INSECTS. Black Cutworm and Armyworm Update (with News About The Hines Report )

Transcription

1 INSECTS Black Cutworm and Armyworm Update (with News About The Hines Report ) Over the past week, we received several reports from University of Illinois Extension educators regarding scattered captures of black cutworm adults in pheromone traps as far north as Ogle, Whiteside, and Winnebago counties. Intense captures (9 or more moths captured over 2 days) were reported by crop systems educators in Adams County (9 moths on April 20) and Ogle County (3 moths on April 17, 7 moths on April 18). Although not included in the formal network in southern Illinois (see the next paragraph), a trap in Massac County captured 10 moths on April 18, indicating yet another intense capture. Numerous intense captures have been reported through the University of Missouri IPM Pest Monitoring Network (ppp.missouri.edu/ pestmonitoring/bcw/bcw08.asp). FOR IMMEDIATE RELEASE No. 5 / April 25, 2008 Executive editor: Kevin Steffey, Extension Entomologist Available on the Web at For subscription information, phone , or acesnews@uiuc.edu Copyright 2008, Board of Trustees, University of Illinois Based on this rather small number of intense captures, cutting by 4th-instar black cutworms may occur in Illinois between May 12 (southern) and May 20 (northern). Warmer temperatures could change these projections, but at least we have some dates to consider in the near future. The small network of insect-monitoring traps in southern Illinois (organized by Ron Hines, Growmark s seed agronomist for the southern region) is now in operation. The latest details are available in The Hines Report on the University of Illinois IPM Web site (ipm.uiuc.edu/pubs/hines_report); you can view reports from traps in five counties: Franklin, Marion, Pulaski, Sangamon, and St. Clair. Once again, I thank Ron for his efforts. Captures of armyworm adults continue to increase in two pheromone traps in Kentucky ( and armyworm adults have been captured in traps in Illinois located as far north as Sangamon County. Wheat fields and grass pastures will be most at risk if numbers of armyworm larvae are large this spring, so producers need to be particularly alert within a couple of weeks, even though much of their attention will be focused on planting corn and soybeans. Kevin Steffey Also in This Issue Corn Flea Beetle: Expectations for Injury in 2008, 38 What s in That Herbicide Premix? 39 Free Soybean Rust Identification Short Course in Florida, 42 Prioritizing When Planting Is Delayed, 42 Regional Reports, 43 Alfalfa Weevil Larvae Should Be Evident in the Southern Half of Illinois As of April 22, 200 degree-days (base 50 F) had accumulated from January 1 as far north as Adams County, southern Tazewell County, and southern Champaign County, suggesting that alfalfa weevil larvae may be active in alfalfa fields in the southern half of Illinois. As of the same date, 300 degree-days had accumulated along a line from St. Louis, Missouri, to White County. Symptoms of leaf-feeding injury caused by small alfalfa weevil larvae should be evident in several southern Illinois counties. Don t forget to scout alfalfa fields, even though most concern will be directed to planting corn and soybeans. Kevin Steffey Corn Flea Beetle: Expectations for Injury in 2008 One of the many spring insects that captures our attention on occasion is the corn flea beetle. Because 37 of the cold and prolonged winter experienced most

2 recently, it is not surprising that we ve received some calls regarding these tiny insects as producers finalize their preparations for planting. The questions and answers here address many of the inquiries on the biology and management of these potentially damaging beetles. Why are these insects termed corn flea beetles? Corn flea beetles are very small insects that cause some concern in the seed production industry each spring, especially in years following mild winters. The flea beetle name is well deserved because of the insects size (1/16 inch, 1.8 mm) and impressive leaping ability when disturbed. Where do corn flea beetles overwinter? Flea beetles spend the winter as adults and are most apt to cause damage when corn plants are slowed in their development by cool spring conditions. Adult flea beetles overwinter in clumps of grass near cornfields. Following mating in the spring, females lay their eggs in the soil of cornfields. Larvae hatch from eggs in approximately 1 week and complete the larval stage and pupate in about 2 weeks. After emergence, adults feed and mate for the remainder of the summer. Why are corn flea beetles of more concern to the seed production industry? Of primary concern to those in the seed production business is the potential for transmitting Stewart s bacterial wilt to susceptible inbreds or sweet corn varieties. Corn flea beetle injury to the epidermis of corn leaves rarely results, in and of itself, in economic losses because relatively little tissue is consumed. Small streaks of absent epidermal tissue serve as evidence of flea beetle feeding. The bacterium Pantoea stewartii transmitted by the feeding of flea beetlescan overwinter in the soil and plant debris as well as within the guts of vectors of the disease. As many as 20% of corn flea beetle adults emerging in the spring may be infected with bacteria responsible for Stewart s wilt. By midsummer, 75% of the corn flea beetle population may serve as vectors of this disease. Stewart s wilt is vectored in the spring, when corn flea beetles feed on corn seedlings. The disease (bacteria) spreads throughout the infected plants, and two phases occur a seedling wilt (at or before the V5 stage) and leaf blight. Infected seedling plants may become stunted, wilt, and exhibit linear lesions. As the infection grows more severe, overall yellowing of leaves intensifies and moves upward on plants. The disease symptoms may be displayed in some sweet corn varieties at any stage of plant development. Most dent corn hybrids are resistant to the wilt phase of Stewart s disease, but many hybrids are susceptible to the leaf blight phase. Early planting dates can exacerbate the severity of Stewart s disease in susceptible inbreds or varieties. Do corn flea beetles feed on any other hosts? Although corn is the preferred host, corn flea beetles are known to feed on other plants, including orchard grass, crabgrass, fall panicum, redtop, witch grass, Kentucky bluegrass, Sudan grass, yellow foxtail, giant foxtail, barley, and wheat. Foxtail, oats, and wheat are known to sustain corn flea beetle populations until the preferred host, corn, begins to emerge. What is this spring s outlook for economic infestations of corn flea beetles? Entomologists have long reported that Table 1. Winter air temperatures for Champaign, DeKalb, and Dixon Springs, Illinois. Months Champaign DeKalb Dixon Springs Dec F 24.1 F 38.3 F Jan F 20 F 32.6 F Feb F 19.8 F 35.2 F Averages 28 F 21.3 F 35.4 F Source: Illinois Climate Network, Illinois State Water Survey. mild winters favor the survival of flea beetles and increase the potential that Stewart s disease may be a problem. Temperatures averaged across December 2007, January 2008, and February 2008 for Champaign, DeKalb, and Dixon Springs were 28.0 F, 21.3 F, and 35.4 F (Table 1). This suggests very low potential in Champaign and DeKalb this season for Stewart s wilt. However, in southern Illinois the likelihood is much greater (Table 2). Can you scout for corn flea beetles and use economic thresholds to rescue infested fields? Despite the fact that winter may have taken its toll on flea beetles for much of the state, we encourage vigilant scouting for corn flea beetles this spring, especially in southern Illinois, particularly where inbreds (or sweet corn varieties) sensitive to Stewart s disease will be grown. If susceptible inbreds are infested before the 5-leaf stage, 2 to 3 adults per plant are found, and 10% of the plants are silver or white because of flea beetle injury, a rescue treatment may be warranted. In certain sweet corn IPM programs in the northeastern U.S., consultants recommend rescue treatments when 6 adults are found per 100 plants. Products labeled for corn flea beetles in commercial corn can be found in the Illinois Agricultural Pest Management Handbook ( iapmh). Because of the large volume of transgenic Bt hybrids that will be planted this spring, many soil insects, including corn flea beetles, will be exposed to the thianicotinoid insecticidal seed treatments (Poncho and Cruiser). Because of the widespread use of these insecticides and their effect on corn flea beetles, along with the cold winter, very low levels of Stewart s wilt are anticipated for central and northern Illinois counties this season. Mike Gray Table 2. Potential Stewart s wilt based on average temperatures in December, January, and February. If the average temperature for December, January, and February is Early-season wilt will probably be Late-season blight will probably be Below 27 F Absent or nearly so A trace, at most Between 27 and 30 F Light Light to moderate Between 30 and 33 F Moderate Moderate to severe Above 33 F Severe Severe 38

3 WEEDS What s in That Herbicide Premix? Though the introduction of novel herbicide active ingredients has slowed during the past several years, a plethora of premix products has proliferated. In the past we have published an article in the Bulletin describing herbicide premix products commercially available for corn and soybean production, and we continue that practice this year. The basic text hasn t changed much over time, and we hope it remains useful to our readers. Updated tables of corn and soybean premixes always accompany the article; they are detailed in the following text. One limitation of these tables is that a single application rate of each product is presented, with product active ingredients and equivalents calculated based on that rate. If you would like to determine product active ingredients and equivalents for a rate different than the one presented, we provide examples of how to do the calculations. Herbicide premixes can be confusing with respect to component active ingredients, product equivalents, application rates, and the like. Table 3 lists many of the corn herbicide premixes used in Illinois, and Table 4 is a similar list of soybean herbicide premixes. Let s examine the information in the tables in more detail. The first column lists the commercial or trade name of the herbicide and its formulation. The commercial or trade name is the name usually most familiar to folks. Another list of names (arguably less familiar than the names in the first column) appears in the second column; these are the common names for each herbicide component of a premix. For example, in Table 3 we see that Lexar (trade name) 3.7L (formulation) is composed of the active ingredients S-metolachlor (common name), mesotrione (common name), and atrazine (common name). Common names are useful because they always refer to the same active ingredient; trade names don t always refer to the same active ingredient. Think back several years to a herbicide with the trade name Option; this product contained the active ingredient fenoxaprop (common name) and was used for postemergence control of grass species in soybean. The Option (trade name) herbicide now on the market contains foramsulfuron (common name) and is used for postemergence control of grass species in corn. Needless to say one does not want to apply fenoxaprop to corn or foramsulfuron to soybean hence the benefit of knowing herbicide common names. The second column also provides the amount of active ingredient or acid equivalent of each component per gallon or pound of formulated product. The third column lists an application rate for each premix. We attempt to select application rates representative for Illinois, but you may want to select a different rate and redo the calculations in columns 4 and 5. The fourth column indicates how much of each active ingredient is applied at the rate listed in the third column. Going back to the example of Lexar, we see that 3.5 quarts of Lexar provides 1.52 lb S-metolachlor active ingredient, lb mesotrione active ingredient, and 1.52 lb atrazine active ingredient. Note that while rates of commercial products are usually expressed in ounces, pounds, pints, or quarts of product per acre, active ingredients are usually expressed in units of pounds of active ingredient or acid equivalent per acre. Finally, column 5 lists product equivalents for each premix component when the premix is applied at the rate listed in column 3. So the 3.5-quart rate of Lexar provides the same amount of S-metolachlor, mesotrione, and atrazine contained in 1.6 pints of Dual II Magnum 7.64EC, 6.27 fluid ounces of Callisto 4SC, and 3 pints of AAtrex 4L, respectively. The application rates in the tables are meant to be used as a reference; for some of these herbicides the rates will vary depending on soil texture, organic matter, weed species and size, and other factors. Always consult the respective herbicide label for appropriate application rates. If you are interested in a rate different than that listed for a particular herbicide, it s relatively simple to do the calculations for your rate of choice. We ll work through an example to make it a little easier to understand. The application rate of Harness Xtra 5.6L (Table 3) is 2.5 quarts per acre. Instead of 2.5 quarts, you want to know how much acetochlor and atrazine are applied at a 2-quart rate of Harness Xtra 5.6L. First, convert 2 quarts to gallons: 2 quarts x 1 gallon = 0.5 gallon acre 4 quarts Next, we can calculate how much acetochlor and atrazine active ingredient are contained in 0.5 gallon of Harness Xtra 5.6L: 0.5 gallon x 3.1 lb ai acetochlor = 1.55 lb ai acetochlor per acre acre gallon Finally, we can determine product equivalents based on these active ingredient amounts: 1.55 lb ai acetochlor x 1 gallon Harness x 8 pints = 1.77 pints Harness 7E acre 7 lb ai gallon 1.25 lb ai atrazine x 1 gallon AAtrex x 8 pints = 2.5 pints AAtrex 4L acre 4 lb ai gallon Aaron Hager 39

4 Table 3. Corn herbicide premixes. If you Herbicide Components (ai per gal or lb) apply per acre You have applied (ai) Product equivalents Basis 75WDG rimsulfuron = 0.50 lb thifensulfuron = 0.25 lb 0.33 oz rimsulfuron = 0.01 lb thifensulfuron = lb Resolve 25DF = 0.66 oz Harmony GT XP 75DF = 0.11 oz Bicep II Magnum 5.5L S-metolachlor = 2.4 lb atrazine = 3.1 lb 2.1 qt S-metolachlor = 1.26 lb atrazine = 1.63 lb Dual II Magnum 7.64E = 1.32 pt AAtrex 4L = 3.26 pt Bicep Lite II Magnum 6L S-metolachlor = 3.33 lb atrazine = 2.67 lb 1.5 qt S-metolachlor = 1.2 lb atrazine = 1.00 lb Dual II Magnum 7.64E = 1.31 pt AAtrex 4L = 2 pt Buctril + atrazine 3L bromoxynil = 1.0 lb atrazine = 2.0 lb 2 pt bromoxynil = 0.25 lb atrazine = 0.5 lb Buctril 2E = 1 pt AAtrex 4L = 1 pt Bullet 4CS alachlor = 2.5 lb 4 qt alachlor = 2.5 lb Micro-Tech 4CS = 2.5 qt AAtrex 4L = 1.5 qt Camix 3.67L S-metolachlor = 3.34 lb 2.4 qt S-metolachlor = 2.0 lb Dual II Magnum 7.64EC = 2 pt mesotrione = 0.33 lb mesotrione = lb Callisto 4SC = 6.34 fl oz Celebrity Plus 70WDG diflufenzopyr = 0.17 lb dicamba = lb nicosulfuron = lb 4.7 oz diflufenzopyr = lb dicamba = lb nicosulfuron = lb diflufenzopyr = lb Clarity 4S = 3.98 fl oz Accent 75DF = 0.66 oz Degree Xtra acetochlor = 2.7 lb 3 qt acetochlor = lb Degree 3.8CS = 2.13 qt 4.04CS Distinct 70WDG Equip 32WDG Expert 4.88SC Field Master 4.06S FulTime 4CS G-Max Lite 5L Guardsman Max 5L Halex GT 4.39L Harness Xtra 6L Harness Xtra 5.6L Hornet WDG 68.5WDG Keystone 5.25L Keystone LA 5.5L Laddok S-12 5L Lexar 3.7L Lightning 70DG Lumax 3.95L Marksman 3.2L atrazine = 1.34 lb atrazine = 1.00 lb AAtrex 4L = 1 qt diflufenzopyr = 0.20 lb 4 oz diflufenzopyr = 0.05 lb diflufenzopyr = 0.05 lb dicamba = 0.50 lb dicamba = lb Clarity 4S = 4 fl oz foramsulfuron = 0.30 lb 1.5 oz foramsulfuron = lb Option 35WDG = 1.28 oz iodosulfuron = 0.02 lb iodosulfuron = lb Autumn 10WDG = 0.3 oz S-metolachlor = 1.74 lb 3 qt S-metolachlor = 1.31 lb Dual II Magnum 7.64EC = 1.37 pt atrazine = 2.14 lb atrazine = 1.61 lb AAtrex 4L = 3.21 pt glyphosate = 0.74 lb glyphosate = 0.56 lb Glyphosate 3L = 1.48 pt acetochlor = 2.0 lb 4 qt acetochlor = 2.0 lb Harness 7E = 2.29 pt AAtrex 4L = 3 pt glyphosate = 0.56 lb glyphosate = 0.56 lb Roundup Ultra 3L = 1.5 pt acetochlor = 2.4 lb atrazine = 1.6 lb 4 qt acetochlor = 2.4 lb atrazine = 1.6 lb TopNotch 3.2CS = 3 qt AAtrex 4L = 1.6 qt dimethenamid-p = 2.25 lb 3 pt dimethenamid-p = Outlook 6EC = 18 fl oz atrazine = 2.75 lb atrazine = 1.03 AAtrex 4L = 2 pt dimethenamid-p = 1.7 lb 4 pt dimethenamid-p = 0.85 lb Outlook 6EC = 18.1 fl oz atrazine = 3.3 lb atrazine = 1.65 lb AAtrex 4L = 3.3 pt S-metolachlor = pt S-metolachlor = 0.94 lb Dual II Magnum 7.64EC = 0.98 pt glyphosate = 2.09 glyphosate = 0.94 lb Glyphosate 3L = 2.5 pt mesotrione = mesotrione = lb Callisto 4SC = 3 fl oz acetochlor = 4.3 lb 2 qt acetochlor = 2.15 lb Harness 7E = 2.46 pt atrazine = 1.7 lb atrazine = 0.85 lb AAtrex 4L = 1.7 pt acetochlor = 3.1 lb 2.5 qt acetochlor = 1.94 lb Harness 7E = 2.21 pt atrazine = 2.5 lb atrazine = 1.56 lb AAtrex 4L = 3.13 pt clopyralid = 0.50 lb 3 oz clopyralid = lb Stinger 3S = 4 fl oz flumetsulam = lb flumetsulam = lb Python 80WDG = 0.69 oz acetochlor = 3 lb 3 qt acetochlor = 2.25 lb Surpass 6.4EC = 2.81 pt atrazine = 2.25 lb atrazine = 1.69 lb AAtrex 4L = 3.38 pt acetochlor = 4 lb 2 qt acetochlor = 2 lb Surpass 6.4EC = 2.5 pt atrazine = 0.75 lb AAtrex 4L = 1.5 pt bentazon = 2.5 lb 1.67 pt bentazon = 0.52 lb Basagran 4S = 1 pt atrazine = 2.5 lb atrazine = 0.52 lb AAtrex 4L = 1 pt S-metolachlor = 1.74 lb 3.5 qt S-metolachlor = 1.52 lb Dual II Magnum 7.64EC = 1.6 pt mesotrione = lb mesotrione = lb Callisto 4SC = 6.27 fl oz atrazine = 1.74 lb atrazine = 1.52 lb AAtrex 4L = 3 pt imazethapyr = lb 1.28 oz imazethapyr = lb Pursuit 70DG = 0.96 oz imazapyr = lb S-metolachlor = 2.68 lb mesotrione = lb atrazine = 1 lb dicamba = 1.1 lb ae atrazine = 2.1 lb imazapyr = lb 3 qt S-metolachlor = 2.01 lb mesotrione = lb atrazine = 0.75 lb 3 pt dicamba = lb ae atrazine = lb Arsenal 2AS = fl oz Dual II Mangum 7.64EC = 2.1 pt Callisto 4SC = 6.4 fl oz AAtrex 4L = 1.5 pt Banvel 4S = pt AAtrex 4L = 1.56 pt 40

5 Table 3. Corn herbicide premixes. (continued) NorthStar 47.4WDG primisulfuron = lb dicamba = lb ae 5 oz primisulfuron = lb dicamba = lb ae Radius 4SC flufenacet = 3.57 lb 20 fl oz flufenacet = lb isoxaflutole = 0.43 lb isoxaflutole = lb Require Q rimsulfuron = lb 4 oz rimsulfuron = lb dicamba = lb ae dicamba = 0.12 lb ae Resolve Q rimsulfuron = lb 1.25 oz rimsulfuron = lb thifensulfuron = 0.04 lb thifensulfuron = lb Shotgun atrazine = 2.25 lb 2 pt atrazine = 0.56 lb 3.25F 2,4-D = 1 lb ae 2,4-D = 0.25 lb ae Spirit 57WDG prosulfuron = lb 1 oz prosulfuron = lb primisulfuron = lb primisulfuron = lb Status 56DF diflufenzopyr = 0.16 lb 5 oz diflufenzopyr = 0.05 lb dicamba = 0.4 lb dicamba = lb Steadfast nicosulfuron = 0.5 lb 0.75 oz nicosulfuron = lb 75WDG rimsulfuron = 0.25 lb rimsulfruon = lb Steadfast ATZ nicosulfuron = lb 14 oz nicosulfuron = lb 89.3WDG rimsulfuron = lb rimsulfuron = lb atrazine = lb atrazine = lb Stout nicosulfuron = lb 0.75 oz nicosulfuron = lb 72.5WDG SureStart 4.16SE Yukon 67.5WDG thifensulfuron = 0.05 lb acetochlor = 3.75 lb flumetsulam = 0.12 lb clopyralid = 0.29 lb halosulfuron = lb dicamba = 0.50 lb ae thifensulfuron = lb 1.2 pt acetochlor = lb flumetsulam = lb clopyralid = lb 4 oz halosulfuron = 0.03 lb dicamba = lb ae Beacon 75WDG = 0.50 oz Banvel 4S = 4 fl oz Define 4SC = 17.9 fl oz Balance Pro 4SC = 2.15 fl oz Resolve 25DF = 1 oz Banvel 4S = 3.85 fl oz Resolve 25DF = 0.92 oz Harmony GT XP 75DF = oz AAtrex 4L = 1.13 pt Salvo 5E = 0.4 pt Peak 57WDG = 0.25 oz Beacon 75WDG = 0.57 oz diflufenzopyr = 0.05 lb Clarity 4S = 4 fl oz Accent 75DF = 0.5 oz Resolve 25DF = 0.75 oz Accent 75DF = 0.5 oz Resolve 25DF = oz AAtrex 90DF = lb Accent 75DF = oz Harmony GT XP 75DF = 0.05 oz Surpass 6.4EC = 0.7 pt Python 80WDG = 0.36 oz Stinger 3S = 1.86 fl oz Permit 75WSG = 0.67 oz Banvel 4S = 4 fl oz Table 4. Soybean herbicide premixes. Components Herbicide (ai/gal or lb) Authority Assist sulfentrazone = 3.33 lb 4SC imazethapyr = 0.67 lb Authority sulfentrazone = lb First70DF cloransulam = lb Sonic 70DF Authority MTZ sulfentrazone = 0.18 lb 45DF metribuzin = 0.27 lb Boundary S-metolachlor = 5.25 lb 6.5EC metribuzin = 1.25 lb Canopy 75DG chlorimuron = lb metribuzin = lb Canopy EX chlorimuron = lb 29.5WDG tribenuron = lb Domain 60DF flufenacet = 0.24 lb metribuzin = 0.36 lb Enlite 47.86DG chlorimuron = lb thifensulfuron = lb flumioxazin = lb Envive 41.3DG chlorimuron = lb thifensulfuron = lb flumioxazin = lb Extreme 2.17L imazethapyr = 0.17 lb glyphosate = lb Fusion 2.56EC fluazifop = 2 lb fenoxaprop = 0.56 lb Gangster V&FR flumioxazin = 0.51 lb Co-Pack cloransulam = 0.84 lb Prefix 5.3EC S-metolachlor = 4.34 lb fomesafen = 0.95 lb If you apply per acre You have applied (ai) Product equivalents 10 fl oz sulfentrazone = 0.26 lb Spartan 4F = 8.33 fl oz imazethapyr = lb Pursuit 2AS = 3.35 fl oz 3.2 oz sulfentrazone = lb Authority 75DF = 2.65 oz cloransulam = lb FirstRate 84WDG = 0.3 oz 14 oz sulfentrazone = lb metribuzin = lb 2.4 pt S-metolachlor = 1.57 lb metribuzin = lb 4 oz chlorimuron = lb metribuzin = lb 1.1 oz chlorimuron = lb tribenuron = lb 10 oz flufenacet = 0.15 lb metribuzin = lb 2.8 oz chlorimuron = lb thifensulfuron = lb flumioxazin = lb 3.5 oz chlorimuron = 0.02 lb thifensulfuron = lb flumioxazin = lb 3 pt imazethapyr =0.063 lb glyphosate = lb 8 fl oz fluazifop = lb fenoxaprop = lb 2 oz (V) flumioxazin = lb oz (FR) cloransulam = pt S-metolachlor = 1.09 lb fomesafen = lb Authority 75DF = 3.36 oz Sencor 75DF = 5 oz Dual Magnum 7.62E = 1.65 pt Sencor 75DF = 8 oz Classic 25DF = 1.71 oz Sencor 75DF = 3.43 oz Classic 25DF = 1 oz Express 75DF = 0.1 oz Define 60DF = 4 oz Sencor 75DF = 4.8 oz Classic 25DF = oz Harmony GT XP 75DF = oz Valor 51WDG = 1.99 oz Classic 25DF = 1.29 oz Harmony GT XP 75DF = oz Valor 51WDG = 2 oz Pursuit 2AS = 4 fl oz Roundup 3L = 1.47 pt Fusilade DX 2E = 8 fl oz Puma 1EC = 4.48 fl oz Valor 51WDG = 2 oz FirstRate 84WDG = 0.6 oz Dual Magnum 7.62EC = 1.14 pt Reflex 2EC = 0.95 pt 41

6 Table 4. Soybean herbicide premixes. (continued) Pursuit Plus imazethapyr = 0.2 lb 2.5 pt imazethapyr = lb 2.9EC pendimethalin = 2.7 lb pendimethalin = 0.84 lb Rezult B&G bentazon = 5 lb 1.6 pt (B) bentazon = 1.0 lb Co-Pack sethoxydim = 1 lb pt (G) sethoxydim = 0.20 lb Sequence S-metolachlor = 3 lb 3 pt S-metolachlor = 1.13 lb 5.25L glyphosate = 2.25 lb ae glyphosate = 0.84 lb ae Storm 4S bentazon = 2.67 lb 1.5 pt bentazon = 0.5 lb acifluorfen = 1.33 lb acifluorfen = 0.25 lb Synchrony XP chlorimuron = lb 0.75 oz chlorimuron = 0.01 lb 28.4DG thifensulfuron = lb thifensulfuron = lb Valor XLT flumioxazin = 0.3 lb 2.5 oz flumioxazin = lb 40.3WDG chlorimuron = lb chlorimuron = lb Pursuit 2AS = 4 fl oz Prowl 3.3EC = 2 pt Basagran 4S = 2 pt Poast Plus 1E = 1.6 pt Dual Magnum 7.62EC = 1.18 lb Touchdown Total 4.17L = 26 fl oz Basagran 4S = 1 pt Blazer 2S = 1 pt Classic 25DF = 0.64 oz Harmony GT XP 75DF = oz Valor 51WDG = 1.47 oz Classic 25DF = 1 oz PLANT DISEASES Free Soybean Rust Identification Short Course in Florida A soybean rust short course will be offered on August 12 and 13 at the University of Florida North Florida Research and Education Center located in Quincy, Florida. The course is free thanks to a grant from the North Central Soybean Research Program. Preregistration is required. The course will give participants hands-on identification training and show them soybean rust field research trials that are ongoing at the Research and Education Center. For more information or for registration material, visit org/desktopmodules/viewdocument. aspx?documentid=2636. Carl A. Bradley CROP DEVELOPMENT Prioritizing When Planting Is Delayed With only 1% of the Illinois corn crop planted as of April 20, it is clear that we are off to a slow start in That does not automatically mean that planting itself will be late at least as measured by the date when 50% is planted. But progress is picking up only moderately so far this week, and many areas will see little or no activity the rest of the week. It s small comfort, but the whole Corn Belt is off to a slow planting start, with little done anywhere. That s been helping the price some. And corn that has been planted early into cool soils has not benefited much from that up to now. The fact that temperatures are now much warmer than they have been before this week is very helpful in getting soils dried out. Warm soils lose water much faster than cool soils, and once soils are warmed up they will tend to retain that heat and so dry out faster following rainfall. Cold fronts will still bring rain that can drop soil temperatures quickly, but we should start to see less saturated soil and faster drying from now on. According to the Illinois Water Survey, soil temperatures at the 4-inch depth under bare soil are now reaching about 70 degrees as a daily maximum a favorable development. As producers have pulled planters out to tinker with them, taken delivery on seed, and lined up fertilizer supplies, questions come up about what to do first when it s finally dry enough to get started. Here are points to consider: 1. No one can make it dry up faster, but get around to different fields and dig in the wetter, drier, and average areas to see how the soil is drying. There have been few it s drier than I thought discoveries this spring, but there could be some as soil temperatures rise. 2. Having the planter and other equipment in shape is a given a priority that should already have been acted on. 3. It should generally not be a priority to make tillage passes on too-wet soil to open it up for faster drying. While it may produce a sense of getting something done, tillage like this can 42 produce clods that are very difficult to break down and that might result in a poor seedbed. Tillage, which is almost always shallow when done in wet soils, also mulches the surface and can delay drying below the depth of tillage. Finally, any tractor and equipment traffic on wet soil will produce compaction, which could be a big problem if it keeps roots from developing fully, especially if we get dry weather later in the season. 4. By now, it is of higher priority to plant when the soil is dry enough than to apply preplant fertilizer. Those who apply fertilizer when it s still too wet to plant often do more harm through compaction and poor sealing (of anhydrous ammonia) than if they had waited to side-dress nitrogen after planting. With auto-steer, it is possible to apply N between the rows after planting but before emergence, or even before planting. There is generally no loss in yield if side-dressing N is delayed up to the 4- or 5-leaf stage of the crop. Placement between the rows also protects the small plants from ammonia damage in case it dries out after planting. If rains continue, ammonia damage will be unlikely, but plants on top of ammonia bands are in considerable danger of damage if it dries out after ammonia was applied in wet soils, even if planting was a week or more after ammonia application. 5. It is a priority to plant as fast as possible once soils are dry enough, especially if it stays dry and fields become ready to plant in rapid sequence. Most producers have large planters and are generally equipped to plant

7 faster than ever, so this is a priority that most have acted on. Auto-steer that allows planting in the dark might be a good investment this year. Unlike many other agronomists, I do not believe that most producers are planting at speeds fast enough to damage yield prospects. It is important to plant at a uniform depth and to have seeds in uniform soil conditions down the row, but planting slower just for better seed spacing is unlikely to produce much payback, unless it also means that plant populations are closer to the target. Many planters drop more seed when run faster, and this can turn out to be an advantage if conditions are good later. That some of these seeds are doubles is unlikely to have much effect, other than the cost of some seed that might not boost yields much. 6. While it is important to get good uniformity in seed depth placement, statements I have seen recently that plants emerging outside of a 24- to 48-hour window become weeds are not correct. Even the most careful planting cannot assure uniformity of emergence. If it rains and soil temperatures come back down after the crop is planted, emergence will be delayed. Delayed emergence almost always means more spread in emergence time within a field, especially when soils have gotten wet again. It takes about 110 to 120 growing degree days from planting to emergence, but factors like crusting and cloddiness affect emergence timing. So we can expect that emergence, from start to end, might take up to a week in some fields, and 3- to 5-day emergence windows are commonplace. In some of our research with delayed planting down the row, plants that emerged even 2 to 3 weeks late sometimes produced small ears or no ears, but they were also less competitive with their earlier-emerging neighbors, which produced more as a result. Late-emerging plants hurt yields, but they were never weeds in that they did not lower yields compared to those when such plants were simply missing (not planted). 7. To reemphasize, the highest priority should be to plant corn seed into the best soil conditions possible, even if it means delaying planting into early May. Early May is a good time to plant corn, with expected yield losses of only 5 to 10 bushels compared to planting in mid-april. It is very easy to lose more yield than this by planting before soils are fit to plant. So while it s hard to wait, those who get aggressive with planting might, depending on how the season goes, end up wishing they had waited the extra few days that experience (or a neighbor or relative) told them would be helpful. One issue that comes into play with planting starting this late is that any replanting that becomes necessary will be costly in terms of late-planting penalty. That raises the value of getting a good stand the first time. It s a challenge I think we can meet if we keep our wits about us. Emerson Nafziger REGIONAL REPORTS Extension center educators, unit educators, and unit assistants in northern, west-central, east-central, and southern Illinois prepare regional reports to provide more localized insight into pest situations and crop conditions in Illinois. The reports will keep you up to date on situations in field and forage crops as they develop throughout the season. The regions have been defined broadly to include the agricultural statistics districts as designated by the Illinois Agricultural Statistics Service, with slight modifications: North (Northwest and Northeast districts, plus Stark and Marshall counties) West-central (West and West Southwest districts, and Peoria, Woodford, Tazewell, Mason, Menard, and Logan counties from the Central district) East-central (East and East Southeast districts [except Marion, Clay, Richland, and Lawrence counties], McLean, DeWitt, and Macon counties from the Central district) South (Southwest and Southeast districts, and Marion, Clay, Richland, and Lawrence counties from the East Southeast district) 43 We hope these reports will provide additional benefits for staying current as the season progresses. East-Central Illinois The weather pattern finally broke. Marion Shier, Extension educator in Livingston County, reported limited fieldwork starting late last week. In the Champaign Decatur area, very little activity was apparent until April 21. In many areas the first sign of activity was burning crop residue that had accumulated at the high-water mark around the ponds. This was followed by dry-fertilizer and anhydrous applications. Several farms now have a good start on corn planting. Northern Illinois There has been limited field activity, which was widespread since late last week until scattered storms went through the area on April 22. Most activity focused on application of anhydrous ammonia and preplant herbicides. There are a few cornfields planted, but an insignificant total. Consistently warm temperatures have improved the condition of alfalfa, pastures, and wheat. Many wheat fields are showing small dead areas due to ice damage from last winter, but very few fields have been abandoned. Though Extension educators monitoring black cutworm moth traps caught moths almost daily from April 16 to 21 due to the storm fronts moving through the area, an intense moth flight (9 or more months captured over 2 consecutive days) has not been reported. Due to the warmer temperatures some fields are showing some green cover from the emergence of winter annuals. Southern Illinois There has still been little or no progress on fieldwork due to wet field conditions. Just as soils begin to dry enough to carry equipment, another shower comes through to add to the delay. Wheat is at Feeke s stage 7. There is some evidence of foliar diseases be-

8 U of I Extension Newsletter Service University of Illinois at Urbana-Champaign 1917 S. Wright St. Ext., MC-710 Champaign, IL ginning to appear on lower leaves, but so far it is minor. Winter annual weed pressure is heavy in many fields. Alfalfa is around 9 inches tall. Alfalfa weevil can be found in some fields, but pressure overall is still low. West-Central Illinois Field conditions continue to be wet across most of the area. A few fields were dry enough to have anhydrous ammonia applied and corn planted before the rain last weekend. Soil temperatures are hovering in the mid-50s range, and producers are searching for fields dry enough to work. Mike Roegge, Extension educator in Adams and Brown counties, reported an intense capture of black cutworm moths over the weekend. With the increased vegetation in many fields, these moths will soon be depositing eggs in fields across the area and should be monitored in future weeks. Wheat fields range from Feeke s growth stage 5-6 in most places, with few disease reports. A few bird-cherry oat aphids are present but not at high levels. Winter annuals in no-till fields are being controlled with herbicide applications as well as final top-dress applications of nitrogen. Alfalfa fields have resumed growth and look good following the winter. Contributing Authors Carl A. Bradley (carlbrad@uiuc.edu), Extension Plant Pathology, Mike Gray (megray@uiuc.edu), Extension Entomology, Aaron Hager (hager@uiuc.edu), Extension Weed Science, Emerson Nafziger (ednaf@uiuc.edu), Crop Sciences, Kevin Steffey (ksteffey@uiuc.edu), Extension Entomology, Published by University of Illinois Extension and Information Technology and Communication Services, College of Agricultural, Consumer and Environmental Sciences, University of Illinois. Copyright 2008, Board of Trustees, University of Illinois Helping You Put Knowledge to Work University of Illinois U.S. Department of Agriculture Local Extension Councils Cooperating University of Illinois Extension provides equal opportunities in programs and employment.