Best Lawns News. Winter 2017 Edition Virginia Cooperative Extension Prince William Unit. Featured in This Issue

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1 Best Lawns News Winter 2017 Edition Virginia Cooperative Extension Prince William Unit Featured in This Issue Understanding Your Soil Test Report 2 Perennial Weed Grass Management 6 Keeping Turf Healthy This Winter 9 All content was written by Thomas Bolles, except where noted, and is based on university research at Virginia Tech, Virginia State and other partner universities in the Land Grant system. Staff contact information Paige Thacker, Extension Agent, Horticulture Phone: pthacker@pwcgov.org Nancy Berlin, Natural Resource Specialist/Master Gardener Coordinator Phone: nberlin@pwcgov.org Thomas Bolles, Environmental Education Specialist/BEST Lawns Coordinator Phone: tbolles@pwcgov.org VIRGINIA COOPERATIVE EXTENSION 8033 Ashton Avenue, Suite 105 Manassas, VA Phone: Fax: Disclaimer Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable.

2 Understanding Your Soil Test Report Regular soil testing is an important management practice for maintaining turf health. With heavier soils like we see in most of Northern Virginia, soil tested is recommended every 3 years to help keep track of changes in the soil. Understanding your soil test results will help you make more informed decisions. Typical soil test results look like this: One of the first things you may notice is that the report does not include a nitrogen (N) analysis. This is because nitrogen is too mobile in the soil for laboratory results to be useful. Nitrogen fertilizer recommendations are based on the plant to be grown. In the case of turf, the soil test note on fertilization is written in general terms to cover a multitude of turf situations. As part of the Chesapeake Bay legislation, a document called the Virginia Nutrient Management Standards and Criteria more tightly governs the application of nitrogen on turf to reduce the likelihood that excess nitrogen and phosphorous end up in our waterways. The Virginia Cooperative Extension BEST Lawns program is designed to make recommendations based on this document in a simple, easy to understand manner.

3 The lab report does include analyses of 4 macronutrients: P (Phosphorous) K (Potassium) Ca (Calcium) Mg (Magnesium). The results are given in pounds per acre. These are rated on a scale from low minus (L-) to very high (VH). In general, adding a nutrient rated as medium (M) or lower should show a response in plant growth. With M+ and H-, you may or may not visibly see a response. With H, H+ and VH, adding these nutrients aren t going to show a response. When you apply nutrients rated H to VH, you are just banking the nutrients for later use. Banking nutrients can be problematic with P because it can be carried into waterways attached to soil particles during storm events. Listed to the right of the macronutrients, are key micronutrients: Zn (zinc) Mn (manganese) Cu copper Fe (iron) B (boron). While not needed in large amounts, these nutrients can be at levels in our soils where they are too low for optimal plant health. Micronutrients are reported in parts per million and are rated as either sufficient or insufficient. It is rare for one of the micronutrient levels to be insufficient for turf in our area. Where a nutrient is insufficient, the report will include a recommendation to bring the nutrient amounts to an acceptable level. The last column of the top row of soil test analysis is listed as S. Salts, which stands for soluble salts. This is not included in the routine soil test. This is a measure of salts in the soil, reported in parts per million (ppm). When soluble salts exceed 844 ppm, plant injury can occur especially in young or stressed plants. This is usually only a problem when fertilizers have been applied at very high rates. The second row of analyses begins with ph. When the soil ph is too high or too low plants can have problems. Our local soils are naturally more acidic than is optimal for turf. Over time these soils tend to revert back to their natural state. Low ph can limit plant growth because of aluminum toxicity. Herbicides are less effective in low ph soils. In high ph soils, key nutrients can be bound up in the soil in forms unavailable to turf. Turf requires the ph in the range. Normally, ph levels in turf are managed by using lime to bring ph to 6.5. Application of excessive lime can result in a ph over 8.0. Lowing ph is difficult to do accurately. With turf, the best course is often to let the soil ph drop over time through natural processes and these take time to see change. Lime recommendations are not based on the soil ph directly, but on the soil buffer index. Buffer index is a measure of the active and reserve acidity in the soil. More simply, it is a measure of how easily soil ph can be changed. Buffer Indexes run from 4.00 to The higher the buffer index is the less lime it takes to change the ph. While turf might be fine with a ph in the range, if the buffer index is low enough, the lab will still recommend lime to maintain the ph in the desired range.

4 Generally buffer indexes in Prince William County are in the 5-6 range. Sometimes a buffer index of N/A is reported. This occurs when the soil ph is 7.0 or greater. The buffer index is cross referenced with the target ph for a given crop and a lime recommendation is made. Est-CEC stands for estimated cation exchange capacity. It is expressed in milliequivalents per 100 grams (meq/100g) of soil. This is an approximation of the soil s ability to hold cations. A cation is any element with a positive charge - several key nutrients are cations. Cation exchange capacity is an indication of a soil s ability to keep some nutrients from leaching. Generally a higher CEC is better, but there are several factors that go into what is a good CEC number. Most of our natural soils are low in organic matter so they usually range in CEC from 1 to 12 meq/100g. A very sandy soil will normally have a CEC of 1 to 3 meq/100g. The CEC value will increase as the amount of clay and organic matter in the soil increases. Because CEC is based in part on calcium and magnesium levels, the CEC value can be erroneously high when the soil ph or soluble salts level is high. In an ideal situation, some clay soils can have CEC numbers up to 50s, but most Virginia soils have much lower CECs. In heavier soils (clay/loam) in Northern Virginia with good amounts of soil organic matter, CECs can be in the high teens or greater. Regular applications of compost to the lawn can help boost CEC over time. The 5 columns to the right of CEC give percentages of various cations. These numbers aren t usually a concern for homeowners. The percent acidity is a ratio of the amount of acid-generating cations (as measured by the Buffer Index) that occupy soil cation exchange sites to the total CEC sites. The higher this percentage, the higher the amount of reserve acidity in the soil. When reported as N/A, means that a buffer index was not determined. The percent Base Saturation is the ratio of the quantity of non-acid generating cations (i.e., the exchangeable bases, Ca, Mg, and K) that occupy the cation exchange sites. The percent Ca, Mg, or K Saturation refers to the relative number of CEC sites that are occupied by that particular nutrient and is a way of evaluating for any gross nutrient imbalance. The final column in this row is the percentage of organic matter in the soil by weight. It is not part of the routine soil test. Generally, the greater the organic matter the better the soil s nutrient and water holding capacities, aeration and soil structure. The ideal soil is said to have at least 5% organic matter. In garden soils, this is relatively easy to achieve. In lawns, it s often much lower. The general recommendation for lawns is to add compost regularly to maintain or slightly improve the organic matter percentage over time. Below the nutrient analyses, are the lime and fertilizer recommendations. These are based on the crop grown so it is important to make sure to select the appropriate crop code when filling out the soil test paperwork. The lime recommendation is given in pounds per 1,000 square feet for lawns. For gardens, it s given in pounds per 100 square feet. When lime is not needed, the report will say so. It s important to know the size of your lawn

5 in order to accurately apply the correct amount of lime. In Northern Virginia, some lawns will not need lime while others can need several hundred pounds of lime per 1,000 square feet. Most lawns in the Greater Prince William area fall in the lbs. per 1,000 square feet range, but it s important to check the soil regularly instead of blindly applying lime as high phs are difficult to correct. Most of the time when lime is needed, agricultural limestone (calcium carbonate) is recommended. When magnesium levels warrant it, dolomitic lime (dolomite) is recommended. Other types of lime (hydrated, quick, slaked, etc.) should not be used. Lime is typically available in pelletized or pulverized (powered) forms. The pelletized is usually a few cents more per pound, but is less dusty. Either form is acceptable. When lime is called for, there is a limitation to the amount of lime that can be applied at one time. Over application can burn or smother the lawn. Fifty pounds per 1,000 square feet is the maximum amount of lime that can be applied at one time. This assumes the lime is top dressed onto an existing crop. Fast-Acting lime is limited to a maximum of 30 lbs. per 1,000 square feet of lime that can be applied at one time. The total amount of lime required does not change when using fast acting lime. For example: If the lime application is for 150 lbs. of lime per 1,000 square feet. If using agricultural lime, it requires 3 applications of 50 lbs. per 1,000 square feet each. If using fast acting lime, it requires 5 applications of 30 lbs. of lime per 1,000 square feet. The fertilizer recommendation is based on the ratings of phosphorous and potassium. In most cases, a turf-type or maintenance fertilizer is recommended. This is a fertilizer with nitrogen and potassium but no phosphorous. Because of concerns about phosphorous getting in waterways, fertilizers with phosphorous should only be applied when the soil test recommends it. When phosphorous is called for, fertilizers with a 1:1 or 2:1 ratio of nitrogen to phosphorous should be used. Specific fertilizer recommendations for turf depend on many things, including: The environmental sensitivity of the soil The species of grass The amount of slow release nitrogen in the fertilizer How the turf is used How much sun the turf gets The level of management These factors play a role in how much fertilizer is applied at one time, how much is applied in total for the year and when fertilizer should be applied. Relying on what the fertilizer bag says for application rate may not be appropriate to the situation in your lawn. Without a soil test you may not even know which is the right type of fertilizer for your lawn. Relying a fertilizer company s standard one size-fits-all program may not be appropriate for your lawn. Fertilizing too much or at the wrong time of year can increase the problems in your lawn. If you have questions about your soil test result or how to fertilize your lawn, Virginia Cooperative Extension s Prince William office can help. Contact us at for assistance. The BEST Lawns program takes much of the guess work out of managing your lawn. We provide nutrient management plans for home lawns as well as lawns for HOAs and houses of faith. Master Gardeners measure your lawn, sample the soil and evaluate the lawn for pests and other issues. Based on the soil test results, a custom nutrient plan is developed addressing fertilizer, lime and other ways to improve your lawn all based on unbiased research from Virginia Tech, Virginia State and other regional Land Grant universities. If interested in enrolling in the BEST Lawns program, please see the Prince William County website ( for the enrollment form. The cost is $25, which includes the sample analysis, shipping, a guidebook for growing turf in Prince William County and a customized nutrient plan.

6 Managing Perennial Weed Grasses Perennial weed grasses are among the most difficult weeds to remove from turf. Nimblewill, johnsongrass, dallis grass, orchard grass and quack grass are common perennial weed grasses in Virginia. In addition, Bermuda grass is both a turf grass and weed grass depending on the situation. Perennial grasses, especially established mature grasses, are much more difficult to control annual weeds like crabgrass. Bermuda Dallis Johnson Nimblewill Orchard Quack There are many products on the market that claim to control various perennial grasses. These products can be effective against young weeds. With more mature plants, however, they may require multiple applications and/or provide little to no control. Controlling mature weed grasses can be expensive and time consuming. The first and best line of defense is using good cultural practices. When managed properly, turf is healthy and strong enough to out compete most weeds. Even with good practices, scouting for weed incursions is crucial. It is important to go beyond the quick snap shot of the lawn seen in passing. Often, problems are not noticed until they become large, glaring issues. Regularly looking for signs of trouble is the best way to prevent a little problem from becoming a large one. Discovering a problem early makes it easier to solve, but it s only part of the puzzle. Once trouble has been spotted, it s important to identify the culprit responsible. Many grasses have similar appearances and growth habits. For example, crabgrass, an annual, and Dallisgrass, a perennial, can look very much alike and are easily confused for on and other. There are a number books and on-line weed identification sites (listed at the end of this article) that can be useful. Weed samples can also be brought into the VCE office for identification. Weeds should be freshly dug. They can usually be identified by the office within a few days. Ideally samples should be brought in early in the week in case the staff needs to forward the sample on to the Weed and Plant Pathology Lab at Virginia Tech for further identification. Once the problem has been discovered and the pest identified, then control recommendations can be made. The Prince William VCE office can provide these in person at the office, over the phone ( ) or via (master_gardener@pwcgov.org). VCE advocates using the least harmful control options first. When a perennial

7 grass weed (or any weed for that matter) is discovered young, there are more options for control. When the problem goes for a while without notice, options become much more limited. With mature weed infestations, the chemical option is usually all that s left. There are some non-chemical options, but in some cases, these can be impractical. Choosing the right option depends on the situation. Non-Chemical Options Hand pulling young plants can usually take care of them. Digging mature grass weeds can be time consuming and labor intensive. Depending on the growth habit of the particular weed, it may only serve to weaken the plant. Bermuda grass, for example, has extensive roots and rhizomes from which it can regenerate if the entire plant is not removed. Digging can also be problematic when the weeds are interspersed among desirable turf grass where sometimes more harm is done than good. Solarization is the process of using the sun to cook the weeds. It s main disadvantages are the time it takes to work and the inability to selective target weeds. Solarization also requires the right environmental conditions to work. Basically the process involves wetting an area and then covering it with plastic to heat into the root zone. Clear, thicker plastic 2-4 mil) is better because it resists incidental rips. For this work, the area must be completely covered and the plastic secured so heat generated by the sun stays inside the plastic. Solarization needs to be done in the summer to be effective. Ideally, secure plastic should be in place by the summer equinox and left for 2-3 months. Heat penetration still may not be deep enough to kill all of the roots of some weeds. Non-Selective Chemical Options Glyphosate, the active ingredient in products like RoundUp, is a non-selective herbicide. It can harm any plant it contacts. It s best used when the plant actively growing. Orchard and Quack grasses are cool season grasses. Bermuda grass, dallis grass, Johnson grass and nimblewill are warm season grasses. When using glyphosate on hot days there is an increased potential for it to volatize and drift on to non-targeted plants. It s very important to follow the label directions about at what temperatures the herbicide should be applied. Wind can also cause glyphosate to drift on to non-target plants. Using shields and/or painting the weed with a disposable foam brush/wiper can help reduce the instance of collateral damage. Selective Chemical Options Selective options depend on the species of the weed grass as well as the species of the desired turf. As most home lawns in Prince William County are cool season turf, this article will only deal with weed control in tall fescue and Kentucky bluegrass. For any other turf type, contact the VCE office for more information.

8 Bermuda grass in tall fescue is by far the most common grassy weed problem in the area. Control requires multiple applications of triclopyr (Turflon Ester) at a rate of 1 quart per acre mixed with fenoxaprop (Acclaim Extra) at a rate of 20 oz per acre. Two to three applications in the spring, beginning after the Bermuda has greened up, should be applied 3-4 weeks apart. This should be followed with 2-3 applications, 3-4 weeks apart in the fall. Fluaziflop (Fusilade II, Ornamec) can be used in place of fenoxaprop in fescue lawns at a rate of 3-6 oz per acre of Fusilade II or oz per acre of Ornamec. You must wait at least 4 weeks between applying triclopyr and overseeding. Bermuda grass control in Kentucky bluegrass is similar to control in tall fescue, except amount of fenoxaprop should be lowered and fluaziflop can NOT be substituted for fenoxaprop. Nimblewill is the other major perennial weed most likely to be found in local home lawns. In both tall fescue and Kentucky bluegrass can be controlled repeated applications of mesotrione (Tenacity). It is applied 2-3 times at 3-week intervals any time nimblewill is green and growing. The use rate is 4-5 oz of mesotrione mixed with at least 30 gallons of water per acre for broadcast treatment or 0.1 oz per gallon for spot treating. Broadcast applications should be avoided unless renovating or reseeding the lawn, because while all cool season turf grasses are tolerant of mesotrione, temporary discoloration may occur especially on perennial rye and fine fescues. Fine fescues seedlings are not tolerant of this chemical, so it should not be used when overseeding with a mix of more than 20% fine fescues. Mesotrione should not be used between the time of seeding until after the new grass has been mowed 2-3 times regardless of the species mix used to overseed. Good cultural practices are the key to reducing the likelihood of perennial grass weeds. Even the best kept lawn can fall prey to aggressive weed grasses like Bermuda so it is important to remember that early identification and control weed grasses is critical. Waiting until a small problem becomes a major infestation will cost time, money and effort to correct. Selective herbicide treatments of mature perennial grasses, for example, can cost over $100 per 1,000 square feet per application! For more information on weeds, weed controls and recommended practices for turf, contact the VCE office at Disclaimer: Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable. For more information on this subject, see Dr. Jeff Derr s article Perennial Grassy Weed Control I Can Do This!, Virginia Turgrass Journal, January/February Weed ID Websites VA Tech Weed Identification Guide - web2.ento.vt.edu/servlet/wid?table=grasses University of Kentucky Turf Science - NC State Turf Files - turfid.ncsu.edu/ Remember to Stay off Saturated Soils to Prevent Compaction!

9 Keeping Your Lawn Healthy This Winter The fescue-bluegrass lawns so common in Northern Virginia are winter reliably winter hardy. Most people don t give the lawn a second thought once cold weather it. Cool season grasses should be fine with the cold, right? While well adapted to winter, cool season grasses can be injured in cold weather. There are number of things homeowners can do and not do to minimize the risk of winter turf damage. As with most turf problems, the first line of defense is maintaining healthy turf through good cultural practices. There are several things that are done in the fall that contribute to winter survival. Fertilizing appropriately in the fall can ensure individual grass plants have proper nutrition potassium is especially important in the immune systems of plants. Proper fertilization will also help the turf develop a strong root system to help plants recover more quickly if they are injured. Leaving turf too high going into winter can cause diseases issues over the winter and into early spring. Cool season turf can be cut on the low side of it s optimal cutting height for the final cut of the fall season. For example, tall fescue s ideal range is inches so it should be cut closer to 3.5 inches. This will help prevent grass blades from fall over onto each other under the weight of ice or heavy snow. When turf blades are matted on top of each other, the fungal problem snow mold often follows. Snow mold hosts include tall fescue, Kentucky bluegrass and perennial ryegrass. It leaves tan to grey circular spots in the lawn. These can be a few inches in diameter to over a foot. The chances of snow mold are further increased by heavy nitrogen applications in late November and leaving fallen leaves on the turf. This damage can be lightly raked in the spring. In Northern Virginia, turf typically grows out of the problem without the need for reseeding. Turf that has suffered from snow mold over the winter/early spring can also susceptible to the fungal disease red thread if not adequately fertilized the previous fall. Red thread hosts include fine fescues, Kentucky bluegrass and perennial ryegrass. Red thread manifests itself in irregular beige patches ranging from a few inches to a few

10 feet in diameter, which often merge into irregular patterns, with red, thread-like filaments among the grass blades. Red thread is not very common in Northern Virginia, but in the spring of 2016 the extended period of cool weather and rain in the spread led to large outbreaks of red thread in much of western Prince William County. Turf will usually grow out of red thread. Once cold weather arrives it s important to be mindful of frost or ice on turf. In addition to be a slipping hazard for people, foot, equipment and vehicle traffic can easily damage plant cells leading to the death of effective grass blades. In the photo below, a light duty truck was driven over a fescue pasture while the frost was still on the grass. The resulting damage was evident within a few hours. Tracks made with frost on the grass. Tracks made with no frost on the grass from the previous day. The photo below shows similar damage to a golf green at the University of Nebraska that occurred when the turf was frozen with ice. Avoid travelling over grass until any frost or ice has melted. This sort of damage tends not to occur with snow will often cushion the impact and can form an insulating layer over the turf to protect it from extreme cold. When snow and ice melt, they can leave the soil saturated. While walking on a lawn with saturated soil will not harm the grass directly, soil compaction can easily occur. Compaction negatively effects soil health and impacts the turf by reducing the soil s drainage capacity and restricting the movement roots. A common winter practice is to use salt on sidewalks, driveways and streets. Most turf species do not perform well in salty conditions. When snow and ice mixed with de-icing salts are repeatedly shoveled onto turf, salts can build up and cause plant injury and even loss.

11 These moderate to high concentrations of deicing salt are temporary. Usually a few spring rains or a couple of thorough soakings from a hose, will wash the salts out of the soil. Damaged areas can usually be repaired by without further salt-related problems. Repair the turf can be done as soon as the soil is workable. In areas where salt injury is an annual occurrence, consider converting the area to mulched beds of salt-tolerant plants. Voles can be another treat to turf in the winter. Voles, also called meadow mice, as small herbivorous rodents. Voles feed on plants and plant roots. They have a preference for ornamental plants rather than turf. Bulbs and the bark of young woody plants are among the vole s favorite foods. Voles can damage turf by can wear complex 1-2 inch wide pathways and shallow tunnels in the lawn. Voles can be more of a problem when there are long periods of snow on the ground. The snow insulates the air between the snow and the soil, protecting foraging voles from wind chill and extreme cold. Snow cover shields voles from birds of prey. Voles need to overwinter in places that provide sufficient food and shelter. Most landscapes provide adequate food. Yards with excessive mulch are much more attractive to voles as they provide insulated shelter for the voles to use for burrows. Removing excess mulch from beds, trees and shrubs is one way to reduce the likelihood that voles will be wintering in the yard. Remove leaf and brush piles from the yard will also help. If voles become a problem, they can be killed using mouse traps placed a burrow entrances and in established runways. Poisons are not recommended as they can be consumed by non-target species. Vole pathways should be reseeded as soon as weather permits. Winter threats to turf are relatively mild. Good cultural practices throughout the landscape can help prevent most potential problems. When winter problems do arise, the grass often recovers in the spring with little or no effort on the homeowner s part.

12 VCE Schedule of Classes Basics of Gardening Location: Potomac Community Library; 2201 Opitz Blvd., Woodbridge, VA When: February 11, February 18, February 25, and a snow date of March 11, 1:00 pm 4:00 pm Discover the science of gardening, plant culture, pest, and disease solutions. The series will focus on research-based knowledge of plant processes, problem avoidance, and the most effective control strategies. This program is FREE, but please register so there is an adequate amount of handouts for each participant. SPACE IS LIMITED. Please call or master_gardener@pwcgov.org to register Sustainable Vegetable Gardening Series Location: Central Community Library; 8601 Mathis Avenue. Manassas, VA When: February 11, February 18, February 25, and a snow date of March 11, 10:30 pm 1:00 pm Discover the science of gardening, plant culture, pest, and disease solutions. The series will focus on research-based knowledge of plant processes, problem avoidance, and the most effective control strategies. This program is FREE, but please register so there is an adequate amount of handouts for each participant. SPACE IS LIMITED. Please call or master_gardener@pwcgov.org to register Well Water Class Initial Meeting March 27, 7:00-8:30 pm, PWC Board Chambers Sample Collection March 29, 6:30-10:00 am, VCE Office on Ashton Avenue Results Meeting May 8, 7:00-9:00 pm, PWC Board Chambers This program provides a low cost well water analysis for homeowners with private water supplies, such as wells, springs and cisterns. There is a $55 fee to have your well water tested. Master Gardener Saturdays in The Garden Location: The Teaching Garden at St. Benedict Monastery When: April 22 nd, May 6 th, June 17 th, July 15 th, August 19 th, September 9 th, October 21 th, 9:00 am to Noon Master Gardener Clinics at Local Garden Centers Location: TBA Saturdays: April 8 th, 15 th, 22 nd, & 29, May 6 th and 20 th, 10:00 am to 1:00 pm Master Gardener Clinics at Manassas City Farmers Markets When: Saturdays, beginning in April, specific dates TBA Master Gardener Clinics at Dale City Farmers Markets When: Sundays, beginning in April, specific dates TBA PLEASE NOTE: All Classes are of these programs are free, except Well Water Sampling. Registration is requested by calling or ing master_gardener@pwcgov.org