioned seem to point to biotechnology's's being involved in some form in agriculture's sustainability.

COTTON

Dr. Will McCarty

June is a critical month for cotton in Mississippi. The squares set in June and early July will essentially be the 1999 crop. You should use every precaution and means to prevent plant damage during this period. The weather is a factor growers cannot control; however, they must manage those things over which they do have control. Keep in mind it is extremely rare that a plant will physiologically abort a square before bloom.

Early Season Management - Early season management is critical in determining final cotton yields and includes such practices as cultivation, postdirected sprays for weed control, insect control, plant growth regulator decisions, and sidedress decisions. You should make every effort to protect young cotton from insect damage and herbicide damage. Sidedress application of nitrogen can begin as soon as a stand is established.

Roundup Ready Cotton - Just a reminder that Roundup herbicide has certain application restrictions in cotton. Read and follow all directions on the Roundup label. If you have any doubts or questions, consult with a Monsanto representative before applications are made.

Staple Herbicide - Staple herbicide is available for over-the-top control of broadleaf weeds. This is an excellent product when used in accordance with its label. Staple over-the-top fits well where no height differential exists between weeds and cotton. If possible, apply Staple in a semidirected spray. This will reduce staple contact with the plant terminal and reduce possible plant stunting. If Staple is used in fields where sicklepod is a particular problem, you may want to add MSMA if you can keep the spray out of the cotton terminals. If no height differential exists and sicklepod is present, you may be better off going over-the-top with fluometuron rather than Staple plus MSMA. (We are not talking about sicklepod control here, just suppression). This application could then be followed by Staple or other appropriate treatment as a directed spray.

On small or uneven stands, use the safest herbicide possible for the first directed spray. In small, broken stands, consider not adding MSMA to the first directed spray unless cocklebur, grass, or sedge is a particular problem. Also, consider the use of low-pressure tips for this treatment, which could reduce herbicide contact with cotton leaves. As cotton gets larger, "hotter" materials and combinations may be used if properly applied.

Nitrogen in Herbicide Sprays - Those who like to use a liquid nitrogen solution at 50 percent of the final solution should not do this with the first directed spray. This has proven to be an effective practice, but cotton must be 10 to 12 inches tall before it is used. With the nitrogen price increase, this treatment is not as economical as it once was. N-Sol in combination with Karmex or Bladex is an effective treatment, but other alternatives exist. Cobra used alone or in combinations is also an effective treatment for hard-to-control weeds. Also, unless it rains within 3 to 4 days, do not count on the N from an N-Sol herbicide combination helping the crop.

Sidedress Nitrogen - Select rates of sidedress nitrogen carefully. Excessive rates of nitrogen will delay maturity while reducing yields and quality. I think growers are doing a better job now (compared to a few years ago) matching nitrogen applications to nitrogen needs. Also, I encourage you to make your sidedress applications as fast as you can. I don't think there is such a thing as putting out sidedress nitrogen too early, but you need to avoid late applications.

It takes about 50 to 60 pounds of supplemental nitrogen per bale of production and on sandy loam to loam soils and about 60 to 70 pounds per bale on clay loams or heavier soils. If some of your cotton is on new cotton land, or has been in corn, rice, or soybeans for several years, or is just strong land, those rates may be reduced by 20 pounds to even 50 pounds in extreme cases. If you are planting cotton into a field where moisture is available and rapid, rank growth has been a problem, evaluate your nitrogen program carefully. Do not take the attitude that you can put out any rate of nitrogen you want and control growth with mepaquat chloride (PIX, etc.). PIX is an excellent material and a good management tool, but that is not the way to use PIX or to grow cotton.

Plant Growth Regulator UseóI receive many questions about the use of mepaquat chloride plant growth regulators (for example PIX). Several options are available on how to use this product. You must base your decisions on a field-by-field basis. This product, or similar products, will not substitute for good management or make a poor crop into a good crop; however, under good management, I feel this product can improve plant efficiency and increase earliness. Proper use should be based on yield history, plant development, fruiting, and crop status. Plant monitoring goes hand in hand with mepaquat chlorate (PIX, etc.) use. I think a key to successful use is to not let the crop become vegetative (with heavy fruit loss) before implementing a plant growth regulator program. Once the crop goes vegetative and fruit is shed, it is difficult to "bring back" into fruiting and, so to speak, be brought under control. Year in and year out, making an application of PIX at first bloom, and if needed making a subsequent application 10 to 14 days later, has been the most successful method of use. Fruit retention and growth potential are critical factors in rate selection.

For more cotton information, please visit my web pages located at: http://ext.msstate.edu/anr/plantsoil/cotton/cotton.html

FORAGES AND PASTURES

Dr. Lamar Kimbrough

In the May issue, it was indicated that I would make a few more comments before my retiring June 30, 1999. Since then, it has been brought to my attention that not all county Extension agents belong to the Mississippi Cattlemen's Association. Let me tell you how to spend your money and suggest you join this association if you have livestock in your county. Also, spend a little more and join the Mississippi Forage and Grassland Council (MFGC), which serves as a standing committee of the Mississippi Cattlemen's Association. This committee generally meets on the first day of the Cattlemen's Convention each fall. These are groups that can help you in working with your county livestock producers. Also, you may have producers that need to become members of these organizations. Without organization, planning, and working together, it is often difficult to stay up-to-date. Yes, if I were the boss, you would all get better paychecks to help pay for this.

With this being my last article before retirement, I would like to say that I have enjoyed working with you and am sure I will miss being your state Extension forage specialist. If you are ever around Starkville and want to go fishing or deer hunting, I might can still help you. However, since we are in such changing time, I will probably become out-of-date on forage production fairly soon . . . then I plan to call on my county Extension agents.

WEED CONTROL

Dr. John Byrd

Yellow and purple nutsedges are two of the most problematic weeds that occur in cultivated areas for some producers. These two sedges are the only two tuber producing sedges that occur in Mississippi, although there are more than two hundred species of sedges that occur locally. Purple nutsedge has been classified as the worst weed in the world. Fortunately, while these weeds infest many acres of cultivated crops, dense populations must exist to reduce crop yields. Also, while the populations are unsightly, if one can obtain some initial control and form a crop canopy over the infested area, the nutsedges are whimps without good sunlight. Generally, there is no need for additional control during the cropping season.

Currently, there are several postemergence herbicides on the market that provide moderate to good control of both purple and yellow nutsedge. In nontransgenic cotton, Staple provides as good control as any other postemergence herbicide, without the potential for delayed maturity associated with topical applications of MSMA or DSMA. In a Roundup Ready cotton or soybean system, Roundup is a good treatment for yellow or purple nutsedge. However, as with many other perennial weeds, Roundup provides the best long-term control, if applied after seedheads emerge. Therefore, application timing usually does not coincide with application timing for general weed control in these crops. And, in cotton, applications at this time of the season would dictate that a directed spray be used to avoid some of the problems that have occurred with fruit retention.

Have received a question regarding the precaution against mixing other herbicides with Buctril in BXN cotton systems. Most of the postemergence grass herbicides are antagonistic when mixed with this herbicide. Sequential treatments are necessary to obtain the expected level of control of both grasses and broadleaf weeds.

This is generally the time of year that many forage and cattle producers receive telephone sales pitches for herbicides. Remember to ask questions and make the seller send a label before the purchase is agreed upon. At the very least, be sure to obtain the active ingredient and concentration before the purchase is finalized. Be sure that the same materials aren't available locally more economically before making the transaction. All too often producers receive the shipment, then realize they could have purchased a more concentrated formulation of the same herbicide ingredient and saved money had they shopped locally.

RICE

Dr. Joe Street

About 50 to 60 percent of the rice crop is flooded or ready to flood which will increase the likelihood of rice water weevil infestation. As the field is flooded, begin scouting for adult water weevils. Feeding scars are an indication that water weevils are present. If the field has a history of water weevil infestation, expect weevils again this season. Some rice stands are somewhat thin and erratic and water weevils will normally be worse in the thin areas. Currently, Dimilin, Furadan and Karate Z are labeled for use for rice water weevil control. Furadan is in very limited supply and existing stocks may be used in 1999.

In April, Dimilin received full federal registration for water weevil control. Dimilin is an insect growth regulator which means it will work slowly, however, it does have good residual activity on rice leaves. Eggs that are deposited after the female water weevils have fed on Dimilin treated leaves will not hatch. The use rate is 12 to 16 fluid ounces of Dimilin within a time frame of 2 to 5 days after permanent flood establishment.

Karate Z, a new formulation, is twice as concentrated as the old Karate 1EC formulation. The use rate range is 1.5 to 2.5 fluid ounces with the average use rate of 1.9 ounces per acre or one gallon to 67 to 70 acres. In most cases, one application of Karate Z within 7 days after permanent flood has effectively controlled adult water weevils. In severe infestations, two applications of Karate Z may be necessary.

If the adults are not controlled and Furadan is not available, the only option for water weevil larvae control is to drain the field and let it dry. This is somewhat risky unless you have an excellent water supply for re-flooding.

Permit, a selective postemergence herbicide, has received a label for use in rice. The primary strong point of Permit is nutsedge control; however, other weeds such as cocklebur, pigweed and smartweed are on the label. Rice tolerance to Permit is very good. Permit may be applied from prior to planting up to establishment of the permanent flood. It is not labeled for post-flood application. Permit may be tank-mixed with any pesticide labeled for use in rice. The use rate is 0.67 to 1.33 ounces of product per acre. In research plots, the lower rates have effectively controlled nutsedge. Permit activity is slow with death of the weeds occurring in about two weeks.

DD50 - A now interactive version of the Rice DD50 program is on the internet at http://ext.msstate.edu/anr/drec/drec.html. If you don't have internet capability, contact your county agent who will run the program for you. This is a text version using real-time weather from the weather station nearest to your farm. If you have any problems, please contact me.

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