Integrated Pest & Crop Management Newsletter University of Missouri-Columbia Vol. 16, No. 5 April 14, 2006 Time to Test for Endophyte in Pastures By Craig Roberts If you have a pasture of common tall fescue, chances are you also have the endophyte. Chances also are that your steers are 60 to 100 lbs. lighter than they should be at time of selling. Here’s why. The tall fescue endophyte is a fungus that grows inside (endo) the plant (phyte). It produces toxins that cause fescue toxicosis, the most serious forage-livestock disorder in Missouri. The symptoms of fescue toxicosis are not always noticeable. For example, it is hard to tell when steers are gaining 1.3 lb/day rather than 1.8 lb/day. But when steers go to the sale barn, the cost is felt. According to research in Georgia and other places, a steer on highly infected tall fescue will go to the feedlot 100 lbs lighter than a steer on non-toxic tall fescue. Some producers are electing to replace their old tall fescue with new cultivars. Others are learning how to manage the Kentucky 31. In either case, producers must first test for endophyte level. If the endophyte level is 20 percent or less, producers should manage what they have. If endophyte level is 55 percent or higher, they should consider replanting or seriously improving the management. It is critical to know the level of endophyte. How do we test for the endophyte? This time of year, it is best to test the growing tillers. The testing process involves clipping each tiller at the soil surface, where it joins the root, then sending it to a good lab. Details about sampling, shipping and costs are provided by the private lab. A good lab is NOT a certified lab; certified labs test for fiber and protein. There is no certification for the endophyte, so a good lab is one with a good record of analysis. Many labs test for the tall fescue endophyte. Some test with the microscope. As your samples arrive, the microscopic labs unpack the sample, stain it, and look for the endphyte growing between the cell walls. These labs are accurate only if the technician is well-trained. Other labs use a chemical procedure. The chemical labs treat your sample with reagents that eventually give a color; this color indicates the presence or absence of endophyte. The chemical lab most often used by MU researchers and extension specialists is Agrinostics, a private lab located in Georgia. The Agrinostics lab has never given an inaccurate reading to our researchers or extension specialists. And they have a quick turnaround time. For more information about testing, check out the Agrinostics website at www.agrinostics.com. Craig Roberts 573-882-2801 ********************************************************************* Foliage Diseases of Winter Wheat and Their Management By Laura Sweets 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 the central part 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. 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. Lesions of Septoria leaf blotch 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. The initial symptoms of tan spot 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 which causes tan spot, Pyrenophora tritici-repentis, 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, orange-red 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 yellowishred 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 this 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 that are 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, pre-harvest 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. C Rotate with nonhost 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 537-884-7307 ******************************************************************** Aphid Problems in Wheat By Wayne Bailey Many wheat fields in southwest Missouri have infestations of greenbug and bird cherry-oat aphids. These aphids can cause direct feeding damage by sucking plant juices, but may also transmit barley yellow dwarf virus (BYD) in wheat. Greenbugs are light or pale green in color with a predominant dark green line running down the back. They may damage wheat plants in both fall and spring, however numbers of this pest have remained low until about 3 weeks ago, when numbers began to build following early spring storms and strong winds blowing into Missouri from more southern regions of the U.S. Thresholds for this aphid are based on the average number of aphids present per foot of row depending on plant height and stage of growth. In general, traditional economic thresholds would be as follows: treatment is justified if 50 or more aphids are present per linear foot of row in the seedling stage; 100 or more present during the 3- to 6-inch stage of growth, and 300 or more aphids when the plants reach 6- to 10-onches in height. Recent research in Missouri and other states suggest that these thresholds may be too high and allow for more damage and subsequent yield loss than necessary. Much of this variability is due to plant size and stand density when infested, the number of aphids and amount of BYD virus present, and spring growing conditions. Another factor to consider is whether biological control agents such as ladybugs and parasitic wasps are active in the field. Insecticide Recommendations for Greenbug Chemical Name Product Name Rates: Amount of Product Preharvest (Unless otherwise noted) Interval (PHI) Dimethoate Dimethoate; See specific label See specific Dimate label Chlorpyrifos Lorsban 4E* 0.5 to 1 pt / acre 28 days Chlorpyrifos Nufos 4E* 0.5 to 1 pt / acre 28 days Chlorpyrifos Several See specific labels See specific formulations* label Gammacyhalothrin Proaxis* 3.84 fl oz / acre 30 days Lambdacyhalothrin Warrior* 3.84 fl oz / acre 30 days Lambdacyhalothrin Several See specific labels See specific formulations* labels * Indicates Restricted Use Based on the preceding information, the recommendation for management of the greenbug is as follows: If the average number of greenbug per linear foot of row equal or exceed 50 to 100 on wheat less than 6-inches in height, then treatment may be needed. Producers should consider the number of beneficial insects present (examples: adults and larvae of pink ladybugs and other species of ladybird beetles, parasitic wasps) and whether the wheat is under other stressors such as drought. The presence of high numbers of beneficial insects will increase the threshold and reduce the need for insecticides, whereas, the greater the stress on the plants, the lower the thresholds as stressed plants are less able to withstand aphid infestations. The bird cherry-oat aphid is typically dark olive in color with a rosy patch of color found on the back of the abdomen. This is a relatively large aphid which can look black in color at times. This insect is present in wheat in most years, but is often control by beneficial insects. The bird cherry-oat aphid can transmit BYD, but because this aphid often attacks the wheat at boot to heading stages of growth, thresholds are based on numbers of aphids present per tiller. In general, if an average of 50 or more bird cherry-oat aphids are present per tiller when the wheat is in the boot to heading stages of growth, then treatment is justified. Feeding by this aphid may result in damage to the flag leaf with the head taking on a hooked appearance as it emerges. We will continue to monitor this pest over the next couple of weeks. Remember to follow all label precautions, instructions and restrictions. Wayne Bailey 573-882-2838 573-864-9905 ********************************************************************* Black Cutworm (BCW) Moth Captures Increased During Past Week By Wayne Bailey Although moth numbers have not reached “intensive capture” levels to trigger our BCW predictive model, moth captures have been moderate to high during the past two weeks. Numbers of BCW moths captured at various sites throughout Missouri can be found at the IPM website at http://ipm.missouri.edu/SEMOmothtrap3.htm. Producers are encouraged to scout fields for the presence of insect pests, even if insecticide treated seed was planted. If heavy BCW populations develop, insecticide seed treatments may not be able to limit BCW larval population levels to below the economic threshold of less than 3 percent - 6 percent cut plants. Scattered reports of foliar feeding by large Dingy cutworms have been received from north Missouri, but numbers of worms in fields are low and damage minor. Wayne Bailey 573-882-2838 573-864-9905 ********************************************************************* Alfalfa Weevil Problems Continue in Southern and Central Missouri During the past week many alfalfa fields have required insecticide applications for control of alfalfa weevil larvae. Foliar feeding damage from alfalfa weevil is moving northward as additional eggs hatch and larvae grow in size. The bulk of damage should occur in central and northern Missouri regions within the next 2-3 weeks. In southern Missouri producers should continue to scout fields for this pest as a second wave of larvae may yet develop. Zoophthora phytonomi , the pathogenic fungus which can cause the rapid collapse of the weevil larval populations, may still occur this season. This fungus will most likely occur in those areas of the state where wet conditions persist for several days. Larvae infected with the fungus will turn from green to light yellow in color and die within 2- 3 days. See the previous newsletter for non-chemical and insecticidal management recommendations. Wayne Bailey 573-882-2838 573-864-9905 -******************************************************************** Foliar Fungicides Labeled for Use on Winter Wheat By Laura Sweets This table was prepared using current company product label books and web sites. However, label registrations can change at any time. Before using any agricultural pesticide, read and follow directions accompanying that product. Product names have been used for clarity. Reference to specific trade names does not imply endorsement by the University of Missouri; discrimination is not intended against similar products not listed. Trade Name Common % of Active Additional Label Company Chemical Name Ingredients Rate Information --------------------------------------------------------------------------- Controls rusts (Puccinia spp.), powdery mildew (Erysiphe spp.), leaf blight and glume blotch (Septoria spp.), tan spot (Pyrenophora tritici-repentis) and Helminthosporium leaf blight. Apply by ground or aerial application or through irrigation equipment. Highest yields are normally obtained when Bumper 41.8 EC is applied to the emerging flag leaf. Bumper 41.8 EC can be Bumper 41.8 EC 4.0 fl. applied until the Makhteshim-Agan propiconazole 41.80% oz. per ligule of the flag acre leaf emerges (Feekes growth stage 8). Do not apply after this growth stage to avoid possible illegal residues. Bumper 41.8 EC may be applied earlier if disease symptoms appear. Do not apply more than 4.0 fl. oz. of Bumper 41.8 EC per acre per season. Do not graze or feed livestock treated wheat forage or cut the green crop for hay or silage. After harvest, the straw may be used for bedding or feed. ---------------------------------------------------------------------------- For control of Helminthosporium leaf Dithane DF 2.1 spot, leaf rust, Rainshield lbs. Septoria glume blotch, Dow mancozeb 75.00% per Septoria leaf spot and AgroSciences acre tan spot. Start applications at the onset of disease or when plants are in the tillering to jointing stage and repeat at 7- to 10-day Dithane F-45 1.6 intervals. The Rainshield mancozeb 37.00% qts. addition of Latron Dow per CS-7 to spray AgroSciences acre solutions will improve performance. Do not make more than three applications during the season. Do not apply after 2.0 Feekes growth stage Dithane M45 lbs. 10.5 or heading, but Dow mancozeb 80.00% per not less than 26 days AgroSciences acre of harvest. Do not graze livestock in treated area prior to harvest. ---------------------------------------------------------------------------- For control of leaf rust, powdery mildew, Septoria leaf and glume blotch, spot blotch, stem rust, stripe rust and tan spot. Headline may be applied at the onset of disease. To maximize yields in cereals it is important to protect the flag leaf. Apply Headline immediately after flag leaf emergence for optimum results. 6.0 to Reapply 10 to 14 days Headline 9.0 fl. later if disease BASF pyraclostrobin 23.60% oz. per persists or weather acre conditions are favorable for disease development. Resistance management: To limit the potential for development of resistance, do not make more than two applications of Headline or other strobilurin fungicides per season. Apply no later than the beginning of flowering (Feekes 10.5). Do not harvest wheat hay within 14 days after last application. ---------------------------------------------------------------------------- Target diseases: Helminthosporium spot blotch and Septoria 1.5 to leaf blotch. Kocide DF copper 2.0 Make first application Griffin LLC hydroxide 61.40% lbs. at early heading and per follow with second acre spray 10 days later. Use the higher rates when conditions favor disease. ---------------------------------------------------------------------------- Target diseases: Helminthosporium spot blotch and Septoria 1.0 to leaf blotch. Kocide 4.5FL copper 1.33 Make first application Griffin LLC hydroxide 37.50% pts. at early heading and per follow with second acre spray 10 days later. Use the higher rates when conditions favor disease. ---------------------------------------------------------------------------- Target diseases: Helminthosporium spot blotch and Septoria 1.5 to leaf blotch. Kocide 101 copper 2.0 Make first application Griffin LLC hydroxide 77.00% lbs. at early heading and per follow with second acre spray 10 days later. Use the higher rates when conditions favor disease. ---------------------------------------------------------------------------- Target diseases: Helminthosporium spot blotch and Septoria 1.0 to leaf blotch. Kocide 2000 copper 1.5 Make first application DuPont hydroxide 53.80% lbs. at early heading and per follow with second acre spray 10 days later. Use the higher rates when conditions favor disease. ---------------------------------------------------------------------------- For the control of powdery mildew. Kumulus DF 6 to 15 Apply when disease Micro Flo lbs. first appears and Company sulfur 80.00% per repeat as necessary or LLC acre with the regularly scheduled insecticide program. ---------------------------------------------------------------------------- For control of Helminthosporium leaf spot, leaf rust, Septoria glume blotch, Manzate 2.0 lbs Septoria leaf spot and Pro-Stick mancozeb 75.00% per tan spot. DuPont acre Start applications at the onset of disease or when plants are in the tillering to jointing stage and repeat at 7- to 10-day intervals. Do not make more than three applications 1.6 during the season. Manzate qts. Do not apply more than Flowable mancozeb 37.00% per 6 lbs. or 4.8 Griffin L.L.C. acre qts./acre/crop. Do not apply within 26 days of harvest. Do not graze livestock in treated areas prior to harvest. ---------------------------------------------------------------------------- For control of Helminthosporium leaf spot, Septoria glume blotch and Septoria leaf spot Make first application 2.0-2.5 at early heading and ManKocide mancozeb + 15.00% lbs. follow with second Griffin L.L.C. copper 46.10% per spray 10 days later. hydroxide Use higher rates when acre conditions favor disease. Do not apply within 26 days of harvest. Do not graze livestock in treated areas prior to harvest. ---------------------------------------------------------------------------- For control of Helminthosporium leaf 0.8 to spot, Septoria leaf Penncozeb 4FL 1.6 spot, Septoria glume Cerexagri mancozeb 37.00% qts. blotch, leaf rust and per tan spot. acre Start application at the onset of disease or when plants are in tillering to jointing stage and repeat at 7- 1.0 to to 10-day intervals. Penncozeb 75DF 2.0 Do no apply more than Cerexagri mancozeb 75.00% lbs. 3 applications in one per season. Do not apply acre more than 6.4 lbs. Penncozeb 75DF or 6.0 lbs. Penncozeb 80WP/acre/crop. Do not apply within 26 1.0 to days of harvest. 2.0 Do not graze livestock Penncozeb 80WP mancozeb 80.00% lbs. in treated areas prior Cerexagri per to harvest. acre Do not apply after heading (around Feekes 10.5). ---------------------------------------------------------------------------- For control of powdery mildew (Erysiphe graminis f. sp. tritici), leaf and glume blotch (Septoria tritici and Stagonospora nodorum) and leaf rust (Puccinia reconditia), as well as suppression of Fusarium head blight (Fusarium spp.). Highest yields are normally obtained when PropiMax EC is applied to the emerging flag leaf. Application may be made through Feekes Growth Stage 10.5 (full head emergence) PropiMax EC 4.0 fl. using ground or aerial Dow propiconazole 41.80% oz. per equipment. Do not AgroSciences acre apply after this growth stage to avoid possible illegal residues. PropiMax EC may be applied earlier if disease symptoms appear. Do not apply more than 4.0 fl. oz. of PropiMax EC per acre per season. Do not apply within 40 days of harvest. Do not graze or feed livestock treated wheat, barley or rye forage or cut the green crop for hay or silage. After harvest, the straw from these crops may be used for bedding or feed. ---------------------------------------------------------------------------- Quadris should be applied prior to disease development from jointing to (Feekes 6 or Zadok’s 6.2 to 31) up to late head 12.3 emergence (Feekes 10.5 fl. oz. or Zadok’s 59). A crop per oil concentrate acre adjuvant may be added for at 1.0% v/v to leaf optimize efficacy. rust, Resistance Management: stripe Do not make more than rust, two foliar stem applications of rust, Quadris or other Qol fungicides per acre Quadris Septoriaper season. Syngenta azoxystrobin 22.90% leaf Do not apply until and glume after forage stage blotch, (Feekes 6 or Zadok’s and tan 31). spot Do not apply later than Feekes growth 7.7 to stage 10.5 (Zadok’s 10.8 growth stage 59). fl. oz. Do not harvest treated per wheat for forage. acre Do not apply more than powdery 0.77 quarts mildew product/acre/season. Do not apply within 14 days of harvest for hay. Do not apply within 45 days of harvest for grain and straw. ---------------------------------------------------------------------------- 7.0 to 14.0 fl. oz. per acre for early season suppression of powdery mildew, Septoria leaf blotch, Stagonospora glume blotch and tan spot. 14.0 fl. oz. per acre for control of leaf diseases (rusts, powdery mildew, Septoria leaf blotch, Stagonospora glume blotch, tan spot). Protecting the flag Quilt leaf is important for Syngenta maximizing the potential yield. Special local Highest yields are needs obtained when Quilt is registration applied when the flag for use leaf is 50-70% in Missouri emerged. extends 7.0 to Applications may be application 14.0 made no closer than a period azoxystrobin 7.00% fl. oz. 14-day interval. Quilt to Feekes propiconazole 11.70% per may be applied up to Growth acre Feekes growth stage 9. Stage 10.5. Do Do not apply more than not 2 applications per apply within 40 acre per year. Do not days apply more than 20.5 of harvest. See fl. oz per acre per SLN season. label for full Do not apply within 45 details. days of harvest for grain and straw. Do not harvest wheat for forage. Do not graze or feed livestock treated forage or cut green crop for hay or silage. Under certain environmental conditions, tank mixes of Quilt plus herbicides and/or fertilizers may cause crop injury in barley, triticale and wheat. ---------------------------------------------------------------------------- For control of glume Stratego blotch, leaf blight, Bayer powdery mildew, rusts and tan spot. Begin applications Special local preventively when needs conditions are registration favorable for disease for use development. A second in Missouri application (minimum extends 10.0 interval of 14 days) application propiconazole 11.40% fl. oz. may be made if needed. period trifloxystrobin 11.40% per Do not apply more than to Feekes acre 2 applications per Growth season. Stage 10.5. Do Do not apply Stratego not after Feekes growth apply within 40 stage 8 (the ligule of days the flag leaf of harvest. See emerges). SLN Do not apply Stratego label for full within 35 days of details. harvest. See label for grazing restrictions. ---------------------------------------------------------------------------- Early season leaf disease suppression: apply 2.0-4.0 fl. oz. per acre for suppression of tan spot, Septoria and powdery mildew. Leaf disease control: apply 4.0 fl. oz./acre at first appearance of disease. Protecting the flag leaf is Tilt important for Syngenta maximizing the yield potential. Special local Highest yields are needs normally obtained when registration Tilt is applied to the for use emerging flag leaf. in Missouri Tilt can be applied extends until the ligule of application 2.0 to the flag leaf emerges period propiconazole 41.80% 4.0 fl. (Feekes Growth Stage to Feekes oz. per 8). Do not apply after Growth acre this growth stage to Stage 10.5. Do avoid possible illegal not residues. Tilt may be apply within 40 applied earlier if days disease symptoms of harvest. See appear. SLN Tilt may be applied by label for full ground or aerial details. application or through irrigation equipment. Do not apply more than 4.0 fl. oz. of Tilt per acre per season. Do not graze or feed livestock treated wheat forage or cut the green crop for hay or silage. After harvest, the straw from these crops may be used for bedding or feed. Laura Sweets 537-884-7307 ********************************************************************* Ordinary nozzles very effective when used properly By Bill Casady There seems to be a concern that we may get caught with our booms down when we eventually do need to treat for Asian rust. In an attempt to be prepared, we sometimes willingly buy whatever product is "best promoted" to do the job. Researchers across the country are still busy determining just what to promote to do the best job. It turns out that the number one strategy to promote for good efficacy from the application of herbicides as well as fungicides is not a specific product, but good knowledge; e.g. knowledge of the correct droplet size, of a method to choose an appropriate nozzle, of good calibration, and proper boom height. There are some relatively exotic or fancy nozzle configurations that can appear to have a corner on the market for applying fungicides for Asian rust. The research, however, does not yet clearly point to any single nozzle or nozzle configuration that is guaranteed to work best. Yet, there are probably more than a dozen nozzles and maybe two dozen nozzles that will provide good coverage of the inside and lower portions of the canopy. Ordinary single nozzles of the turbo and extended range varieties will work just fine for applying fungicides. However, it is important to choose a nozzle that will produce a medium to fine droplet for applying fungicides (refer to MU publication G1270). Very fine droplets will not do a better job because they will tend to drift off rather than reach the target. It’s also important not to skimp on water. Twenty gallons is typically recommended. Finally, remember that for the application of any pesticide, the information on the label supersedes anything you might read in this newsletter. It’s not just good advice. It’s the law. And as always, wear good personal protective equipment and be safe. Bill Casady (573) 882-4370 ********************************************************************* Fertilizer Efficiency - What’s the Limit? By Peter Scharf Over the past fall, winter, and spring, I have received many calls and e-mails from individuals asking about fertilization practices to improve efficiency. High fertilizer prices will make it harder for producers to be profitable, and the same is probably true for input suppliers. Whether it’s producers considering knife application of P and K, or corporations working on N-efficient germplasm, efficient fertilizer use is a good thing. However, producers and corporations alike seem to hope that increasing fertilizer efficiency will allow dramatic reductions in fertilizer rates. Unfortunately, this is not the case. No matter how fertilizer is applied, and no matter how it’s taken up by crops, it’s impossible for efficiency to go above 100 percent. And if a low rate is 100 percent efficient, but is less than what is removed in the harvested crop, the system is being mined. That can only go on for so long. In some cases, mining nutrients from the soil is appropriate. In soils that are very N-rich, it can be a use-it-orlose- it situation. With P and K, loss is rarely an issue, but it can be a good business and agronomic decision to mine soils with high native soil test levels for a period of years. Some of our river-bottom fields would fall into this category. But in the long run, every field must eventually come to the point where nutrients applied, as fertilizer or otherwise, are at least as great as nutrients removed. It is worthwhile knowing typical nutrient contents for your crops and thinking about how many pounds of N-P2O5-K2O are being removed when you harvest. Values for some of our most important crops are shown in this table: Amounts removed: Crop Unit N P2O5 KO Corn lb/bu 0.8 0.45 0.35 Soybean lb/bu 4 0.8 1.4 Wheat lb/bu 1.4 0.6 0.3 Fescue Hay lb/ton 40 12 35 Alfalfa Hay lb/ton 45 15 45 Fescue pasture Cow/calf pair 10 7 1 Peter Scharf 573-882-0777 ********************************************************************* Weather Data for the Week Ending April 10, 2006 By Pat Guinan -------------------------------------------------------------------------------- | Monthly | Growing Weekly Temperature (deg. F) |Precip (in.)|Degree Days^ -----------------------------|------------|------------ Ext- Ext- Depart| Depart|Accum Deprt Avg. Avg. reme reme from |Mar 1- from |since from Station County Max. Min. High Low Mean avg. |Mar 14 avg. |Apr 1 avg ---------------------------------------------------------|------------|------------ Corning Atchison 73 43 86 30 58 +10 | 1.06 0.17 | 70 +70 St. Joseph Buchanan 69 42 79 33 56 +6 | 1.10 0.19 | 63 +59 Brunswick Chariton 70 41 78 31 57 +7 | 0.91 0.06 | 68 +61 Albany Gentry 71 40 80 28 56 +7 | 0.64 -0.34 | 56 +54 Auxvasse Audrain 69 40 80 32 56 +6 | 0.37 -0.59 | 68 +61 Columbia Boone 69 42 79 32 56 +5 | 0.60 -0.55 | 72 +56 Sanborn Field Boone 71 43 81 34 58 +6 | 0.34 -0.82 | 84 +65 Novelty Knox 68 39 77 31 54 +5 | 0.64 -0.17 | 46 +44 Linneus Linn 69 39 76 29 55 +6 | 0.68 -0.08 | 57 +55 Monroe City Monroe 68 39 80 29 54 +3 | 0.13 -0.84 | 49 +42 Versailles Morgan 71 44 79 34 58 +5 | 0.36 -1.00 | 86 +58 Green Ridge Pettis 70 43 77 33 57 +7 | 0.34 -0.71 | 74 +70 Lamar Barton 70 44 78 33 58 +5 | 0.87 -0.16 | 85 +55 Cook Station Crawford 70 38 79 27 55 +2 | 0.74 -0.27 | 74 +42 Alley Spring Shannon 73 35 83 25 55 +2 | 0.39 -0.63 | 72 +47 Round Spring Shannon 73 37 83 27 56 +3 | 0.63 -0.39 | 73 +47 Delta Cape 68 41 80 33 55 +1 | 0.50 -0.62 | 71 +28 Girardeau | | Cardwell Dunklin 73 46 84 37 59 +2 | 0.60 -0.97 | 111 +46 Clarkton Dunklin 71 43 84 32 57 +1 | 0.72 -0.52 | 93 +36 Glennonville Dunklin 72 44 85 34 57 +1 | 0.12 -1.08 | 96 +37 Charleston Mississippi 70 43 83 36 57 +3 | 0.99 -0.31 | 83 +37 Portageville- | | Delta Center Pemiscot 71 46 83 36 59 +3 | 1.29 -0.12 | 104 +43 Portageville- | | Lee Farm Pemiscot 71 46 84 37 59 +3 | 1.06 -0.34 | 105 +44 Steele Pemiscot 74 46 86 34 60 +4 | 0.13 -1.32 | 116 +59 -------------------------------------------------------------------------------- * Complete data not available for report ^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