University of Missouri Turfgrass Research Center

Properly maintained turfgrasses provide competition against weeds, diseases and insects. Fertilizer applications alone, will give 50 to 60 percent control of summer annual grassy weeds.

Did you miss the fall seeding for your clients lawn? Did your fall seeding establish as well as you would like? Don’t worry, all is not lost. While fall still remains the best time of the year to establish cool-season turfgrasses, getting an early start, in March, can lead to a successful spring seeding by following some simple steps.

First, we always recommend taking a representative soil sample of the area you wish to seed and have a regular soil test conducted. Knowing the soil pH with levels of phosphorus (P) and potassium (K) will help to determine if adjustments are needed prior to seeding. Optimum pH levels should fall between 6.6 to 6.8, while P and K should be in that medium to high range for seed establishment. Adjustments to a low pH can be made with lime by taking the neutralizable acidity (N.A.) times 25 to equal pounds of lime required per 1,000 square feet, not to exceed 50 pounds of lime per 1,000 square feet in a single application. Adjustments to a high pH can be made with the use of fertilizers containing sulfur or with humic acid. Levels of P and K can be increased with the use of a good starter fertilizer (a 10-24-18) at time of seeding. Starter fertilizers are usually applied at a rate of 1 pound of nitrogen per 1,000 square feet.

Next, prepare a good seedbed once the soil has thawed and firmed up. Good seed/soil contact is critical to improve germination and reduce the amount of time required for germination. Seed with good soil contact has better contact with needed moisture and nutrients. Spreading seed on the soil surface without working it into the soil reduces stand vigor and requires more seed and time for good establishment. The use of a verti-slicer or slit-seeder, are excellent tools for preparing and planting seed.

Select turfgrass species and varieties that grow best in your area. There are many sources and recommendations available to select turfgrass species based on use, shade, pets, etc. Each specie of turfgrass has varieties ranked according to quality, color, density, wear tolerance, disease resistance, etc. So be sure to select locally adapted species/varieties of turfgrasses that best fit your situation. Information can be found at your local extension office, the National Turfgrass Evaluation Program, garden centers, nurseries and/or seed suppliers.

Summer annual weeds such as crabgrass can be a real threat to good turfgrass establishment in the spring. Conditions that promote good seed germination of turfgrasses also promote weed seed germination competing for sunlight, nutrients and moisture. There are two approaches to consider for control of annual grassy weeds.

The first is the use of Tupersan (siduron) – trademark of Pbi/Gordon. Tupersan is a pre-emergence herbicide that controls annual grassy weeds, such as crabgrass, foxtail and barnyardgrass. It is the only pre-emergence herbicide that can be applied at time of seeding. Follow label recommendations for rates and timing. Sequential applications of Tupersan 6 to 8 weeks apart seems to work best in control of annual grassy weeds.

Another approach would be waiting until the turfgrass reaches a height of 1 1/2 to 2 inches and has received two mowings. Planting seed early should accomplish this by late April to early May. At that time a product called Dimension herbicide – trademark of Dow AgroSciences formerly Rohm & Haas, can be applied over the top controlling any early crabgrass that may have emerged, but also giving pre-emergence control for any future crabgrass outbreaks. Follow the label recommendations for rates and timings.

Watering new seed is usually the biggest downfall in establishment next to preparing a good seedbed. Seed planted in the upper 1/3 of soil only needs to be kept moist, not wet. That may require several short applications of water throughout the day to keep the surface from drying out. AVOID puddles and runoff. Straw can be used for mulch at a rate of one bale per 1,000 square feet, if your seeded area is totally bare soil. Frequency and amount of water can be reduced as seedlings begin to root more deeply.

One final option we recommend with a spring seeding of cool-season grasses is the use of a bio-stimulant, called Launch. Launch is a liquid concentrate of manure extract and bio-stimulants that include cold water kelp extract, humic acid and fulvic acid. These ingredients are combined with chelated iron and an improved surfactant for good soil penetration. This product is used only as a supplement to a standard fertility program based on soil test recommendations. We have seen improved germination and quality of spring planted grasses with this product, which is so very important in establishing competition against weeds and maintaining good growth to help combat diseases and insects. It is applied at a rate of 1 quart per 1,000 square feet at time of seeding. A second application can be applied 14 days later.

Spring seeding of cool-season grasses can be rewarding if you are able to start early and practice good establishment procedures. Soil testing, soil preparation, seed selection, weed control and proper watering all play a vital role in the successful establishment of turfgrasses.

Spring Weed Control for Established Lawn

Aerification reduces soil compaction and allows air, water and nutrients to reach the root-zone of turfgrass plants where they are needed the most. Aeration allows fertilizers to be used to their maximum benefit.

When caring for a lawn and trying to keep it 'weed-free' the saying that "the best defense is a good offense" holds true. Weeds are opportunistic and invade weakened lawns; thus the best weapon to fight weeds is a dense, healthy stand of turfgrass.

There are several good management practices that give lawns a fighting chance against weeds, such as planting the appropriate grass for a particular location, over-seeding thin stands, proper fertilization, aerification and correctly mowing and watering. Mowing height influences competition against weeds such as crabgrass – the higher the cut the lower the crabgrass infestation. Excellent mowing heights for cool-season turfgrasses range from 2 1/2 to 3 inches. Optimum watering practices involve less frequent "deep-soak" watering that encourages a deep, healthy root system and maintains a dry surface area where weeds get their advantage. Frequent light sprinkling encourages shallow-rooted weeds and seed germination.

Crabgrass is the most common summer annual weedy grass specie. It is a course- textured grass that germinates in the spring and grows well throughout the heat of the summer. Its wide leaf blades, heat tolerance, and prostrate growth habit make it an eyesore in lawns and allow it to smother nearby desirable turf species. Other common summer annual grassy weeds would include goosegrass, foxtail, barnyardgrass, fall panicum and sandbur. The primary control measure for these summer annual grassy weeds are pre-emergent herbicides.

Pre-emergent herbicides are so-named because they must be in place before crabgrass seedlings and other weeds begin to emerge. As a general rule, crabgrass may begin to germinate when daily high temperatures begin to reach 70 degrees F or above. A more precise rule to follow is when soil temperatures reach 55 degrees F in the top inch for four to five consecutive days. In the transition zone this may occur during the first two weeks of April. Keep in mind that these dates will vary greatly from region to region, so check with your local extension office for recommended dates of application.

Following the soil temperature rule allows for the most optimum application time to have your pre-emergent herbicide work the maximum length of time into the growing season. If you regularly apply pre-emergent herbicides, lets say March 15th, and the soil temperature indicator occurs April 15th, you essentially lost 30 days of residual activity for late season control. Highest crabgrass emergence begins to occur as daily high temperatures reach 80 degrees F.

Most pre-emergent herbicides will not kill crabgrass that has already emerged.

A pre-emergent herbicide must be present in the soil surface to kill the summer annual grassy weed seedlings when its first root contacts the soil. Therefore, it is imperative that the pre-emergent be applied at the right time and watered down into the soil surface either by light irrigation or rainfall.

Many effective products are available; almost all of which are combinations of fertilizer with the pre-emergent herbicide (or crabgrass preventer) in the same bag. These combinations are an effective way to fertilize lawns and control annual grassy weeds with one application. Both need to be watered in to be activated (effective). All products are available as sprayable material and common names of available products include benefin, benefin+trifluralin, bensulide, dithiopyr, oryzalin, oxadiazon, pendimethalin, prodiamine and simazine.

Many summer annual grassy weeds that escape pre-emergent control can be handled with a post-emergent herbicide when seedlings are in a 1- to 3-leaf stage of development. Post-emergent herbicides available include dithiopyr, fenoxaprop-ethyl, MSMA, quinclorac and 2,4-D+MCPP+dicamba+MSMA.

Weed and feed combinations of fertilizer and broadleaf weed control herbicides such as 2,4-D often fail to effectively control target weeds like dandelions because of poor herbicide contact and uptake by the weed. The problem is one of placement.

To effectively kill the dandelion the herbicide must be taken up by the foliage. Most granules will fall off leaf surfaces down to the soil surface; root uptake of 2,4-D is poor resulting in poor dandelion control. These products perform better when applied to wet leaf tissue as with a heavy dew in the morning. Many product labels do recommend this practice.Several broadleaf weed control herbicides are available as sprayable products and are pre-mixed in two and three-way combination products. They include combinations of 2,4-D, clopyralid, dicamba, MCPA, MCPP and triclopyr.

Sedges are grass-like weeds that become major problems in low lying, wet thinned turf areas. Sedges are perennial weeds with a triangular shaped stem that develop and spread from small nutlets in the soil. Bentazon, halosulfuron-methyl and MSMA are excellent post-emergent herbicides for control of sedges.

When applying weed control products, read the label directions carefully. Do not over apply, either by excessive overlapping or applying more product than recommended to a specific area. Applying too much product could result in damage to turfgrass roots. Calibration of sprayer and spreader equipment should be performed several times throughout the growing season.

Effective use of herbicides and fertilizers is only as good as the calibration of your equipment and application techniques used. Determine the effective application width of your rotary spreader and space out each spreader pass to ensure uniform coverage with minimal overlap. It is also recommended to apply one-half of the rate required in two directions. This allows better distribution of the particles and avoids striping. Do not spread crabgrass weed and feed products into flower or garden beds; they will restrict rooting of new plantings. For further information on lawn weed control, you can refer to MU Extension Guide G6752 (http://muextension.missouri.edu/xplor/agguides/hort/g06752.htm).

Getting the Most from Your Fertility

Variation in lawn standards, turfgrasses and soil types require different approaches when fertilizing a lawn. The ideal program provides for uniform moderate growth throughout the season based on regular soil testing. Always apply what is needed, nothing more.

Problems arise when rates and forms of fertilizer cause irregular "spurts of growth" especially in spring and summer. Excessive spring and summer fertilization favors shoot growth over root growth, requiring more mowing and resulting in a less-tolerant lawn during the summer. The optimum time to fertilize a cool-season lawn is in the fall of the year, however, if a lawn is stunted, pale to yellow-green in appearance, a very moderate feeding in the spring would be advisable. When turf is not fertilized enough, it has little competitive ability against weeds, diseases and/or insects.

All lawns should be fertilized at least once a year. Additional fertilization will depend on the desired level of turf appearance, turfgrass species, soil type and fertilizer carrier. If only one fertilization per year is desired, early fall in an excellent target date to feed a cool-season lawn. When a second application is desired, do so in the spring when the initial surge of growth is over. Cool-season turfgrasses look and perform best when receiving 2 to 4 pounds of nitrogen per 1,000 square feet per year. Spring applications should not exceed 1 pound of nitrogen per 1,000 square feet, especially if the nitrogen form has a high percentage of quick-release nitrogen. Beyond a fall, and then spring application, a second late fall application approximately 60 days after the first fall application is usually recommended.

Aeration is a cultural practice that allows fertilizers to be used to their maximum benefit. Aerification is the mechanical break-up of compacted clay- or silt-type soils that create barriers for healthy root development. Well aerated soils allow oxygen, water and nutrients (fertilizer) to reach the root-zone of turfgrass plants where they are needed the most.

Aeration should be done at least once a year, and perhaps more, if compaction is a problem in your area. Cool-season turfgrasses should be aerated primarily in the fall, however, secondary aerification in the spring prior to initial growth and spring fertilization can have its’ benefits also. Following aerification with a fertilizer application is one of the best practices you can follow to insure the maximum benefit of your fertility efforts. Always try to avoid the heat of mid-summer when aerifying.

Controlling Those Moles

Use of a verti-slicer or slit-seeder provides good seed/soil contact for improved seed germination and turfgrass density. Seed with good soil contact has better contact with needed moisture and nutrients.

"How do we control those nasty moles?" is a common spring time question we receive. There are many misconceptions about moles, but a few enlightening facts will give some basis for aiding in their control. While most people are well aware of the damage they cause to lawns and flowerbeds, many individuals have never seen a mole.

The Eastern Mole is 5 1/2 to 8 inches long, with a somewhat cylindrical body and elongated head. Their grayish-brown, velvety fur often has a silvery sheen. Their fleshy snout serves as a highly sensitive organ of touch and smell to seek out numerous food sources. Their tiny eyes are concealed in fur and covered by fused eyelids; sight is limited to distinguishing light from dark. Their well-developed front feet are enlarged claws that have a specialized bone attached to the wrist, which aids in digging.

Moles can construct networks of feeding tunnels at a rate of 1 foot per minute. They tend to feed and rest on a two-hour cycle, 24 hours a day. About 85 percent of their diet are animal foods including primarily earthworms (their main source of water) and grubs, however considerable amounts of millipedes, centipedes, spiders, sow bugs, snails and slugs are consumed as well. Moles are insatiable eaters and can consume 70 to 80 percent of their body weight daily.

There are liquid repellants (Mole-Med) on the market that are available and can be purchased at distributors, local nurseries or garden centers. Most of these tend to be based on castor bean oil as the active ingredient. These products need to be sprayed at regular intervals to maintain a barrier that repels these small mammals.

Controlling earthworms is not recommended since they are considered a beneficial organism that aerates the soil and help to break down organic materials. Poison peanuts are not very effective since 85 percent of the mole’s diet is earthworms and insects.

Trapping is the most efficient means of controlling moles and anyone can be successful by following a few simple steps. The most effective trapping is done on networks of shallow runways used for feeding. The key to successful trapping is to locate the active runways. First, with a small stick or broom handle, poke holes in various runways over the entire network. Inspect these holes two hours later.

Tunnels with holes plugged back up indicate which runways are active feeding tunnels at that time. These tunnels are where you set your traps. Then set the trap and there are several types to choose from. The Nash hoop-type and the Victor "Out O’ Sight" scissors-type will trap moles, but seem to be more difficult to set. The Victor "Harpoon or Gig" type trap has been the most successful trap used at the MU Turfgrass Research Center. To set this trap, push down a four-inch length of the runway with your foot.

Summer annual grassy weeds, such as crabgrass, are best controlled with pre-emergent herbicides. Applying pre-emergent herbicides at the proper time will provide optimum season long control.

Before setting the harpoon, push the trap into the soil with the gigs over the runway and move up and down several times to reduce the friction of the soil against the tines. This will insure a quick and decisive thrust of the harpoon. While the trap is in the soil, pull the harpoon up and lock it in position with the trigger pan (flat plate) slightly touching the depressed runway. Poke a hole in the runway on each side of the trap one foot away, then wait a couple hours or until you notice the trap has been sprung.

The holes on each side of the trap will indicate the direction the mole approached the trap. If one hole is plugged, then you more than likely caught the mole on that side of the trap. If both holes are plugged, then the mole more than likely made it through the trap. Simply reset the trap on the same runway or over another active runway.

Your success in controlling moles is dependent on locating active runways and the proper placement of a trap.