Mid-Atlantic Regional Agronomist Quarterly Newsletter

Transcription

1 Mid-Atlantic Regional Agronomist Quarterly Newsletter Dr. Richard W. Taylor, Editor University of Delaware Supporting Agronomists: Dr. Wade Thomason, Va Tech Dr. Bob Kratochvil, University of Maryland Dr. Greg Roth, Penn State Dr. Peter Thomison, Ohio State University Dr. Chris Teutsch, Va Tech March 2013 To subscribe or unsubscribe, please send your request to the editor at Comments, suggestions, and articles will be much appreciated and should be submitted at your earliest convenience or at least two weeks before the following dates: February 28, May 30, August 30, and November 30. The editor would like to acknowledge the kindness of Mr. Todd White who has granted us permission to use his scenic photographs seen on the front cover page. Please go to to view more photographs. 1

2 Contributors for This Issue Dr. Bob Kratochvil, UMD Dr. Ben Tracy, Va Tech Dr. Mark VanGessel, UD Dr. Robert Dyer, UD Mr. Del Voight, PSU Mr. John Bray, PSU Ms. Alyssa Collins, PSU Dr. Greg Roth, PSU Ms. Joanne Whalen, UD Mr. Bill Cissel, UD 2

3 Table of Contents Issue 8; Number 1 Contributors for This Issue... 2 Table of Contents... 3 Effect of Cereal Cover Crop Species on Full Season Soybean Performance... 5 Glyphosate-resistant Palmer Amaranth Confirmed in Delaware... 6 Plant Description... 7 Chemical Control... 9 Prevention... 9 Managed Grazing for Improved Soil Health and Environmental Protection Dry Cow Mastitis and Strategies Designed to Reduce the Risk of New Intramammary Infections (IMI) during the Dry Period Introduction Assessing Dry Cow Status and Challenges Risk factors for new IMI in the dry period Cow and quarter factors Herd management factors Dry Cow Programs Blanket dry cow therapy Rational dry cow programs based upon scientific input Conclusion References On-Farm Bio-Forage Response Study On-Farm Ratchet Response Study On-Farm Molybdenum Response Studies On-Farm Plant Stress Input Study Soybean Planting Date Study Soybean Induced Branching Study Slug Management in Conservation Tillage Corn: Part I Pre-Plant Shingle Trapping Introduction Pre-Plant Shingle Trapping Pre-Plant Shingle Trapping Conclusion Notices and Upcoming Events Fencing for Controlled Grazing Systems Weed Science Training: Back to the Basics Weed Science Training: Back to the Basics Fencing for Controlled Grazing Systems Eastern Virginia Forage and Grazing Conference Fencing for Controlled Grazing Systems Southern Piedmont Equine Extravaganza Trail Riding in Virginia Pasture Lambing Workshop

4 2013 Beginning Grazier School Cool Season Workshop AFGC National Tour Weed Science Field Day Weed Science Field Day Weed Science Field Day Grazing for Profit in the 21 st Century Delaware Soybean Tour Herbicide Resistance Field Day Sustainable Agriculture and Reduced Tillage Organic Grain Field Day Mid-Atlantic Crop Management School Delaware Ag Week Newsletter Web Address Photographs for Newsletter Cover

5 Effect of Cereal Cover Crop Species on Full Season Soybean Performance Dr. Robert Kratochvil Extension Specialist Grain and Oil Crops University of Maryland Does choice of cereal cover crop species affect full season soybean? Does cereal cover crop kill date matter? These are questions that soybean farmers are asking as Maryland cover crop acreage continues to increase. To address these questions, three years of research was conducted by planting three cereal species (barley, wheat, and rye) as cover crops at the Wye Research and Education Center (fall 2009 and 2010) and Central Maryland R&E Center-Beltsville (fall 2010 and 2011). A no cover crop treatment (only fall-winter weed growth) also was included. Three (Wye) and two (Beltsville) cover crop spring kill dates that supported varying amounts of cover crop biomass production were used. The kill dates at Wye are defined as 1) extra early kill for only the rye and the no cover treatments (mid-late March during the two study years); and at both Wye and Beltsville 2) early kill date for all treatments (ranged from 13 April to 23 April); and 3) late kill date for all treatments (ranged from 2 May to 16 May). Soybean varieties Asgrow brand 3539RR2 (mid MG 3) and Asgrow brand 4630RR2 (mid-mg 4) were planted into all cover crop treatments between 2 and 3 weeks after the last kill date. Soybean harvest dates were considered normal ranging from 17 October to 3 November during the three years. Approximately three weeks post-planting, stand emergence was assessed to see if the cover crop species or kill date treatments impacted stand establishment. Over the three year period, no emergence differences were observed indicating that neither choice of cereal cover crop nor spring kill date had a detrimental effect on soybean germination and emergence. The most important criterion when planting full season soybean into a cereal cover crop is attainment of good seed-soil contact. Starting approximately mid-june each year, a weekly measurement of growth stage progression was done by randomly selecting 5 plants in each plot, determining the growth stage according to Fehr and Caviness (1971), and averaging the growth stage. The primary growth differences observed were associated with the two varieties. Both varieties progressed through vegetative growth similarly. The onset of reproductive growth always was observed for the earlier of the two varieties, as expected. The weekly readings continued until early-mid September. Occasionally, only very minor differences in growth stage progression for the soybeans were observed for either the cover crop species or the kill date treatments. These differences were inconsistent across the assessment dates and are considered to have no influence on soybean growth and performance. Soybean yield (72 bu/acre average) was excellent during the three years. The most consistent yield difference observed was associated with variety, however there was no consistent trend favoring one over the other. At Wye, the MG 3 variety produced better than the 5

6 MG 4 variety during and the opposite occurred during During at Beltsville, the MG 4 variety was best and during , there was no yield difference between the two. Response of soybean yield performance to cover crop species and kill date varied by location. During the two years at the Wye, a cover crop species (by) kill date interaction was observed. For the March kill date (extra early), soybeans planted into the no cover crop treatment produced 10% ( ) and 4% ( ) better than soybeans following rye. For the 2010 April kill date (early), soybeans planted following any of the three cover crop species produced the same (62 bu/acre) but soybeans following the no cover treatment yielded nearly 10% more (68 bu/acre). In 2011, the April kill date produced no yield differences (~67.5 bu/acre average) among the four cover treatments. For the two years the study was conducted at Beltsville, there was no cover crop species kill date interaction during but in this interaction was significant. At Beltsville in , soybeans planted where cover crops were killed during April produced over 6% greater than soybeans following the May kill date. However during this study year, there were no differences in soybean yield associated with any of the cover crop treatments. During , soybeans following either barley or wheat cover crop produced the same for the two kill dates. However, soybeans that followed either rye or the no cover crop treatment, produced approximately 12% greater following the May kill date. Based on three years of data collected in this study, answers to the two primary questions about soybean performance following cereal cover crops are: 1. Does choice of cereal cover crop species affect the performance of full season soybean? The performance of full season soybean following a cereal cover crop cannot be predicted by the cereal species grown. Differences may occur but they will be associated with location and kill date. 2. Does cereal cover crop kill date influence soybean performance? The optimum kill date for cereal cover crops followed by full season soybean is difficult to predict. Factors that can affect soybean performance for any particular kill date are location, year, weather, and variety. Glyphosate-resistant Palmer Amaranth Confirmed in Delaware Dr. Mark VanGessel Extension Weed Specialist University of Delaware mjv@udel.edu Palmer amaranth (Amaranthus palmeri S.Wats.) is a summer annual broadleaf weed, native to Sonora Desert in the Southwestern United States. It is also called Palmer pigweed or carelessweed. Palmer amaranth can reach final heights of over 6 feet. Palmer amaranth is a very 6

7 competitive plant, capable of causing dramatic yield loss and dominating disturbed sites by outcompeting other weeds and vegetation. Competitiveness of this weed is due to its rapid growth during the seedling stage. Research comparing various amaranthus species found Palmer amaranth to be the most competitive species in the trial, much more competitive than redroot pigweed. Plant Description Palmer amaranth is closely related to the common pigweed species in the mid-atlantic region, smooth pigweed (Amaranthus hybridus) and redroot pigweed (Amaranthus retroflexus). Unlike smooth and redroot pigweeds, Palmer amaranth is a dioecious plant which means there are separate male and female plants. The male plants produce pollen that is wind disseminated to female plants. Palmer amaranth plants look very similar to smooth and redroot pigweed. However, Palmer amaranth leaves, stems, and petioles do not have hairs (smooth and redroot pigweed do have fine hairs). Palmer amaranth s leaves have long petioles that are often as long, or longer, than the leaf blade. As a result, the leaves often droop. Occasionally, leaves will have a variegated V mark across the leaf blade. Palmer amaranth is only one of two pigweed species in Delaware with this watermark. Spiny amaranth is the other, but spiny amaranth has a diagnostic pair of ¼ to ½ inch spines at the base of most leaf petioles and along the central stem. 7

8 Palmer amaranth s seed heads are very long, ranging from ½ to 1½ feet in length. Only the female plants produce seeds. Seeds are small, shiny black and smooth. A single female plant can produce over 600,000 seeds when grown under optimum conditions. Palmer amaranth plants will continue to germinate throughout the summer and early fall. Palmer amaranth densities appear to be lower in no-till than conventional tillage situations. However, altering tillage alone is not adequate for Palmer amaranth control. Most of the Palmer amaranth plants emerge from seeds that are within the top two inches of the soil surface. It appears that Palmer amaranth seeds are relatively short-lived with only 20% survival after three years in the soil. Biotypes of Palmer amaranth have shown to become resistant to a wide range of herbicides including dinitroanilines (Group 3), ALS inhibitors (Group 2), photosystem II inhibitors (Group 5), and ESPS enzyme inhibitor, glyphosate (Group 9). Furthermore, biotypes resistant to both glyphosate and ALS inhibiting herbicides have been reported in Georgia, Mississippi, Tennessee, North Carolina, and Virginia. Amaranthus palmeri Maryland reported glyphosate-resistant Palmer amaranth in 2011, based on field tests. In January 2013, greenhouse studies of plants from Delaware suspected of glyphsoate-resistance were conducted. Four samples from Delaware and eastern shore of Maryland were confirmed resistant. In many situations, the genes for herbicide resistance are male-traits that are disseminated in the pollen. Pollen from Palmer amaranth plants can move at least 1000 ft and is believed to be an important factor in the rapid spread of resistant biotypes. 8

9 The competitiveness of Palmer amaranth, the prolonged period of germination, its likelihood to develop resistance to many herbicide modes of action, and the long distance spread of resistance traits through pollen are why Palmer amaranth is a species requiring special management for its control. Preventing seed production is critical to managing this species. Viable seeds can be produced as soon as 2 to 3 weeks after flowering. Chemical Control Excellent Palmer amaranth control can be achieved in corn and full-season soybeans. Control programs should consist of an effective soil-applied residual herbicides followed with postemergence herbicide applications as needed. Due to the ability of Palmer amaranth to emerge throughout the season, postemergence applications with a herbicide providing residual control should be considered. To preserve the usefulness of herbicides currently effective on Palmer amaranth: always use an effective soil-applied herbicide program shortly before or at planting; never apply glyphosate by itself when emerged Palmer amaranth plants are present; do not overuse ALS-inhibiting herbicides (Group 2 such as Classic, Synchrony, Pursuit, Raptor, Resolve, etc) postemergence applications must be made to small (less than 3 inch) plants; in fields with corn/soybean rotation, UD Weed Science recommends use of PPOinhibiting herbicides (Group 14) in one year, followed by an HPPD-inhibiting herbicide (Group 27) the following year. For instance, use Group 14 herbicides (Valor, Authority, or Reflex) for soybeans, and Group 27 herbicides (mesotrione, tembotrione, or topramezone) for corn. Prevention Palmer amaranth is a prolific seed producer and these seeds can be spread by many means. Preventing or limiting seed production is very important. This may require post-harvest mowings, tillage operations or herbicide applications to stop seed production. When using mowing, repeated mowing are necessary to prevent seed production. Of particular importance is the spread of seeds carried with crop harvesting equipment. Proper cleaning of equipment requires use of an air compressor, pressure hose, or sweeping. Letting the equipment run to clean itself out is not adequate. Machinery should be cleaned in the field where Palmer amaranth is present (or suspected), rather than transported to another field prior to cleaning. Do not allow Palmer amaranth plants outside the field to produce seed. Ensure that organic materials such as straw, mulch, manures, and seeds that are used in your fields are not infested with Palmer amaranth or other weed seeds. Palmer amaranth plants have a taproot as well as fibrous roots. The large root system allows Palmer amaranth to obtain more water and nutrients than most crops and contribute to its rapid growth and competitiveness. Developed roots have the ability to re-root or regrow after mechanical disturbances. Broken stems and roots can regrow and produce seed. As a result, cultivation needs to be performed on small, susceptible plants (3 inches or less). 9

10 Palmer amaranth requires sunlight to thrive, so a dense crop canopy can effectively shade out later emerging Palmer amaranth plants. Use good agronomic practices to ensure the crop develops quickly and forms a dense canopy. Managed Grazing for Improved Soil Health and Environmental Protection Dr. Ben Tracy Department of Crop and Soil Environmental Sciences Grassland Ecosystem Management Specialist Virginia Tech bftracy@vt.edu This past fall, I along with a group of Virginia Tech researchers received a Conservation Innovation Grant (CIG) from USDA-NRCS to demonstrate how different types of managed grazing might affect soil health and other variables. The project will focus on comparisons among continuous, rotational, and so called mob grazing. Mob grazing, in particular, has received a lot of press in recent years. It was first promoted by Savory in the 1980s as part of a more holistic approach to rangeland management. With mob grazing, a high density of animals is restricted to a small paddock, either eating or trampling all the plants before being moved to new grass sometimes after a few hours. Stocking livestock at densities over 100,000 lbs/acre is common. Mob grazing usually starts later in the season (e.g., late May/June in Virginia) when grasses are near maturity and is followed by a long recovery period usually days before paddocks are grazed again. Paddocks under mob grazing should be used only once or twice per growing season usually. Rotational grazing is similar in principle to mob grazing except stocking density is lower and pasture recovery periods are much shorter e.g., days. Continuous grazing is probably the most common type of management here in the mid- Atlantic region. It usually involves confinement of livestock within defined partitions of pastureland with minimal management of stocking rate or control of forage removal. A major reason for initiating this project was to provide graziers with some comparative information about these different grazing methods. In particular, we wanted to provide more information about mob grazing and its apparent benefit to soils and plants since this method has drawn a lot of interest and controversy among livestock producers. Some of the purported benefits associated with mob grazing include: 1. Healthier soils with high organic matter, water-holding capacity, and an abundance of microorganisms, earthworms, and dung beetles. 2. More even distribution of recycled soil nutrients and organic matter across pastures from the intensive management of animal stocking density. 10

11 3. Desirable plant diversity with few weeds and consistent seasonal ground cover that will help build organic matter and reduce soil erosion. To demonstrate these claims, we will be conducting grazing trials at two farms near Blacksburg and Steeles Tavern, Virginia. Grazing at both sites is scheduled to begin April 2013 and will continue through In the end, we hope to see how mob grazing measures up to both rotational and continuous grazing in terms of its potential to improve soil health, forage quality, and reduction in nutrient losses from water runoff. To meet these objectives, several academic departments at Virginia Tech will be working together including the Department of Crop and Soil Environmental Sciences, the Department of Animal and Poultry Sciences, and the Department of Biological Systems Engineering. We are excited about getting this project started so keep on the lookout for future articles, pasture walks, and workshops associated with this endeavor. It should be an interesting three years! Dry Cow Mastitis and Strategies Designed to Reduce the Risk of New Intramammary Infections (IMI) during the Dry Period Dr. Robert M. Dyer, VMD, PhD Associate Professor Department of Animal and Food Sciences University of Delaware Introduction The dry period is a two edged sword: An optimal time for self-cures of major contagious and environmental pathogens coupled with a risk for acquisition of new intramammary infections. The dry period has been historically recognized as the pivotal time for restoration of intramammary health through resolution of pre-existing intramammary infections (IMI). Research over the past 2 decades has clearly determined the dry period is also an important time during which intramammary infection occurs. Thus, the prevalence of IMI in dry period cows is really a balance between (1) end of lactation cows entering the dry period with contagious and environmental IMI, (2) cure rates of IMI during the dry period, and (3) acquisition of new IMI during the dry period. Epidemiologically, the dry period is an important contributor to herd problems with contagious, major intramammary pathogens, environmental pathogens, and minor pathogens of mastitis. In all cases, intramammary infection during the dry period leads to lower productivity in succeeding lactations with increased incidence of clinical flare up during the first 100 DIM in the next lactation. Intramammary infection is common during the dry period with major mastitis pathogens being isolated from as high as 50% of dry cows (Green et al., 2005). In one survey, nearly 20% of dry cows harbored major mastitis pathogens in more than 1 quarter. 11

12 Mastitis remains the greatest loss to dairy producers. Average costs of contagious mastitis is estimated at $ in the U.S. (Bar, et al., 2008) with the highest cost in cows with high expected future returns and lowest in cows targeted for culling due to reproductive, lameness or low productivity. Losses from mastitis and IMI are estimated at $115 from reduced milk yields, $14 due to increased mortality, and $50 from treatment costs. Importantly, the cost of mastitis has recently been shown to depend upon the type of mastitis pathogen (major, minor, gram negative and gram positive pathogens) (Cha et al., 2011). Modeled costs of gram negative IMI were greatest at $211 while losses from gram positive IMI were considerably less at $133. Interestingly, the greatest source of gram positive IMI costs was related to treatment whereas loss in milk yields generated the greatest cost for gram negative IMI. Costs of sub-clinical IMI with Staphylococcus aureus were estimated at $170 (Wilson et al., 1997). Recently, model estimates of additional costs from subclinical IMI during lactation were $117 per cow in a 100 cow herd when the subclinical infection remained untreated during lactation (van den Bourne et al., 2010). Successful treatment within 1 month of diagnosis during lactation reduced transmission across herds; and therefore, minimized costs associated with clinical flare-ups, losses in milk yield, treatment costs, and culling losses. Additional costs are derived from market deductions due to elevated somatic cell counts (SCC) associated with subclinical IMI. These losses are reduced with on farm control measures and management strategies designed to minimize cow to cow transmission and dry cow IMI. IMI spreads through the lactating herd via several widely recognized routes. Clearly, milking procedure management is a key contributor to the incidence of contagious as well as environmental pathogen transmission. Wearing gloves, application of pre- and post-milking dipping procedures, and timely, proper claw and vacuum maintenance critically impact incidence rates. Indeed, anything that increased callous formation on teat ends was associated with high incidence of contagious IMI (Dufour et al., 2012). Wearing gloves has been proposed to be one of the most crucial components of milking technique because the number of S. aureus organisms on gloves is likely to be much lower than numbers on the skin of milking personnel. Pre-milk dipping likely controls both environmental and contagious pathogen transmission (Nickerson and Brody, 1997, Piccininni et al., 2009). Factors such delayed or inappropriate milk let down, inadequately maintained and adjusted automatic take offs, vacuum fluctuations or inappropriate vacuum levels, or personnel distraction that prolongs milking time predisposes teat ends to extensive callous formation. Stall beds of cement or sand rather than rubber or mattress were associated with lower prevalence of IMI. Management factors associated with increased incidence of IMI transmission of contagious pathogens are milking personnel not wearing gloves, overcrowding during the first 1-60 days in milk (DIM), and lack of a culling program based upon repeated clinical flare-ups from a contagious IMI. Transmission of contagious mastitis pathogens across quarters and cows is also highest in herds with high SCC and a high prevalence of contagious IMI. Indeed, Dufour et al. (2012) noted that a 5% increase in the prevalence of quarter infections in a herd was associated with a doubling of the incidence of new IMI infections. The effect was observed across cows as well as across quarters within cows. Thus, cows with contagious mastitis in one or more quarters were 12

13 at high risk of transmission to other IMI free quarters. Indeed, dry cow programs designed to treat and cure subclinical IMI infections with contagious pathogens reduce transmission rates of contagious pathogens within herds. Most importantly however, the longer an IMI persists without treatment during lactation, the greater the transmission across herd mates. This effect can negate any advantage well-orchestrated cull programs or dry cow cure rates offer for reducing the incidence and prevalence of contagious pathogen IMI in a herd. There are environmental pathogen challenges to both lactating and dry cows. These pathogens are endemic in the cow s environment and therefore present a constant threat to the mammary gland. Environment also impacts IMI problems by reducing immune resistance through enhanced stress, increasing the likelihood of teat skin-streak canal contact with environmental pathogens, and enhancing environmental loads of intramammary pathogens by providing moisture and temperatures that sustain microbial growth and viability. Interestingly, the environmental effect may be both parity and stage of lactation-dependent. Environments that appear safe for 3 rd and greater lactation animals may increase prevalence of IMI in first parity heifers. Dufour et al, (2012) speculated facility design and management practices in the future may have to be adjusted to the cow rather than the cow being asked to adjust to the environment. The dry period is an important time during which IMI are acquired while pre-existing IMI are eliminated. The most important dry cow IMI challenge is from environmental pathogens like the enterobacteria and environmental Streptococci sp. These challenges typically occur with greatest incidence very early and then very late in the dry period. Acquisition of these new IMI in the dry period often results in clinical flare ups during the first DIM in the next lactation. Research has shown mammary pathogens isolated late in the dry period are very often not the same pathogen isolated from the mammary gland at the time of dry off (Green et al., 2005). One explanation for these results is the mammary gland establishes sterility but then trades that sterility off for new intramammary infections as the cow progresses through the dry period. The most common pathogens isolated are Escherichia coli, Streptococcus uberis, Streptococcus dysagalactaie, coagulase negative Staphylococcus. epidermitis and the contagious, coagulase positive Staphylococcus sp. Thus, with the exception of coagulase positive Staphylococcus sp., a high proportion of major pathogens involved in dry cow infections tend to be environmental bacteria. Moreover, the prevalence of major pathogen recovery from dry cow glands increases as one approaches the day of parturition even in glands with antimicrobial dry cow treatments. Conversely, the prevalence of minor pathogen recovery decreases as one approaches parturition. These differences are in part attributed to the self-cures during the dry period that favor eradication of minor pathogens from the mammary gland. As a result, IMI with major pathogens are associated with greater risk of culling during the next lactation. Assessing Dry Cow Status and Challenges Preventing new IMI and eliminating pre-existing IMI during the dry period is a key element in herd mastitis control programs. Bacteriologic culture pre- and post-dry period remains the 13

14 gold standard for assessing efficacy of dry cow management programs. Realize bacteriologic culture is not without sensitivity problems. A negative culture of course does not necessarily mean the absence of IMI. The problem with bacteriology is that the method is labor intensive and costly. Since SCC can serve as surrogates for IMI however, assessing SCC at dry off and SCC after freshening can serve as a proxy for monitoring dry period management schemes. Indeed, 200,000cels/ml of composite milk sample from all 4 quarters can be utilized as the threshold indicator for the presence of IMI in the dry period (Cook et al, 2002). Newer work suggests this threshold may be too high and 150,000 cells/ml might be a better indicator of major pathogen infection in composite samples. Regardless, currently available composite SCCs are very useful predictors for the presence of major pathogen infections (Dufour and Dohoo, 2012). The composite SCC appear to be somewhat less reliable for predicting the presence of a minor pathogen IMI. Pre-existing IMI at the time of dry off should generate pre-dry last day milk sample SCC > 200,000 cells/ml. Glands could be considered free of IMI if the last pre-dry test day milk sample has < 200,000 cells/ml. Acquisition of a new IMI during the dry period should result in SCC in the first test day milk sample in the next lactation >200,000 cells/ml. Thus, the benchmark goal is a SCC 200,000 cells/ml: also a reasonable goal is to have < 10-15% of all cows freshening with SCC >200,000 cells/ml at first test. Elimination of IMI during the dry period would appear as pre-dry SCC >200,000 paired with post dry period SCC < 200,000. Acquisition of an IMI during the dry period would be evidenced by a pre-dry SCC< 2000,000 and a first test day post calving SCC >200,000. Using these criteria and procedures (Cook et al, 2002) noted 24% (range 0-70%) of dry cows across all herds developed new IMI over the dry period. The incidence and prevalence of new IMI in the dry period were greatest during July, August, and September. Cure rates for dry cow IMI estimated by drop in a high SCC at dry off to < 200,000 cells/ml after freshening was 63% across all herds (range %). The new infections are primarily but not inevitably attributable to the environmental bacteria E. coli, Streptococcus uberis, and Streptococcus dysagalactiae. In other herd studies, the minor pathogen, coagulase negative Staphylococcus sp. (e.g. Staphylococcus epidermidis), and the environmental bacteria Streptococcus non-agalactiae and Escherichia coli caused most of the IMI before and during dry off (Pantajo et al., 2009). In the later study, 93% percent of IMI at the time of dry off were bacteriologically cured after calving. The high rate of IMI resolution over the dry period occurred across all bacterial agents. However, cure rates for major pathogens of IMI (e.g. Staphylococcus aureus) are considerably lower than cure rates for minor pathogen IMI over the dry period. IMI sustained across the dry period or newly acquired in the dry period reduced milk yields in the next lactation. Greatest risk for acquisition of IMI in the dry period is very early and the very late in this period. In this regard, milk yields at the time of dry off and the method of dry off can increase the risk of IMI during the dry period. IMI free cows producing 253 lb. milk in the last week before dry off were 7 fold more likely to develop an IMI during the dry period than cows milking 165 lb. milk over the week before dry off (Newman et al., 2010). The risk occurred even though all cows were blanket treated with dry cow antimicrobial preparations. Even though a majority (75-80%) of these newly acquired IMI will resolve during the dry period, those due to major 14

15 pathogens were 7-8 fold and those from minor pathogens were 3-4 fold more likely to produce IMI into next lactation compared to uninfected glands. The increased risk of IMI during the early dry period with higher yields has been attributed to the greater amount of intramammary pressure, milk leakage from the streak canal, delayed keratin plug formation for streak canal closure, and the reduction in intramammary defense mechanisms that follow abrupt cessation of milking. Intermittent milking during the last week before dry off reduces these effects and thereby reduces the risk of newly acquired IMI at dry off. Reduced milk yields at the time of drying off were associated with quicker onset of streak canal closure (Odensten et al., 2007), lowered SCC and reduced pathogen recovery in the first milk sample post calving (Green, 2008, Rajala-Schultz et al., 2005). Increased accumulation of milk components in the mammary gland at the time of dry-off and then again at the time of colostrum production (colostrogenisis) dilute antimicrobial defense mechanisms such as lactoferrin and inhibit white blood cell (phagocytic cell) defense functions in the gland. In addition, the higher amounts of milk fat, protein and sugars provide a superior nutrient environment for sustained IMI pathogen growth. Milk fat and protein (casein) are particularly efficient inhibitors of phagocytic cell function in the mammary gland (Burvenich et al., 2007). Phagocytic cells normally leave the vascular tree, migrate into the mammary gland and accumulate highly effective levels by a week after dry-off. While entering the mammary gland, these cells ingest milk fat, milk casein and intramammary cellular debris. As a result, they become de-activated and function less effectively against intramammary bacteria. Lactoferrin, a protein that binds free iron, acts as an intramammary defense mechanism by limiting the amount of intramammary iron available to support bacterial growth. Milk accumulation during early dry-off and colostrogenisis dilutes lactoferrin amounts thereby also decreasing the function of this defense structure. By 4-6 weeks post dry-off, involution of the mammary gland is complete and intramammary defense mechanisms are maximal. Streak canals are plugged, intramammary phagocytic cell numbers are greatest and phagocytic cell function is least inhibited. Intramammary levels of lactoferrin are high while immune compromising milk fat and casein is lowest during this time. Spontaneous cures of IMI from E. coli and minor mastitis pathogens (for example, coagulase negative Staphylococcus aureus) are very common during this period. During the second half of the dry period, the onset of intramammary alveolar function generates milk and colostrum secretion. As a result, milk fats and proteins diminish phagocytic cell functions, lactoferrin is once again diluted and intramammary susceptibility to IMI increases. Lastly, increased intramammary pressure due to colostrogenisis leads to milk leakage, keratin plug removal, diluted antimicrobial functions and bacterial entry into the mammary gland. Thus, colostrogenisis is often associated with high incidence and prevalence of IMI acquisition. Risk factors for new IMI in the dry period The potential for IMI during the dry period is affected at three levels: quarter, cow and herd management factors. All of these factors impact the amount of teat end and quarter exposure to environmental pathogens. In addition, the accumulation of milk constituents increases 15

16 susceptibility to IMI via the erosion of intramammary defense structures during the dry period. These factors were evaluated in a large investigation involving 8,700 dry periods in 6,800 cows housed in doors and nearly, 10,000 dry periods in 7,500 cows on pasture (Green et al., 2007). The factors impacted risk of dry period IMI across the pre-dry off, the dry and the post dry (postparturient) period. Cow and quarter factors: Aside from the method of dry off and the level of production at the time of dry off, there are other important cow factors serving as risk factors for new IMI in the dry period. Certainly mastitis events and elevate SCC >200,000 in the previous lactation increased odds of dry cow IMI and high SCC in the first DIM in the next lactation. The effect of high SCC is greatest if SCC > 200,000 exist in the last 90 DIM before dry off (Green et al., 2007). IMI that developed closer to dry off served to place the cow in greater risk for an IMI in the next lactation (Pinedo et al., 2012). Elevated SCC >200,000 at the time of dry off and then again in the first sampling day post calving were highly likely to have major or minor pathogen IMI (Pantoja et al., 2009). Dry period length as long as days past the usual day length were reported to increase risk of IMI (Pinedo et al 2009) but other work indicated this effect was inconsistent (Pinedo et al., 2012). Older parity animals are at higher risk for IMI during the dry period. The parity effect likely reflects an erosion of streak canal integrity, breakdown of the median suspensory ligament, and onset of pendulous glands with inappropriate teat placement. In addition, the type of bacterial colonization on teat ends, the presence of streak canal callus, cracked skin on the teat end, and the time of keratin plug formation in the streak canal all impact the onset of dry cow IMI. Inadequate keratin plug formation elevates the risk for IMI during the dry period. Lack of adequate keratin plug formation is a serious issue for all herds given 25-30% of dry cows never complete formation of the keratin plug (Dingwell et al., 2004). Culling strategies impact dry cow risk of IMI and remain important events within herds. Multiparous cows with persistently elevated SCC across multiple test dates and the dry period, with a history of flare up and culture positive for major pathogens such as the environmental Streptococcus uberis, Streptococcus dysagalactiae or Staphylococcus aureus should be targeted for cull rather than dry cow therapy (Barkema et al., 2006). Otherwise, these animals serve as the end of lactation reservoir of pre-existing infections that increase the size of the pool of dry cow IMI. Herd management factors: Green et al., (2007) concluded herd factors all tended to center about hygiene and increased risk of environmental pathogen challenge. Hygienic factors included technique of intramammary dry cow infusion, cleanliness, and management of dry cow and calving environments. Interestingly, Green et al., 2007) noted strategies designed to address rational product selection in dry cow treatment was an extremely important factor. The driving force was consideration of product selection (and not product per se) based upon knowledge of pre-existing or absence of IMI at dry off. See Rational dry cow programs based upon scientific input (Bradley et al., 2002,, Green et al., 2002.) In addition, allowing cows to remain standing for 30 minutes after dry cow therapy reduced the risk of IMI. 16

17 Environmental practices designed to reduce moisture levels and remove conditions favoring sustain microbial viability reduce the risk of IMI. Thus in both pastured and housed dry cows, bed care, sanitation, drainage, and cleanliness were all management factors that reduced the risk of IMI. Reduced stocking rate and use of dry cow stalls that are well groomed during the dry period is also associated with reduced SCC post calving (Green 2008). In pastured herds, strategies that shift grazing cows across fields every 2 weeks with rest periods of 4 weeks for each field reduced the risk of IMI. The effect is likely attributable to a time dependent drying of the ground, and the exposure to UV light to reduce soil contamination with environmental pathogens. Maintaining body condition score across both types of dry cow housing systems was important in reducing IMI. Fly control anytime during the dry period reduces teat end damage as well as teat end exposures to major and minor mastitis pathogens. One of the key herd factors is bulk tank SCC. High bulk SCC is associated with high prevalence of IMI in the herd and is a risk for new IMI in the dry period. SCC is almost entirely determined the prevalence and incidence of IMI and is therefore an important index of intramammary health and milk quality. Indices of herd SCC can be garnered from bulk tank SCC or as the average of all individual SCC in the herd. Management practices associated with lower herd or bulk SCC include wearing gloves during milking, pre- and post-dipping disinfection, milking cows with high SCC or clinical IMI last, annual inspection and certification of the milking system, keeping cows sanding for extended periods of time post milking, producer educational background and positive attitude about mastitis control, use of sand-based stall floors, cleanliness and frequency of calving stall cleaning, blanket dry cow therapy programs, monitoring dry cow and lactating cow quarter health, and finally institution of a pro-active well designed culling program designed to remove and eliminate cows at risk of repeat and chronic IMI infections. These include but are not limited to cows with broken medial suspensory ligaments, large pendulous udders and damaged calloused teat ends (Dufour et al., 2011). Dry Cow Programs Blanket dry cow therapy: The aims of blanket dry cow therapy are (1) resolution of pre-existing IMI and (2) prevention of new IMI during the dry period. Although cures of pre-existing IMI still play a role in lowering SCC, preventing new IMI during the dry period has emerged as the main strategy behind blanket therapy in many herds. Although public concern over the blanket use of antimicrobials may eventually limit these programs, there is little doubt intramammary antimicrobial therapy in the dry period lowers the risk of new IMI during the early dry period. Awareness of the role of more than one microbial pathogen in dry cow mastitis is an important element to consider during decisions about antimicrobials best suited for the herd dry cow program. Recognizing the relative incidence and prevalence of pre-existing versus newly acquired IMI at dry off can affect dry cow antimicrobial selection strategies. Knowledge about the dominant organism(s) involved in pre-existing IMI and newly acquired IMI during the dry period provide added scientific basis for antimicrobial selection. Antimicrobials targeted toward environmental Streptococci may not be well suited against gram negative environmental enterobacteria. Antimicrobials selected to prevent new IMI during the early dry period (environmental streptococci and enterobacteria) may in turn not always be best 17

18 suited to resolve coagulase positive, contagious IMI due to Staphylococcus aureus. Information about the relative importance of contagious IMI during lactation and environmental IMI during the lactation and dry periods impact dry cow antimicrobial strategies. Moreover, knowledge of antimicrobial sensitivity pattern (s) of the dominant organisms involved in IMI in the herd will augment appropriate dry cow antimicrobial selection. Thus, clear identification of goals, the patterns of IMI, and the sensitivity of major and minor IMI pathogens help form the correct dry cow antimicrobial selection. One drawback of blanket antimicrobial therapy during the dry period is the lack of antimicrobial persistence in the intramammary tissues. Dry cow formulations are generally designed to sustain antibiotic levels by preventing systemic absorption while providing slow release into the gland. Most dry cow antimicrobial preparations provide sufficient antimicrobial activity for 4-6 weeks into the dry period. Accordingly, during the late colostrogenic phase of the dry period, when the second wave of IMI infections occurs, there may be insufficient dry cow protection in programs based solely upon blanket antimicrobial therapy. Since the goal(s) of most dry cow programs are to clear pre-existing IMI and/or prevent new IMI in the dry period, programs should be in place to help monitor the effectiveness of the dry cow programs. The gold standard of individual quarter or composite quarter culture is prohibitively expensive. Therefore, use of SCC is the practical and economically viable proxy for a monitoring program (figure 1). SCC for 1-2 months prior to dry off and then 1-3 months after parturition can help determine the cure and prevention of IMI in the dry period. The tool depicted in figure 1 can be extremely helpful in determining success or failure in the dry cow programs. Cows with paired SCC locating them in the 1 st quadrant represent IMI cures during the dry period. Cows with paired SCC locating them in the 2 nd quadrant represent existing IMI s not cured or existing IMIs cured but followed by another new IMI during the dry period. Cows with paired SCC locating them in the 3 rd quadrant are cows with complete prevention of new IMIs. Cows with paired SCC locating them in the 4 th quadrant represent cows with newly acquired IMI s during the dry period. Moreover, herds struggling with a high prevalence and incidence of contagious coagulase positive Staphylococcus aureus IMI could be expected to see high bulk tank SCC coupled with persistently high SCC in consecutive test days across lactation. Since major contagious IMI pathogen like Staphylococcus aureus resist resolution even in the dry period, many animals in these herds would be expected to reside in the 2 nd quadrant of figure 1. Other tools that can be employed to assess outcomes of the dry cow program are to record the incidence or prevalence of clinical IMI occurring during the first DIM. A high incidence of environmental pathogen mediated clinical IMI in this period is often associated with acquisition of environmental IMI during the dry period (Bradley and Green, 2000, Green et al., 2002). Alternatively, high numbers of cows residing in the 2nd quadrant could also occur because of a great deal of IMI pathogen resistance to the antimicrobial employed in the dry treatment. A strategy to address this type of problem would require updating the bacterial cultures and sensitivity patterns for the IMI. 18

19 Teat sealants provide added technology to drive dry cow program success. Sealants are available as external or internal sealants. External sealants produce a physical barrier that coats the outer skin of the teat end and streak canal. These products tend to be short lived on teat ends as they fall off by days post dipping. Accordingly, one time use at the time of dry off provides protection during the early dry period when there is a high incidence of newly acquired environmental dry cow IMI. In the absence of intramammary dry cow antimicrobial therapy and reapplication of the external sealant, cows remain vulnerable to IMI during the late dry period. Thus, frequent reapplication is warranted with external teat sealants. Newly developed internal sealants generate physical barriers within the teat cistern and streak canal by formation of plugs in the teat cistern following intramammary application. These products provide a persistent, sustained barrier to IMI across the entire dry period. This provides relief from barrier loss associated with the external sealants. The advantage of both sealants is they eliminate concerns about antimicrobial residues and the inevitable antimicrobial resistance generated by use of intramammary antibiotics (Mollenkopf et al., 2010). Many studies documented combinations of teat sealants and dry cow antimicrobials reduced newly acquired IMI in the dry period by as much as 20-60%. In addition, pre-existing IMI at the time of dry off can experience cure rates as high as 90%. These effects carry over into cost effective reductions 19

20 in newly detectable IMI in the first 60DIM of the next lactation (Petrovski et al., 2012, Berry and Huxley, 2007). Because sealants only provide barrier function and do not increase intramammary antimicrobial function in the dry period, these products only reduce acquisition of new IMI by environmental pathogens during the dry period (Mutze et al., 2012). Thus, any anticipated reduction in pre-existing IMI at the time of dry off would be unfounded. Use of sealants to resolve pre-existing contagious major pathogen IMI by bacteria such as coagulase positive Staphylococcus aureus would likely result in little success unless accompanied by antimicrobial therapy. Indeed, combined treatments with internal teat sealants and antimicrobials in cows with high SCC at dry off enhanced dry period cure rates and reduced the incidence of clinical mastitis in the first 100 DIM in the next lactation (Newton et al., 2008, Bradley et al., 2010). Beneficial effects of this combined treatment on cows with low SCC before dry off were not quite as obvious. Rational dry cow programs based upon scientific input: Bradley et al. (2003) proposed dry cow programs be designed to address (1) resolution and/or treatment of pre-existing IMI at the time of dry off and (2) prevention of new infections in dry off. Treatment of pre-existing infections requires selection of an antibiotic with activity against the most prevalent pathogen in the herd. This data can be assembled from culture and sensitivity records of samples from acute flare-ups or cows and/or cows with persistently elevated SCC (>200,000) across several test day samples within 100 days of dry off. Alternatively, others suggested cows with contagious IMI could be reliably identified as (1) 3 test day milk sample SCC >200,000 with no history of contagious IMI during the lactation or (2) a history of contagious IMI early (<90DIM) in the lactation with SCC >100,000 in test day milk samples afterward (Torres et al., 2008). Persistent elevation of SCC likely stems from major environmental Streptococci sp. or the coagulase positive Staphylococcus aureus. Many times the dry cow drug of choice would be penicillin, cloxacillin, or cephalasprin. However, an evidence-based approach to dry cow antimicrobial selection should be driven entirely off retrospective culture and sensitivity data. Selection based upon the major enterobacteria pathogen, Escherichia coli is not likely to be necessary in most cases because this pathogen is often eradicated from udders at the time of lactation flare up or during self-cure in mid-dry period. Successful strategies to eradicate persistent pre-existing IMI should also include the integration of well-designed culling programs into the management scheme. Older parity cows with > 3 flare ups in a single lactation, with more than 1 quarter IMI and SCC persistently >200,000 cells/ml over several test day milk samples should become cull rather than treatment candidates. Other factors rendering these cows into the cull cow pool should be high bulk tank SCC, high prevalence of Staphylococcus aureus and a high IMI rate determined as SCC>200,000 cells/ml at the time of dry off. Bradley et al., (2003) also stressed a successful dry cow strategy should include a program designed to prevent acquisition of new IMI in the dry period. As mentioned earlier, these IMI are most often due to environmental Streptococci sp. and minor pathogens like coagulase 20

21 negative Staphylococcus epidermidis. The ideal choice of dry cow agent would be any preparation based upon retrospective sensitivity data on these organisms or a long acting antibiotic with activity against gram positive organisms (e.g. pennicillin, cloxacillin, or cephalosporin). In addition, frequent application of external teat sealants (minimally at the beginning and end) in the dry period will further prevent new dry cow IMI. Alternatively, use of an internal teat sealant at the time of dry off should be employed to establish a sustained barrier against acquisition of a dry cow IMI. Conclusion The dry period offers an enormous opportunity to deal with contagious mastitis pathogens, reduce bulk tank SCC and improve production. This period, however, can also increase the risk for new intramammary infections attributable to environmental pathogens. Indeed, earlier control programs for mastitis have reduced the problems with contagious mastitis pathogens but failed to address the acquisition of new infections during the dry period. As a result, problems with environmental pathogens have increased in herds. Susceptibility to these new environmental pathogen infections is highest on either end of the dry period. Environmental, cow and quarter factors also greatly impact the outcome of intramammary challenges during the dry period. One of the major costs of successful infection during the dry period is increased prevalence of clinical mastitis flare up during the first 100DIM in the next lactation. Dry cow IMI also elevate quarter, composite and therefore bulk tank SCC. Strategies to control IMI during the dry period should be directed toward increasing cure rates for pre-existing IMI at the time of dry off, while establishing a sustainable streak and teat end barrier to prevent new IMI during the dry period. References Bar, D., Tauer, L.W., Bennett, G., Gonzalas, R.N., Hertl, J.A., Schukken, Y.H., Schulte, H.F., Welcome, F.L., and Y. T. Grohn The cost of generic clinical mastitis in dairy cows as estimated by dynamic programming. J. Dairy Sci. 91: Barkema, H.W., Schukken, Y.H., and R.N. Zadoks Invited review: The role of cow, pathogen and treatment regimen in the therapeutic success of bovine Staphylococcus aureus mastitis. J. Dairy Sci. 89: Berry, E.A., and J.E. Millerton Effect of an intramammary teat seal and dry cow antibiotic in relation to dry period length on postpartum mastitis. J. Dairy Sci. 90: Bradley, A.J., Breen, J.E., Payne, B., Williams, P., and M.J. Green The use of cephalonium containing dry cow therapy and an internal sealant both alone and in combination. J. Dairy Sci. 93: Bradley, A.J., and M.J. Green A study of the incidence and significance of intramammary enterobacterial infections acquired during the dry period. J. Dairy Sci. 83:

22 Bradley, A., Huxley, J., and M. Green A rational approach to dry cow therapy 2. Product selection. In Practice 25: Burvenich, C., Banneman, D.D., Lippolis, J.D., Peelman, L., Nonnecke, B.J., Kehrli, M.E.J., and M.J. Pappe Cumulative physiological events influence the inflammatory response of the bovine udder to Escherichia coli infections during the transition period. J. Dairy Sci. E39-E54. Cha, E., Bar, D., Tauer, L.W., Bennett, G., Gonzalas, R.N., Schukken, Y.H., Welcome, F.L., and Y. T. Grohn The cost and management of different types of clinical mastitis in dairy cows estimated by dynamic programming. J. Dairy Sci. 94: Cook, N.B., Bennet, T.B., Emery, K., M., and K.V. Nordland Monitoring nonlactating cow intramammary infection dynamics using DHI somatic cell count data. J. Dairy Sci Dingwell, R.T., Leslie, K.E., Schukken, Y.H., Sargeant, J.M., Timms, L.L., Duffield, T.F., Keefe, G.P., Kelton, D.F., Lissemore, K.D., and J. Conklin Association of cow and quarter level factors at drying off with new intramammary infections during the dry period. Prev. Vet. Med. 63: Dufour, S. and I.R. Dohoo Monitoring dry period intramammary infection incidence and elimination rates using somatic cell measurements. J. Dairy Sci. 95: Dufour, S., Dohoo, I.R., Barkema, H.W., DesCoteaux, L., DeVries, T.J., Reyher, K.K., Roy,J., P. and D. T. Scholl Manageable risk factors associated with lactational incidence, elimination and prevalence of Staphylococcus aureus intramammary infections in dairy cows. J. Dairy Sci. 95: Dufour, S., Frechette, A., Barkema, H.W., Mussell, A., and D.T. Scholl Invited review. Effect of udder health management practices on herd somatic cell count. J. Dairy Sci. 94: Green, M.U., Bradley, A.J., Medley, G.J., and W.J. Brown Cow, farm and herd management factors in the dry period associated with raised somatic cell counts in early lactation. J. Dairy Sci. 91: Green, M.J., Green, L.E., Medley, G.F., Schukken, Y.H., and A.J. Bradley. 2002, Influence of dry period bacterial infection on clinical mastitis in dairy cows. J. Dairy Si. 85: Green, M.J., Green, L.E., Bradley, A.J., Burton, P.,R., Schukken, Y.H., and G.F. Medley Prevalence and associations between bacterial isolates from dry mammary glands of dairy cows. Vet. Rec. 156: Green, M., Huxley, J. and A. Bradley A rational approach to dry cow therapy 1. Uddeer health priorities during the dry period. In Practice. 24:

23 Mollenkopf, D.F., Glendening, C., Wittum, T.E., Funk, J.A., Tragesser, L.A., and P.S. Morley Association of dry cow therapy with the anitimicrobial susceptibility of fecal coliform bacteria in dairy cattle. Prev. Vet. Med. 96: Mutze, K., Wolter, W., Failing, K., Kloppert, B., Bernhardt, H., and M. Zschock The effect of dry cow antibiotic with and without internal teat sealant on udder health during the first 100 d of lactation: a felid study with matched pairs. J. Dairy Res. 79: Newton, H.J., Green, M.J., Benchaoui, H., Cracknell, V., Rowan, T., and A.J. Bradley Comparison of cloxacillin and cloxacillin combined with internal teat sealant for dry cow therapy. Vet Rec. 162: Oldensten, D.J., Berglund, B., Walker, K.P., and K. Holtenius Metabolism and udder health at dry-off in cows of different breeds and production levels. J. Dairy Sci. 90: Pantoja, J.C.F., Hulland, C., and P.L. Reugg Dynamics of somatic cell counts and intramammary infections across dry cows. Prev. Vet. Med. 90: Pantoja, J.C.F., Hulland, C., and P.L. Reugg Somatic cell count status across the dry period as a risk factor for the development of clinical mastitis in the subsequent lactation. J. Diary Sci. 92: Petrovski, K.R., Caicedo-Cakiias, A., Williamson, N.B., Lopez-Villalobos, N., Grinberg, A., Parkinson, T.J., and I.ZG. Tucker The efficacy of a novel dry period teat sealant containing 0.5% chlorhexidine against experimental challenge with Streptococcus uberis in dairy cattle. J. Dairy Sci. 94: Piccinini, R.L., Cesaris, V., Dapra, V., Borrmeo, C., Picozzi, C., Secchi, C., and A. Zecconi The role of teat skin contamination in the epidemiology of Staphylococcus aureus infections. J. Dairy Sci. 76: Pinedo, P.J., Fleming, C., and C.A. Rosco Events during the previous lactation, dry period and peripartum as risk factors for early mastitis in cows receiving 2 different intramammary dry cow therapies. J. Dairy Sci. 95: Pinedo, P.J., Risco, C. and P. Melendez A retrospective study on the association between different dry period lengths and somatic cell counts, milk yield, reproductive performance and culling in Chilean dairy cows. J. Dairy Sci. 94: Rajala-Schultz, P.J., Hogan, J.S., and K.L. Smith Association between milk yield at dry off and probability of intramammary infection at calving J. Dairy Sci. 88: Torres, A.H., Rajala-Schultz, P.J., DeGraves, F.J., and K.H. Hoblet Using dairy herd improvement records and clinical mastitis history to identifiy subclinical mastitis infections at dry off. J. Dairy Res. 75:

24 Van den Bourne, B.H.P., Halasa, T., van Schaik, G., Hogeveen, G., and M. Nielen Bioeconomic modeling of lactational antimicrobial treatment of new bovine subclinical intramammary infections caused by contagious pathogens. J. Dairy Sci. 93: Wilson, D.J.,.Gonzalas, R.N., and H.H. Das Bovine mastitis pathogens in New York and Pennsylvania: Prevalence and effects on somatic cell count and milk production. J. Dairy Sci. 80: On-Farm Bio-Forage Response Study Mr. Del Voight Extension Educator 5 dgv1@psu.edu Mr. John Bray jsb32@psu.edu and Dr. Greg Roth Professor of Agronomy gwr@psu.edu The following on-farm study is part of the Pennsylvania On Farm Soybean Network project sponsored by Penn State Extension and the Pennsylvania Soybean Promotion Board. Site coordinators included Mena Hautau, Andrew Frankenfield, Jen Bratthaur, Jon Rowehl, and Jeff Graybill with Penn State Extension. The study was designed to evaluate two biostimulants: StollerUSA s Bio-Forge at 1 pint per acre applied at the R3 growth stage and Fertileader Axis at 2.5 pint per acre applied at the R3 growth stage versus an untreated control. Soil type, variety, and management practices varied based on the individual cooperators. The project had five participating growers and was conducted in Berks, Dauphin, Franklin, Lancaster, and York Counties in Pennsylvania with replicated strip trials and including 17 replications. The data collected are reported in Table 1. 24

25 Table 1. Soybean yields as affected by two biostimulants in on-farm studies in Pennsylvania during the 2012 growing season. # Bio-Forge Control Fertileader Statistical Cooperator County Reps Bushels/acre significance* Leslie Bowman Franklin ns Troy Alderfer Berks ns Harold Miller York ns Dwight Cottrel Franklin ns Merle Stoltzfus Lancaster p=0.10 Mean for 5 sites ns * Statistical differences: ns = not significant, 0.10 = 90% and 0.01 = 99% confidence level. In this trial, cooperators were enlisted to evaluate two biostimulants, Fertileader and Bio- Forge. Replicated field scale trials were used to assess the biostimulants potential to increase soybean yields. A significant yield difference between Bio-Forge application and the untreated control was detected only at one of the five sites. At that site, a yield response of 4.6 bushels per acre was observed. However, averaged over all sites, yield differences were not significant. No yield response to the Fertileader product was detected at the Alderfer location. In general, conditions were good for soybean production at these sites with some mid-season drought stress and with moderate to good recovery in August On-Farm Ratchet Response Study Mr. Del Voight Extension Educator 5 dgv1@psu.edu Mr. John Bray jsb32@psu.edu and Dr. Greg Roth Professor of Agronomy gwr@psu.edu The following on-farm study is part of the Pennsylvania On Farm Soybean Network project sponsored by Penn State Extension and the Pennsylvania Soybean Promotion Board. Site coordinators included Andrew Frankenfield, Jeff Graybill, and Jen Bratthaur with Penn State Extension. 25

26 The study was designed to evaluate the potential of a new growth promoter, Ratchet, applied at the R3 growth stage of soybeans compared with an untreated check. Soil type, variety, and management practices varied based on the individual cooperators. The project had nine participating growers and was conducted in Berks, Lebanon, Dauphin, Franklin, Lancaster, and Chester Counties in Pennsylvania with replicated strip trials and including 33 replications. The data collected are reported in Table 1. Yield responses varied by site. At two of the nine sites, significant (p=0.20) yield responses of 5.0 and 2.7 bushels per acre were documented. Averaged across all sites and replications, the yield difference or 1.0 bu/acre was not significant. In general, conditions were good for soybean production at these sites with some mid-season drought stress and with moderate to good recovery in August. Table 1. Soybean yields as affected by a new growth promoter, Ratchet, in on-farm studies in Pennsylvania during the 2012 growing season. # Reps Ratchet Control Cooperator County ---Bushels/acre--- Response* Stanley Burkholder Franklin ns Dwight Zook Berks ns Eugene Sensenig Berks ns David Wolfskill Berks ns Glenn Krall Lebanon ns Darren Grumbine Lebanon ns Merle Stoltzfus Lancaster P=0.20 Bill Beam Lancaster P=0.01 Milton Hershey Dauphin ns 9 Sites ns * Statistical differences: ns = not significant, 0.20 = 80%, 0.10 = 90%, 0.01 = 99% confidence level. 26

27 2012 On-Farm Molybdenum Response Studies Mr. Del Voight Extension Educator 5 dgv1@psu.edu Mr. John Bray jsb32@psu.edu Ms. Alyssa Collins aac18@psu.edu and Dr. Greg Roth Professor of Agronomy gwr@psu.edu The following on-farm studies are part of the Pennsylvania On Farm Soybean Network project sponsored by Penn State Extension and the Pennsylvania Soybean Promotion Board. The first study was designed to assess the potential of molybdenum containing seed treatments on soybean yields. The second study conducted at the Southeast Research and Extension Center in Landisville, PA was conducted to further evaluate the need for molybdenum (Mo) in seed treatments following small but significant yield response in 2010 and In study 1, the control treatment was Apron Maxx RTU at 5 oz per 100 pounds of seed and the treatment arm was Apron Maxx plus Molybdenum at 5 oz per 100 pounds of seed. The study was conducted in Lebanon County, PA on the Darren Grumbine farm using a replicated strip plot design with five replications. In the past some visual differences have been observed with the use of molybdenum seed treatments and yield responses have been small at 1 to 3 bushels per acre. In this study, the molybdenum seed treated strips were apparent in aerial photography (see photo below compliments of Google Earth) throughout the growing season. 27