IPM Leading to Holistic Plant Health Care for Turfgrass: A Practionner's Perspective
Dan Dinelli, CGCS
North Shore Country Club
Integrated Pest Management has been defined as the selection, integration and implementation of pest control based on predicted economic, ecological and sociological consequences (Bottrell 1979). Though this is an accurate definition, I feel that an important goal of IPM is to minimize the use of pesticide treatments by sound cultural and biological practices. The term Best Management Practices (BMPs) has been used as a label for this. In turfgrass IPM, healthy, growing turf is the best defense against pest problems. My approach to plant health care recognizes that the health of the plant depends on its environment and the interactions of a multitude of other organisms. The challenge is to understand these interactions and develop strategies to stimulate the environment to favor the desired plant. Tools used in the strategies formulated need to be economically and ecologically sound. Often multiple tactics are used coordinating cultural, mechanical, biological and chemical functions. As science reveals more of the biological mysteries that exist in and around the plant, better decisions can be made taking us further to a holistic health care program.
Reasons for IPM
The importance of practicing IPM is simple - The principles associated with IPM offer all the tools available with plant health care. In the past, turfgrass management has been viewed as a fairly antiseptic, sterile practice. Chemical pesticides were largely the tool of choice. Now, scientists are exploring deeper into the ecology of turfgrass. An understanding of this powerful world will be a driving force in plant health care as more is learned in managing these systems. This ecological approach to plant health care systems is key in turfgrass management.
Implementing Integrated Pest Management and Best Management Practices
Everyone on a golf course has an active roll in IPM. Golfers need to be educated at a level of understanding in the basic agronomic needs of the course. With this comes tolerance of management practices and respect. Beyond this more passive role, golfers directly contribute with proper ball mark and divot repair, and utilizing "spikeless" golf shoe attire. In one season of banning traditional metal spiked shoes, we have seen true, smoother putting surfaces with less wear and desiccation around the cups. We have been able to slightly raise mowing heights because of the improved putting surface. We reach our golfers thru newsletters, bulletin boards, and conversation. Continuing education is a must for myself and crew, assuring a sound knowledge of identification, biology and control options of pests; and turfgrass ecology.
Scouting and Monitoring
is one of the most important aspects of IPM. Intense regular monitoring is the most time consuming, demanding practice in IPM. It is critical to detect and identify pests and potential problems as early as possible. This task is done at least twice a day. Once in the morning during course set-up, once in the afternoon. At peak times an additional check is done before leaving the course. With this approach the more trained eyes, the better. Part of our continuing education program for the crew is informative posters displayed in the shop with videos and other references on pest identification and management. Scouting goes hand in hand with monitoring and written note taking. In time, trends develop where "hot spots" emerge. These hot spots are consistent, usually from micro climates that exist on every golf course. Plotting these areas on a map works well for future reference.
Methods we use to be more efficient in monitoring are:
- Scouting Insect traps
- Degree day models
- Key indicator plants, phenology
- Disease forecasting models
- Historic information, mapping vulnerable site specific areas - record keeping
- Chronic testing
- Consulting with other superintendents and professionals in the field - networking
Insect Pest Trapping
We have used pheromone traps and a black light trap. Pheromone traps are used to trap certain insects. Black light traps are more general, collecting many types of insects. Traps help us to better understand the population cycles and density of insects as well as scheduling scouting intensity. Most traps capture the adult stages of pests, which may appear before the caterpillars or grubs that are damaging to the turf. The black light trap has helped us track the local Japanese Beetle population explosion. The steady increase in beetles confirmed the steady increase and damage of the grubs. We use the cutworm pheromone trap to capture the adult moth. We use this information to judge when we should collect clippings and compost them off site. Typically, we like to return clippings and compost them in place on the turf. However, when high numbers of cutworm moths are trapped, we collect clippings which in turn yields the majority of eggs laid. This practice has reduced our insecticide applications. Greens are the only concern with cutworm damage. During course set-up the greens are assessed for holes caused by cutworms. Often the number of burrows are few enough to simply spot treat by a hand sprayer.
Degree Day Models
Insect development relies on many factors. One of the largest factors is heat. Scientists have come up with a way to better predict insect emergence and activity by tracking accumulated heat, expressed as degree days. The Metos calculates degree days by summing 120 air temperature measurement for the day, and dividing that sum by 120 to get an average temperature for the day. This integrated average is much more accurate than simply adding the day’s maximum and minimum temperature and dividing by two. This was the method we used in the past. Once the average is obtained, the degree total for the day is this average minus the base temperature. We use a degree base of 50F. So, for a day with an average temperature of 59F, at base 50F, the degree days for that day would be 9.
e.g., DD = ([Max. Temp. + Min. Temp]/2) - 50°F
Each day, this calculation is repeated and the result added to the previous days’ figures to get the running total of accumulated degree day values. If the average temperature for the day is less than the base, the degree days for that day are zero, not a negative number. Researchers have developed degree day thresholds for many insects. Knowing the degree day value and referencing it to a particular insects’ development, in effect, creates a calendar of insect activity. Following such a calendar helps the turf manager to focus on intense scouting for a particular insect and better target pesticide applications if needed.
Other biological activity can be predicted using degree day. Plants respond to accumulated heat as well. Some plants’ determination to flower or set fruit can be predicted with degree days. Poa annua has a degree day model for its flowering period. Understanding the plants physiological state can better determine the timing of plant growth regulator applications. Because plants and insects share this heated phenomena, field observations of plant activity can also help in determining insect and weed activity. An example is applying preemergence herbicide for control of crabgrass when the Bridal Wreath Spirea (Spiraea X Vanhouttei) blooms. I found that phenology is not only helpful but fun.
We also use indicator plants as key plants. A bentgrass nursery is maintained on site, maintained and grown in the same manner as the turf used by the golfer, except no plant protectants are used. This nursery is home to over 35 varieties of creeping bent. Each variety has its own characteristics. Cultivars within turfgrass species differ in their relative susceptibilities to various diseases. Some are more susceptible to Dollar Spot (Sclerotinia homoeocarpa) than others. Some more susceptible to Brown Patch (Rhizoctonia) than others. Observing these key plants gives us an early look at what we may see in the field due to there high susceptibility as a disease host.
Observing other species of grasses grown on site can also help in early forecasting. Plots of perennial ryegrasses that are susceptible to Pythium blights may be observed for disease development. If Pythium is seen on these grasses, and conditions favorable for Pythium development continue, other less susceptible grasses may develop disease symptoms. Observing symptoms on these susceptible plants will give an early indication that disease development is likely else where if favorable conditions persist.
Disease Forecasting Models
Our Metos weather station has three prediction models for turf diseases, Pythium Blight (Pythium aphanidermatum), Brown Patch (Rhizoctonia solani), and Dollar Spot . The predictive models are based on complex mathematical calculations to estimate severity and timing of disease events. The calculations include information collected from sensors of air temperature, soil temperature, rain or irrigation, relative humidity and length of leaf wetness. These predictive disease models are used as indicators of favorable environmental conditions for disease. It does not account for inoculum pressure, species or cultivar resistance to disease, fertility or future weather (environmental) conditions that may or may not favor further disease development. Ultimately, it is the turf manager who makes the decision on disease pressure verses needed controls.
Effective testing is conducted. Periodic tissue testing coupled with annual soil testing is done to assure proper nutrient balances. Water testing is done once every three years with our new water source. Our old water source was high in sodium, at that time annual testing was done. Diagnostic tests are done to identify or confirm what pathogen is responsible for the symptoms. In our annual operating budget we have a separate account just for testing fees.
Consulting with other professionals is very helpful. Finding what other golf course superintendents or university professionals are seeing in the area often indicates what I may soon be seeing.
The use of computers has helped us in many ways. From our computer in the office we can access our weather station and bring up degree day figures, raw weather information, disease forecasting models, evapotranspiration, soil temp and moisture. The computer has also helped us in the very important task of note taking. Two complete sets of drawings are scanned into our computer. Each set is a hole by hole drawing to a scale of 1’ to 100 feet. One set has our irrigation and drainage, the other is used to map "hot spots". The computer is also used to go on-line. Several golf course superintendents bulletin boards are accessed which helps greatly in networking with others. There are several services available over the wire also. One being the Turfgrass Information Center at Michigan State University. This reference allows me to research topics quickly.
The following is an overview of cultural practices that I feel made a significant favorable impact under our growing conditions. By no means does this include all cultural methods used.
Proper pruning and thinning of trees. This ensures better air movement and solar radiation on the turf canopy. Root pruning of trees that surround all greens, tees and fairways. This practice is done every five to seven years. A powered pipe puller with a vibrating plow is used. Irrigation needs are reduced by this practice.
Overseeding is done using improved cultivars. On greens, tees and fairways, compatible cultivars are used in blends of Bentgrass. We choose fine leaf texture and upright growth habit varieties. In the roughs, mixtures are used, utilizing Endophyte enhanced varieties when possible. We look for similar leaf texture, growth habit, color and fertility requirements in our compatibility evaluations. Our goal is to achieve genetic diversity with adaptive potential.
Dew and guttation water is removed daily. First task of the day is to either mow or dragging. A length of high pressure spray hose is used between two trucksters to manually remove the exudates on fairways. This has improved early morning playing conditions and removes free water favorable for disease development.
Vertical mowing is done each time the greens are mowed. On tees and fairways brushing or combing is done with each mowing. This with overseeding upright, fine leaf textured cultivars, keeps turf grain free. Golfers like this for better golf ball lie and trueness in ball roll. When this is achieved, slightly higher mowing heights can be used without sacrificing playability.
Rolling greens after mowing is done prior to golf events. This allows us faster ball roll without lower mowing heights. With the incorporation of a high sand upper root zone, compaction and wear has not been observed.
The following is our basic fertility program. Though we constantly fine tune our program, I feel the products used have given us a great life support system for plant health and essential soil micro-organisms required to build a strong, healthy, aggressive growing plant while improving the productivity of the soil naturally. Annual soil tests are performed, both acid extraction and base saturation. With this, tissue tests are performed periodically as a ‘snapshot’ of the plants activity. We strive towards balancing nutrients to turfgrass requirements, noting proper ratios of nutrient elements to one another and pH. The backbone of our fertility program is based upon many natural and organic fertilizers. Products used are derived from activated sewage sludge, hydrolyzed feather meal, meat meal, bone meal, poultry meal, blood meal, fish meal, langbeinite and sunflower seed hull ash. These carriers contain carbohydrates, fats, proteins, sugars, humus and humic acid. Also, over 12 amino acids and vitamins like E, B12, Riboflavin, Biotin, Chorine, Thiamin, folic acid and niacin. These bio-stimulants enhance biological activity, as well as a source of plant food nutrients. When applying fertilizer, the program is to apply light and frequent applications, stimulating microbial activity without excessive top growth. Occasionally foliar sprays are used with readily available elements. Calcium Glucoheptonate, as chelated calcium; Ferric Nitrate as soluble iron; Potassium Nitrate, Magnesium Sulfate, Sodium Silicate. Hormonal applications are made as biostimulators. Seaweed extract is used as a source of Cytokinin. Recently we have used yard waste compost as a soil amendment, fertilizer and disease suppressant on fairways. Overall results of this topdressing amendment has proven well, with fewer localized dry spots, reduced thatch and increased earthworm activity. Integrating these various inputs has created an environment for the turf plant to better withstand harsh environments, suppress disease and offer better playing conditions promoting a dense stand of turf, with good wear tolerance and surface resiliency.
Compaction relief by deep shatter tining is done on greens and tees. This practice has helped our rooting tremendously. Half inch tines, are used penetrating 10" deep. Holes are left open to allow rootmass to develop. As the internal holes collapse (2 to 3 years time), trails of organic matter is left, allowing for deep root penetration without the visible hole. This tool has greatly improved our soil gasses exchange and water percolation.
On tees, fairways and roughs, coring is done spring and fall. On tees the cores are removed. On fairways and roughs the cores are broken up and worked back into the thatch and soil profile. On fairways we have included a topdressing of yard waste compost as part of the operation. The procedure on fairways is to: 1.) Pull up cores, 2.) Breakup cores with vertical mower, 3.) Topdress with well decomposed yard waste compost, 4.) Mix and drag in virgin soil/compost mix, 5.) Blow off debris from fairway into rough, 6.) Pickup debris from rough with rotary mower equipped with bagging attachment. Mid-season cultivation on greens and tees is done by high pressure water injection when needed.
Information from our weather station, combined with daily field monitoring, dictates our irrigation needs. The weather station figures evapotrtanspiration (ET) according to the Penmann formula. A soil moisture sensor is located two inches deep in our fourth green. The readings reflect soil water tension or suction. This physical force of soil water is a direct indicator of how hard the plants root system has to work to extract water from the soil. The sensor uses centibars as a measure 0 - 200. The drier the soil, the higher the reading. We target consistent soil moisture of 50 - 60 centibars, avoiding severe drying cycles. On the average this constitutes daily light watering opposed to deep infrequent watering. Periodic rains are often enough to purge and ensure soil moisture deeper in the root zone. Each day during course set-up the turf is surveyed for malfunctioning heads and dry spots. Soil moisture along with rooting assessment is done while changing the cups on the greens. Collectively, information is gathered to judge irrigation needs.
Several water treatment additives are injected into our irrigation system. Surfactants are used according to label directions to aid in water retention and percolation. Another injection system incorporates Urea-Sulfuric acid. The acid is injected at a rate of one gallon per 35,000 gallons of water on the average of every third watering cycle. This system helps manage high bicarbonate levels in the irrigation water. It is not my intent to use this material to alter soil pH. The overall goal is to have irrigation water that moves thru the soil profile well, will not precipitate calcium and offer quality water for life support systems. A third injection system involves a bio-reactor to incorporate antagonistic bacteria for disease suppression. This is covered in "Biological Controls".
Chemical Methods and Considerations
Our plant protectant program is designed to minimize the use of chemicals. When used properly on turf, chemicals pose little threat to wildlife and human health. However, animals tolerances differ with each individual. All human activities have an element of risk. Peanuts for example, are found in many health foods, but people have died eating them due to their hypersensitive reactions. The reasons we strive to avoid chemicals are due to their known side effects; including: modifications in carbohydrate metabolism, alterations of tissue and nutrient contents, changes of microbial composition, reduced nitrogen mineralization. Plant pathogens have developed resistance to certain fungicides. Under certain conditions an increase of incidence and severity of both target and nontarget diseases occur with fungicides. Pesticide degrading microorganisms are enhanced with multiple used pesticides. Pesticides are expensive. Costs are driven up from the extensive testing required by the Environmental Protection Agency (EPA).
When pesticides are used, they are chosen carefully and used according to label instructions. Considerations are made on how it may affect biologicals, especially the microorganisms we are using. Every effort is made to maximize the chemicals use. pH is tested to assure alkaline hydrolysis is minimized. Covered spray booms are used equipped with flat fan high pressure nozzles. This assures good spray distribution deep into the sward. Being covered, drift is prevented putting all the product on the target. With the exception of putting greens and some diseases, I adhere to a curative chemical program. Many of the patch diseases caused by ectotrophic root-infesting fungi, Pythium and Winter diseases are still controlled by preventive applications, when conditions favor these diseases. I look forward to better using biologicals for these organisms, along with better prediction by disease forecasting models or immunoassays. The Pythium and Brown patch model I use from the weather station works well indicating the need to scout. Non-traditional chemical controls are also considered. Ammonium sulfate, for example, used as a nutrient and pH alteration. The acidifying effect has helped control take-all patch. Antitranspirants and surfactants have been used to minimize powdery mildew.
What has made the largest impact on reducing chemical use is my attitude toward diseases. In the past strict preventive spray programs were followed. If any symptoms of disease (with some tolerance for dollar spot) was observed, first I tried to figure how the disease 'got thru' the preventive spray program. Then I would figure what should be sprayed the next day to stop any further disease development. I have learned that tolerance of some plant diseases is ok. Many times the symptoms go away by microbial antagonism, immunity or change in environmental conditions. I have also learned that it was me who demanded the perfect disease free turf not the golfer. Golfers do not recognize minor disease symptoms unless they are on the putting greens.
Our program has largely moved to a preventive program by the use of cultural, biological and bio-stimulant approaches. This has afforded us to move to a curative chemical approach. This change is challenging for several reasons. First, a more intimate understanding of the plants ecosystem is needed to understand plant health care. It is easier to budget for preventive spray programs. And it is unnerving to monitor disease symptoms taking a 'wait and see' approach.
Biological Practices and Control
A brief study of microbiology quickly demonstrates that microbial activity governs the world. Though largely invisible with the naked eye, microorganisms effects on earth is colossal. Their powerful world is a network of living organisms with great diversity. Each has developed a way to inhabit their ecological niche. Their basic population interactions are antagonism, competition, predation, parasitism, pathogenicity. It is an understanding of these functions that enables us to harness their powers to favor turfs ecology. Interrelationships occur throughout the plant, both above ground and below. Microorganisms, topography, climate and parent material of soil, largely dictates what plant communities may thrive.
My overall management to plant health care has grown from turfgrass management to turfgrass bionomics. The goal is to enrich microbial activity, enhance resident antagonists and inoculation of antagonists to suppress disease. Countless microorganisms exist, but only few are commercially available. It is difficult to make generalizations or summarize microbial management. It is a dynamic science that I do not know enough about to make accurate broad statements. In the past names like Rhizoctonia, Fusarium, Typhula meant plant diseases. Now science has discovered that species of Rhizotonia controls Brown Patch; Fusarium species that control Dollar Spot and Typhula phacorrhiza controls plant pathogenic Typhula. The following is a list of organisms I have used: Bacillus subtilus, Bacillus licheniformes, Bacillus megaterium, Bacillus thuringiensis, Pseudomonas aureofaceans, Pseudomonas cepacia, Pseudomonas fluorescens, Trichoderma harzianum, three proprietary strains of endo-Mycorrhiza VAM, Azospirillum brasilense, endophytes and Steinemema riobravis.
I have seen good results with some of these organisms and others were difficult to quantify. Scientifically I can share some data collected. VAM Mycorrhizal inoculation increased our percent root colonization from 34% to 55%. Root depth increased from 6.7 cm to 10.3 cm. Trichoderma harzianum successfully colonized the turfs root system of 5x10 to the fifth colony forming units (CFUs). Microorganisms are living organisms requiring specific needs. Those needs may not be met from one course to the next. Before subscribing to broad applications, small areas are tested for effectiveness. For organisms to be effective, thresholds must be overcome maintaining high enough populations. In soils, this is a difficult task, for competition with native populations is immense. Often frequent applications are needed to ensure high enough counts. I have used an irrigation injection system for two seasons. It is a self contained microbial fermentation device that delivers microorganisms each time we water. This approach overcomes many of the difficulties posed in the past. As this system is perfected, known antagonistic microorganisms inoculate the turf each night while irrigating. The system delivers live organisms (opposed to dormant) at high counts. The procedure is done at night overcoming ultraviolet light degradation. Since the incorporation of this device, I now water early at night. Any free water on the plant is laced with antagonistic organisms preventing plant pathogens to develop. I have seen good results implementing this procedure. As the system improves multiplying high counts and as more microorganisms become available for use. I can see this becoming a very common practice.
My experiences with biologicals as a whole have been favorable. However, there are many more questions than answers at this time. Science is just now learning how to take apart the components of the ecosystem and understand the functions of the turfgrass community.
Greens, tees and often fairways are disturbed sites. I look forward and welcome the challenge as science moves from theory to function in restoring these sites for optimum turfgrass health, that's in harmony with nature. Genetic modification of turfgrass cultivars teamed with management of favorable microbial populations is a long-term view of sustainable procedures in holistic plant health care.
If golfers only knew!
My experiences and practices are based on 20 years of experience at North Shore Country Club located 20 miles north of Chicago, Illinois. It is a temperate climate suited for cool season grasses in hardness zone 5 (average annual minimum temperature of -20 degrees fehrenheit). Though it is an agronomically diverse region of over 145 different soil types, we basically have heavy clay loam soil. The golf course was designed by H. S. Colt and C. H. Alison and built in 1924. We maintain tees and fairways on virgin soils and the greens are based on push-up construction utilizing virgin soil as the base with a modified high sand/peat layer approximately 3" deep via toppdressing. Grasses on greens, tees and fairways are creeping Bentgrass and Poa annua.