IPM NEWSLETTER Update for Field Crops and Their Pests

Transcription

1 The University of Tennessee IPM NEWSLETTER Update for Field Crops and Their Pests West TN Research Education Center 605 Airways Boulevard Jackson, TN No. 23 September 24, 2010 Past newsletters and other information can be found at UTcrops.com Special Wheat Issue: Production Weeds Diseases Insects Economics also Economics of Cotton Second Picking Crop Watch UT Resources for Wheat: Slides from 2008 Wheat Production Conference Weed Control Recommendations for Wheat Insect Control Recommendations for Wheat Cotton Defoliation Tests (Chris Main, Extension Cotton and Small Grains Specialist) Continued warm temperatures are making defoliation easy this year. Two additional defoliation plots were established last week (sprayed on 9/17). One in Haywood County near 5670 Stanton-Koko Road ( N, W) and in Lake County near the north-west corner of the intersection of Madie Road and Highway 78 ( N, W) just north of Ridgely. Signs should be setup by Friday afternoon (9/24) if you wish to observe the results. Wheat Agronomic Considerations (Chris Main, Extension Cotton and Small Grains Specialist) SEEDING DATES AND RATES Dates: For best winter survival and top grain yield, plant wheat from October 15 to November 10. Do not plant wheat until after the fly-free date of October 15. However, planting early in the recommended window typically leads to top yields. Wheat should be planted early enough for young plants to become well-rooted and develop 3 to 4 inches of top growth before going into the winter (December 21 st ). Research indicates that planting during the latter half of the recommended planting period or planting treated seed (systemic insecticide) reduces the incidence of barley yellow dwarf by avoiding or controlling aphids that transmit the virus to wheat. In most Tennessee fields, an insecticide seed treatment will at least pay for itself by controlling early-season aphid populations. Rates: Wheat seeding rates vary from 1.5 to 2.0 bushels per acre depending upon the condition of the seedbed, time of seeding, quality of seed and method of seeding. A seeding rate of 2 bushels per acre should generally be used. Increase the rate to 2.0 to 3.0 bushels per acre (1) if seed are broadcast, or (2) when seeding is delayed until November 1 st. Ideally, you want to end up with 1.3 to 1.5 million plants per acre. Method and Depth: Sowing wheat with a drill instead of broadcasting insures a more uniform depth of covering, higher germination, less winter injury and generally higher yields. Drill or cover wheat to 1

2 a depth of 0.75 to 1.5 inches when adequate moisture is available. When soil is dry, a slightly greater depth is advisable, but should not exceed 2 inches. Broadcast Seeding: The two most important aspects to consider when broadcast-seeding wheat are to insure that adequate seeding rates are used and that good seed-to-soil contact is established. To accomplish these goals, 2 to 3 bushel of seed should be broadcast uniformly and incorporated by a shallow pass with a do-all or similar equipment. Seed that are broadcast and left lying on the soil surface are subject to animal predation, poor germination and frost heaving. All will lead to a loss of stand. FERTILIZATION Apply lime and fertilizer based on soil test recommendations. If lime is needed, it should be applied before seeding. All the phosphate and potash can be applied immediately before or at planting (Table 1). Note, a high soil test for P and K does not require additional P and K inputs for the wheat or double crop soybeans. When double-cropping wheat with grain sorghum or soybeans, fertilizer should be applied to the soil with the total amount of phosphate and potash needed for both crops prior to planting wheat. Apply 15 to 30 pounds of nitrogen at seeding time to stimulate vigorous plant growth unless following soybean which will supply residual nitrogen. Apply 30 to 60 pounds of nitrogen as a top-dressing February 15-March 30. Use the earlier date if the wheat stand is thin to encourage more tillering. All the nitrogen should be applied before wheat begins to joint. Research has shown no difference in source of nitrogen (ammonium nitrate, urea or liquid nitrogen) when applied according to recommendations. Total economical nitrogen needs for a wheat crop grown in Tennessee should be between 45 to 90 lbs. per acre. Consider split-applying the top-dress nitrogen application when wheat is planted after November 15 or when there is an average of less than four tillers per plant in early January. Table 1. Wheat Fertility Recommendations. Soil test level Wheat alone Wheat with double-crop beans P(P 2 O 5 ) K(K 2 O) P(P 2 O 5 ) K(K 2 O) Low Medium High Very High *Nitrogen should be applied from 45 to 90 lbs per acre. Wheat Control in Wheat (Larry Steckel, Weed Specialist) Potential herbicide carryover needs to be considered before planting wheat. Fomesafen can carry in and injure wheat. According to the label four months must pass between planting wheat this fall and a fomesafen (Flexstar, Prefix and Reflex) application. The highest probability of carryover is in fields that have seen little rain this summer. This is another ramification of managing glyphosate resistant Palmer amaranth. 2

3 Volunteer Roundup Ready Corn Management. We had a number of fields that were going to be planted to wheat in the fall of 2008 where volunteer Roundup Ready corn was a real problem. This in part was due to the drought that caused more small ears to be produced that readily dropped through the snap rollers of the combine. This could crop up again in some of our more stressed areas this year. In our research there have only been two herbicide applications that controlled the volunteer corn. One was oz/a of Gramoxone Inteon applied with 0.25% NIS at 15 gal/a. Coverage and rate are critical to make this work. The other option was to use 0.5 oz/a of Finesse which also did a good job plus it provides residual control of ryegrass and many broadleaf weeds. Finesse has been used in Tennessee for about three years now and has for the most part worked well. Of course like all pres it works best when it receives a rain oz/a Finesse to 10 days after application to activate it. However, if it does not get an activating rain the weed control can be inconsistent. One thing to remember is if Finesse is used, only STS soybeans can be planted for double crop in the summer. Bluegrass Control in Wheat. Bluegrass (aka Poa) can be a serious issue in some wheat fields. In cases where it was a problem it became established before or with the wheat. If Poa becomes established with the wheat it can deter tillering and readily compete for nitrogen. Typically one of the best ways to manage bluegrass is to start clean. Using either tillage or Gramoxone Inteon at 40 oz/a will be a good way to manage this pest. Still another option is to apply Sencor at 3 to 4 oz/a post emergence over the wheat that is at 2 to 4lf. This timing of a Sencor application has been a very inexpensive way to manage bluegrass and just establishing broadleaf weeds like henbit. Ryegrass Control. When it comes to ryegrass control, some type of two pass approach works best. It can either be a pre followed by a post or two post applications. One reason for this is that wheat is more susceptible to yield loss from ryegrass that emerges with it in the fall than ryegrass that emerges in the spring. Therefore a pre or early post application can remove that potential yield loss. Over the last several years we have had a fairly extensive flush of ryegrass in the spring. A post application is often need to clean this up. Finally, we have confirmed Osprey resistant rye grass up in Dyer County this past year. Using a two pass program that utilizes two different modes of action will be the most sustainable method to manage rye grass long term. A few years ago we only had one option for ryegrass control in wheat and that was Hoelon. Now we have Osprey, Axial, Finesse Grass and Broadleaf and PowerFlex. Osprey has been the main go to herbicide the last several years and it has performed well particularly applied in the fall controlling ryegrass, many broadleaf winter annuals and even small bluegrass. It is applied at 4.75 oz/a with 0.5% NIS plus spray grade ammonium sulfate (AMS) or 32% nitrogen solution. Axial XL has also performed well controlling ryegrass. It will not provide any control of bluegrass or broadleaf weeds. Axial XL is a new formulation with the surfactant included that is to be applied at 16.4 oz/a. Finesse Grass and Broadleaf for the first time in 2008 and it has provided good control of ryegrass, broadleaf weeds and even some bluegrass. The rate for Finesse Grass and Broadleaf is 0.75 to 0.9 oz/a along 3

4 with 0.25% NIS. STS soybeans must be used for double crop behind a Finesse Grass and Broadleaf application. PowerFlex which first came on the scene in 2008 has performed very well in controlling ryegrass. It also has good activity on other broadleaf weeds as well as wild garlic. It is weak on blue grass. One final point is that Axiom and Prowl H2O are good herbicides for bringing residual ryegrass control. Most importantly they use a different mode of action to control ryegrass compared to the herbicides mentioned above. We must start using some diverse modes of action in wheat if we are to keep rye grass from rapidly developing resistance to Axial, Osprey, PowerFlex and Finesse Grass and Broadleaf. Fungicides for Wheat Seed Treatments in 2010 (Melvin Newman, UT Extenion) Seed treatment fungicides have been recommended in Tennessee for many years. This planting season is an especially good time to use this practice. There were a lot of diseases in the wheat fields this past season including Fusarium Head Scab, Loose Smut and Glume Blotch. Seed treatment fungicides will not prevent all diseases but may reduce the amount of fungal spores on the seed and inside the seed. However, if wheat is planted behind wheat or corn there still may be significant disease occurring from the previous crop reside. Loose Smut is carried within the seed and most recommended fungicides will penetrate the seed coat and kill the fungus causing Loose Smut. Other disease spores from Fusarium Head Scab and Glume Blotch can be carried on the seed surface. Most fungicides will reduce the amount of carryover on the seed. The best management practice (BMP) is to treat seed intended for planting this fall with a seed treatment fungicide. There are many seed treatment fungicides available, but the following have been researched by Dr. Patrick Lipps at Ohio State University and found to be effective in reducing Fusarium Head Scab, Loose Smut, Seedling Disease and Glume Blotch. They are: Dividend XL, Dividend Extreme, Raxil-Thiram, Raxil MD, Raxil XT, RTU Vitavax-Thiram, Vitavax 200, Charter. As always, read and follow label all directs when applying fungicides. Insect Management in Wheat (Scott Stewart, Extension IPM Specialist) Planting Date Effects on IPM. Don t plant your wheat until October, preferably mid October. October 15 is the Hessian fly-free date, and this date corresponds to the approximate date of first freeze in West Tennessee. Hessian flies have two generations - one in the fall and one in the spring. Adult Hessian flies begin emergence from summer dormancy in late August and September. After a freeze, adult Hessian flies are no longer active. Thus, you can avoid potential infestations by abiding by the fly-free date above. There are other benefits to planting after the fly-free date. September planted wheat is sometimes attacked by fall armyworms, but pest rarely causes problems in wheat planted in October. Also, early planted wheat is more exposed to 4

5 aphids. Aphid colonization of wheat fields is less likely in late fall and winter as the weather gets colder. Aphids can transmit barley yellow dwarf virus (BYDV), and fall transmission of virus has more potential to reduce yields than later transmission. Pictured: Hessian fly larva and pupa (flax seed stage) at base of wheat stem. Another important management component is to destroy any volunteer wheat that may be persisting by no later than late August of early September. We had some major problem with the spring generation of Hessian flies during Some fields were not harvested. The worst infestations were in late planted fields following volunteer wheat that was not burned down until shortly before harvest. In some cases, heavily infested fields were nearby volunteer wheat that was either kept for production or just ignored. Volunteer wheat can be a nursery for the fall generation, and the subsequent spring generation of Hessian flies infested nearby fields. Fortunately, there does not seem to be much volunteer wheat around this year. At-planting or Scheduled Insecticides for Suppression of Aphids/BYDV. Aphids only occasionally cause direct yield loss, but as mentioned above, most species of aphids found in wheat are capable of transmitting BYDV. Pictured: greenbugs (light green aphids) and bird cherry-oat aphids (darker colored) in wheat. There are a several options to consider for managing aphids in wheat. The first is to do nothing. The occurrence of BYDV (and aphids) varies considerably from field to field, year to year, and across planting dates. It is not a sure bet that treating for aphids will increase yield. But keep in mind that you can t put the horse back in the barn if aphids do show up in numbers. By the time aphids are common in the field it is probably too late to treat with the hopes of preventing any disease transmission. I often recommend some type of fall aphid treatment for wheat planted in October. Seed treatments such as Cruiser ( oz/cwt) or Gaucho ( oz/cwt) do a good job of controlling aphids populations during the fall, and treatment benefits may carry over into the spring. Data indicates an average seed treatment response of about 3-4 bushels per acre in Tennessee. I had a test at the WTREC last year where treatments with a Gaucho seed treatment yielded 8-15 bushels above the check, so bigger responses are possible. Foliar application of insecticide is an alternative to using a seed treatment. Pyrethroid insecticides or Dimethoate are common choices for aphid control. An application can be made about 30 days after planting, or some states recommend a treatment threshold of one aphid per foot of row. This aggressive approach is designed to prevent aphid colonization and BYDV infection. Consider this approach on early planted (October) wheat if a seed treatment was not used. Another foliar application may be justified in late winter prior to jointing (February-early March) if aphids are re-colonizing the field, or this may be a first application for late planted wheat. I have 5

6 several data sets showing a late winter application can give a nice yield bump when a fall application or seed treatment was not used. We need more data about the potential value of a late winter insecticide application if insecticides were used in the fall. Cruiser and Gaucho seed treatments do offer some control of Hessian flies during the fall, and this is a potential benefit for early planted wheat. Below ground insects sometimes reduce stands and vigor of wheat. These include critters like white grubs and wireworms. Foliar insecticide applications will have little effect on below ground pests. On the plus side, foliar applications are relatively inexpensive especially if they can be piggybacked with applications of herbicides or other products. Other Considerations. Cereal leaf beetles and true armyworm are other pests worth mentioning, but these are springtime problems so I won t elaborate here. Both are very occasional pests, but populations should be monitored beginning in April. Treatment thresholds and insecticides recommended by UT are available on line (link here). Farm Management Update Wheat (Chuck Danehower, Area Specialist Farm Management) Although this issue of the IPM Newsletter is focusing on wheat, when the economics of wheat is being discussed considerations have to be made for competing crops. When producers consider wheat and the double crop soybeans that are usually planted behind wheat, then the 2011 farm plan has started being formulated. Even then the plan can and generally is tweaked based on crop economics. So when we are considering wheat, we are considering how wheat and double crop soybeans will stack up against full season soybeans, corn, or cotton. Prices for all crops are up from just a month ago when I examined crop economics in the August 12 issue. The supply of wheat seed may be questionable so that may be a determining factor on whether to plant wheat. Moisture at time of planting will also be a critical factor. Producers planning on or just thinking about planting wheat should let their crop insurance agent know. The sales closing date for crop insurance in Tennessee is September 30. There have been some policy changes in crop insurance. Producers who want individual coverage on their farm have three choices: Yield Protection, Revenue Protection, or Revenue Protection Without Harvest Price. With the volatility in prices and the potential for wheat prices to decline by harvest time of next year, the Revenue Protection product looks to offer the best risk management protection. The projected price for the Yield Protection and Revenue Protection has been set and is $7.14 per bushel. I still like a diversification of crops and crop rotation as we just don t know what crop will yield the best. It does not take much of a yield increase at today s prices for one crop to overshadow the other. However, farmers with irrigated land and with hopefully a more stable production would have the capability to focus on profitable crop selection more so than dry land. The table below examines returns from corn, cotton, soybeans, and wheat/soybeans. Expected yields based on Tennessee 5 year average yields and trend line yields. Prices are based on current offerings for Prices no doubt will change during the next year, so producers may want to look at various pricing scenarios as well as different yields. Costs are based on the 2010 UT Extension budgets and have been tweaked to consider higher seed cost for wheat (hopefully on the high side) and increased weed control in soybeans to combat glyphosate resistant weeds. Weed control is an issue that has to be planned for. Land costs are 25% of revenue. 6

7 2011 Projected Per Acre Returns Corn Cotton Soybeans (Full Season) Wheat Soybeans Yield 125 bu. 875 lbs. 40 bu. 60 bu./28 bu. Price $4.70 bu. $0.80 lb. $10.40 bu. $6.75/$10.40 bu. Revenue $588 $700 $416 $696 Variable Cost $270 $ 409 $225 $436 Returns over VariableCost $ 318 $ 291 $191 $260 Land Costs (25% share) $ 147 $174 $ 104 $174 Returns over Variable and Land $171 $ 117 $ 87 $86 Costs Fixed Costs $39 $58 $37 $77 Returns over Specified Costs $132 $59 $51 $ 9 Breakeven $3.65/97 bu. $ 0.73/801 lbs. $9.13/35 bu. $6.67/59 bu. $ 10.24/28 bu. This is at least a starting point for 2011 planning. In crop decisions where there are no equipment changes, I look closely at Returns over Variable Costs for own or cash rent ground or in the case of share rent - Returns over Variable and Land Costs. If equipment changes are going to be made, I might consider fixed costs, but really recommend a whole farm plan. In the above scenario, wheat and double crop soybeans are worth considering, but mainly on own or cash rent ground. It generally seems the yield of double crop soybeans is key to the viability of the system. It loses its advantage with share rent, but is comparable to full season soybeans. Wheat on its own would return $150 per acre over variable expenses or $49 per acre over variable and land costs. With the increase in soybean weed control, corn and cotton at current prices start to pull away. Cotton does have a higher cost structure and needs average yields and above to be sustainable. However, there is only a difference of 34 to 68 pounds at $0.80 a pound in the returns of cotton and corn depending on whether it is on cash rent or owned ground or share rent ground. The difference does start to narrow at higher yields especially when considering that higher corn yields will need additional nitrogen. There is a difference of 8 to 12 bushels of soybeans at $10.40 between corn and full season soybeans. Develop your own estimates and use your numbers in making an informed decision. Wheat with double crop soybeans can have a place in the crop mix. I would be cautious about planting a higher cost wheat seed that I don t know anything about in a market that is volatile. Discuss with your supplier, fertilizer and other inputs. There is growing concern, that fertilizer prices will be higher in 2011 than they are currently. If commodity prices stay strong or increase, fertilizer and other input prices will most likely increase. Producers who know what their phosphate and potash needs are for 2011 may want to consider applying them this fall or locking in current prices. Every farm situation is different so plan ahead to make informed decisions in your operation. If you would like assistance in developing a farm plan or budget, contact your local County Extension office, Area Specialist Farm Management, or call the MANAGEment Information Line at

8 Second Picking Cotton (Chuck Danehower, Area Specialist Farm Management) Although many fields of cotton appear to be picking clean and have a high percent of first harvest, the price of cotton has many producers thinking about picking cotton a second time. The feasibility of this issue is dependent on how much cotton is left in the field, price of cotton, and the cost to pick cotton the second time. Let s review the second picking costs. Below are second picking tables depending on the whether a 4 row picker or 6-row picker is used. Included are the costs for the accompanying module builder, and boll buggy. When making a decision on whether to second pick it is important to examine the variable or cash costs of repairs, diesel, and labor. The fixed or ownership cost of equipment although important, is not as critical to recover as the variable or cash cost. From the table below, a 4 row picker picking at 4 mph would incur variable cost of $48.52 per acre. To just recover that cost, a producer would need to pick 57 lbs./acre of cotton at $.85 lb. That is one bale to 8.4 acres. A 6 row picker at 4 mph would have variable cost of $39.83 and it would take 47 lbs. per acre or one bale to 10.2 acres to recover its cost. Cost per acre will vary with the speed of the picker. Use the tables below in helping you make that decision. If I can assist you, please give me a call Second Picking of Cotton 4-Row Cotton Picker Pounds of Cotton Lint/Acre to Breakeven Over Variable Cost Picker Speed (MPH) Variable Cost per Acre (a) $64.69 $48.52 $38.81 Price ($) Lint/Lb. Lbs/Acre (a) Includes variable cost for 4 row cotton picker, boll buggy, and module builder. Please note that if Fixed Cost (depreciation, interest) were included lbs/acre would be doubled. Producers need to at least cover variable costs (fuel, repairs, and labor). For share rented ground, take pounds per acre X [1 + share rent]. Ex. 1/4 rent, $.85 cotton at 4 MPH = 57 X 1.25 = 71 lbs. to breakeven over variable costs. Diesel fuel cost is based on $2.40 gallon. 6-Row Cotton Picker Pounds of Cotton Lint/Acre to Breakeven Over Variable Cost Picker Speed (MPH) Variable Cost per Acre (a) $53.10 $39.83 $31.85 Price ($) Lint/Lb Lbs/Acre (a) Includes variable cost for 6 row cotton picker, boll buggy, and module builder. Please note that if Fixed Cost (depreciation, interest) were included lbs/acre would be doubled. Producers need to at least cover variable costs (fuel, repairs, and labor). For share rented ground, take pounds per acre X [1 + share rent]. Ex. 1/4 rent, $.85 cotton at 4 MPH = 47 X 1.25 = 59 lbs. to breakeven over variable costs. Diesel fuel cost is based on $2.40 gallon. 8

9 Crop Watch (Chuck Danehower, as reported by National Agricultural Statistics Service) Crop Progress % September 19, 2010 September 12, 2010 September 19, Year Average Corn - harvested TN 84% 72% 12% 49% US 18% 11% 4% 10% Cotton - harvested TN 14% 4% 0% 3% US 13% 8% 7% 10% Soybean - harvested TN 12% 6% --- 8% US 8% NA 2% 6% The University of Tennessee is an EEO/AA/Title VI/Title IX/Section 504/ADA/ADEA institution in the provision of its education and employment programs and services. All qualified applicants will receive equal consideration for employment without regard to race, color, national origin, religion, sex, pregnancy, marital status, sexual orientation, gender identity, age, physical or mental disability, or covered veteran status. The University of Tennessee Institute of Agriculture, Agricultural Extension Service, Tim Cross, Dean. DISCLAIMER STATEMENT This publication contains pesticide recommendations that are subject to change at any time. The recommendations in this publication are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. The label takes precedence over the recommendations found in this publication. Use of trade or brand names in this publication is for clarity and information; it does not imply approval of the product to the exclusion of others which may be of similar, suitable composition, nor does it guarantee or warrant the standard of the product. The author(s), The University of Tennessee, The Institute of Agriculture and the University of Tennessee Extension assume no liability resulting from the use of these recommendations. Scott D. Stewart (Editor), Extension IPM Specialist 9