Dr. Tom's Corner - Dr. Tom Watschke, Professor Emeritus of Turfgrass Science, Penn State University / Floratine Director of Research
Dr. Tom's Corner May 2016
May 31, 2016
Dr. Tom's Corner Spring 2016
Warm Season Winter Recovery Spring 2015
May 4, 2015
Dr. Tom’s Corner
Spring 2015 (Warm season grass version)
In my Dr. Tom’s Corner article last year (WINTER 2014), I commented about how the turf industry had reacted to a succession of mild winters by establishing warm season grasses (particularly bermudagrass) in more northern locations than in the past. Even as far north as the Philadelphia area, bermudagrass has been established (on driving ranges and other locations).
I have witnessed this cycle in the past, where we established promising bermudagrasses at the Penn State Valentine Research Center as far back as the seventies. Depending on the winter/spring weather conditions, the bermudagrass would survive and flourish during the hot and sometimes, dry summers. However, every five or six years later, we would have an open, windy, cold winter and the bermudagrass would all perish. The only warm season survivors were Zoysia grasses.
The quality of bermudagrasses during times of hot and stressful summers is very seductive for folks in the north, which leads to choices that are, sometimes ill-advised.
The annual bluegrass winter damage that I discussed in my previous Dr. Tom’s Corner (2015), was much more localized than in the previous winter (which was geographically very wide spread). It appears that the winter losses of warm season grass this year, has similarities to the losses this year by annual bluegrass (that is, being somewhat geographically localized and not particularly wide spread). Although the metabolism of annual bluegrass and bermudagrass is quite different in nature, the susceptibility to winter damage has many of the same causal agents.
In parts of Tennessee and North Carolina, and much of Kentucky where bermudagrasses were injured over this past winter (even on greens), there were very short periods (a day or two) of warm weather in late February and early March, which triggered the early stages of the end of dormancy. This weather, however, was quickly followed by cold snaps that were prolonged and, in some cases, produced record breaking cold. This scenario is the ‘perfect storm’ if you will, for warm season grasses to sustain significant cellular damage. Areas that are shaded, with poor drainage and compaction, which might also be associated with wear, appeared to have sustained the most damage.
In areas further south, the cold snaps were not quite as intense nor did they last as long. Therefore, the injury was significantly lessened or did not happen at all. In these regions, warm season grasses are rarely damaged by winter/spring weather events.
In order to lower the potential for warm season grass damage due to adverse winter weather conditions, management action must be taken during the previous fall. Do not force growth when fall approaches as it will deplete carbohydrate reserves. These reserves are essential for re-growth in the spring, particularly the new rooting that occurs once the soil begins to warm. Use low dose foliar nutrient sources, particularly those containing iron, to maintain color without causing much growth and carbohydrate consumption. There is evidence that potassium applications in the fall also improve winter tolerance (particularly when/if the soil potassium levels are low). Some advocate using growth regulators to reduce growth in the fall, thus also conserving carbohydrates (there is little research evidence that this phenomenon is valid).
In the spring, if and when winter damage has occurred, the use of foliar nutrient sources, applied once the warm season grass breaks dormancy, will facilitate growth and recovery. Keep nitrogen rates on the high side, at least until full recovery by the bermudagrass has been achieved. Use sources that also contain cytokinins to encourage new rooting at stolon and rhizome nodes and to enhance the expansion of the existing root mass.
When significant losses occur, always consider seriously the establishment of the more winter tolerant cultivars (Latitude 36 for example) into the damaged areas either by sprigging or re-sodding.
The winter tolerance of such cultivars has been shown to be outstanding and brings a new dynamic to the use of bermudagrass in more northern climes.
Remember that you are not alone in this fight. Maintaining turf in the transition zone has always been the most difficult job in the country. Be sure to communicate to the best of your ability, to those that use the facility that your challenge is to manage turfgrasses that are diverse in genetics and metabolism (when they are good they are great, but when they are not, bad things just happen). Continue to fight the good fight and stay positive in spite of negative things around you. Your glass is always half full!
Winter Kill: Spring 2015
May 1, 2015
Dr. Tom's Corner: A Brutal Winter Transitions to Summer
June 24, 2014
Dr. Tom’s Corner
What an experience this past winter and spring has been for those in the Mid-Atlantic, Northeast, and all the way to the upper Midwest!
There are still courses that have temporary greens, courses that are trying to get good recovery, and those that are considering many options for renovation and re-grassing. In many locations, this past winter has been one for the record books. Unfortunately, the past several winters have been relatively mild and have provided grasses a false sense of security. Many annual bluegrass eco-types that do not ordinary survive have had very few problems in the past several years. In addition, these eco-types also often do well during the summer growing season and are competitive with creeping bentgrasses for space. Consequently, they often become a significant portion of the mixed ‘Poa/bent’ sward that exists on many golf courses.
Then when an extremely harsh winter comes along, these evolving eco-types cannot tolerate the cold and harsh environmental conditions and they perish. This scenario was played out throughout a significant geographic portion of the eastern half of the country this time around. All that being said… Now is the time to start initiating pre-stress conditioning for the coming ninety days of potential environmental stress!
Everyone knows that managing turfgrasses is like herding cats! There is no norm, there is no “spot on” solution when stresses are present, and that managing biological systems is as much fun as a sharp stick in the eye! However, it is a challenge that you accept and you also embrace, as you should, the notion that what you do is a combination of art and science.
Science reinforces that managing environmental stress on cool season turfgrasses must begin before the stress appears. For many areas of the country that time is now! Fundamentally, pre-stress management is about providing the turf with the best carbohydrate status possible. The following is a listing of those management practices that can be employed to accomplish the best carbohydrate management possible:
---Apply nutrients using foliar applications, with light rates and frequent applications
---In the foliar applications, also include products containing bio-stimulants (particularly cytokinins, anti-oxidants, and vitamins)
---Use growth regulators prudently to control growth and conserve carbohydrates
---Make an extremely small increase in the height of cut, but increased rolling frequency should help green speeds if they become too slow
---Monitor rooting to be sure that all cultural inputs are improving rooting and/or preserving the current level of rooting
Irrigation management is definitely a key component of pre-stress conditioning. It is a balancing act that requires particular attention to detail. In other words, monitor rooting depth and keep adequate moisture available throughout that depth (otherwise roots will be lost). Remember that letting the rootzone get too dry does not encourage deeper rooting (roots do not have eyes and therefore have a hard time ‘looking’ for water). By not letting the rootzone get too dry, localized dry spots will be less of a problem as summer stresses becomes a problem.
Obviously, disease and insect scouting are a must as part of the overall stress management scenario. Early detection is mandatory in order to insure optimum control and efficient use of pesticides.
So, here we go for another season of challenges that are opposite in nature from what you have been battling. All the best to you and do not forget to seek help from your peers, university extension services, consultants, and your friendly vendors when you have problems. We are all in this industry together and support is abundant and available, so don’t be shy about asking for it.
Dr. Tom: Surviving Winter-geddon 2014!
March 13, 2014
Dr. Tom’s Corner
From the record snows and cold from the mid-Atlantic to Maine, to the record cold all the way to Florida and the Eisenhauer tree being lost at Augusta, to record cold in the upper Mid-West. on down to parts of Texas, to the record drought in California, I guess it must be climate change, or maybe, nature going through another cycle that has not been seen before. In any event, the bigger question of all is what might be going on with our turfgrasses throughout of this current cycle?
Perhaps we should begin by examining how the turf industry has reacted to the mild winters of the past several years. Bermudagrasses have been established on greens, tees, and fairways further north than ever before. This phenomenon has not just occurred on golf courses, but some athletic fields as well. Considerable concern has been expressed by those that have gone this route in the past, because a winter come along much like the current one and things do not go well. It does seem a bit paradoxical that turf managers that have embraced the bermudagrasses in more northern climes, have now joined the club of those northerners that have feared winter turf losses because they are managing annual bluegrass, which is very prone to winter turf losses!
All turfgrasses begin the hardening process by gradually dehydrating, which is ultimately followed by dormancy. This hardening provides the grasses the mechanism to withstand cold and, only after they begin to re-hydrate do they become increasingly susceptible to winter injury. In the broadest context, most winter injury can be associated or caused by fungi, desiccation, direct low temperature kill, or crown hydration. The use of very effective fungicides to protect grasses from pink and gray snow molds has decreased the amount of turf loss as a result of these diseases. In the case of this winter, desiccation (which occurs most commonly in areas where there is little or no snow cover and windy conditions during periods of low humidity) should not be a significant causal agent for turf injury. The amount of snow cover provides and insulating effect to protect against desiccation and also protects against direct low temperature injury. The question of whether or not crown hydration will become an issue will depend upon the rate at which the snow pack and frozen soils diminish in the coming days. Less injury is favored by a rapid melt with temperatures staying above normal after the melt. Alternating freezing and thawing from day to day, is the worse case scenario, particularly when most of the snow pack has melted. Grasses tend to absorb moisture during late winter as the hardening period diminishes, days are longer, and the sun angle provides more radiant heat energy. Cold nights following warm days often are the conditions that cause significant crown hydration turf injury.
Creeping bentgrass is one of the most tolerant species for surviving long term snow/ice coverage. Annual bluegrass, on the other hand, is probably the least tolerant of the cool season grasses. With respect to the bermudagrasses, some of the newer ones have been released because of their cold tolerance, but snow and ice issues have not been sufficiently studied to make any reasoned predictions. In many cases, we are in a wait and see mode with regard to warm season grasses and their tolerance to this year’s winter conditions.
What can turf managers do? Unfortunately for some, should turf losses occur there will be the need to over-seed, sod, and give careful consideration to what grasses are re-introduced as part of the recovery process. However, much like managing the impending environmental stresses of summer that affect cool season grasses, the best management practices, are pre-stress conditioning through balanced and well timed nutrition, conservation of carbohydrates, and the judicious use of irrigation, which are the same pre-stress conditioning practices that should be used prior to the winter months.
Balanced and well timed nutrition is part of, if not the key, to pre-stress conditioning. Maintaining a consistent, but reduced level of nutrition as the turf begins to harden will allow the grass to dehydrate without growing too much (which would unnecessarily consume carbohydrates). The best way to provide this balanced and well timed nutrition is through the use of foliar feeding. Foliar feeding is efficient, effective, and provides the turf manager with optimum control of nutritional rate and utilization.
On the flip-side, the same principle applies to foliar feeding being the best nutritional managerial tactic to enhancing the turf recovery rate from winter injury problems. Injured turf recovers faster when provided with a balanced nutritional diet supplied in the most efficient and effective way. Applications of foliar fertilizers to brown leaf tissue is not particularly effective and the degree to which injury has occurred cannot be properly assessed until re-growth (green-up) has occurred. Therefore, once green leaf tissue has begun to replace brown and desiccated leaves, foliar applications of fertilizers is the most effective way in which to provide nutrition and promote recovery.
Dr. Tom on Nematodes
July 22, 2013
Dr. Tom’s Corner
Plant parasitic nematodes are, perhaps, one of the most misunderstood, under-rated, and potentially chronic problems afflicting golf courses (particularly putting greens) in almost all areas of the country.
Nematodes have long and narrow bodies, resembling a thread, which is the origin of their name (from the Greek word nema that means ‘thread’). There can be thousands of different nematodes in a handful of soil. Most (those causing turf problems) are microscopic and not detectable to the naked eye. So, be wary of anyone looking at a handful of your rootzone mix and then makes the statement, ‘You have a nematode problem’! Such a diagnosis could be completely bogus.
Therefore, nematode counts should be made by a reputable laboratory and, in the northern latitudes; the counts are most often at their highest in mid-May which is the best time for sampling. One of the primary reasons that a mid-May sampling provides the best nematode count information, is that, these little critters are capable of “Cryptobiosis”. Perhaps you know, but in case you don’t, cryptobiosis is a term coined by David Keilin in the Proc. Roy. Lond. B. 150, 1959, p.140-191 in which he states that cryptobiosis is “the state of an organism when it shows no visible signs of life and when its metabolic activity becomes hardly measurable, or comes reversibly to a standstill”. Harsh environmental conditions, i.e. dryness, cold, wetness, lack of oxygen, heat, etc., can trigger nematodes into a cryptobiotic state. In a state of cryptobiosis, nematodes survive these adverse conditions by slowing their metabolism to a point that they cannot be easily detected, which then can produce a ‘false read’ for any counts being taken. When environmental conditions become favorable again, the nematode is capable of resuming a normal life.
Further, the current thinking among Nematologists is that, nematodes are related to arthropods and priapulids in a newly recognized biological group, the Ecdysozoa. This group is characterized by having a thick cuticle that is periodically shed (up to four times) during life and before becoming an adult. Under their epidermis, nematodes have long muscles, aligned longitudinally along the inside of the body, which allows the body of the nematode to bend from side to side. They do not crawl or lift themselves as a means of moving through the soil, thus when looking at them under a microscope, they appear to be thrashing about aimlessly.
Nematodes, on their own, do not often cause significant damage to healthy turf. However, when their presence has weakened the turf (mostly by feeding on the roots) and other negative influences are present (environmental stress and/or stresses from other pests), the nematode infected turf exhibits far greater damage than turf that does not have nematode issues.
With the recent incidences of bacterial wilt being diagnosed on putting greens in the northern states, attempts are being made to link this problem to higher than normal nematode counts. The bacteria need to have openings to get into the plant, which could be provided by the nematodes that are consuming the roots. Clearly, anyone battling bacterial wilt should have nematode counts done to establish whether there might be a relationship. Nematode counts do not have to be exceedingly high, because slightly above normal readings could be all that it would take to enhance the potential for bacterial wilt problems.
The symptoms of plant parasitic nematode injury can include yellowing of leaves, stunted growth, earlier than normal signs of moisture stress, thinning, and poor rooting (depth and mass). Parasitic nematodes usually exist in clusters which complicates a positive identification because there is rarely a characteristic ‘pattern’ of injury to the above ground portion of cool season turfgrasses.
With Nemacur being banned as a chemical control product, turf managers maintaining annual bluegrass (probably the most susceptible grass to nematode problems) and creeping bentgrass, must rely more heavily on cultural strategies as a means of combating nematodes. Cultural programs that emphasize root growth and plant health work the best. The use of micronutrient packages and products containing cytokinins and other materials that promote rooting are mandatory elements in any effective management strategy. Also, providing sustainable and available macro-nutrient sources, especially nitrogen (using foliar feeding), will keep the nutritional levels constant in the foliar tissues.
In some southern states the soil fumigant Curfew is labeled for use on bermudagrass and creeping bentgrass greens. This material is applied as a pressurized liquid directly to the site using a knife injection system. Once applied the liquid quickly volatilizes to a gas, which is toxic to the nematodes and some insects as well as the turf. Currently, only custom applicators are allowed to provide applications of Curfew.
An excellent reference for plant parasitic nematodes can be found on pages 201-211 in the recently published revised edition of the book ‘Managing Turfgrass Pests’ by Watschke, Dernoeden, and Shetlar (April 2013 published by CRC Press). The pages referred to above are written by Dernoeden, while Shetlar offers a very nice drawing of a nematode on page 249. Obviously, I recommend these pages for your reference without any reservation.
It is always important to consider all possibilities when trouble shooting turfgrass problems. Some visible symptoms can mimic an array of different problems and miss-diagnosis frequently leads to the introduction of solutions that are not appropriate and can even make matters worse. Don’t ‘shoot from the hip’, but rather be methodical, diligent, and thoughtful as you work though the, often times, difficult path to solving your pest problems.
Until next time…….Dr. Tom
Cold Spring: Jump Start Your Turf
April 19, 2013
Dr. Tom’s Corner
Fickle Ole Mother Nature is at it again this spring in the cool season turfgrass areas. No one needs to be reminded how early and extremely above normal last year was when temperature records were shattered in many locations. This year, quite the opposite has been the case so far.
These extremes in weather make the ideal timing for the application of growth regulators for the suppression of Poa annua seedheads a difficult task at best.
Before further discussing application timing, we need to review/learn some foundational information concerning the production of seedheads by Poa annua so that we may make good decisions about product choice, supplementation, nutrition, etc. in the longer term.
In the late fall, when air and soil temperature is decreasing, day length is shortening, and Poa annua is entering the hardening phase in preparation for the winter months, hormonal changes occur in the plant (known as the induction phase), which is not outwardly noticeable, but leads to the formation of the seedhead in the spring (during the differentiation phase). In other words, the grass tiller changes from a vegetative organelle to a reproductive one. In the spring, once the Poa annua tiller re-hydrates, cells begin to differentiate into reproductive tissue in order to ultimately form the seedhead. This early seedhead formation occurs in the ‘boot’ of the tiller which precedes emergence.
Logically, weather conditions play a role in how rapidly these processes take place (the faster the air and soil warm the faster the processes occurs). Thus, over twenty years ago, the development of computer models to predict seedhead emergence were developed using the Growing Degree Days (GDD) concept. While the GDD method is of value for predicting emergence, many other indicators are used to assist in the decision making process with respect to application timing, such as:
---full bloom of forsythia
---initiation of lilac bloom
---morphological examination of the basal tiller (examining the boot of the plant)…..best method for determining proper timing, but tedious work to accomplish
Determining the proper timing of application is the key to the level of success one can attain for seedhead suppression. To further complicate the process other variables must also be considered:
---how segregated are your greens (many different eco-types often exist on any one green which influences the degree of seedhead production)?
---how quickly to GDD accumulate?
---how many different micro-climates exist on your course (seedheads emerge at different times depending on topography, slope, shade, exposure, etc.)
Given all the variables that exist during any given year, it is little wonder that a certain level of angst occurs for golf course superintendents when weather conditions are askew from normal!
A few suggestions at this point seem to be appropriate:
---Maintain the best possible plant health (use foliar nutrition/bio-stimulants once the leaf canopy is close to 100% green tissue)
---Make every effort to take the time to look for the developing seedhead in the ‘boot’
---Regardless of whether Embark or the combination of Primo/Proxy is used for seedhead suppression, supplement the growth regulation products of choice with foliar nutrition and bio-stimulants (such supplementation will enhance effectiveness and improve the efficiency of the plant growth regulators)
---Do not use root absorbed GA inhibitors (Trimmit, Cutless, etc.) for seedhead suppression as these products have little effect on cell division (the primary growth method for the seed stalk of the emerging Poa annua seedhead). Also, the emerging seedhead is often very short and will stay below the cutting height for many days.
---Always keep your long term objective in mind. Remember that the suppression of seedheads enhances the ability of Poa annua to tolerate stresses of all kinds and enhances its ability to compete with creeping bentgrasses. Therefore, if part of your management philosophy is to improve Poa annua, strive to enhance the level of seedhead suppression you can attain. However, if your management strategy is to increase the amount of creeping bentgrass on your greens, communicate to your clientele that by letting the Poa annua produce seedheads will make it weaker and less competitive and the PGR’s that selectively suppress Poa annua will be more effective (Trimmit, Cutless, and combination thereof).
Accomplishing excellent seedhead suppression year in and year out is tricky management to say the least. However, take stock of your overall management objectives, due the best you can to determine the proper timing of application, and keep an eye on the weather. It just might be that we will have a very short spring (late in arriving and an early onset of summer), this year which will close the window even more for the best timing of growth regulator application. Good Luck all!
It Was A Wicked Hot Summer!
September 17, 2012
Dr. Tom’s Corner
It has been another summer of wicked weather in much of the country, particularly the Mid-West, where numerous records for high temperatures (both day and night) were set. Such conditions have plagued the same region for three summers in a row, although two years ago, heavy rains and flooding also added to the misery. In any event, prolonged tropical weather in the cool humid region of the country has not been favorable for cool season grasses to flourish.
Cool season grasses are amazingly adaptive to adverse weather, provided the adversity is not too protracted. However, cool season grasses have a defense mechanism in place to help them overcome the adversity and that is called dormancy. Unfortunately, dormancy is not a pretty sight as the grass canopy looses it’s normal green color, turns brown, and essentially looks dead ( a common phenomenon seen in the rough on courses where the rough is not irrigated). To avoid this ‘dead’ appearance, irrigation and other cultural tactics are usually imposed on the grass by turfgrass managers so that it does not go dormant. This is done in order to provide consistent playing conditions and aesthetic appeal as long as the adverse weather conditions persist. Years ago, when there were very few irrigated fairways, the turf went dormant, tee shots traveled much further on hard ground and brown grass, and the minor amounts of annual bluegrass that were present, actually perished (more about that later). The result was that annual bluegrass was only a problem on greens, surrounds, tees, and other areas that were irrigated to keep them green (essentially, annual bluegrass was a non-issue).
As we consider the realities of the situation that exists today on most golf courses in the world, annual bluegrass is a common enemy, playing conditions must be consistent every day, green speeds must be acceptable to all, and if turf is lost for any reason, it must be put on the fastest track to recovery that is humanly possible.
Therefore, we need to return to the issue of dormancy and the role that it plays in the manner in which turfgrasses recover from environmental stresses. It is known. that turfgrasses utilize carbohydrates rapidly when environmental stresses occur, in order for them to accommodate the energy and respiratory demand caused by the stresses. As internal carbohydrate levels decrease and cannot be adequately replaced by photosynthetic activity (due to the reduction in the efficiency of the photosynthetic process that is caused by the stresses), a critical level of carbohydrate is reached which triggers the dormancy mechanism. This mechanism is inherent in all most all grasses, with the exception of annual bluegrass. Annual bluegrass (particularly the annual ecotypes) does not have a very effective mechanism for dealing with environmental stresses, therefore, once permanent wilting has occurred the plant often perishes. By contrast, at least physiologically, the other cool season grasses are much better equipped to survive the adverse environmental conditions.
The recovery from such environmental stresses primarily results from the vegetative generation of new tillers from stolon and rhizome buds and from the surviving crowns of existing plants (perennial ecotypes of annual bluegrass also have this capability). This vegetative recovery is relatively slow and requires water and the return of cooler air and soil temperatures. Much of the recovery that occurs for annual bluegrass is the result of the germination of seed from the seed bank in the soil.
Regardless of the mechanism that is inherently in place for recovery, studies have shown that the availability of nutrients, particularly nitrogen is critically important to enhance and hasten recovery. The irrigation that may have been applied in an attempt to ward off the stresses, moves nutrients downward in the soil and below the active rootzone. Nitrogen, being relative mobile through the soil as well as potassium, becomes less and less available for uptake.
Once the environmental stresses have subsided and new growth from vegetative propagules is noted, it is critically important to have nitrogen and potassium available to the emerging shoots. Foliar applications of nutrients that are applied to this new growth can quickly make these nutrients available and they will be rapidly utilized, thus enhancing rate of recovery. In addition, the application of bio-stimulant products containing cytokinins will enhance the newly developing root system which will also support and facilitate the recovery process.
On another note, it is important to not impose mechanical stresses during this recovery process. Although it is very seductive to want to vent and disturb the site mechanically, such an approach is most often counter productive. Mother Nature will work wonders as long as management is in a facilitative mode, so do not interrupt the natural processes that you can work hand in hand with, during this period of recovery.
My best to all of you!
Biostimulants: In Before the Cold GCI Article
December 5, 2011
As Seen in Golf Course Industry December 2011
Biostimulants are well-regarded for dealing with summer stress. Dr. Tom Watschke, formerly of Penn State, discusses how they help during the season’s wind-down.
Do biostimulants do anything differently in fall than during other times of the year?
Knowing what we know about biostimulants and managing carbohydrates and looking at plants as they move away from more stressful seasons and toward lower soil temperatures and all the associated environmental stresses, I think one can argue that the principal role isn’t that much different. There could be a difference, of course, in the choices of what one uses. When the soils are heating up, in late spring and summer, they’re essentially in a physiological state when they can’t produce new root growth. That’s where having the biostimulants and carbohydrates make a difference. In the fall, soil temperatures are coming down and biostimulants can aid in the development of new roots.
The most that can be derived from the research with biostimulants is that they’re most impactful when they are applied prior to stresses of any kind. This is pre-stress conditioning philosophy, which is very sound.
If we fast forward then through the summer to the fall and whatever has happened has happened, the positioning of the application of biostimulants is again important prior to the onset of cold temperatures so they’re available before the soil temperatures go significantly down and re-rooting occurs. You want the biostimulants down so they are there when the soil temperature’s low enough to trigger new rooting. Those new roots are going to come out and need to have things in position so they can access it as quickly as possible and have the impact you want to have.
When is the best time to apply biostimulants in the fall?
It really should’ve already been done, if you plot soil temperatures in this latitude, at least. It’s going to peak in late July to early August and then as the days shorten and the direct solar radiation heat load is starting to wane. It should be done by Sept. 1 in most years. This year’s been a bit of an anomaly. My own judgment is when the soil temperature in the upper inch is in the low 70s F for most of the day, things are going to start happening. This year in the Midwest, soil temperatures stayed up in the 80s for a long time – summer just didn’t want to give it up.
What benefits can biostimulants bring during this season?
For the balance of this growing season, their presence will not be that visual because it’s addressing physiological needs. By that, I mean keeping hormones and auxins in balance and storing carbohydrates for winter – we’re talking about physiological changes for winter that we aren’t able to see. The health of the plant is subjected to the kind of physiological status it possesses. The processes that are connected to good growth and health and avoidance of stresses are those things that are helped by biostimulants, things that can be subtle i.e. your fungicide apps might last longer. Not necessarily more clippings in the basket or a deeper green color – the biostimulant is helping make the plant more healthy.
It does, in fact, help next year in the sense that the plants as they progress toward dormancy that have had biostimulant apps do handle winter conditions better and they’re well-positioned in the spring to break dormancy and commence growth.
Invest in Your Root 'Bank' Now!
March 23, 2011
Cool season turfgrasses have cyclical root production throughout the growing season. In the spring when the root zone is cool and moist, cool season grasses produce their maximum amount of root mass for the year. Once the soil temperature gets higher (a result of the radiation heat load that is produced by sun angle and day length), root production slows to the point where much of the root system that has been produced during optimum growing conditions will slough off and end up contributing to soil organic matter content. That is why it is a common observation for cool season grasses that, by mid-summer, the root system is much shorter than earlier in the year. Cool season grasses struggle to produce new roots once the soil temperature has risen, which presents a significant challenge to the golf course superintendent as he/she must adjust irrigation management strategies to accommodate the above ground plant needs for water and nutrients with a limited root system in place to meet those needs.
In the fall, when radiational heat load lessens and the days become shorter, soil temperatures lower and new roots are formed from adventitious buds at the base of the crown. These new roots are highly active in terms of their ability to absorb nutrients and water. It is during this time that cool season grasses flourish and recover from the environmental stress that were encountered during the hot summer months. During the winter, in locations where the soil is frozen for extended periods of time, many of the new roots produced in the fall slough off, much like the sloughage that occurs when the soils get hotter in the summer time. Hence, cool season grasses produce two root systems during the course of the year.
Going into the summer stress period, the best managerial approach for maintaining healthy and active root system, is to help the turf produce as much of a system possible during the late spring root production period (before the soil temperature rises to the point where new root initiation slows significantly). It is much like a bank account, wherein, new root production can be considered to be deposits into the rootzone bank account, while carbohydrate consumption via top growth and elevated respiration rates can be considered as withdrawals from the account. Therefore, the more root system that can be developed, the greater the deposit sum, which will benefit the account when withdrawals exceed deposits.
From a management perspective, anything that can be done to enhance the turf’s ability to grow roots would be a bonus for the account. Cytokinins, for example, have been linked to root growth to a significant degree, so making them available to the turf during ideal root growth periods will provide considerable advantages. Applications of cytokinin containing products well in advance of the production of new roots with continued applications during the optimum rooting period would provide the most beneficial results.
HOT HOT HOT Summer!
September 24, 2010
What a summer it was! Temperature records, rainfall records, the number of days over 90 degrees, etc. from, just west of the Mississippi River, to the Atlantic seaboard. Unusually warm/hot conditions began to occur earlier than normal and the mid-August ‘break’ failed to materialize. Some areas were abnormally hot and dry, where others were abnormally hot and humid with record rainfall (the Chicago area had the second wettest June on record). As a result, superintendents were faced with managing cool season turfgrasses that were suffering from prolonged and excessively rare weather conditions. Well managed and pre-conditioned cool season grasses can survive and persist in inclement weather, but only for so long. Only warm season grasses are able to physiologically adjust and tolerate semi-tropical to tropical weather that plagued much of the Eastern half of the country this season. One could only notice how vigorous and robust the warm season annual grasses (crabgrass, goosegrass, etc.) were this year, even when typically successful control measures were applied.
So now what?
The USGA Green Section and the GCSAA have done a great job of publishing information pertaining to the challenges that have faced superintendents this year. The scope and magnitude of the problems that have been faced and recommended strategies for coping have been very helpful for many.
Finally, the weather has essentially transformed into a more typical early fall mode as the result of the occurrence of shorter days, less radiant heat load, and decreasing soil temperatures. Cool season grasses are producing vibrant new adventitious roots, new basal tillers are sprouting, and new plants are emerging from stolon and rhizome buds. Also, in most areas, the first germination of Poa annua has begun, which will fill in many voids very quickly (like it or not). In areas where high populations of Poa annua were present, there is the possibility to make some gains via over-seeding, but that activity precludes the use of any pre-emergence herbicide for the Poa annua, which becomes a Catch-22.
For many, the need for aggressive renovation of some areas is required and everyone is hoping for a mild and long fall growing season. The weather will turn out to be what ever it is, and nothing can be done about it, except to adapt to any eventuality you might face. One thing is clear, fertility and nutritional management must be the focus during the next few weeks. The need to push growth and enhance grow-in in damaged areas is paramount, but the need to be sure that the turf enters the winter in a hardened condition must not be over-looked.
The best management strategy for nitrogen fertilization during the next few weeks is to maintain as much managerial control as possible. Thus, the use of quickly available nitrogen sources (both foliar and granular) will provide the best control of nitrogen availability and release. Nitrogen must be provided in a consistent fashion to avoid any ‘ups and downs’ in the growth pattern and should not create unnecessary top growth at the expense of root growth and tillering. The availability of nitrogen should also be gradually decreased as the cooler weather of late fall slows growth and the need for winter hardening becomes the nutritional focus.
Obviously, the use of nitrogen sources that can be applied with a true ‘foliar feeding’ approach are preferred because their plant availability and utilization can be controlled. Low rates of application with narrow sequential spacing will work well because such use eliminates the ‘ups and downs’ referred to earlier. Also, the use of foliar materials that contain bio-stimulant compounds should be favored as the recovering turf is in need of hormonal and auxin support for the metabolic processes that facilitate recovery and winter survival.
Good luck with your renovations and recovery this fall and be assured that it is highly unlikely that the 2011 season will be a replica of 2010!
Pre-Stress Conditioning for Improved Turfgrass Health
March 25, 2010
“Dr. Tom’s Corner”
Professor Emeritus of Turfgrass Science, Penn State University
Floratine Director of Academic Research
March, 2010 Issue
There is a lot of buzz in recent months about the PRE-STRESS CONDITIONING of turfgrasses and the importance of managing carbohydrates for improved turfgrass health. These issues are vitally important and have not received enough attention from the turfgrass research community over the years. However, in their defense, funding sources and products that provide the turf with beneficial inputs have both been limited. The time has come to initiate more research projects that are designed to quantify turfgrass responses to products capable of enhancing pre-stress conditioning and separate the ‘wheat from the chaff’ with regard to claims and actual results. Pre-stress conditioning and managing carbohydrates are inter-connected and co-dependent in many ways. Products that enhance the conservation of carbohydrates and support their efficient utilization for various metabolic processes (in cool and warm season species) are the keys for managing turf in a proactive, pre-stress conditioning mode.
By providing turfgrasses with an enhanced ability to build carbohydrates for plant health maintenance prior to the onset of stress (regardless of the type, i. e. mechanical, environmental, nutritional, etc.); the level of stress, when it finally does occur, is not nearly as detrimental to the plant compared to what happens without pre-conditioning.
In 2009, Floratine Products Group (FPG) funded several studies at universities in different geographic locations. Two of these studies (conducted at Virginia Tech and Purdue University) were identical and were designed to evaluate the effect that applications of four FPG products would have on the ability of creeping bentgrass to ‘heal’ following core cultivation. It was determined that the evaluation of mechanical stress was the most ‘controlled’ stress induced phenomenon that could be evaluated. The turf was only treated prior to the core cultivation (pre-stress), and in both studies, the pre-stress applications resulted in turf that was better able to accommodate the mechanical stress, i.e. the holes closed up more quickly and the turf had enhanced quality compared to both the untreated turf and turf that was treated with a nutritional ‘standard’. These results are available on the FPG website along with my summary and interpretation of those results. The reproducibility of the results from two different geographic locations was significant and speaks volumes to the authenticity of the research that was conducted.
In another study conducted at Michigan State University, the issue of enhanced turfgrass health as a result of the applications of FPG products containing bio-stimulants was tested and resulted in better basal anthracnose disease control. Fungicides without FPG products provided acceptable disease control, but the combination of FPG and fungicide resulted in better control and an improvement in overall turf quality. The FPG website has links to this information so that you can print it off and keep it at hand.
The picture is becoming more and clearer that low rates of nitrogen applications (foliar) and the use of products containing bio-stimulants helps the turf become pre-conditioned to an array of stresses (mechanical, environmental, and those associated with disease). This improved ‘plant health’ condition not only helps the turf endure stresses, but any control associated with the application of fungicidal products, increases the efficacy of these materials.
The bottom line is that, controlling growth with judicious and timely nitrogen applications plus keeping NPK in the proper ratio, using the appropriate plant growth regulators at the right time, and making applications of products containing bio-stimulants which enhance many metabolic reactions, provides the turf with an enhanced ability to maintain good carbohydrate levels. Applications using the above strategy also insure that the turf has been pre-conditioned so it can better tolerate stresses when they occur.
As we approach the new growing season in the regions where cool season turfgrasses are the predominate species, it is imperative that a pro-active management style be used. Make applications of those materials that will provide pre-stress conditioning and help in the maintenance of carbohydrate reserves. Have a great season and another issue of Dr. Tom’s Corner will be in front of you in the not too distant future.
My Roots are Disappearing! July 2009
July 20, 2009
“I seem to have reasonable rooting depth by the first of June every year, but by early August, my root depth/mass has diminished significantly.” It comes as no surprise that this is a common refrain during the summer months. And we all know that once we get into that situation alarm bells start ringing. So what can we do?
First, a little perspective. In most locations, cool season turfgrasses lose their roots twice a year (during the hottest months of the summer and during the coldest months of the winter). For most species, peak root production occurs from early May through mid-June in response to cool soil temperatures, good air/water relationships, and available growth materials (carbohydrates). That is the time to prepare for what I will refer to as the ‘marathon’, the upcoming heat and stress of summer that the plant will have to fight through to survive.
New roots are initiated from adventitious buds at the base of the crown, therefore, when conditions are conducive (as described above), root growth is vigorous and prolific. However, as soil temperatures increase and carbohydrates are no longer in abundance, initiation of new roots (our bank account for saving carbs) slows dramatically and older roots become less functional and ultimately slough from the plant and become part of soil organic matter.
As a result, the observation that “my turf has lost its roots” is accurate. This obviously adds to the superintendent’s own summer stress level as we move into the stressful summer months and your grass plant has to run the aforementioned marathon with little in reserve. Therefore it is in our best interests to prepare the turf accordingly.
Now we are at the time of the year with heat and humidity, and good or bad, we now need to be ‘reactive’ and help our turf cross the proverbial finish line!
It is much like managing a bank account, in the sense that, when things are going good, deposits to the bank account / roots (carbohydrates) can be increased knowing that when withdrawals begin to exceed deposits, there is a source of reserve to draw from in order to better tolerate environmental stresses and to maintain the best root system possible.
However, once the temperature (both soil and air) exceeds that which allows the turf to easily provide carbohydrates, the turf will become physiologically stressed and less able to meet the daily demand for carbohydrates. Once the turf has reached that point, needed carbohydrate can only be supplied by that which is in reserve (the roots) or via supplemental feeding. It is obvious that if your roots are disappearing, the plant is going to have a difficult task of absorbing nutrients from the soil. Foliar feeding, which bypasses the root system, offers a very effective means to help the plant through times of stress, basically, helping the plant through the marathon, much like a runner’s glyco-gel packs and sports drinks help them finish those punishing races.
Nitrogen sources that are soluble provide the best managerial control of N release and facilitate the proper timing for sequential applications. Properly balanced Bio-stimulant products that contain gibberellins, cytokinins, auxins, and/or other organic compounds (derived from various sources) are valuable for providing growth materials without over stimulation. Foliar sources of essential amino acids and complex sugars will assist the turf when the conditions for growth are less than optimal. The whole goal is to help the plant work as little as possible to manufacture the carbohydrates it needs to survive and foliar feeding can do that very effectively.
Once soil temperatures begin to decrease (usually in late August) the turf will begin to produce new roots, but never as prolifically as in the spring (primarily because the days are getting shorter and the level of radiant energy being received is lessening).
The bottom line is that by properly managing carbohydrates, the more likely it is that your turf can maintain root growth longer, slough less, and be more tolerant of environmental stresses. The same holds true when the stresses of summer hit, as the superintendent now has tools to supplement the plant’s nutritional needs to help his turf efficiently produce the carbohydrates that will help it survive during the actual “marathon.”
Until next time, Dr. Tom hopes that the summer stresses to you and your turf will be minimized and September will be here before you know it!
Thoughts on Plant Growth Regulators March 2009
March 12, 2009
As I travel around the world speaking to superintendents, I am often asked what the effects, if any, biostimulant products have on the efficacy of the plant growth regulators such as Primo.
For the most part, biostimulant products are quite compatible with turf growth regulators. Considerable research has been conducted over the recent years evaluating this very issue. If anything, the inclusion of biostimulant products with turf growth regulators tends to enhance the activity of the growth regulator. Research at Penn State has shown that the efficacy of Primo Maxx can be increased with the addition of certain biostimulants (to the extent that half rates can mimic the growth suppression attained when a full rate is applied without the added biostimulant).
There is some question amongst golf course superintendents with regard to whether or not biostimulant products that contain some gibberelin (GA) might compromise the efficacy of turf growth regulators that inhibit the biosynthesis of GA. The question is primarily couched in the knowledge that turf growth regulators that inhibit the biosynthesis of GA can be antidoted with applications of gibberelin. While this antidote phenomenon is essentially true, the rate of applied gibberelin used to accomplish this response would have to be very high (usually in the range of 5 grams per acre). No biostimulant product has anywhere near that concentration of GA. When field trials have been conducted to determine whether biostimulant products containing GA do, in fact, comprise the growth suppression capability of GA inhibiting growth regulators, no significant evidence has been documented that such a situation exists. That being said, it should be clear that using biostimulants containing GA at rates higher than recommended on the label or at shorter intervals than recommended, could bring about a different result than what has been found. Attached is a study conducted by Syngenta that looked at the use of plant growth regulator,Primo MAXX , with the biostimulant product, Astron. The outcomes of this study show that “Astron does not appear to have significant affect on the growth regulation characteristics of Primo MAXX when applied at rates set out in this trial.”
Another issue, particularly pertaining to the use of Primo Maxx, is that superintendents that have used the product for several years for managing clippings (primarily on fairways) are frustrated that the degree and longevity of suppression decreases over time. Often the using biostimulants that contain GA are blamed for this gradual loss of efficacy from Primo Maxx applications. The more likely scenario is, that over time, since Primo Maxx applications enhance the competitiveness of Poa annua, the stand of Poa annua being treated undergoes a population shift in the direction of increased numbers of aggressive perennial ecotypes. As a result, the ability to suppress growth by applying Primo Maxx at the same rates and timings as originally used, no longer provides the same level of growth suppression (which necessitates higher rates/shorter application intervals). Such a result is certainly not a bad thing, but must be understood in the proper context using turf growth regulators for clipping management.
Until next time, Dr. Tom wishes you a winter season filled with educational opportunities so go out and indulge yourself!
Biostimulants October 2008
October 1, 2008
Question: Dr. Tom, Are biostimulants for real? And if so, what are they and should I use them?
Dr. Tom: Many superintendents seem to have questions surrounding biostimulants. There appears to be some confusion and / or skepticism in the field surrounding the subject. Some superintendents were exposed to them in school while others may have little to no exposure to the topic.
“Answers to Some Questions Golf Course Superintendents Have Concerning the Use of Biostimulants”
To answer your first question, YES! They are very much ‘real!’ And they have been researched for some time. There is a very nice paper that I would recommend you reading on the subject. It is by R.E. Schmidt and E.H. Ervin, Professor Emeritus and Assistant Professor, respectively, Turfgrass Ecology and Physiology, Virginia Polytechnic Institute.
In this paper, they say “Our research has documented that applications of (biostimulants) have conditioned turfgrasses to tolerate environmental stresses and improve grass growth, particularly root development.” From my experience and based on my colleagues research, I can say again, yes, biostimulants are for real.
To your second question, ‘what are they?’, in very simple terms and as the aforementioned paper highlights biostimulant properties can be found in seaweed extracts, humic acids, and triazole fungicides among others. While the content of each varies, research shows that seaweed and humic acid are two the most commonly used biologically active ingredients, and even then the sources of each need to be examined closely.
Most relevant to you as a superintendent managing turf in very demanding conditions, Schmidt and Ervin state “Biostimulants enhance plant metabolic activity to condition the plant to tolerate stresses. Therefore biostimulants have a greater impact when applied prior to the turf being subjected to anticipated stress.” This is obviously something you need to consider when planning your turf nutrition program. Biostimulants should be viewed as a proactive step in managing healthy turf as Professors Schmidt and Ervin point out: “… better results are obtained when sequential treatments are made and the second year is better than the first. Monthly applications prior to and during the stress periods (three to six applications per year) should be programmed....”
As managers of ‘extremely maintained’ turfgrass , you face myriad stresses along with your turfgrass! There are cultural practices and environmental pressures that put extreme stress on your turf. There are budgetary and player demands that put extreme stress on you. I am a proponent of ‘getting ahead of the curve’ through proactive nutrition practices instead of getting caught in ‘reactive’ mode. I think biostimulants, as part of a comprehensive turf nutrition program, can go a long way in helping superintendents relieve two stresses: their turf’s and theirs!
Until next time, Dr. Tom wishes you strong root mass and safe travels!!