By Ric Bessin and Jonathan L. Larson; UK Entomology Extension Specialists
Face flies are annoying pests for cattle that can impact the animal’s welfare by just constantly molesting the eyes of our animals. These flies are looking to feed on tears but will also feed on saliva, blood, and nasal discharges. They do this by using their unique mouthparts, which resemble sponges and help them consume their liquid foods. Recently, county Extension agents informed us that they have received a large influx of questions regarding the connection between these pests and their transmission of pink eye.
Identification & Life cycle
Face flies look very similar to house flies in shape and coloration but are slightly larger than their close relative. They are dark grey with four black stripes that run down their back. As with a lot of flies, the maggots develop in fecal material. Specifically, face fly maggots develop in freshly deposited cattle manure. The maggots will hatch from eggs and then go through four stages of development over 15 to 25 days, depending on the weather. During the summer, face flies are not often found in structures, but the adults do overwinter in barns or attics and will become active again in the spring to start the next generation of flies.
Pink Eye Transmission
High numbers of face flies are associated with higher rates of pink eye issues. The feeding style of the flies causes more avenues of introduction by scratching the eyes, and the flies have been demonstrated to carry the causative agent of pink eye as well. Some estimates put the cost of pink eye in cattle at about $150 million annually.
Management Must Be Multifaceted
Fly control is essential, but can be difficult as face flies are only on the animal for a small percentage of the time. Therefore, addressing the egg and larval stages of the fly, as well as the adults, is most effective. A moderate to heavy fly infestation is when there are 10 to 20 flies per animal during the middle of the day. A single fly-control program will not work on every farm, so it often takes multiple tactics of control to achieve good results.
Fly tags (mid- to late May, through mid-September-October)(one ear tag or session or two sessions; be sure to use the number of tags required by the manufacturer), insecticide pour-ons, back rubbers (no 2 diesel), dust bags and knock-down sprays (Bachpack or ATV) are helpful in reducing the number of adult face flies on your animals. Fly traps in barns can also be helpful in reducing the number of flies. Feed additives with insect growth regulators are available that target the maggots that are laid in the manure. Encouraging dung beetles, which break down the manure pat, will also decrease egg survival.
Face flies can develop resistance to pesticides over time, so switching the drug mode of action of pesticides used every year is important. For example, if pyrethrins are used one year, then organophosphates should be used the following year. Waiting until the start of fly season to apply fly tags and removing the old fly tags in the fall also decreases the development of resistance. It is also extremely important to follow the safety precautions recommended by the manufacturer, as these insecticides can be toxic to people if handled improperly.
Appropriate grazing, along with clipping pastures will prevent seed-head development, reducing the irritation to the eyes of cattle, as well as reducing the resting areas for the flies. Clipping pastures to a low stubble height in May just after the seed heads emerge and again in mid-summer when weeds appear is recommended. Shaded areas need to be available to decrease the ultraviolet (UV) exposure and, in Herefords, breeding for pigmented eyelids has been successful, as this is a heritable trait. A good management program, including an appropriate vaccination program [especially infectious bovine rhinotracheitis (IBR) and bovine viral diarrhea (BVD)] and having good quality nutrition and minerals available at all times, will improve the overall condition of the cattle and decrease the incidence of this disease. Overhead hay feeders should be lowered and round bales should be rolled out. Ensuring adequate bunk space will decrease direct contact between the animals. Animals that develop pinkeye should be isolated if possible.
Kristin Hildabrand, Warren County Horticulture Agent visits with grower Jean Bowles of Kentucky Cuts to discuss her flower farm.
Jean is a cut flower grower who specializes in growing sunflowers, zinnias, and lisianthus during the summer season. In the Kentucky Farms Kentucky Flavor segment, she explains to Kristin the process she takes in growing cut flowers on the farm from seed to harvest. Jean shared that she got into farming because she enjoyed being outside and first started farming flowers, when her kids were young. She quickly figured out that it was going to take much more time than she could devote, so she left farming flowers for several years. Now that she is retired and her kids are grown, Jean is back to flower farming again! Her goal for the farm is to make it more self-sustaining! In the future, she hopes to try growing different flower varieties that most people don’t grow.
Kristin shows us how to make a fresh flower arrangement using seasonal flowers grown on the farm from Kentucky Cuts.
Before starting the arrangement process, gather a few items from around the house: a sharp pair of scissors, container or vase for the flowers, fresh water, and freshly harvested flowers. To begin making the arrangement, make sure that the container or vase is clean. Next, add fresh room temperature water to the vase. Now, the flower arranging process can begin! Use the thriller, spiller, and filler method, when arranging flowers. The thriller flower provides the height in the arrangement, the spiller plant cascades down and softens the sides, and the filler flower fills in the dead space. Place the thriller plant in the vase first. The thriller flower should only be about 1.5 to 2 times the height of the container. Make stem cuts at a diagonal to allow water to easily transport through the stem. Add the spiller plant next followed by the filler flowers. For more information about flower arranging, please contact the local Extension Office in your area.
Do you have trouble starting small seeded crops like lettuce, turnips, or cabbage in the garden? Does the seed end up blowing away in the wind or washing away after watering? Do you dread going back to thin out plants later?
If you answered “yes” to several of those questions, don’t worry, there is an easier solution called seed tape! Seed tape makes it easy for gardeners to grow crops from tiny seeds. With seed tape, gardeners apply seed to tape and then plant the entire seed tape outdoors in the garden. Gardeners don’t have to worry about seeds floating away and there is no need to thin out plants. An added bonus is the seed tape disintegrates overtime and returns nutrients to the soil.
Seed tape is available commercially through garden supply companies, however avid gardeners can make their own seed tape at home inexpensively! Making seed tape at home requires a few basic items and materials collected from around the home. Read here to find out how to make do-it-yourself (DIY) seed tape at home using this easy step- by- step photo guide.
Step 1: Gather up all supplies needed to make the seed tape. Grab a roll of toilet paper, make glue or use all-purpose glue, toothpick, garden seed packets, clear ruler, and a black permanent marker.
Step 2: Next, unroll the toilet paper from the roll and lay out on a flat even surface. Cut the toilet paper in half using a pair of scissors. The toilet paper serves as the “tape” portion of the seed tape project.
Step 3: Lay the seed tape on a flat surface and mark the correct plant spacing according to the crop being grown. Refer to the back of the seed packet to see how far apart to space between the seeds. Measure the plant distance using a ruler and mark the spot on the seed tape with the black permanent marker. If making multiple seed tapes for different crops, it is a good idea to label the seed tape with the crop name and the variety in the top right hand corner using an ink pen.
Step 4: Make the glue to adhere the seed to the tape. Mix 2 tablespoons of flour and 2 tablespoons of water together in a small mixing bowl until a thick paste forms. If needed, add additional water to make a glue type consistency. All-purpose glue also works good for seed tape.
Step 5: Before starting this step, empty the contents of the seed packet on a white plate or white piece of paper. This step makes it easy for gardeners to see the seed and pick it up to go on the seed tape.
Dip the end of a toothpick into the glue and place a small dot on the seed tape. Then, take the toothpick and pick up a seed to place on top of the freshly applied glue. Continue this process until all the seed tape is filled. Allow the glue to dry and roll the tape on the toilet paper roll. Store it in the refrigerator until environmental conditions are ready for planting.
Step 6: When conditions are favorable, make a seed bed for planting. Place the seed tape in the planting row making sure to plant at the correct depth. Refer to the back of the seed packet for the correct planting depth. Lightly cover the seed tape with soil and water it in. Wait and watch for the seeds to germinate and come up in a perfectly straight row!
To watch this process from start to finish, click on the picture above or Click Here to view this how to video for making DIY seed tape from our Warren County Agriculture YouTube channel.
Kristin G. Hildabrand, Horticulture Extension Agent for Warren County
The KY Dept. of Agriculture will provide the sprayer and enough chemical for the treatment of 10 acres. KDA representative will demonstrate proper mixing and application techniques. A number of nuisance weeds can be treated under this program. This program is limited to broadleaf weeds. If additional chemical is provided by the participant, an additional 10 acres can be treated. The participant must provide water source, tractor and operator. All chemical products must be labeled and product label will be followed. A maximum of 7 participants per county. This program is designed to target weeds that have a negative impact on agriculture.
If you are interested in participating in this program you will need to complete the online application found at http://www.kyagr.com/consumer/nuisance-weed-spraying-program-application.aspx. Applications can be completed from February 1 to February 28. You can NOT have participated in the last 3 years!
Contributors: Kenny Burdine, Todd Davis, Jerry Pierce, Will Snell, Tim Woods, (Ag Economics), Jeff Stringer, Bobby Ammerman, Chad Niman, and Billy Thomas (Forestry)
U.S. Agricultural Economy
The U.S. agricultural economy entered 2017 following three straight years of declining income and prices, after an unprecedented/record breaking period of growth during the 2007-2013 period. USDA is projecting 2017 net farm income to total $63.2 billion, up $1.7 billion (+2.7%) relative to 2016, but still off nearly 50% from the record high established in 2013. U.S. ag cash receipts are forecast to be 2.4% higher in 2017 in response to improved livestock sales (+7.6%) versus slightly lower crop receipts (-2%). Production expenses were up slightly (+1.5%) with higher labor, fuel, livestock, and interest costs, but lower feed, seed, fertilizer and chemical expenses. Government farm payments fell to $11.2 billion (-$1.8 billion) as large declines in Agricultural Risk Coverage (ARC) payments offset higher Price Loss Coverage (PLC) payments. These direct government payments (excludes crop insurance indemnities) accounted for 17.6% of the U.S. net farm income in 2017 vs 21.1% in 2016.
Despite a lot of political discussion and ag-related concerns about trade this past year, U.S. agricultural exports rebound to $140.5 billion (+8%), in FY 2017, benefiting from a weaker U.S. dollar, an improving global economy, and abundant U.S. supplies. The U.S. exports agricultural commodities/products to nearly 200 nations, but our top three foreign customers – China, Mexico, and Canada, account for nearly one-half of the U.S. ag export value. Undoubtedly the strong export market helped support ag prices in 2017 in the midst of abundant global supplies. Any future disruption in trade could put additional downward pressure on prices.
Ag lenders remain cautious in the midst of a prolonged downturn in the farm economy. Relatively low interest rates (along with cash purchases) have constrained growth in farm debt levels and also provided support to land values in the midst of the sharp-downturn in the ag. Despite the slumping farm economy, the overall balance sheet for U.S. agriculture as a whole remains relatively strong compared to the farm crisis days of the early 1980s. However, available cash flow/working capital for lower-tiered managers and some highly leveraged/young producers remains a concern for bankers, especially if the current economic conditions lingers.
Without a major supply shock, prices for most ag commodities will likely remain relatively low in 2018 (compared to levels observed during the 2011-2014 period) in response to abundant global grain supplies, growing meat supplies, and potentially a stronger U.S. dollar.
Politically, agriculture will continue to monitor changes in trade policy, tax, health care, and immigration reform, along with debate over the 2018 farm bill and the increasing concentration among agricultural input suppliers and processors. Food price inflation remained benign in 2017 and is expected to remain below historical levels in 2018 as consumers benefit from intense competition in the grocery sector, abundant ag/food supplies, and continued food marketing efficiencies and innovations.
Kentucky’s Agricultural Economy
The University of Kentucky’s Department of Agricultural Economics is forecasting that Kentucky ag cash receipts will rebound in 2017 to $5.6 billion, 3.5% higher than last year, but well below the record $6.5 billion in 2014. Improved prices will enable sales growth for most Kentucky livestock enterprises –poultry (+10%), horses (+10%), cattle (+5%), dairy (+12%), and hogs (+11%). Poultry also benefitted from a rebound from avian influenza outbreaks, which constrained growth the past two years. Increased soybean acres and record yields are expected to elevate soybean production to record levels. Potentially record corn yields will help offset lower acres and depressed prices. Kentucky’s tobacco sector rebounded from a poor crop in 2016, with sales expected to once again exceed $300 million.
Poultry remained Kentucky’s number one ag enterprise, accounting for 20% of projected 2017 sales, followed by equine (18%), soybeans (15%), cattle (14%) and corn (13%). For 2018, Kentucky ag cash receipts are expected to be relatively flat ($5.7 billion) with modest gains in poultry, horses, and soybeans, offsetting expected losses in tobacco, corn, and cattle. Look for continued growing demand for local produce/meats, nursery items, and value-added agriculture.
Kentucky net farm income has followed national trends, falling to $1 billion in 2016 compared to averaging $2.1 billion over the 2013-2015 period. Average net farmincome for farms participating in Kentucky’s Farm Business Management (KFBM) program declined to around $100,000 in 2015 and 2016, down from record highs exceeding $400,000 during 2011-2013, and compared to a ten year average of $283,000. Preliminary indications reveal that KFBM average net farm income will improve modestly in 2017 due primarily to higher crop yields, improved livestock prices, and stable input prices.
Commodity Spotlights (2017-2018)
- Calf prices rallied from fall 2016 levels and are roughly $30 per cwt higher than one year
- Growth in the beef cow herd still ongoing, but has likely
- Increases in production for all major meats will pressure beef (and cattle) prices in
- Backgrounding/stocker operations should be opportunistic on placement and aggressive with price risk management.
- Wholesale broiler prices are up from 2016
- Sector largely back on track following avian influenza outbreaks in recent
- Production likely to increase another 2% nationally in 2018, with continued growth in Kentucky.
- Kentucky inventory continues to grow, breeding herd up 7% in 2017.
- Eastern Corn belt hog prices to average $7 per cwt carcass basis higher in 2017.
- Sizeable production increase likely at national level for 2018, prices unlikely to hold at 2017 levels.
- Equine market has generally been steady since recovering from the global recession.
- Signs point to strength in 2017 –Keeneland yearling sale up 13%, Fasig Tipton yearling and breeding sale up as well.
- Equine likely to gross nearly $1 billion in Kentucky farm receipts for 2017, with modest growth in 2018.
- Farm level milk prices increased by more than $1 per cwt in 2017, with lower feed and hay prices leading to improved margins.
- 2017 was a better year than 2016, but certainly not a good year for dairy producers.
- Kentucky dairy cow numbers continue to decline.
- Increase in S. cow numbers and milk per cow suggest another production increase and consequently lower farm prices in 2018.
- U.S. corn harvested area reduced by 3.6 million acres in 2017 to 83.1 million acres. A record U.S. yield of 175.4 bu./acre produced the 2nd largest crop of 14.6 billion bushels.
- Carryout expected to increase to 5 billion bushels, which is the largest quantity since 1987. The stocks-use ratio in 1987 was 55% but is 17% in 2017 because of strong use.
- The 2017 S. Marketing Year Average Farm Price projected at $3.20/bushel, which is only 5% above the 2006 U.S. MYA price.
- U.S. soybean planted area increased by 6.8 million acres in 2017 to 90.2 million acres. The 2nd largest U.S. yield of 52.5 bu./acre produced a record crop of 4.4 billion bushels.
- Carryout expected to increase to 425 million bushels, which is the largest quantity since The stocks-use ratio in 2006 was 19% but is 9.8% in 2017 because of strong use.
- The 2017 S. Marketing Year Average Farm Price projected at $9.30/bushel which is 45% above the 2006 U.S. MYA price.
- Wheat harvested area reduced by 3 million acres in 2017 to 37.6 million acres. The 2017 yield was also reduced 6.4 bu./acre from last year to 46.3 bu./acre. The 2017 wheat crop is 568 million bushels smaller than last year to 1.7 billion bushels.
- Carryout expected to decrease by 246 million bushels to 936 million The stocks-use ratio in 2017 is 43.8%, and is below 50% for the first time since 2014.
- War of attrition on supply side is reducing stocks – not strong growth in
- The 2017 S. Marketing Year Average Farm Price projected at $4.60/bushel, which is $0.71/bu. higher than last year. However, the 2017 U.S. MYA price is only 8% above the 2006 U.S. MYA price.
- Global burley supply and demand appears more balanced entering the 2017 marketing season, primarily in response to a 30% reduction in world burley production over the past three years.
- S. burley demand remains soft with exports down nearly 30% since 2015, domestic cigarette production down 8% so far this year, and imports currently accounting for nearly 2/3 of use by domestic manufacturers.
- A better quality crop and improved supply/demand balances should result in leaf prices being stable to slightly higher, boosting the value of Kentucky’s tobacco crop to around $350 million in 2017 compared to a post-buyout low of $283 million in 2016.
- Anticipated ample burley supplies and softening demand will likely reduce U.S. burley contracts in 2018, with modest growth in snuff consumption enabling dark contracts to remain relatively stable.
Fruits, Vegetables and Greenhouse
- Markets were generally stronger for produce in Kentucky in 2017 as hurricane effects substantially elevated prices for late summer and fall crops.
- Market signals typically tied to nursery production and services (home improvement market, housing starts) have indicated steady recovery from the most recent recession.
- Accelerating local food movement and demand for value added products provides additional opportunities for growth, but labor uncertainties remain a major concern potentially constraining future growth.
- Overall forestry sector increased to an estimated $14.5 billion in total economic contribution to Kentucky in 2017 with primary industries including sawmilling showing the largest increase of over 14% from 2016.
- Exports and high domestic demand for white oak and tie logs will remain strong in 2018 pushing overall timber prices up.
- Pulpwood markets still sluggish but potential re-opening of Wickliffe pulp and paper plant may positively affect markets in Western Kentucky.
Soybean Delivery App released in time for harvest
Jordan Shockley explains the technology and guides the user through customization in a short, easy-to-follow YouTube video.
The app, named Best Bean Buyer, was developed by UK agricultural economist Jordan Shockley and Joe Dvorak, Sam McNeill and Ricky Mason, all in the UK Department of Biosystems and Agricultural Engineering, using checkoff dollars invested by the Kentucky Soybean Board to provide value and a competitive advantage for Kentucky’s producers.
While increased on-farm storage has decreased the amount of beans that some farmers directly deliver to the elevator, farmers face a reduction in price paid at the elevator for beans sold with high moisture content. Storing the crop to lessen the moisture content is an expensive proposition, though. Farmers have to truck the grain to their on-farm storage bins, load it into the bins, then load the grain back into trucks and haul it to the elevator. This process results in extra fuel costs and additional labor.
Not all farmers have on-farm storage, and this app may very well be the tool that helps them determine their profit margin by calculating transportation costs to various elevators. With high moisture content grain that is trucked straight to the elevator from the field, the moisture discount can make a significant difference in profit by the load and for the crop year.
This free app, available now on both the Apple and Android platforms, calculates in real-time the comparative prices that a producer can expect to receive from different elevators based on grain moisture and costs to haul it to each elevator. While the inputs affecting transportation and moisture discounts may be complex, this app helps producers eliminate the unnecessary cost of delivering to an elevator that will result in a smaller net profit.
It relies on five important features of mobile devices: mobility and availability, connectivity and real-time information, computational power, sensors and individual customization.
The mobility and availability of these devices means that the producer can use this service in the field. Internet connectivity means that the app can easily request the driving distance between a location and every elevator under consideration. This same connectivity provides the mechanism for farmers to enter current prices for each elevator. The computational power of these devices is used to evaluate the complicated equations that govern grain drying so that comparisons between different elevators are possible. The location sensors on a device are used to determine current field location if the producer is using the app in the harvested field. The app can also store information such as individual producer costs for grain transportation.
The app does require some set-up and customization to make it fully functional. Shockley developed a short YouTube tutorial to help producers get the app set up and ready to use. It may be found at https://youtu.be/2KvGAy-B5LE.
Grazing certain forages and weeds can bring the threat of prussic acid poisoning to livestock. If caution is used, this threat can be greatly reduced. Plants such as sorghum, sudangrass, sorghum-sudan hybrids, Johnsongrass, wild cherry and others can contain cyanide-producing compounds. After a frost or during a drought it is important to use extreme caution and it is advised to keep livestock off these pastures for up to three days after a killing frost. If soils that are deficient in phosphorus and potassium are applied with high levels of nitrogen, the levels of prussic acid may increase. Leaves, new shoots, and tillers have higher levels of prussic acid.
If large amounts of prussic acid are consumed, the compound interferes with oxygen utilization and livestock can die from respiratory paralysis. Symptoms appear quickly after forage is consumed. These symptoms may include cherry red colored blood, staggering, labored breathing, spasms, foaming at the mouth, falling, thrashing, severe convulsions, and death. Immediate treatment by a veterinarian is needed to save livestock suffering from prussic acid poisoning.
When cut for hay, prussic acid content decreases significantly during the curing process. A fair amount of this poison escapes as gas during fermentation when used for silage. Although the risk decreases, it is still important to be cautious when feeding forages with possible high prussic acid content.
The risk of prussic acid poisoning this season can be reduced by following these practices:
- Wait 10-14 days after non-killing frost with no additional frost action before grazing.
- Do not graze after a killing frost until plant material is dry (the toxin usually dissipates within 72 hours.)
- Do not graze at night when frost is likely. High levels of toxins are produced within hours after frost occurs.
- Delay feeding silage for six to eight weeks following ensiling.
Register Now for the Kentucky Grazing Conference: Pasture Management to Control Weeds and Improve Production
The 2017 Kentucky Grazing Conference will focus on pasture management to control weeds and improve pasture production and will be held: October 17th in Lexington and October 18th in Hopkinsville. The Keynote speaker is Kathy Voth, who has presented nationally on using grazing to control weeds and is a founding partner and editor of the popular online newsletter “On Pasture.”
Other speakers will discuss management and chemical options to control weeds including: Dr. Chris Teutsch, UK; Dr. Scott Flynn, DOW; Dr. Greg Brann, NRCS; Dr. Michael Flessner, VT; and Bill Payne, retired dairyman. The popular KFGC Forage Spokesperson contest will be held at the Lexington location. Early registration is $40 and ends October 4 or you may choose the value option of conference registration plus a one year KFGC membership for $50. KY Forage and Grassland Council membership is normally $25. Early registration ends October 4th. Go to the UK forage website and click on “Grazing Conference Tab” to register (www.uky.edu/Ag/Forage) or for full program. Exhibitor and sponsorship opportunities are also available.
We have had several calls about yellowing alfalfa lately and wanted to share this article.
Alfalfa fields may periodically exhibit yellowing of foliage. There are several possible causes for such symptoms.
Leaf spot diseases. During springtime, several leaf spotting diseases–including Lepto leaf spot and summer black stem & leaf spot—are common in alfalfa. Very wet weather in spring and early summer favor activity of leaf spotting diseases in first and second cuttings. Wet and humid weather during summer favor other leaf spotting and blighting diseases. In all such cases, leaf spots and blights weaken the plant but alfalfa often outgrows the damage in later cuttings. Maintain a regular cutting schedule, cutting at 30- to 35-day intervals.
Potato leafhopper. Potato leafhoppers are common in Kentucky alfalfa fields. Information on recognition, scouting, and control are available from UK’s Entomology Extension program. See our previous article or your county Extension office.
Soil compaction. Wet soils this spring during preplant operations or hay harvesting operations can result in severe compaction in some fields. Check for soil compaction by digging and examining both root systems and soil structure. If the compaction is so severe that the taproot cannot pass through the compacted zone, yields will be reduced significantly and plowing and replanting might be the only option. Remember, it is much easier to prevent than to alleviate soil compaction.
Potash deficiency. High quality alfalfa removes a large amount of potassium from the soil each year. Soil test K levels should be monitored closely and fertilizer K should be applied whenever it is recommended. It is possible that some plants in your field may exhibit mild potash deficiency symptoms even if potash levels in the soil are adequate, since roots that are limited by compaction and/or root rots will be less effective at taking up potash. Maintaining soil test levels and preventing soil compaction will help to assure maximum productivity and stand longevity.
Root rots. There are a variety of root-rotting diseases of alfalfa that are favored in the saturated soils. The most damaging is Phytophthora root rot; which can attack any part of the root system of plants of any age. Aphanomyces and Pythiumorganisms are also known to attack the fine feeder roots of mature plants of alfalfa when soils are saturated. Always select varieties with R or HR ratings to Phytophthora and Aphanomyces root rots when seeding alfalfa in Kentucky. Unfortunately, there is no known resistance in commercial cultivars to Pythiuminfection, but improving soil drainage and minimizing soil compaction will help with all three diseases.
Poor nodulation. Check nodulation of new seedings by carefully digging and washing root systems and examining for nodules. Poor nodulation of roots may be the result of root-rot infections or of poor viability of the Rhizobium bacterium on the seed. If poor viability on the seed is the cause, an inexpensive practice to improve the chances for nodulation can be found at: http://plantpathology.ca.uky.edu/files/ppfs-ag-f-04.pdf.
Crown rot diseases. Dig plants and cut into the crowns. Those that are showing brown discoloration are exhibiting crown rot. A variety of soil-boirne fungi can cause crown rot. Adapted varieties of alfalfa can sometimes recover from crown rots. However, if severe, crown rots can be a significant problem for long-term health of the stand. Thus, if you see a high frequency of crown rot in a particular field, that is usually a flag to rotate.
Probably the best indication of when to rotate is stand density. Approximate guidelines as to economically acceptable stands from Dr. Garry Lacefield, UK Forage Agronomist, are:
3 crowns per square foot for hay
1 crowns per square foot for grazing
Dr. Lacefield points out that these are approximate guidelines. For example, a beef cattle producer often will meet his/her production goals well with a much lower density of alfalfa crowns than a hay producer. He also indicates that, for the Upper Midwest, for high-quality dairy hay productions, the standards are based on stem density, since this more closely correlates to forage production than crown density.:
55+ stems per square foot: no yield reduction
40-55 per square foot: some yield reduction
Below 40 per square foot: give consideration to replanting
If stands are less than needed for your yield goals, plan a rotation away from alfalfa followed by re-seeding.
~ Drs. Paul Vincelli, Chris Teutsch and Kiersten Wise, revision from an early extension article on this topic by Paul Vincelli and Greg Schwab.