IPM NEWSLETTER Update for Field Crops and Their Pests

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1 The University of Tennessee IPM NEWSLETTER Update for Field Crops and Their Pests West TN Experiment Station 605 Airway Boulevard Jackson, TN No. 2 March 18, 2005 Past Newsletters and other information can be found at CONTENTS (links): General Cotton Remarks - Burndown - At-planting Insecticides Announcement: Cotton Scout School, Friday, May 27, West Tennessee Experiment Station (registration begins at 8:00 am) Cotton - General Remarks (Chism Craig, Assistant Professor) It appears that Tennessee will make a new record crop of over 900 lbs. per acre. According to my figures, we have classed 958,557 bales as of March 10, 2005 on approximately 510,000 acres. With those figures, Tennessee producers will average 902 pounds of lint per acre. Advances in cotton production like boll weevil eradication and Bt cotton along with extremely favorable growing conditions are mostly responsible. Table 1 gives a concise look at the classing data for Table 1. Tennessee cotton classing data for ,557 bales classed on 510,000 acres = 902 lb./a C. Craig, 2005 Micronaire units 0.7% < % % % 50 > Fiber Strength g/tex 1.5% % % % >30 Fiber Length inches 30.1% 33 < 38.5% % % 36 > Color scale 20.9% 11& % % % 51 It appears that cotton acreage will go up in Tennessee due in part to last year s success, higher nitrogen costs, the threat of Asian soybean rust and the price outlook for grain crops. Most of the talk at this time is about varieties and what will be planted. Variety trial results can be obtained from your local Extension office or found on the web at 1

2 Producers continue to plant more and more acres to full season varieties, but we must remember that Tennessee grows cotton in a northern environment. Full season varieties have done well in this area for three years in a row, but harvesting has been pushed later in the season. Planting full season varieties can spread risks and result in excellent yields, even in Tennessee. However, committing too many acres to full season cotton might come back to haunt us. As we begin a new year, I encourage producers to evaluate and prioritize the inputs that will offer the most return for their investment dollar. Maintaining current yield levels while cutting costs will not be easy, but having a base plan in place prior to seed going in the ground could mean the difference in breaking even or making a profit. I continue to get questions about cutting inputs and saving money. While I agree that cotton is over-fertilized in some cases, cotton is often under-fertilized as well. In years like these, soil testing is extremely important. Determining where you stand prior to fertilization could result in lower costs and/or higher yields. A reduction in soil-applied nutrients is possible, but cutting fertility inputs without soil testing could be disastrous. One last thing, as you evaluate our planting intentions for the upcoming year, ask yourself how many acres can be efficiently farmed and harvested. Planting too much cotton for your current cotton infrastructure could be more detrimental than the reasons for the increased acreage. Cotton and Soybean Burndown Considerations (Larry Steckel, Chism Craig and Angela Thompson, Assistant Professors) Where has the winter gone? Some have started burndown applications this week and many will begin over the next couple of weeks. Many winter annual weeds that are difficult to control like horseweed, cutleaf evening primrose, annual bluegrass (Poa) and annual ryegrass are prevalent in many fields. Horseweed Cutleaf eveningprimrose The next 30 to 40 days is when the majority of winter annual burndown applications will be sprayed prior to cotton, soybean and corn planting. Following are some considerations when using some of the more popular burndown programs this spring. 2

3 0.75 lbs ae/a glyphosate + 8 ozs/a Clarity a. Has been the most consistent winter annual control option the past several years. b. Provides very consistent glyphosate resistant horseweed and cutleaf evening primrose control. a. 21 day re-crop interval before planting soybeans or cotton. b. Sprayer clean-out of Clarity is critical before applying post products to soybeans or cotton. c. Will provide inconsistent control of annual bluegrass lbs ae/a glyphosate + 32 ozs/a of a 4 lb/gallon 2,4-D a. It is a relatively inexpensive burndown application. b. Has provided good control of most winter annual broadleaves. a. Has been inconsistent in some cases controlling glyphosate resistant horseweed at the 16 ozs/a rate. Higher rates (32 ozs/a) may be needed to control horseweed. b. 30 day re-crop interval before planting soybeans or cotton. c. Proper sprayer clean-out of 2,4-D is very time consuming and difficult. However, cotton is extremely sensitive to even minute amounts of 2,4-D that might be left in the sprayer. See UT bulletin W ozs/a Ignite a. Crops can be planted anytime after an Ignite application. b. Will control glyphosate resistant horseweed when it is actively growing. c. Very easy to clean out of sprayers. a. The overall best fit for Ignite is when it is applied within a couple weeks of planting when daytime air temperatures average above 60 F weeds are actively growing (i.e. horseweed Bolted Horseweed has bolted). b. Will not provide good control of winter annual grasses like ryegrass and annual blue grass. c. Early burndown before winter annuals are actively growing should have 8 oz of Clarity added for good control of horseweed. d. A total of only 80 oz/a of Ignite may be applied to Liberty Link cotton. Therefore either glyphosate or Gramoxone should probably be used for burndown to save the 32 oz of Ignite for in-season use. 3

4 32 ozs/a Gramoxone + 8 oz/a Clarity or 32 oz/a 2,4-D a. Gramoxone is the best burndown product for annual bluegrass. b. Will control glyphosate resistant horseweed. c. Very easy to clean out of sprayers. a. 21 day (Clarity) or 30 day (2,4-D) re-crop interval before planting soybeans or cotton. b. Sprayer clean-out of Clarity or 2,4-D is critical before applying post products to soybeans or cotton. c. Control of ryegrass can sometimes be inconsistent. Glyphosate + Ignite (Glufosinate) Tank-Mixes Some have considered using a tank mix of glyphosate and Ignite (glufosinate). Research conducted last year with this mixture has shown that there is an extreme amount of antagonism which results in very poor weed control. Herbicides that Provide Residual Control of Horseweed Research in Tennessee has shown that horseweed can emerge almost year around with peak emergence events in March and April. Therefore it is not uncommon after a successful burndown of GR horseweed for follow up flushes of this weed to become a serious problem in cotton and soybeans. A common question is: what are some good options to keep GR horseweed from emerging after the 21 or 30 day before planting burndown applications? Following are some good residual control options: Valor at 2 ozs/a can be added to a 30 day preplant burndown program to cotton. Valor can be applied anytime prior to soybean emergence. Valor will provide residual control of horseweed for 30 days or more depending upon weather conditions. Valor will not burn down existing horseweed. In cotton Caparol at 32 oz/a or Cotoran at 32 oz/a or Direx at 16 ozs/a can be applied preemergence to control later emergence events. Cotton can be planted anytime after these herbicides are applied. Limited research has shown good residual control with these products. In soybeans Sencor at 4 oz/a is a good choice. The question has come up about cutting the rates of these soil applied herbicides. I would not cut back on these herbicides applied this early. Though this will definitely cut costs the problem with cutting these rates back is that applied in March they will very likely play out, right around planting, when they are needed most. Generic Dicamba There are several generic dicamba products that have or will be getting 21 day before planting burndown labels. Some growers have asked if these generic products can replace Clarity in their burndown program. One should consider that though the active ingredient is the same (dicamba) the generic products are formulated with a different salt than is used with Clarity. We have 3 plus years now with good results with Clarity burning down GR horseweed. We have no such track record with any of the generic dicamba products. Therefore, I might try a generic dicamba product, provided it is labeled, on a few acres. However, I would be very hesitant to use it over the whole farm. 4

5 At-Planting Insecticides for Cotton (Scott Stewart, Assistant Professor) Cutworms. The decision to apply insecticide, usually a pyrethroid, at planting or with your burndown application is not really that critical considering the low cost of the application. Spring tillage usually replaces the need for making a cutworm application. However, if this tillage was done well in advance of planting, cutworms may have re-invaded fields and will be present at the time of planting. In no-till fields, treating for cutworms is recommended unless the field was burned down and kept essentially weed free for 3-4 weeks prior to planting. Herbicides can substitute for tillage, and thus insecticide, causing weed hosts and cutworm numbers to dwindle. The key factor for both tilled and no-tilled fields is maintaining the as field weed free for at least 3-4 weeks before planting. If banding applications, maintain at least a 7-10 inch width. Insecticides recommended for cutworm control. Insecticide Lb Active Ingredient per Amount Formulation per s Treated per Gal or Lb of Dry Product acephate (Orthene 90S) lb 1.25 bifenthrin (Capture 2, Discipline 2, Fanfare 2) oz chlorpyrifos (Lorsban 4) oz cyfluthrin (Baythroid 2) oz cypermethrin (Ammo 2.5, Up-Cyde 2.5) oz deltamethrin (Decis 1.5) oz esfenvalerate (Asana XL 0.66) oz gamma-cyhalothrin (Prolex 1.25) lambda-cyhalothrin (Karate 2.08) oz thiodicarb (Larvin 3.2) oz 5.3 zeta-cypermethrin (Mustang Max 0.8) oz Thrips Control. There are many good thrips control products (see table below). The use of an atplanting insecticide for thrips control is strongly recommended. Options include Temik (which should be selected if reniform nematodes are present), in-furrow application of acephate, and seed treatments. Seed treatments include Cruiser, Gaucho Grande, and acephate. However, those choosing the acephate seed-treatment option are advised to make a post-emergence application with acephate, Bidrin, dimethoate or Monitor at the 1 st or 2 nd true-leaf stage. Remember, when using an in-furrow systemic insecticide (particularly Temik), an in-furrow fungicide is strongly recommended because injury caused by the insecticide may increase the occurrence of seedling diseases. Temik is not a fungicide! Gaucho and Cruiser seed treatments have become very popular, but your thrips-control choice will depend upon price and your farming operation. There is no law against using different options for different fields or planting dates. For example, if you are already using an in-furrow fungicide spray, this simplifies applying acephate. Temik is an excellent choice for early plantings because this product historically provides the best residual control. Although all the above choices give reliable thrips control, be aware there are subtle differences that sometimes come into play. For example, only Temik will have significant activity on early-season spider mites, and acephate will not control early-season aphid populations that may occur. 5

6 Recommended thrips control treatments. Insecticide Lb Active Ingredient per Amount Formulation per In furrow Systemic Granules: aldicarb (Temik 15G) lb --- In-furrow Systemic Sprays: acephate (Orthene 90S) lb disulfoton (Di-Syston 8) oz Foliar Sprays*: acephate (Orthene 90S) oz 5 dicrotophos (Bidrin 8) oz dimethoate oz methamidophos (Monitor 4) oz Treated Seed: acephate (Orthene 90S) imidacloprid (Gaucho Grande 5) thiamethoxam (Cruiser 5) s Treated per Gal. or Lb of Dry Product oz Orthene 90S/acre for hopper box (to achieve application rate of 3-4 oz per acre) mg active ingredient per seed (about 5.3 oz Gaucho Grande per 250,000 seed, NOT to exceed 12.8 oz Gaucho Grande per 100 lb seed) mg active ingredient per seed (about oz Cruiser 5FS/250,000 seed) Note: The 2005 Cotton Insect Control Guide, including and a PDA-friendly version for download are available at: DISCLAIMER STATEMENT Pesticides recommended herein were registered for the prescribed uses when this publication was printed. Should registration be canceled, the University of Tennessee will immediately discontinue its recommendation of the pesticide. 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 that may be of similar, suitable composition, nor does it guarantee or warrant the standard of the product. The Agricultural Extension Service offers its programs to all eligible persons regardless of race, color, national origin, sex religion, disability or veteran status and is an Equal Opportunity Employer. COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS. The University of Tennessee Institute of Agriculture, U.S. Department of Agriculture and county governments cooperating in furtherance of Acts of May 8 and June 30, Agricultural Extension Service, Charles L. Norman, Dean. Scott D. Stewart (editor), Extension Cotton IPM Specialist 6