GreenCast UK Tech-Notes

Tech Notes Issue 15

Daria Gonetskaya — Wed, 03 Mar 2010 00:23:38 GMT

Maintaining a Quality Practice Range Tee is Difficult but Critical to the Success of a Golf Club

With spring soon to arrive maintaining a quality practice tee through the season is a difficult challenge. Factors like size of the hitting area, and the intensity of use factor in the success of maintaining the tee. A few suggestions for maintaining a tee through the year are provided below.

Setup

The key to maintaining turf quality is to controlling where the golfers practice. Some suggestions on setup have been provided by the United States Golf Association.

Place ropes approximately 2 to 2.5 meters apart across the width of the tee. Anchor the ropes so they can't be moved.
Create hitting stations approximately 3 meters apart within the roped area. Hitting stations can be defined with dividers, bag holders, bucket of balls, or small buckets containing topdressing for divot repair.
Given that most golfers will use the right-hand portion of the hitting station, the following day move the hitting stations to the left (sideways). This will allow for 2 days of use within the same roped area.
Every other day move the roped area. Moving the ropes should be coordinated timed with the mower operator to save time. The ropes can be moved forward (or backward) 1 or 1. 5 meters. They do not need to be moved 2 to 2.5 meters because golfers tend to shy away from hitting to close to the ropes.

Using the setup described above a practice range tee with a width of 30 meters, it would take between 40 and 60 days before returning to the same spot.

Topdressing

In addition to proper setup, daily topdressing and seeding of the damagedareas is needed. This can be done withthe remaining topdressing mix(containing seed) in the divot buckets orfrom material provided. Additionally,some fertilizer should be added to thetopdressing mix (topdressing/seed) tohelp in seedling establishment.If the golf professional is in charge of therange the topdressing mix can be spreadin the evenings by the person or peopleresponsible for range cleanup. If themaintenance personnel are responsiblethe topdressing mix can be spread earlyin the morning prior to play.

Maintenance

The practice range tees should be coredtwice yearly in conjunction with a mediumto heavy topdressing. The teeshould be adequately fertilized. Summerannual weeds like crabgrass (Digitariaspp.)and goosegrass (Eleusine indica) are a serious problem on highly wornpractice range tees. Although preemergentherbicides can be used to controlthese weeds they tend to lose efficacytoward the end of summer resultingin a burst of weed growth. In addition,the herbicides can/may restrict seed germinationof tee topdressing mix containingseed. The most effective cool seasonturfgrass to use in the divot mix forquick establishment and most competitiveagainst weeds is perennial ryegrass.Golf Mats installed toward the back ofthe range can provide hitting stationscan reduce wear and excessive injury tothe practice range tee during periods ofinclement weather saving the practicerange tee from excessive damage.

Reference:

Foy, J.H. and J. Beljan. 1994. Turfmanagement in a battle zone: Practiceranges. USGA Green Section Record 32(6):1-8.

Tech Notes Issue 2

Daria Gonetskaya — Wed, 03 Mar 2010 00:18:27 GMT

Strobilurin (QoI) Fungicides

Strobilurin fungicides trace there origions to a fungal antibiotic produced by the pine cone fungus Strobilurus tenacellus. It's believed that this wood rotting fungus, and similar fungi, produced strobilurin to help protect it from microbes present in the woods. Over the years researchers enhanced the natural strobilurin synthetically leading to the class of fungicides known as strobilurins.

Widely used in Agriculture, it was not until 1997 when the first one, azoxystrobin, was registered for turf use in the USA. Since azoxystrobin, additional fungicides in this class have been released in the turfgrass market including fluoxastrobin, pyraclostrobin, and trifloxystrobin.

Although these fungicides are commonly called strobilurins, they are more properly referred to as Q_oI fungicides. For those of you who may not be familiar with the Q_oI terminology, the Q_o is part of the Q-cycle found in mitochondrial respiration (cytochrome system where electron transport occurs. Q_o is the binding site for ubiquionone, which acts as an electron acceptor in this process). These fungicides inhibit fungal respiration by attacking the site Q_o in the cytochrome system of the mitochondria.

The Q_oI fungicides have a wide spectrum against a number of turfgrass diseases. Although Q_oI fungicides have similar mode of action, they do differ in regard to the molecule itself, leaf absorption and transportation within the plant, and diseases controlled. Due to the broad spectrum control properties and high level of efficacy, these fungicides have been well received and are now widely used by golf course superintendents. When applied correctly they are extremely effective and an integral part of any fungicide program.

The Q_oI fungicides mode of action however is highly specific; and for this reason the potential for fungal resistance to occur is high. With the upcoming winter disease season almost upon us, it is important to be aware of the potential for resistance and know that certain rules need to be followed when incorporating Q_oI fungicides into a disease control program. The guidelines for reducing the likelihood of resistance to QoI fungicides as outlined by the Fungicide Resistance Action Group (FRAC) are:

1) Use integrated pest management and cultural practices to reduce disease pressure. If disease pressure is low fewer applications are required and a rate more closely associated with the minimum labeled fungicide rate is more likely to be used.

2) Limit the number of Q_oI fungicide applications to no more than ¹/₃ of the total number of fungicide applications per season.

3) Use pre-mixtures or tank mixtures of Q_oI fungicides with a different mode of action group. HEADWAY MAXX is a recent example of a pre-formulated combination of a strobilurin (azoxystrobin) and an unrelated mode of action fungicide (propiconazole).

4) Make preventative applications to keep disease pressure low.
Contact Syngenta for help with a targeted prevention GreenSure Plan.

Tech Notes Issue 1

Daria Gonetskaya — Wed, 03 Mar 2010 00:14:00 GMT

It seems like it never gets too hot for Pythium blight

Pythium blight is a severe disease of many turfgrasses during the summer months. Cool season turfgrasses like creeping bentgrass are most susceptible but couchgrass and other warm season turfgrasses can also be infected under the proper environmental conditions.

Pythium attacks when daytime temperatures are above 30 C and nighttime temperatures remain above 20 C. Wet humid conditions along with high temperatures are most favorable for this disease. Pythium is most severe on turf that is poorly drained or have little air movement (shaded conditions).

Extreme Heat Stress Can Result in Curvularia Diseases

With the high summertime temperatures turfgrass plants become susceptible to diseases not normally considered a problem. Curvularia species (ex. C. lunata , C. trifolii, C. eragrostidis) are normally weak pathogens but can become severe on turfgrass plants weakened from heat and/or moisture stress.

Curvularia disease symptoms are most evident on senescing plant tissue primarily leaves. On senescing tissue conidia from the pathogen infect and sporulate profusely. Symptoms initially appear as indistinct yellow and green mosaic type of pattern extending from the leave tip down (the oldest part of the leaf is the tip).

The leaves eventually shrivel and turn a grayish color; except with creeping bentgrass where the leaves appear tan. If warm wet weather occurs rapid infection of plant tissue can occur.

Curvularia is a difficult disease to control because the turf plants are under severe environmental stress. Practices like minimizing soil compaction, providing a better growing environmental condition, and proper cultural management (balanced fertility, proper watering, etc.) can help make for a healthier turfgrass plant.

In some instance registered fungicide applications would be warranted.

Picture: Advanced stage of Curvularia with the turf showing the grayish color. Curvularia can live saphrophytically on plant debris

Tech Notes Issue 1

Michael Murphy — Tue, 16 Feb 2010 16:34:26 GMT

Irrigation Water Influenced by Soil Texture

Irrigation water quality is always a concern during the summer. Suitability of irrigation water is determined by the electrical conductivity
of the irrigation water (EC_i) and the level of sodium (Na⁺), magnesium (Mg⁺²), and calcium (Ca⁺²) ions.

Electrical conductivity is measured in decisiemens/ m (dS/m). In some instances the value maybe reported in microsiemens/cm (dS/m). The EC threshold for turfgrasses is higher on well drained sandy soils versus a clay soil. For example the threshold for couchgrass (Cynodon dactylon) is two and half times higher on sand than on clay.

Wilt Symptoms Can Be Caused by Several Factors

As summer progresses turf wilt symptoms become quite apparent. There are a couple of causes of "wilt symptoms" besides lack of rainfall or irrigation water.

Localised dry spots (LDS) are a serious problem on sand-based creeping bentgrass or couchgrass putting greens or athletic fields throughout South Africa and Australia. Symptoms appear as circular areas varying from 100 cm to several meters in diameter that progress from a bluish wilt to a whitish brown color. In some instances, symptoms appear more serpentine.

The cause of LDS is due to a hydrophobic soil condition that occurs in the upper 5 cm of the soil profile. Sand particles are partially coated with an organic material that repels water resulting in the wilt/drought like symptoms. The source of the organic material may be a result of soil fungi. Fairy ring is often, but not always associated with LDS.

To determine if LDS is present take a soil core from the suspected site and add water droplets along the soil profile. If the droplet beads and fails to penetrate LDS is present. Usually the water will bead in the upper 2 to 4 cm of the soil profile. Wetting agents are effective in many situations and should be used if LSD is a problem. Reducing the amount of thatch accumulation, and coring on a regular basis may help reduce LSD severity. In some instances where fairy ring is the cause, drenching an appropriate fungicide after coring may help alleviate symptoms.

If LDS is not the problem, check for grub damage. A common misdiagnosis for these "wilt symptoms" is the irrigation heads are not working properly. Take a minute to peel pack the turf to check for grub damage.

Click here to download the article in pdf

Tech Notes Issue 2

Michael Murphy — Tue, 16 Feb 2010 16:34:24 GMT

Photograph: Rapid bllight

Rapid Blight Can Hit Bentgrass Under Salt Stress

Rapid blight (pathogen: Labyrinthula terrestris) can occur on winter grass or creeping bentgrass greens. Symptoms appear as irregularly shaped patches of yellow or brown turf ranging from 5 cm to 2 meters in diameter. Rapid blight outbreaks are associated with dry periods associated with high salt content in the soil or through irrigation water. Creeping bentgrass or winter grass growing on soils with salt readings above 2.7 dS m^-1(Saturated Paste Extraction Method 1:1) are predisposed to this disease. If this disease is a concern, frequent leaching needs to be done to reduce salt levels.

A Sign of Summer Stress is the Presence of Anthracnose

Anthracnose is a destructive disease of wintergrass (Poa annua L.) and to a lesser extent creeping bentgrass greens. The pathogen, Colletotrichum cereale (formerly C. graminicola) spends most of its life cycle as a saprophyte, primarily in the thatch. However, with the arrival of high temperatures and humidity, this fungus becomes pathogenic infecting leaf, stem or root tissue. The disease is most prevalent on
shortly mowed greens but can occur at higher heights of cut found on fairways.

Anthracnose initially appears as small patches of yellow to reddish-brown turf 2 to 5 cm in diameter. These patches can progress into relatively large irregularly shaped areas. Plants weakened by environmental or mechanical stress, are predisposed to attack by the pathogen at the stem and basal region of the plant. If the infection is severe enough the plants are easily pulled from the turf. As the infection progresses, the pathogen will produce small black protrusions immediately below the leaf epidermis. These smooth protrusions represent the early stage of the reproductive structure called the acervuli. As the acervuli matures spines (called setae) are produced.

Photograph: Acervuli with setea

Cultural practices to reduce the severity of anthracnose include reducing shade affects to the turf, fertilize or more specifically spoon feed through the summer to preventnutrient deficiency, and watch carefully watering practices. Too much or too little water can increase anthracnose severity. Anthracnose is a difficult disease to control curatively. Fungicide control is most effective as preventative applications. To increase the effectiveness of curative fungicide treatments, try to reduce the severity of management practices. Examples of reducing management practices might include changing from double cutting to single cutting, using a walk behind mover versus a triplex, switching to solid rollers, and reducing the number of rollings and verticutting

Click here to donwload the article in pdf

Tech Notes Issue 3

Michael Murphy — Tue, 16 Feb 2010 16:34:23 GMT

An Overview of Some Summertime Diseases

Dollar Spot (Sclerotinia homoeocarpa). Active between 15 and 30 C under high humidity and/or dew. Cool season turfgrasses susceptible at this time.		Pythium blight (Pythium spp.) is most severe under wet humid conditions with high temperatures (30-35 C) and warm nighttime temperatures (> 20 C)
Gray leaf spot (Pyricularia grisea) occurs under humid conditions when temperatures range between 28-32 C. In the US associated with Lolium perenne, but can attack kikuyugrass		Take-all patch (Gaeumannomyces graminis var. avenae) occurs on new or young creeping bentgrass turf. Generally associated with high pH rootzone mixes.
Brown Patch (Rhizoctonia solani) occurs under warm humid conditions primarily at this time on cool season turfgrasses. Most active when nighttime temperatures remain above 21 C.		Root decline of warm season turfgrasses (G. graminis var. graminis) is similar to take-all but occurs under cloudy warmer conditions on both new and old turf.
Summer patch (Magnaporthae poae) occurs at temperatures between 28 –35 C. Highly destructive on Poa pratensis and Poa annua		Curvularia (Curvularia spp.) is primarily a problem on ultradwarf couchgrass. It occurs under high temperatures and cloudy wet conditions.

Click here to download the article in pdf

Tech Notes Issue 4

Michael Murphy — Tue, 16 Feb 2010 16:34:22 GMT

Ecology and Control of Poa annua in Overseeded and Non-overseeded Bermudagrass: Part I

The major winter weed in overseeded and nonoverseeded couchgrass is Poa annua. It is common throughout Australia and South Africa.
Although both annual and perennial biotypes exist of Poa annua, the predominant biotype that occurs in couchgrass is the annual type. For timing preemergent herbicide treatments the conditions favorable for Poa annua germination might be valuable.

In a recent paper¹, 8 "annual" Poa annua biotypes were collected from the southeastern United States and the seed harvested. Conducting standard seed germination studies the researchers found that the optimum temperature for Poa annua seed germination was 19 C (day)/10 C (night) (Figure 1). Significant Poa annua germination also occurred at 29 C (day)/19 C (night). I would assume as autumn approaches and temperatures drop below, germination will start and increase to reach optimum germination around 19/10 C.

Additionally, the germination studies were done under different photoperiods (hours of daylength) across the various temperature regimes. The striking result from the study is the high percentage of Poa annua seed that germinated under complete darkness (Figure 2, 0/24 treatment). The common perception that weeds that produce a small seed need light to germinate does not apply to Poa annua. The implication is that Poa annua will germinate in your couchgrass even under a full undisturbed canopy cover.

In the next issue we will look at controlling Poa annua.

Literature Cited:
1. McElroy, J.S., R.H. Walker, and G.R. W. Edzard van Santen. 2004. Annual bluegrass (Poa annua) populations exhibit variation in germination
response to temperature, photoperiod, and fenarimol. Weed Science 52:47-52.

Figure 1. Effect of temperature (day/night)on Poa annua seed germination (average of 8 annual biotypes)¹

Figure 2. Effect of photoperiod on Poa annua seed germination (average of 8 annual biotypes)¹

Click here to donwload the article in pdf

Tech Notes Issue 5

Michael Murphy — Tue, 16 Feb 2010 16:34:21 GMT

Suggestions for Winter Overseeding

If winter overseeding couchgrass with either perennial ryegrass (Lolium perenne) or rough bluegrass (Poa trivialis), the ideal time to overseed is when soil temperatures drop to 21 C. Trinexapacethyl (Primo®) applied 1 to 5 days prior to overseeding enhances establishment of the cool season turfgrass significantly. Topdressing after overseeding promotes good seed/soil contact and research has found that the establishment rate is 50% faster compared to non-topdressed areas.

Control of Poa annua in both Overseeded and Non-Overseeded Couchgrass: Part II

Successful Poa annua control in both overseeded and nonoverseeded couchgrass is dependent on rate, timing, and application of both preemergent and postemergent herbicides.

Strategies for controlling Poa annua include applying a preemergent herbicide at the time of germination, or waiting until most of the Poa annua has germinated and visible then treat with a postemergent herbicide. In overseeded turf, preemergent herbicide applications are the primary means of controlling Poa annua. With the use of traditional postemergent herbicides applications need to be made 8 to 10 weeks (in the case of prodiamine 10 weeks) prior to overseeding with perennial ryegrass (Lolium perenne). Some of the newer herbicides - sulfonylurea - can be applied closer to overseeding (Always follow labeled instructions and use turfgrass labeled products).

Most failures with the initial pre-emergent application are due to the appropriate rate was not applied, or excessive overlap occurred. In the case of inadequate application rate, potential for Poa annua germination and survival is higher. With regard to overlap, the excessive rate applied
inhibits the overseeded cool season turfgrass species. One method of reducing the risk of overlap is to apply ½ rate in two directions.

In non-overseeded couchgrass turf the pre-emergent herbicide should be timed closer to Poa annua germination in the autumn and then a second treatment, midwinter is recommended where Poa annua infestation is heavy (Again, follow labeled instructions).

Photograph: Poa annua germination in germintaion in overseeded counchgrass turf

Click here to download the article in pdf

Tech Notes Issue 6

Michael Murphy — Tue, 16 Feb 2010 16:34:19 GMT

Growing Degree Days and How You Can Use Them

Growing degree-daymodels are used topredict pest or plant lifecycles. Growing degreedays are basedon temperature or heatunits.

A growing degree day is a measureof heat above a threshold forone day. A growing degree day(GDD) is = (maximum temperaturefor the day + minimum temperaturefor the day) divided by 2 giving the average daily temperature minus a base temperature.The base temperature is the minimum temperature needed forgrowth and is commonly 10 C, but can vary depending on the use, plant or pest.

For example, if we had a day witha maximum temperature of 20 C and a minimum temperature of 14C, and were using a 10 C base temperature the calculation would look like:

GDD = {(20 + 14)/2 - 10} = 7

GDD have no units associated with them. A GDD is calculated daily and a running total or total accumulated growing degree days would be the result of adding consecutive daily values. For example, if on the second day theGDD was 4, the total accumulated GDD for the two days would be (7 + 4) = 11.

A negative growing degree daydoes not exist. For example, if you were to calculate a - 2 GDD, the value would be set to 0 fort hat day.

Predicting Poa annua Seedhead Emergence

In the northern United States(temperate region) growing degree-day models are used to predict Poa annua inflorescence (seedhead) appearance. The value of a seedhead emergence model is to more accurately timea plant growth regulator application that would suppress seed head emergence. These GDD models specifically are best used on a regional basis because the start date at which they begin is variable.

For example, a commonly used model that was published 25 years ago uses an April 1 start date because that is when snow cover typically ended in Michigan where the model was developed. This GDD model would not to applicable for Australia and South Africa. However, the ease at which the models can be developed - the association between temperature (GDD) and a biological event like seed head appearance can be easily developed no matter where you are in the world.

Photograph: Poa annua patch going to seed.

Tech Notes Issue 7

Michael Murphy — Tue, 16 Feb 2010 16:34:18 GMT

A Few of Mites Can Weave a Web of Intrigue

During the winter months, mites can cause damage to both cool and warm season turfgrasses months. Their needle-like mouthparts pierce the plant or leaf sucking out the plant juices. Although mite damage for the most part is sporadic, symptoms can appear speckled with a purplish shade or a bleached straw color. Severely damaged plants may appear stunted or killed. A potential sign of mite damage occurs in early spring when the turf fails to green up.

Most mites are no larger than a period at the end of sentence. Adult mites have 8-legs versus the 6-legs typically associated with insects. This is one reason that mites are more closely associated with spiders than to insects. The term spider mite is often used as an umbrella term for several different types of mites that may have not been specifically identified.

Of the many mites a few produce significant and large scale webbing.

Without proper identification, it is difficult to tell the mite species, but two types of mites, the Banks grass mite and the Australian redlegged earth mite are copious web formers. The Banks grass mite, sometimes referred to as a true spider mite, can attack both
cool and warm season turfgrasses including couchgrass and seashore paspalum. The Australian redlegged earth mite is associated with more temperate climates like those found in southern Australia. The winter grain mite found in the United States is a close relative of the Australian redlegged earth mite.

The life cycle of mites consists of several stages including the egg, larva (when newly hatched contain three pairs of legs), nymphs,
and adults. During winter (late fall through early spring) turf infestation eggs and the various stages of development are often present
at the same time. Control of mites is very difficult. Several mites are immune to many of the turf insecticides.

Photograph 1. Webbing caused by a mite on seashore paspalum.

Photograph 2. Large scale webbing across a couchgrass sod field.

Photograph 3: Winter grain mites (close relative of the Australian Redlegged Earth Mite).

Tech Notes Issue 8

Michael Murphy — Tue, 16 Feb 2010 16:34:16 GMT

Dollar Spot (Sclerotinia homoeocarpa) Can "Sneak Up" During Winter and Early Spring

With cooler temperatures of winter approaching, dollar spot under the right conditions can occur on both cool and slow growing warm season turfgrasses. On short cut cool season turf like putting greens dollar spot appears as small circular patches that can become sunken. Dollar spot can appear as small - the size of a fingertip - pitted spots to circular patches no larger than 5 cm in diameter. These patches however can coalesce when the disease is severe forming large blighted areas. Dollar spot is spread primarily by maintenance equipment and mowers, but can also be spread by shoes, and traffic activity.

If dew is present, the white cobweb- like mycelium of the pathogen (Sclerotinia homoeocarpa) is observed. As the leaves dry the mycelium disappears. Leaf lesions often appear as hour-glass shaped but can appear oblong or oval. The lesion appears a tan to
a bleached-out color with a brown border extending the entire width of the leaf. The brown or reddish border along the outer edge of the lesion is present on all cool season turfgrasses except on Poa annua. Dieback from the leaf tip can occur with the entire leaf becoming
blighted.

Dollar spot is most active within the temperature range of 15 to 30 C with high humidity and leaf wetness. In general, warm humid days, cool nights, and heavy dews are quite favourable for disease development. Although canopy moisture needs to be present, dollar spot is more severe on dry soils.

To reduce the severity of dollar spot maintain adequate soil moisture and fertility levels. Dollar spot is most severe on low or deficient nitrogen turf. Additionally, remove dew early in the morning through poling, dragging, or mowing. Removing dew reduces the wetting period necessary for disease development. For example, research has found that waiting to remove dew in mid-morning or for it to dry results in a greater amount of dollar spot than removing the dew in early morning.

Photograph 1: Dollar spot symptoms on creeping bentgrass tee								Photograph 2: Dollar spot symptoms on seashore paspalum fairway

Tech Notes Issue 9

Michael Murphy — Tue, 16 Feb 2010 16:34:15 GMT

A Camouflage Turf Appearance is Due Most Likely to Cool Temperatures

Chilling injury is defined as low temperature stress in the absence of freezing (Levitt, 1980). It readily occurs on warm season grasses growing in the subtropical to tropical regions when temperatures drop below 12 C in late autumn or early winter. In addition to temperature, high light intensity can enhance the chilling effect. Although chilling is most often associated with couchgrass, it occurs on other warm season turfgrasses.

Chilling injury causes several metabolic of physiological dysfunctions to the plant including 1) disruption of the conversion of starch to sugars (amylotytic activity), 2) decreased carbon dioxide exchange, 3) reduction in net photosynthesis, and 4) the destruction/degradation of
chlorophyll.

Given the range of temperature from freezing (0 C) to 12 C that chilling can occur symptom expression can vary. The most striking symptoms occur, again under high light intensities with rapid temperature drop to - or close to - freezing. Under this scenario symptoms are expressed in 24 to 48 hours. Symptoms appear as bleached out turf often in a camouflage appearance.

The bleached out leaves is due to rapid pigment degradation. Although we are not aware of any data or studies, the consensus opinion among researchers in this area is that the serpentine or camouflage pattern occurs because of differential settling of cold air. In other words cold air settles into the lower areas of the turf causing more injury, similar to what occurs in a valley or at the base of a mountain range.

At temperatures in the 8 to 12 C chilling injury occurs much slower and is not as drastic. Chilling symptoms appear more uniform and the turf color is a combination of purple, blue, and red shades due to the slow degradation of chlorophyll and the corresponding expression of other pigments and carotenoids.

Control

Preventing chilling injury is nearly impossible if temperatures get cold. If conditions can be predicted prior to occurring covering the turf may help reduce the severity. Most of the
practices mentioned work best if the chilling period is short in duration. Covering the turf can reduce the effects of chilling but may not be practical for large areas.

Tech Notes Issue 10

Michael Murphy — Tue, 16 Feb 2010 16:34:14 GMT

With Increased Sensitivity Over Phosphorus Applications, Know the Proper Fertilizer Ratio to Use

Phosphorus is one of the three major (macro) nutrients required for plant growth. Phosphorus is important in seedling establishment in newly seeded areas. As the turf stand matures phosphorus is a critical component of adenosine tryphosphate (ATP) the energy transferring molecule in cells. In the United States the application of phosphorus to turf is facing increased scrutiny. The greatest concern is in States that border the Great Lakes where phosphorus restriction or bans are being instituted primarily on homelawn turf.

Detrimental affects associated with phosphorus include enhancing algae blooms that can ruin the aesthetics of lakes and streams, and also cause depletion of oxygen impacting the health of fish and other water organisms. Whether the amount of phosphorus from homelawn runoff is of the same magnitude that municipal sewage, detergent, and agriculture fertilizers that caused water pollution in the 1960's and 70's is debatable. However, like all nutrient and chemical applications, phosphorus should be applied in an environmentally responsible way.

Suggestions for Your Phosphorus Fertilization Program

In planning your phosphorus fertilizer program, conduct or check your soil test reports to ascertain the phosphorus levels. This will help you decide whether to increase, decrease, or maintain your phosphorus soil levels. Given that major nutrient (nitrogen, phosphorus, potassium) concentrations in turfgrass leaf clippings remains rather constant - 4:1:3 (N:P2O5: K2O), the given fertilizer ratio can impact soil phosphorus levels. For example using a fertilizer with a N:P2O5 of 4:1 you will roughly maintain the current soil test levels of phosphorus. If you use a ration less than 4:1 like 2:1 or 3:1 you will contribute to the phosphorus levels in the soil. Conversely, if you use a fertilizer with a ratio greater than 4:1 like 8:1 or 10:1 you will slowly deplete the phosphorus levels in the soil.

Tech Notes Issue 11

Michael Murphy — Tue, 16 Feb 2010 16:34:13 GMT

Although not the Same as Chilling on Warm Season Turfgrasses, Cool Temperatures Can Cause Purpling

With cool wintertime weather creeping bentgrass and wintergrass putting greens can turn a purplish color. The purplish color may appear uniformly across the green, but is more likely to appear as patches on older creeping bentgrass and wintergrass greens. The purpling is most pronounced on 'Penncross' greens but can occur on all bentgrass cultivars. There can be a difference in purpling intensity among biotypes or clones that develop in these wintergrass and/or creeping bentgrass greens.

In most cases the purpling is a physiological response to warm sunny days followed by a rapid drop in temperature at sundown. Daytime temperatures in the 16's to lower 20's followed by nighttime temperatures in the single digits are optimum condition for purpling. Under these conditions the turfgrass plant is actively photosynthesizing and creating sugars during the day. At night the sugars are translocated down into the storage areas of the plant. However, if temperatures drop rapidly at sundown the sugars are trapped in the leaf and fail to translocate.

The sugar molecules left in the leaf attach to a plant pigment called anthrocyanin (purple or blue pigment). The buildup in anthrocyanin results in the expression of the purplish color. Once warmer temperatures arrive, the purpling will diminish. If symptoms do not disappear with the arrival of warmer temperatures, check your soil test reports for phosphorus deficiency. Symptoms of a phosphorus deficiency are purple leaf blades.

Picture 1. Purple patch on a creeping Picture 2. Close up of the purpling on
bentgrass green the leaves of creeping bentgrass

Tech Notes Issue 12

Michael Murphy — Tue, 16 Feb 2010 16:34:11 GMT

Weather conditions Favorable for Microdochium patch

Winter weather conditions are favorable for Microdochium patch in southern Australian States and up through New South Wales. Temperatures in the range of 0 to 7 C along with extended periods of wetness are ideal for disease development. Wintergrass (Poa annua) is especially susceptible under these conditions. The classic symptoms are circular pink colored patches that can reach a diameter of 25 cm. However, during periods of extended wetness or rain, the spores can spread along water flow (drainage) patterns. The result is a streaking symptom that is sometimes confused with cool temperature pythium.

Spring Dead Spot is a Serious Disease of Couchgrass through the Winter

Spring dead spot is a common disease of both common couchgrass (Cynodon dactylon) and the hybrids (C. dactylon x C. transvalensis). The pathogens associated with the disease in the southern hemisphere are Ophiosphaerella narmari and Ophiosphaerella korrea. Symptoms appear as circular white to bleached out patches varying in size up to 1 meter in diameter. Symptoms often appear in early spring when couchgrass begins to break dormancy. However, symptoms can appear from late autumn through winter during periods of cool wet weather. Symptoms can persist well into the summer even when couchgrass is actively growing.

The pathogens associated with spring dead spot attack the root system of couchgrass during the winter months when soil temperatures range from 12 to 14 C. A sign of this disease is the production of brown runner hyphae on the outside of the roots.

To reduced the severity or likelihood of spring dead spot fertilize with moderate rates of nitrogen, correct any potassium deficiencies (ammonium sulfate along with potassium over time appears to reduce the severity of the disease), and raise the mowing height slightly. Raising the height appears to be only effective with reducing the severity of the disease on the hybrids.

Fungicide control of spring dead spot is challenging. Generally, applications should be timed during the autumn when the pathogen is actively infecting the root system.

Photograph: Spring dead spot symptoms still visible during summer

Tech Notes Issue 13

Michael Murphy — Tue, 16 Feb 2010 16:34:10 GMT

With Spring Quickly Approaching Conditions

Become Favorable for Take-All

Take-all patch is a potentially serious disease of creeping bentgrass turf less than 10 years old. In contrast Poa annua is resistant to Take-all patch. The pathogen, Gaeumannomyces graminis var. avenae infects the roots of creeping bentgrass during cool wet periods of spring. The disease is most apparent during periods of hot dry weather. Symptoms appear as circular patches ranging from a few centimeters in diameter (initial infection) to 1 meter in diameter. The patches are a reddish-brown to orange-brown color. Often times these patches will eventually be colonized by weeds.

Take-all as previously mentioned occurs on newly established creeping bentgrass turf on low organic matter, high pH sandy soils or rootzone mixes. The severity of the symptoms, in general are most severe within the first 3 to 5 years, decreasing in severity beyond this time.

Symptoms of Take-all

(Above left) Early spring symptoms of Take-all on a newly stablished creeping bentgrass tee. (Centre)Take-all symptoms under adequate moisture. (Above right) Take-all symptoms under moisture stress.

Cultural Practices

If soil pH is high (> 6.5) gradually try to reduce the pH through the use of acidifying fertilizers.
If possible, minimize the use of alkaline topdressing materials.
Maintain a balanced soil fertility level. Manganese deficiency can greatly
enhance take-all patch.
Minimize moisture stress to the infectedarea. Moisture stress enhances
the expression of symptoms.

Chemically

Fungicides are available that can suppress symptom expression. The fungicides that have shown good activity on Take-all include a few of the DMI (demethylase inhibitors) products and one of the strobilurins. The effectiveness of the fungicide treatments is based on timing. Check local fungicide labels for registered use.The fungicides should be applied when the pathogen is infecting roots, normally in early to mid-spring. Applications should be made as a drench treatment, which should be in excess of 800 litres of water per hectares.

Tech Notes Issue 14

Michael Murphy — Tue, 16 Feb 2010 16:34:08 GMT

With Spring Arriving: The Topics are the Good, and the Bad (also Ugly)

First the good, a recent study out of Sweden found that playing golf can increase life expectancy¹. The study was based on 300,000 golfers and showed that the death rate amongst golfers is 40 per cent lower than the rest of the population. This would approximate an increased life expectancy of five years.

The researchers found that golfers had a lower death rate regardless of sex, age and social group. The effect was greater for golfers from blue-collar professions than for those from white-collar professions. The lowest rates are found in the group of players with the lowest handicap.

Professor Ahlbom who was one of the authors was quoted in ScienceDaily saying, "Maintaining a low handicap involves playing a lot, so this supports the idea that it is largely the game itself that is good for the health."

In the July (2008) issue of the Journal of Agricultural and Food Chemistry, researchers from the University of Massachusetts Amherst reported that in the worst case scenario the estimated exposures to golfers following full rate and full course applications of carbaryl and chlorpyrifos were 19 to 68 times below current U.S. EPA values designed to protect human health.

In a press release from the University, Dr. John Clark a professor of veterinary and animal sciences who specializes in toxicology was quoted as saying, "This study, which also included measuring insecticide residue transfer from treated turfgrass and airborne insecticide residue, provides a novel and complete database on golfer exposure."

It looks like the more you play golf walking the healthier and longer that you will live. Umm, maybe pesticides are not as detrimental to golfers health as we are often led to believe.

And Now for the Bad & the Ugly…

From late winter to early spring, mole crickets become active primarily on couchgrass. Mole crickets overwinter as adults and nymphs. The nymphs however become adults in spring just in time for mating season. During this time the males will begin to tunnel causing turf damage. Both males and females fly on warm, humid nights, sometimes in huge numbers. Normally, eggs take 14 to 28 days to hatch. From a control perspective, the nymphs that hatch are small and most susceptible to control measures.

Reference
1. B. Farahmand, G. Broman, U. de Faire, D. Vågerö, A. Ahlbom. Golf: a game of life and death - reduced mortality in Swedish golf players. Scandinavian Journal of Medicine & Science in Sports, Published article online: 28-May-2008.

Tech Notes Issue 15

Michael Murphy — Tue, 16 Feb 2010 16:34:06 GMT

Determining Whether an Acid Injection System is Warranted is Dependent on Soil and Water Tests

Acidification is a popular treatment for low quality soil and irrigation water. The most common mistake made in obtaining and using acid injection systems is a failure up front to determine if their use is appropriate.

The following are conditions where an acidifying treatment would be recommended:

1) Sodium-affected soils with poor infiltration. How severe the sodium level? Usually, an Exchangeable Sodium Percentage (ESP) greater than 15%. Additionally, adequate free lime needs to be present in the soil.

2) Water with a high adjusted Sodium Absorption Ratio (SAR) and a residual sodium carbonate (RSC) level greater than 1.25

The justification or not of using acid injection systems can be determined by your soil and water test reports.

There are several options for applying acidifying amendments including surface applied sulfur, acidifying fertilizers, sulfur burners, and direct injection of sulfuric acid into the irrigation system. For this article sulfur burners are used as an example of an injection system. Sulfur burners are generally cheaper than direct injection of sulfuric acid. In general how these units work is that a solid form of is added and then heated to form sulfite (SO₃), which is a gas that then reacts with water to form sulfurous acid (H₂SO₃). In acid injection systems sulfuric acid (H₂SO₄) is used. Sulfurous acid and sulfuric acid have similar affects on soil and water.

The effect from the sulfur burner and also the acid injection systems is to react with calcium carbonate forming gypsum to prevent sodium accumulation. Additionally, the systems can drive off carbonates and convert calcium and magnesium in the water to more soluble forms. The sulfur burners are simpler to work but are often considered to be aesthetically unpleasing due to the smoke that given off and because they are located next to the irrigation pond. Attention needs to be paid to the mixing uniformity of the acidified water in the lake or pond.

Photograph: Portable sulfur burner
located on the banks of a golf course
irrigation pond. In this case the burner
was being used to lower water pH.

Tech Notes Issue 16

Michael Murphy — Tue, 16 Feb 2010 16:34:05 GMT

On Warm Season Turfgrasses, Large Patch is Often Prevalent under Springtime Conditions

Large Patch is an early - mid spring disease of warm season turfgrasses. First reported on zoysiagrass, the disease was initially named Zoysia patch. After the pathogen was identified on numerous warm season turfgrasses, the common name "Large Patch" evolved. Although most severe on zoysiagrass, large patch is increasingly becoming more prevalent on seashore paspalum.

The pathogen Rhizoctonia solani is similar to the pathogen that causes brown patch on cool season turfgrasses, except the large patch pathogen belongs to a different anastomosis group (AG-2-2 (LP). The optimal temperature for infection is 25-28C but can infect at temperatures ranging from 10 to 30 C. Generally, large patch is most severe under moist or wet conditions.

Cultural practices that minimize surface moisture will help reduce the severity of large patch. Prolonged periods of fog or dew enhance the severity of this disease. Although, eliminating fog is beyond our management abilities, reducing dew periods through dragging, poling or lightly syringing will decrease disease severity. During winter and early spring maintain moderate to low nitrogen levels during periods when Rhizoctonia is active.

Fungicides are available that will control Large patch. In general preventative treatments are more effective than therapeutic (curative) treatments.

(Above left) Large patch symptoms on zoysiagrass. The symptoms often appear as the turf is breaking winter dormancy. (Centre) Large patch symptoms on most warm season turfgrasses appear as a whitish color and rather large areas are affected. (Above right) Large patch is becoming more of a common disease of seashore paspalum. The picture below was taken on a ‘SeaDwarf’ seashore paspalum fairway.

Tech Notes Issue 17

Michael Murphy — Tue, 16 Feb 2010 16:34:04 GMT

Irrigation methods for Managing Turf Sites High in Salt

Maintaining turf on salt affected sites is one of the most difficult challenges a golf course superintendent or athletic field manager can face. Salt affected sites is a growing problem due to several factors including the increased use of irrigation sources that contain salt, salt water intrusion into coastal turf areas, and limitation of water use and the quality of water used in dry or arid regions.

Leaching is one management practice that is used to avoid salt build up in the soil. There are two leaching methods that are practiced. The first is termed flushing or leaching where irrigation water is applied in sufficient amount to move the salts downward out of the rootzone. The volume of water needed is dependent on the amount of salts, and the soil type.

However, as a general rule 15 cm of water needs to flow in through the rootzone or soil profile to drop the electrical conductivity (EC) of the soil by 50 percent. This is equivalent to 1.63 million liters per hectare. The amount can be reduced if done frequently or a smaller drop in EC is desired.

The second method of reducing salt concentrations is known as the leaching requirement. This is the minimum volume of water need to keep the salt concentration within the salt tolerance of the turfgrass species. In contrast to leaching, which is done infrequently, this method is done each time irrigation is conducted. This method requires that you know the salt tolerance of the turfgrass species that you are attempting to manage.

Using a couchgrass athletic field as an example, if the irrigation water has a EC of 3.0 dS m^-1 and given the salt tolerance of the couchgrass is 8 dS m^-1, the leaching requirement is 3.0/8.0 x 100 which equals 38%. This means that each time you irrigate you would need to add 38% more water than you normally would. So if your normal watering time was 15 minutes, to account for the leaching requirement you would need to increase the watering time 5.7 minutes (.38 times 15) for a total of 20.7 minutes.

Reference
Stowell, L.J, and W. Gelernter. 2008. Side effects. Golf Course Industry. September, pages 46, 48, 50, 52, 54.

Photograph: There are two philosophies in irrigating to reduce salt buildup

in the rootzone - an infrequent heavy leaching, The photograph is a result of salt buildup