Dr. Milt F.A.Q. - Your turfgrass questions answered!

Dr. Milt Engelke, an agronomist specializing in the identification, production and maintenance of turfgrass provides professional advice and guidance for Jacobsen customers worldwide. Engelke is an agronomic resource available for interaction and education via this Discussion page.

Select questions provided with Dr. Engelke's professional responses will be posted to this web site on a monthly basis.

To ask a question, visit Ask the Expert.

Q. How should I monitor soil temperatures?
A. Soil temperature influences plant growth, microbial activity and chemical reactions. Check soil temperatures in your fairways, greens and rough at a depth of 4” frequently throughout the year.

Q. What is the best way to combat weeds?
A. Seed germination, including weeds, occurs in the Spring when soil temperatures rise above 55° F (17 C). Schedule pre-emergent herbicide application according to soil temperatures, not the calendar.

Q. When is it best to aerate or vertically mow warm season grasses?
A. Early aerification or vertical mowing can do more damage than good if the plant is not actively growing. Check to make sure soil temperatures for warm season grasses are in the mid-60’s F (18 - 20 C).

Q. What is the best temperature for Bermuda grass?
A. Remember, in the Spring, high ambient air temperatures promote crown and leaf development at the expense of the root system in Bermuda grass. When soil temperatures rise above 65°F (18 C) root growth starts. The plant is able to pick up appropriate nutrients and access deeper soil-water resources. When soil temperatures are above 65°F , more aggressive plant growth can be met with more aggressive cultural practices.

Q. When does fertilizer nutrient release happen?
A. Organic fertilizers will not break down as readily when soil temperatures are cool due to reduced microbial activity.

Q. What is the best grass of acidic or alkaline soil?
A. Is your soil acidic or alkaline? Soil pH, a measure of alkalinity or acidity, directly affects the availability of nutrients. The appropriate soil pH for optimum turf grass growth will range between 6.0 and 7.5.

Certain plant species are better adapted to acidic soils and others to alkaline soils. Knowing the difference is very important in providing appropriate cultural inputs.

Knowing the soil pH will help you manage your turf better. Warm season grasses are more sensitive to soil pH. Paspalums, and Centipede grasses do much better under acidic soil conditions, while Buffalo grass almost demands an alkaline pH.

In highly acid soils manganese and Aluminum can be toxic to the turf.

In alkaline soils, an accumulation of salts can impair soils structure and soil integrity.

If the pH is below 7.0 – acidic – adjusting the pH upward can be accomplished with the addition of lime.

When the soils are alkaline – pH above 7.0 – adjusting the pH can be done with the generous application of gypsum or Aluminum Sulfate. Gypsum is also used frequently in managing salinity build-up and conditions of the soil.

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Q. Why is aerification recommended?
A. Aerification may be the Primary Cultural Practice responsible for maintaining a strong root system. Soil oxygen is required to support active microbial activity, root growth and development and plant health. The absence of adequate levels of soil oxygen will result in a loss of microbial activity and suffocation and loss of plant roots.

Q. Why is lack of soil oxygen is unhealthy?
Prolonged loss of adequate soil oxygen will result in poor plant growth and development, accumulation of organic layers in the soil profile, retention of higher than desirable levels of soil moisture and eventually the formation of black layer.

Q. What types of aeration are there?
A. Use cultural practices to provide aerification to the root zone.

1) Core extraction – opens the turf with probing tines, reaching to the depth of the root zone removing the accumulated organic layer.

2) Vertical mowing – vertical blades cut to a depth of 1/2"to 1 1/2"” to sever the crown, tillers, stolons and even rhizomes. They also extract the upper surface of accumulated organic materials.

3) Venting – solid tines that probe deeply into the root zone to create vertical channels to permit movement of soil gases and promote increased evaporation to remove excess soil moisture.

4) Deep tine aerification – generally requires specialized equipment to probe deeply into the root zone profile. May use solid tines (creating vents), tube or open back tines for deep extraction. Excellent for older greens, native soil greens and root zone profiles noted for layering due to incompatible or untimely top dressing practices.

Q. Why is fertilization important?
A. Proper plant nutrition is absolutely necessary for healthy turf. Selecting appropriate fertilizers requires knowledge on the needs of the plant. Frequent plant tissue testing along with periodic soil test will provide you with the information you need to select the proper turf amendments to use for healthier turf.

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Q. When should I fertilize?
A. The timing of fertilizer application is likewise important as nutrients are utilized by all living organisms and will take advantage dependent on environmental conditions.

Q. Why is over-watering harmful?
A. Periods of excessive rain can result in undesirable conditions for plant growth and development. Heavy rains will aid in removing salts, which have accumulated in the crown area of the plant, but in excess will also leaching much of the nutrients from the soil profile.

Prolonged wet periods may support the possibility of disease organisms becoming pathogenic. Combined with a ready source of nutrients, the wet and hot periods of time with lots of nutrition are prime conditions for disease infestation. Whenever possible,avoid applying soluble nutrient sources during periods of high temperatures and excessive rainfall.

Q. What is a recommended fertilization schedule?
A. Late fall fertilization:

 September - October in the north, October – November in the mid-south and November – December in the south.

Q. How do I treat brown patch disease?
A. The occurrence of brown patch disease in warm season grasses is often associated with cooler ambient temperatures, the application of soluble nutrient sources late in the fall when fall rains are the most prevalent.

Growth has slowed due to cool soil and air temperatures, but the pathogenic organisms are still active and capable of out growing the grass with ample nutrients.

Q. What are preventative measures to brown patch disease?
A. Timing summer fertilization to optimize plant growth and carbohydrate storage in mid-august then delaying subsequent fall fertilization until after the first hard frost will often reduce the incidence of fall disease activity. As an offshoot, this practice may further delay or eliminate the onset of spring disease activity.

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Q. What type of fertilizer is recommended for preventative measures?
A. Using an organic or slow release type fertilizer for late fall fertilization (after frost) will avoid putting a soluble nutrient source when the microorganism needs it. It also optimizes the nutrients availability to when the plant will need it in the spring as soil temperatures begin to warm.

With this practice, early spring nutrient application is not needed, and again no soluble nutrient source is provided in the upper turf canopy. Restricting the quantity of available nutrients in the upper turf canopy favors “nutrient starvation of pathogenic organism” further delaying the onset of spring diseases during wet periods. The late fall applied fertilizers move into and below the turf canopy to the root zone where it becomes readily available to the plant in the spring.

Q. What is Black Layer?
A. Black layer is a physical phenomenon most often manifested during the mid – late summers on areas of turf, which have one or more of these characteristics: Poorly drained, heavily shaded, poor air circulation, or suffering from material layering in the soil profile. It is a serious and prolonged case of poor internal drainage and lack of gas exchange.

Q. What causes Black Layer?
Black layer is caused by a group of anaerobic organisms which thrive under conditions of low or no soil oxygen.

The low oxygen conditions result from poor soil structure, poor irrigation practices, broken water lines and continuously saturated root zone conditions. Excessive salts, usually in the upper 1/4 - 1/2", may be the initial cause of suffering from poor infiltration. Once the surface is sealed the roots will quickly shrink and over 4 - 20 months the black layer will begin.

Soil oxygen is essential to the growth and development of plants, micro flora and micro fauna. Without such, all beneficial life in the soil profile dies.

Q. What is the cure for Black Layer?
A. The simplest remedy is to aerify the greens, making certain you are getting entirely through the layer. TopDress with appropriate sand to refill the holes.

Assuming your pH is above 7, apply gypsum (CaSO₄) or greens-grade lime (CaCO₃) at 10-11 lbs. per 1,000 sq. ft. Lightly irrigate the area to aid in dissolving the salts. Within a couple days, attempt to flush or leach your greens. The aerifying ahead of time is essential.

Within 4-5 days begin venting the greens using solid tines going as frequently as possible (10-15 day cycle), along with Calcium applications monthly. It will be necessary to core aerate 3+ times per year using as large of tines as possible. If you are on sand-based greens it is only necessary to go through the layer into good sands below; if you are on native soil, push-up type or older greens you may want to consider deep tine coupled with Drill-n-fill to reestablish internal drainage.

If you're only able to penetrate 6" in the first pass, I would recommend a second pass in a relatively short time span to continue deeper penetration. This process needs to be addressed in earnst in the spring with an upcoming growing season and not too heavily in the fall when you are facing dormancy.

 

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Q. Our turf is Bermuda grass, but St. Augustine grass has taken over in a fairly large patch. What is the best way to get rid of the St. Augustine and not harm the Bermuda grass around it? Also how do we get the patch to fill in as quickly as possible?
A. I would suggest that you scalp the patch and remove as much of the dead and dying St. Augustine grass as possible. Next, broad-cast hulled Bermuda grass seed throughout the scalped area. After seeding, add fertilizer. (I recommend 1 pound of Nitrogen per1000 sq ft of area using a Nitrogen, Phosphorus and Potassium ratio of 3 - 1- 2). Once the seed and fertilizer are spread, drag the area with a mat or hand rake it to work the seed closer to the soil layer. Apply irrigation to the area frequently for the first 7 - 10 days. Be careful not to over-saturate the area. In 7 - 10 days the seed should germinate. Reduce the frequency of irrigation to approximately 1x per day until the plant begins to spread.

Q. I recently put 80 lbs. of Ironite on my lawn, which is about 12,000 sq. ft., and was wondering if this is the best time of the year to apply this amendment. The treated area has irrigation, but is in partial shade. If there is any other products that you recommend then I would appreciate it.
A. Thank you for an interesting question concerning plant nutrition. All plants need certain nutrients to grow and maintain good health. What is actually needed by the turf, relative to supplemental applications such as you’ve used, is highly dependent on the natural soil nutrition and soil pH.You applied an excellent source of Iron plus other micro nutrients. If the soil is deficient in these chemicals and nutrients, then you will realize an advantage. Without a soil test, there’s really no way to know, so I highly recommend that you have the soil tested for the major nutrients of N (nitrogen), P (phosphorous) and K(Potassium) and for pH. If your soil pH is below 7.0, then it will be considered acidic. If it is below 6.0 it may be necessary to raise the pH with the addition of Lime. If it is above 9.0 it would be best to use gypsum. As to the second part of your questions, the plant doesn't have any particular preference as to where its nutrients come from, it just needs food. Usually we recommend between 3 - 5 pounds of actual N per 1000 sq. ft per year, but again, that is dependent how the turf is being used and the species of grass that you are using. In either case, a soil test will help point you in the direction you need for proper plant health.

Q. I have a question about moles in my Bermuda fairways. What is the best way to remove them?
A. Moles are one of nature’s creatures that provides for highly effective aerification of the root zone. Unfortunately they don't cooperate with the turf grass manager and can create tremendous problems. There are a number of baits which should be available through your local chemical distributor. Because there are too many local and regional controls over these chemical, a local source of knowledge will be your best source of which on to use.

To take a non-chemical approach one can use traps which are the most effective when the mole population is low but using them does require considerable persistence.

Q. I am a golf course supt in taegu korea, we are planning to renovate all fairways,what grass would you use? Soil here are heavy clay.
A. Regardless, your are in the land of many possibilities, however during my travels through Korea in the early 80's it was quite apparent to me the grass of choice should be one of the countries native species - Zoysia grass. There havebeen considerable improvements in the development of zoysia grass for fairway use and I would encourage you contacting local producers or at the very least the University of Seoul in Suwon. They have an excellent turf group and should have the most current information on local sources as well.

Other alternatives include the use of Bermuda grass (Tifway is the old standby, but greater emphasis is not being directed to Tifsport) not knowing if these cultivars are readily available to you. If you have the choice of importation and can get past the agricultural import issues then Tifsport becomes a possibility. If that is the case, I would suggest that you also investigate the possibility of some of the newer US developed cultivars such as Cavalier - from Texas A&M, or Zeon from Blade runner Farms. Both are Z. matrella types and produce a high quality turf for golf fairways. You can find more information on both of these by searching the web site for zoysia grass and by name.

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Q. I took your Management of Zoysia course at the GCSAA Conference in Orlando and forgot to ask an important question. We sodded our fairways in the fall of 2001 and much of the grass was put down dormant. Should we attempt to apply RoundUp this winter on fairways that have no roots or should we "bite the bullet" and wait until next winter?
A. In retrospect the use of roundup in the winter months must be very judicious in making certain that the turf is fully dormant including close examination of the stolons below the turf canopy. Round up applications by spraying even on apparently dormant turf can cause considerable damage if stolons are still green. The spray will create a fine mist which will permeate the turf and contact the stolons. If you have severe areas of weed infestation and don't have an alternative, I would suggest using a rolling applicator or wiping type applicator which provides for direct contact of the leaf surface to the target weed and not rely on spray application.

Generally new sod will also have greater weedy tendencies the first year and personally I would prefer that you delay use of herbicides during the first year. Most grasses and especially Zoysiagrasses will be more competitive in subsequent years and require less use of post emergence herbicides. A good pre-emergence program will play an important role in maintaining quality turf.

 

The opinions and commentary of Dr. Milt Engleke are strictly his views and do not necessarily reflect the views of Jacobsen, A Textron Company or its affiliated entities.

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