Integrated Pest and Crop Management Newsletter Vol. 17, No. 7 April 27, 2007 ********************************************************************** Troubleshooting Field Crop Problems By Allen Wrather Producers will experience problems with crops in some Missouri fields this year. I don’t know what type of problems will develop, but I do know they will occur because they always have in past years. The problems will most likely be caused by too much or too little fertilizer, too much or too little water, cold weather, crust over the planted row, insects, diseases, herbicide drift or carry over, and other things. Producers should get the cause of each problem diagnosed so action can be taken to prevent or reduce the problem from worsening or developing next year. Diagnosis of crop problems can sometimes be easy, but it is more often diffi cult. This article is a brief summary of the material in University of Missouri Extension Guide G4050 that describes a six-step process to help farmers and crop consultants diagnose the cause(s) of field crop problems. This guide, Troubleshooting Field Crop Problems, was written by Laura Sweets, Andy Kendig and me, and it is online at http://extension. missouri.edu/explore/agguides/ crops/g04050.htm. First, determine the variety and the age of the plant. An investigator should identify the plant variety because some are more resistant or susceptible to certain diseases, insects and herbicides, and this information may be very useful when diagnosing the cause of the problem. Second, identify all the symptoms affecting the leaves, stems, roots and fruit. An investigator should observe all parts of abnormal plants when troubleshooting a field crop problem including the leaves, stems, fruit and roots as well as the tissue inside roots and stems. Frequently, the point of injury to the plant is not where the symptoms appear. For example, leaves on one or several branches may be discolored and withered because of a canker on a lower branch or a borer in the stem. Nutritional deficiencies and injuries from herbicides may damage both roots and leaves. Examine individual plants in detail and determine the location of symptoms on the plant. Are symptoms on old or young leaves, upper or lower stems, or perhaps on one side of the plant? Look for insects and insect feeding damage. Cut stems to check for discoloration inside the stem and for insect feeding. Hold leaves up to the light to check for mosaic, other viral symptoms, or the presence of webbing and mites. Investigators should look for leaf abnormalities in color, size, shape and texture. Also, carefully dig up roots and examine them. Check for galls, rot, abnormal root color and feeder root condition, and assess root growth. While probing the soil, check for soil compaction, soil structure, texture and organic matter, and the presence and depth of hardpans. Also take note of odors, insects, fertilizer placement and the depth of planting. Third, estimate the percentage of plants damaged in the affected part of the field. Were all plants in an area or only 10 percent affected? Symptoms of injury due to insects and disease may appear on every plant in an area, but this is unusual. Symptoms of injury due to herbicides, improper placement of fertilizer and lightning will usually appear on every plant in an area. Fourth, determine the distribution or pattern of the problem in the field. Look at the entire field to determine where the problem appears. Determine the distribution of the problem in the field as it relates to field characteristics such as areas with light soil, and drainage patterns. Is the problem only in wet areas? Take notice of whether the problem is associated with certain rows or areas of lower or higher elevation. Fifth, evaluate whether the crop and weeds in the field share similar symptoms. Examine the weeds in the area where the crop is injured and in nearby fence rows. Symptoms caused by nutritional disorders are usually not plant specific. For example, most plants growing in low-pH soils, including crops as well as weeds, will be stunted. However, diseases are usually plant-specific, and weeds in the area are normally not affected by the same diseases that can attack corn or soybean. Sixth, determine the history of the problem. Ask when the problem was first noticed, and whether crop problems were observed in the same area during previous growing seasons. The answers to these questions may provide a clue that could be useful in diagnosing the cause of a field crop problem. Following these suggested procedures will give field crop consultants and producers a better chance of diagnosing the cause of field crop problems. Allen Wrather Professor Division of Plant Sciences ********************************************************************** Two Beneficial Weevils Active on Musk Thistles By Ben Puttler The rosette weevil buds have been active all last fall through the winter and early spring. Eggs have been laid and hatching larvae are developing in the crowns of the rosettes, feeding on the meristematic tissue and also secondary buds. This produces a necrotic area that enlarges as the weevil continues to develop. Infestations of rosettes are now quite evident in many areas of the state and will continue for the next two weeks. Larval feeding can kill a rosette outright, or it can change the growth pattern of the thistle causing a shorter, bushier plant that produces few flower heads, which in turn are smaller and contain less seeds. These plants are still susceptible to attack by the flower head weevil, the other beneficial weevil. Due to the prolonged egg-laying period, new adults of the rosette weevil occur on the plants from mid-May to mid- June. The flower head weevil adult will start emerging the last week in April and begin feeding in crowns of the thistle. From May 5-15 as plants start to bolt, more weevils will become evident, and the adults will start laying eggs on the bracts of the developing flowers. These eggs are covered with a secretion of chewed plant material that gives the eggs a dirty scalelike appearance. Larvae hatch from the eggs and tunnel into the flower receptacle where they feed on the developing seeds. The weevil larvae become very conspicuous in late May and June and can be readily seen by breaking open the flower head, especially the earliest ones formed. For more detailed information, refer to MU publication IPM 1010, Biological and Integrated Control of Musk Thistle in Missouri at http:// muextension.missouri.edu/explore/ agguides/pests/ipm1010.htm. Ben Puttler 573-882-1457 ********************************************************************** Foliage Diseases of Winter Wheat and Their Management By Laura Sweets Certainly the big question with this year’s winter wheat crop still is the extent of damage from the unusually low temperatures the first week in April. In many fields it is becoming much more evident which plants have been killed and which may survive. However, there are still some fields in which it is diffi cult to know how much of the stand has been affected or what the yield potential will be. There have also been a few questions on which foliage diseases are showing up and if any will be more severe because of the cold temperatures. There have been a few reports of leaf rust and stripe rust on wheat in southern states over the last few weeks. However, there have not yet been any reports of leaf rust or stripe rust on winter wheat in Missouri. Wheat fields in various areas of the state are showing scattered Septoria leaf blotch lesions in the lower canopy but, thus far, the incidence of Septoria leaf blotch is quite low. Powdery mildew has been reported in fields in the southern third to half of the state. Powdery mildew may be more prevalent in lodged wheat. It does not require actual moisture on the leaf tissue to develop but does prefer high relative humidity. The appearance of powdery mildew in fields may be related to lodging due to low temperature damage to stems. The development of foliage diseases on wheat and their severity this season will depend to a large degree on the weather conditions the rest of the season. Most wheat foliage diseases are favored by warm, wet conditions. Frequent light rains, heavy dews, high relative humidity and warm temperatures would be ideal for the buildup of the foliage diseases. The buildup of foliage diseases prior to flowering can led to yield losses, especially if weather conditions remain favorable for disease development during and after flowering. It is important to scout wheat fields for foliage diseases, especially if there are scattered periods of precipitation as the temperatures warm up. There are a number of foliar fungicides labeled for use on winter wheat. This year in particular, it will be important to evaluate fields for stand and yield potential as well as for incidence and severity of foliage diseases before making a decision on foliar fungicide application. Septoria leaf blotch Lesions begin as light yellow flecks or streaks. These flecks expand into yellow to reddish-brown, irregularly shaped blotches. Dark brown specks (fruiting bodies or pycnida of the causal fungus, Septoria tritici) may be scattered within the centers of mature lesions. Lesions may coalesce killing larger areas of leaf tissue. Stagonospora glume blotch Formerly called Septoria glume blotch; may also begin as light yellow flecks or streaks on leaves. The lesions also turn yellow to reddish-brown but usually have a more oval to lens-shaped appearance than those of Septoria leaf blotch. Again, the dark brown specks or fungal fruiting bodies of the causal fungus Stagonospora nodorum may be evident within the lesions. Symptoms of Stagonospora glume blotch are more common on heads than foliage of wheat. Infected heads will have dark blotches on the glumes. Tan Spot The initial symptoms are small tan to brown flecks on the leaves. These expand into tan to light brown elliptical lesions, which often have yellow borders. The centers of mature tan spot lesions may have a dark brown region caused by outgrowth of the fungus. But the fungus that causes tan spot, Pyrenophora triticirepentis, does not produce pycnidia or fruiting bodies as the Septoria fungus does. So mature tan spot lesions do not have the distinct dark brown specks scattered throughout the centers of the lesions as do Septoria leaf blotch lesions. Leaf Rust Lesions appear primarily on the upper leaf surfaces and leaf sheaths. Initially, lesions are small yellow to light-green flecks. Eventually, leaf rust appears as small, circular to oval shaped, orangered pustules. These pustules break open to release masses of orange-red spores of Puccinia recondita. The edges of the open pustules tend to be smooth without the tattered appearance of stem rust pustules. Heavily rusted leaves may yellow and die prematurely. Stem Rust Caused by the fungus Puccinia graminis f. sp. tritici, is most common on stems and leaf sheaths of wheat plants, but may develop on any of the above ground portions of the plant, including both upper and lower leaf surfaces and glumes and awns. Stem rust pustules are small, oval and reddish-brown. The ruptured pustules tend to have more ragged edges than leaf rust pustules. Frequently, both leaf rust and stem rust occur on the same plant and both types of pustules may develop on an individual leaf. Stripe Rust Caused by the fungus Puccinia striiformis, has become more prevalent in Missouri over the last few years. Stripe rust may develop earlier in the season than leaf rust or stem rust. The pustules of stripe rust are yellow or yellowish-red and occur in obvious stripes or streaks running lengthwise on the wheat leaves. This disease is more commonly associated with cooler temperatures, especially cooler night temperatures. Powdery mildew Infections begin as light-green to yellow flecks on the leaf surface. As powdery mildew develops, the leaf surfaces become covered with patches of cottony white mold growth of Erysiphe graminis f. sp. tritici, the causal fungus. These patches eventually turn a grayish white to grayish brown in color and small black fungal fruiting bodies may be visible within the patches of mildew growth. The fungi which cause most of these wheat foliage diseases survive in infested wheat residues left on the soil surface. The next growing season spores are produced during moist periods and are carried by wind currents to susceptible wheat leaves where infection may begin. Disease problems tend to be more severe when wheat is planted in fields with infested wheat residue left on the soil surface. Eventually spores that are produced in the initial lesions on plants are wind blown to other leaves or other plants causing secondary infection. Leaf rust, stem rust and stripe rust are exceptions to this simplified explanation of disease development. The rust fungi do not survive in infested residue left in a field. Rather, the rust fungi are reintroduced into the area each season when spores are carried up on air currents from the southern United States. Most of the foliage diseases of wheat are favored by warm, wet or humid weather. Frequently, infection begins on the lower portion of the plant. If weather conditions are favorable for disease development, the disease may move up through the plant. Severely infected leaves may yellow and die prematurely. Yield losses tend to be highest when the flag leaves are heavily infected. There are several fungicides labeled for use on wheat to control fungal foliage diseases. It is important to scout wheat fields and determine which leaf diseases are occurring as well as the level of their severity before making a decision to apply a foliar fungicide. In particular, be on the lookout for Septoria leaf blotch, Stagonospora glume blotch, tan spot, leaf rust and stripe rust. When scouting fields, try to identify the disease or diseases which are present, determine the average percent of infection on a leaf and the number of leaves showing infection and determine the stage of growth of the crop. Generally, the profitable use of foliar fungicides on wheat depends on a number of factors including varietal resistance, disease severity, effectiveness of the specific fungicides and timing of fungicide application. The greatest increases in yield are usually obtained when fungicides are applied to disease susceptible varieties with high yield potential at the early boot to head emergence growth stage when the flag leaf is in danger of severe infection. Fungicide applications are seldom beneficial if applied after flowering or after the flag leaf is already severely infected. It is also important to read the fungicide label for specific information on rates, recommended timing of application, frequency of applications, preharvest intervals and grazing restrictions. A management program for foliage diseases of wheat should include the following steps: * Plant disease free seed of varieties with resistance to diseases likely to occur in your area. * Rotate with non-host crops for one or more years. * Manage residues- if tillage system is a conservation tillage system, particular care should be given to rotation and variety selection. * Maintain good plant vigor with adequate fertility. * Control volunteer wheat. * Use foliar fungicides if warranted ( see accompanying table of foliar fungicides labeled for use on winter wheat). Laura Sweets Plant Pathologist SweetsL@missouri.edu ********************************************************************** Possible Flea Beetle Problems in Field Corn? By Wayne Bailey Mild winter temperatures during the months of December, January and February increase the potential for high populations of flea beetle. The flea beetle model for Missouri is calculated by adding together the average monthly winter temperatures for the months of December, January and February. If the average monthly temperatures for these months add to less than 90 degrees, then the risk of economic flea beetle infestations is low. If the total is between 90 degrees and 100 degrees, then moderate flea beetle damage can be expected. Heavy damage is possible if the three monthly averages total 100 degrees or more. Data from Commercial Ag Weather Stations located around the state are summarized by region and specific counties in the following table. Corn most at risk are those fields located in areas where the cumulative average monthly temperatures for the months of December through February are in excess of 90 degrees and seed treatments were not used. Rescue treatments are also effective in managing this pest and are discussed in detail in the following table. My thanks to Jim Jarman (regional agronomy specialist) for providing the following table. Table 1: 2007 Corn Flea Beetle Predictions for Missouri Table 1. The sums of average monthly Fahrenheit (F) temperatures for December 2006, January and February 2007 are used to predict flea beetle survival in Missouri. The University Missouri Commercial Agriculture Automated Weather Station Network on the Agricultural Electronic Bulletin Board (AgEBB) provided average Fahrenheit temperatures. --------------------------------------------------------------------------------------------- | County, University of Missouri | Sum of | | Commercial Agriculture automated | average winter| | weather station location (specifics) | temperatures | | | | --------------------------------------------------------------------------------------------- | Northern Missouri Region Average Temperature | 89.04o | | Atchison County, Graves Memorial Plots (3 miles north of Corning) | 88.40o | | Gentry County, Hundley-Whaley Farm (Albany) | 86.00o | | Linn County, Forage Systems Research Center (Linneus) | 88.60o | | Knox County, Greenley Memorial Center (1 mile east of Novelty) | 88.00o | | Buchanan County, Buchanan County Extension Center (St. Joseph) | 91.10o | | Central Missouri Region Average Temperatures | 103.81o | | Audrain County, 6 miles northwest of Auxvasse | 93.90o | | Chariton County, 4 miles west of Brunswick | 91.10o | | Boone County, South Farms (4 miles southeast of Columbia) | 96.70o | | Boone County, Sanborn Field (University of Missouri-Columbia) | 99.60o | | Monroe County, Monroe City (Monroe City Airport) | 89.20o | | Morgan County, Versailles R-II Outdoor Classroom | 102.00o | | Pettis County, Green Ridge R-VIII School District | 96.80o | | Callaway County, Williamsburg (Prairie Fork Conservation Area) | 86.50o | | South West Missouri Region Temperature | 103.70o | | Barton County, Lamar (Barton County Electrical Cooperative) | 103.70o | | South Central (Ozark) Missouri Region Average Temperatures | 105.13o | | Crawford County, Wurdack Farm (2 miles east of Cook Station) | 104.40o | | Shannon County Alley Springs (Ozark National Scenic Riverways Network) | 106.40o | | Shannon County Round Springs (Ozark National Scenic Riverways Network) | 104.60o | | South East Missouri (Bootheel) Region Average Temperatures | 117.11o | | Cape Girardeau County, Delta | 109.50o | | Dunklin County, Cardwell | 119.30o | | Dunklin County, Rice Farm (1 mile east of Glennonville) | 117.20o | | Dunklin County, Rhodes Memorial Research Farm (north of Clarkton) | 115.70o | | Mississippi County, (5 miles south of Charleston) | 115.10o | | Pemiscot County, Delta Center (Portageville) | 119.40o | | Pemiscot County, (6 miles west of Steele) | 120.90o | | Pemiscot County, Lee Farm (5 miles southeast of Portageville, MO) | 119.80o | --------------------------------------------------------------------------------------------- | | | Check the average winter temperature near your location. | | Average daily winter temperatures are used to estimate the likelihood of flea | | beetle survival. If the combined monthly averages are less than 90 degrees, then | | low flea beetles survival is likely. Average temperatures between 90 degrees and | | 100 degrees suggest flea beetle damage is possible. When these temperatures are | | above 100 degrees, flea beetle survival will be good and damage is likely. | | | --------------------------------------------------------------------------------------------- Biology/ Damage Flea beetles are small, dark, jumping beetles that overwinter as adults. In early spring they move to seedling corn and feed on plant foliage from the time of plant emergence through about the fourth-leaf stage of growth. Adult beetles strip the chlorophyll layer (green tissue) from the surface of seedling corn leaves resulting in the formation of "window panes" or translucent areas in leaf surfaces. Damage is often seen as translucent tracks or lines which run parallel to the veins of the corn leaf. Heavy flea beetle infestations cause plants to look "tattered" and wilted, similar to the type of injury caused to seedling corn when blasted by blowing sand. The most injurious flea beetle attacking corn is the corn or maize flea beetle. Typically, infestations are most severe in years where mild winters allow for increased survival of adults and cool temperatures and drought conditions during spring result in slowed growth of corn plants. Flea beetles may transmit Stewart’s wilt (a bacterial wilt) to corn, although most field corn has resistance to this plant pathogen. The economic threshold for implementation of control methods for flea beetles in field corn is an average of five or more beetles per corn seedling up through the four-leaf stage of development. To scout for flea beetles, examine corn plants for feeding damage and determine the average number of flea beetles present per corn plant. This is most readily accomplished in the early morning or late afternoon by walking slowly through the field and counting beetles as they feed on leaf surfaces. Remember, flea beetles are easily recognized by their jumping ability similar to grasshoppers. Although several species of flea beetles can be found in field corn, the maize or corn flea beetle typically causes problems in this crop. Management Options Corn most at risk from flea beetle damage are fields located in areas where winter temperatures are elevated (see table) and corn plants are not protected with a commercially applied seed treatment. Many seed treatment trials have shown quick suppression of flea beetle numbers during early-season feeding by this pest. In addition, the widespread use of seed treatments for corn during the past few years may be suppressing flea beetle problems statewide, similar to what Bt corn has done to the European corn borer populations throughout the Midwest. Rescue insecticide applications are also effective management options for flea beetles. Producers should scout seedling corn for the presence of flea beetles and apply a rescue insecticide treatment when the flea beetle population reaches or exceeds the economic threshold of an average of five or more flea beetles per corn seedling up to the four-leaf stage of plant development Insecticides and rates labeled for flea beetle management used as rescue treatment on field corn include the following: ********************************************************************** First Intensive Captures of Black Cutworm Moths By Wayne Bailey The first intensive capture of BCW moths in pheromone-baited traps occurred during mid-April. Intensive captures of moths indicate heavy moth activity, which may result in problems with black cutworm larvae in field corn. Intensive moth capture date along with meteorological data (30-year average) are used in the Missouri Black Cutworm Predictive Model to calculate a date for first occurrence of cutting damage by 4th instar black cutworm larvae. These predicted dates of first cutting are based on meteorological averages in the area of the trap and may vary depending on weather conditions and temperatures from the time the eggs are laid through development of larvae. For instance, if temperatures are warmer than average, the rate of black cutworm growth and development will be increased by as much as one week. If conditions are cooler than normal, development of this pest will be slowed and cutting will occur later than predicted. To account for some of this variation in local environmental conditions, the predicted date is updated daily using data from a weather station near the trap site. Intensive moth captures do not always result in economic infestations of black cutworm, but do predict a date of first cutting. Scouting activities should occur from first emergence of corn plants and continue through the 5th leaf stage of plant development. If this is not possible, then scouting of fields should begin a minimum of one week prior to the predicted date of cutting. Early damage by black cutworm larvae smaller than 4th instars may be visible as leaf feeding on corn plants. For more information on the black cutworm predictive model and the counties currently monitoring for black cutworm, please visit our Website at: http://ipm.missouri.edu/ pestmonitoring/blackcutworm/index. htm. Listed below are the trap locations with intensive captures (as of 4/22/07) and predicted dates of first cutting of field corn by black cutworm larvae: * Ray County (Richmond): Intensive capture date, 4/11/2007. Predicted first cutting, 5/18/2007 * Barton County (Lamar): Intensive capture date, 4/13/2007. Predicted first cutting, 5/14/2007 * Callaway County (Fulton): Intensive capture date, 4/18/2007. Predicted first cutting, 5/20/2007 * Audrain County (Mexico): Intensive capture date, 4/2/2007. Predicted first cutting, 5/17/2007 Please be aware that intensive captures in pheromone traps only indicate a need for scouting fields. Intensive captures DO NOT indicate treatment is necessary. The black cutworm, Agrotis ipsilon (Hufnagel), can be a severe pest of field corn and other crops in Missouri. Moths migrate into the state each spring from more southern states to mate and lay eggs on grasses, low growing winter annual weeds (henbit, chickweed, curly dock, others), in winter cover crops or soybean residues, and sometimes even on bare soil. These activities occur during early spring generally prior to the planting of corn. When this vegetation is killed and corn planted, surviving larvae readily attack emerging corn seedlings. Each female moth is capable of laying about 1,300 eggs either singularly or in small clumps. Larvae grow rapidly and reach the larval stage (4th instar) capable of cutting corn plants in 2-3 weeks. Corn plants may be cut near the soil surface or below ground. The economic threshold for black cutworm larvae attacking field corn seedlings is three- five percent cutting above ground and two-four percent cutting below ground. Most feeding damage typically occurs within seven to ten days following plant emergence. Black cutworm larvae vary in color from light gray to dark black. The skin is rough or granulated and often appears greasy in texture. The sides and top of larvae are generally a solid gray or black color with an indistinct pale stripe running the length of the back. Black cutworm larvae can be confused with the dingy cutworm, although in Missouri dingy cutworm larvae often occur in the field at least two weeks prior to occurrence of black cutworm larvae. Additionally, dingy cutworms are typically foliage feeders during their larval stages, whereas, the black cutworm foliage feeds when small and cuts corn plants when it reaches the 4th instar stage of growth. There are a total of six instars for the black cutworm with several generations produced each year. However, larvae from the first generation are generally responsible for attacking field corn. Several management options are available for black cutworm in field corn. The destruction of winter annual weeds and vegetation at least two weeks prior to planting corn is a good nonchemical option. This method depends on larvae mortality caused by exposure to harsh conditions and limited food. Seed treatments are another option which provide about 50 percent control of the insect in Missouri insecticide evaluations. In most years this rate of control may be suffi cient to keep larval numbers below economic threshold levels. In years with high black cutworm larval numbers, economic damage may occur with this method. Producers can also apply an insecticide prior to or at the time of planting. Several insecticides are labeled for this use and are generally effective for black cutworm larval control. A rescue application of insecticide is also effective in controlling this pest. This insecticide application is applied when scouting of the crop finds damage to the crop has reach or exceeded the economic threshold levels based on the quantity and type of cutting. Regardless of the method used, producers are encouraged to scout field corn at least twice per week from the time of emergence through the 5th leaf stage of plant development. Most early season insect corn pests can be found and successfully managed with good scouting practices and the use of an effective integrated pest management program. Wayne Bailey 573-864-9905 cell ********************************************************************** Insecticides for Black Cutworm Control in Corn - 2007 By Wayne Bailey --------------------------------------------------------------------------------------------------------------------| |Chemical name | Trade name | Rate of Formulated | Placement/Comments | --------------------|-------------------|--------------------------------------|------------------------------------| |esfenvalerate | Asana XL | Material/Acre | Pre- or post-emerge | |tebupirimphos + | Aztec 2.1G | 5.9 to 9.6 fl oz/acre | At planting | |cyfluthrin | | 6.7 oz/1000 row ft | Pre- or post-emerge rescue, or | |beta-cyfluthrin | Baythroid XL | 0.8 to 1.6 fl oz/acre | At planting | |bifenthrin | Capture 2EC | 1.47 to 2.2 fl oz/acre (2ee MO label)| Pre- or post-emerge rescue | |bifenthrin | Capture LFR | 3.4 fl oz/acre | Pre-emerge, | | | Capture LFR | 3.4 to 6.8 fl oz/acre | T-band or in-furrow (see label) | |bifenthrin | several products | see specific labels | see specific labels | |tefluthrin | Force 3G | 3.0 to 5.0 oz/1000 ft row | At planting, See specific label | |chlorethoxyfos | Fortress 2.5G | 6.0 to 7.5 oz/1000 ft row | At planting t-band or in-furrow | |chlorethoxyfos | Fortress 5G | 3.0 to 3.75 oz/1000 ft row | Use only with SmartBox system | | | | | T-band or in-furrow | |chlorpyrifos | Lorsban 4E | 1 to 4 pts/acre | Pre- or post-emerge | |chlorpyrifos | Lorsban 15G | 8.0 to 16.0 oz/1000 ft row | At planting | | | Lorsban 15G | 6.75 to 13.5 lb/acre | preplant broadcast | |chlorpyrifos | numerous products | see specific labels | see specific labels | |zeta-cypermethrin | Mustang Max | 1.28 to 2.8 fl oz/acre | Pre- or post-emerge, at planting | | | Mustang Max | 0.16 fl oz/1000 ft row | At planting | |permethrin | Pounce 1.5G | 6.7 to 13.3 lbs/acre | Pre-emerge broadcast | | | Pounce 1.5G | 8.0 to 16.0 oz/1000 ft row | At planting | |permethrin | Pounce 3.2EC | 4.0 to 8.0 fl oz/acre | Pre- or post-emerge broadcast | | | Pounce 3.2EC | 0.3 to 0.6 fl oz/1000 ft row | Pre- or post-emerge band | |permethrin | numerous products | see specific labels | see specific labels | |gamma-cyhalothrin | Proaxis | 1.92 to 3.20 fl oz/acre | Foliar broadcast | | | Proaxis | 0.66 fl oz/1000 ft row | At planting t-band or in-furrow | |Lambda-cyhalothrin | Warrior | 0.2 fl oz/1000 ft row (2ee MO label) | T-band or band only | --------------------------------------------------------------------------------------------------------------------| |SEED TREATMENTS | --------------------------------------------------------------------------------------------------------------------| |thiamethoxam | Cruiser | see product label | On seed | |clothianidin | Poncho | see product label | On seed | --------------------------------------------------------------------------------------------------------------------| |(Missouri trials show suppression of black cutworm larval populations with use of seed treatments) | --------------------------------------------------------------------------------------------------------------------| |Read and follow all label direction, precautions, and restrictions. | --------------------------------------------------------------------------------------------------------------------| | * Designated a restricted use product. | --------------------------------------------------------------------------------------------------------------------| ********************************************************************** Eastern Tent Caterpillars Possible Threat to Horses By Wayne Bailey and Craig Roberts If you have pregnant mares and have noticed the growth of eastern tent caterpillars on your farm, it would be wise to consider controlling the caterpillars. In a next few weeks, mature tent caterpillar larvae will move from host trees and wander about searching for a suitable site in which to pupate and eventually emerge as moths. Large larvae can move into forage vegetation, at which time they could be consumed by horses. If this occurs, pregnant mares may experience serious foaling problems. In Kentucky, six years ago, the equine industry suffered an epidemic called "mare reproductive loss syndrome," abbreviated MRLS. It caused the deaths of fetuses in all breeds of horses and cost the industry $336 million. The losses were initially attributed to infected Kentucky 31 tall fescue. For a while, losses were attributed to poison hemlock, a toxic plant that had been growing on many of these horse farms. Today, MRLS has been linked to eastern tent caterpillars. The current thinking of researchers at the University of Kentucky is that as horses accidentally eat the caterpillars, the hairs of the caterpillars penetrate the digestive tract of the horses and cause bacterial infections. The result is death of the fetus. Eastern tent caterpillar larvae are hairy in appearance with fuzzy covering of white hairs protruding from their black body. They have a white stripe running the length of the back and brown and yellow lines along each side. In addition, larvae will have a row of distinct oval blue spots present on each side. The biology of this native North American insect begins with moths laying egg masses on the limbs of several tree species including wild cherry, apple, crabapple, hawthorn, maple, pear, and plum. Egg masses containing from 150 to 400 eggs are laid in a ring around branches of the host tree where they will remain until spring. In early March the eggs hatch and larvae emerge. This insect is social in nature with larvae from individual egg masses staying together to spin a silken nest in limb crotches of their host tree. Larvae grow rapidly as they feed on developing leaves during early morning, late evening, and at night. During the day they often remain in the silken nest which protects the larvae from parasites, predators, and harsh weather conditions. In 4 to 6 weeks following emergence from the egg mass, larvae will be large in size and leave the host tree in order to locate a suitable sites in which to pupate. Moths will emerge and egg masses will be laid on host trees during late summer or early fall. Eastern Tent caterpillar is best controlled on the tree as insecticides for control on forages are limited. There are several products recommended for control on the tree. Craig Roberts 573 882-2801 and Wayne Bailey 573 864-9905 Eastern Tent Caterpillars Possible Threat to Horses By Wayne Bailey and Craig Roberts ********************************************************************** Weather Data for the Week Ending April 23, 2007 By Pat Guinan -------------------------------------------------------------------------------- | Monthly | Growing Weekly Temperature (deg. F) |Precip (in.)|Degree Days^ -----------------------------|------------|------------ Ext- Ext- Depart| Depart|Accum Depart Avg.Avg. reme reme from |Apr 1 from |since from Station County Max.Min. High Low Mean avg. |Apr 16 avg |Apr 1 avg. ------------------------------------------------------|------------|------------ Corning Atchison 76 51 82 45 64 +9 | 1.60 -0.74 | 129 +84 St. Joseph Buchanan 73 51 78 41 62 +6 | 1.06 -1.73 | 115 +47 Brunswick Chariton 74 47 82 37 61 +4 | 1.16 -1.35 | 114 +40 Albany Gentry 73 48 80 38 61 +6 | 0.83 -2.12 | 99 +48 Auxvasse Audrain 73 47 83 38 61 +5 | 1.81 -1.11 | 114 +41 Columbia Boone 73 48 81 40 61 +4 | 2.25 -0.88 | 117 +19 Sanborn Field Boone 74 50 82 41 62 +4 | 1.89 -1.25 | 134 +28 Williamsburg Callaway 74 46 82 38 61 +5 | 2.95 -0.34 | 121 +46 Novelty Knox 71 46 81 38 59 +3 | 2.23 -0.29 | 88 +24 Linneus Linn 73 47 81 37 60 +5 | 1.10 -1.56 | 101 +45 Monroe City Monroe 72 44 82 37 59 +2 | 1.97 -0.68 | 97 +15 Versailles Morgon 75 50 82 39 63 +4 | 2.50 -0.87 | 137 +9 Green Ridge Pettis 73 49 80 41 61 +5 | 2.60 -0.27 | 119 +50 Lamar Barton 73 51 80 45 62 +3 | 2.21 -1.02 | 130 +1 Cook Station Crawford 77 43 85 33 61 +2 | 2.63 -0.47 | 124 -13 Alley Spring Shannon 79 39 86 31 60 +2 | 2.29 -0.73 | 108 -11 Round Spring Shannon 80 40 85 32 61 +3 | 2.75 -0.28 | 112 -8 Delta Cape 74 47 84 39 61 +1 | 2.61 -0.22 | 130 -35 Girardeau | | Cardwell Dunklin 77 50 82 43 64 +2 | 2.65 -0.94 | 160 -51 Clarkton Dunklin 75 47 83 40 62 0 | 1.80 -1.17 | 143 -62 Glennonville Dunklin 74 50 83 43 63 +1 | 2.05 -0.82 | 150 -57 Charleston Mississippi 74 48 82 41 62 +2 | 2.32 -0.88 | 145 -17 Portageville- 75 52 83 45 64 +2 | 2.50 -1.09 | 165 -39 Delta Center Pemiscot | | Portageville- 76 51 83 45 64 +2 | 2.56 -1.00 | 165 -36 Lee Farm Pemiscot | | Steele Pemiscot 77 52 84 45 64 +2 | 2.92 -0.57 | 170 -31 -------------------------------------------------------------------------------- ^Growing degree days are calculated by subtracting a 50 degree (Fahrenheit) base temperature from the average daily temperature. Thus, if the average temperature for the day is 75 degrees, then 25 growing degree days will have been accumulated. -------------------------------------------------------------------------------- Pat Guinan Commercial Agriculture Program 573-882-5908 GuinanP@missouri.edu