Herbicide damage on Spruce and Pine

The Plant and Pest Diagnostic Lab (PPDL) has recently received several samples of Norway spruce and white pine with symptoms that appear to be associated with injury caused by synthetic auxin (growth regulator type) herbicides. Typical off-target symptoms caused by these herbicides can include epinasty (twisting and curling) of the shoot and tips (Fig. 1) of branches. On conifers, affected new growth may turn brown and die (Fig. 2). On broadleaf plants, leaf cupping (upward or downward), bending or twisting may occur on new growth and in extreme cases, new leaves may appear irregular in size and shape (usually smaller than normal) and have abnormal leaf margins. These symptoms are similar regardless if it is an ornamental broadleaf plant or a weed. The new growth on the conifers submitted to the lab appeared to be brown and dying. Samples of Norway spruce and white pine submitted to the PPDL and injury reported in other areas of the country appear to be linked back to the common denominator of the herbicide aminocyclopyrachlor applied to nearby lawns for broadleaf weed control. The damage appears to be from root uptake rather than drift or volatilization.

Fig. 1.
Epinasty (twisting and curling) of the shoot and tips on white pine caused by an auxin herbicide. Photo by Gary Crum.

Fig. 2.
New growth on Norway spruce is dying due to injury from a synthetic auxin herbicide. Photo by Gary Crum.

Herbicides with good soil activity may cause problems on nearby broadleaf ornamentals through root uptake if they are applied within root zones of non–target plants or if drainage patterns funnel run-off to trees. Many herbicide labels have statements that say “Do not apply this product directly to, or allow to be under, ornamental ground covers, foliage plants, flowers, nearby crops or other desirable plants; or to the soil where potentially sensitive plants…” or “…care should be taken within the dripline of trees or shrubs.” It is unclear if the samples received this spring were from misapplications (within dripline or directly to foliage) but it appears that spruce and pine injury may also be occurring due to the expansive root system of these trees beyond the dripline of the tree. It is important to read all labels thoroughly to avoid applications that are not recommended on the label. A list of synthetic auxin herbicides commonly used on turf is shown in Table 1.

Table 1. Synthetic auxin herbicides labeled for use in turf in Indiana.


Trade Name(s)


2,4-D Amine 4, Barrage HF, Clean Amine, Hardball, Saber, WEEDestroy AM40, Weedone LV4 EC, Weedar 64






Banvel, Diablo, Vanquish




MCPA-4 Amine, MCPA ester 4

mecoprop (MCPP)

MCPP-p 4 Amine, Mecomec 2.5, Mecomec 4


Drive XLR8, Drive 75DF, Eject 75DF, Quinclorac 75DF, QuinPro Herbicide


Turflon Ester, Turflon Ester Ultra

Other products containing one or more of the above ingredients

2-D, 3-D, 4-Speed, 4-Speed XT, Battleship III, Brushmaster, Celsius WG, Chaser, Chaser 2 Amine, Chaser Ultra2, Confront, Cool Power, Eliminate, Eliminate LO, Eliminate-D, EndRun, Escalade 2, Horsepower, MEC Amine-D, Strike 3, Millennium Ultra 2, Momentum Q, Momemtum FX2, Onetime, Power Zone, Q4, Q4 Plus, Quincept, Speed Zone, SquareOne, Solitare, Strike Three Ultra 2, Super Spoiler, Surge, Tailspin, Threesome, Three-Way, Three-Way Ester II, Triamine, Triamine II, Trimec, Trimec 1000, Trimec 992, Trimec Bentgrass Formula, Trimec Classic, Trimec Encore, Trimec LAF-637, Trimec Plus, Triplet, Triplet Low Odor, Triplet Sensitive, Triplet SF, Tri-Power, TruPower2, Turflon II Amine, TZONE, Vessel, Yukon

Other spruce maladies such as conifer dieback from abiotic stress, Rhizosphaera and Stigmina needle cast, spider mites, and frost damage are also common on spruce in Indiana. Drought injury is especially common right now on spruce after the drought experienced last July-November in Indiana.

For evergreens injured by auxin herbicides, we are recommending the following management based upon recommendations from Bruce R. Fraedrich, Ph. D., Bartlett Tree Research Laboratories:

  1. Trees usually recover from light herbicide injury. Irrigating the plant during dry periods will help recovery and minimize moisture stress. Irrigation also will help leach root active herbicides from the root zone of the plant.

  2. Fertilization should be avoided for a minimum of one growing season following injury, because stimulating excess growth can compound injury from certain herbicides.

  3. Similarly, if branch dieback results, pruning should be delayed for at least a year to fully assess the extent of the injury. This will avoid additional pruning of dead branches that may result from continued decline. However, immediate pruning is necessary if dead branches pose a danger to life or property.

For additional information on herbicide injury to plants see “Diagnosing Herbicide Injury on Garden and Landscape Plants”, ID-184-W.

The Office of Indiana State Chemist (OISC) is aware of the issue concerning the application of Imprelis herbicide. Lawn care operators (LCO) and homeowners have reported growth regulator type injury (twisting and curling of new growth) to their evergreens including Norway spruce and white pine. DuPont, the manufacturer of Imprelis, is also aware of the issue and has released a letter to turf professionals and turf distributors (read here). As DuPont collects more information, further written communication regarding Imprelis will be coming in the near future.

If you or your clients want the OISC to investigate injury to evergreens that may have been caused by an application of Imprelis, you should contact George Saxton at (765)494-1582 or at saxtong@purdue.edu. As with any OISC investigation, lawn care operators will routinely be asked for information regarding their applications.

Lawn care operators may have affected clients contact OISC on their own or the LCO may contact OISC for their clients. If the lawn care operator decides to contact OISC for their clients, please make sure the clients are aware that the OISC will need access to the client’s property. If you have questions or require more information on this issue please contact the OISC pesticide section at (765)494-1492.

Aaron Patton, Assistant Professor of Agronomy, Turfgrass Extension Specialist
Gail Ruhl, Plant Disease Diagnostician, Purdue Plant and Pest Diagnostic Lab
Steve Weller, Professor of Horticulture and Landscape Architecture
Joe Becovitz, Pesticide Program Specialist, Office of Indiana State Chemist

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Turf Disease Watch

A new posting has been added to Turfcast. See Turfcast (http://btny.agriculture.purdue.edu/turfcast/ ) to read more about this post and for a daily summary of risk for several turfgrass diseases.

Rick Latin, Turfgrass Pathologist

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Mound Making on Greens and Tees

In addition to earthworms, there are several insects that can create small mounds of soil above the surface of turfgrass. Usually such mounding is of minimal consequence and, in fact, is beneficial to turfgrass environments as it accomplishes the same thing as cultivation, aeration and top-dressing - only on a very small scale.

On occasion, however, the mounds can become a nuisance, especially on closely mown greens where they may interfere with putting and ball roll.

In such cases it is important to know the identity of the insect in question. Because mounds alone are difficult to identify, associated insects should be used for validation.

Look for insects directly associated with the damage in question. Sometimes these insects are difficult to find because they are nocturnal or because they live in tiny burrows beneath the mounds.

One suggestion is to use a small probe or trowel to dig beneath the mound to a dept of several inches. Quickly deposit the core into a glass jar and look closely for any insect that might be present. Be persistent. Groups of typical mounds seldom fail to produce at least one token specimen, by which an identification can be made.

Ants and ground nesting solitary bees can sometimes cause mounds to appear. Both of these insects are easily managed with the use of carbaryl, among other pesticides.

Some tiny beetles such as scarabs (Geotrupes) and ground beetles (carabids) also can tunnel and deposit soil in small mounds on the surface of the turfgrass.

The above photo was submitted, compaining of nuisance ‘mounding’ on a putting green. This was reportedly occurring on a daily basis on 6 greens during June. A subsequent sample of the soil below revealed two ground beetles that we commonly know as seed corn beetles.
Despite their name, corn seed are not the primary food source for seed corn beetles. Rather, they feed on other things that they find in the soil including other insects. We also know that they are highly attracted to and fly to lights at night. There are two generations per year, typically occurring in May/June and again in August.

Their appearance is more likely in cool, wet conditions, typical of this spring.

Management recommendations for these beetles usually include applying a surface insecticide as soon as mounds appear. Insecticides recommended for seed corn beetles control include any of the contact pesticides labeled for use in turf.

Tim Gibb, Turfgrass Entomologist

Doug Richmond, Turfgrass Entomologist

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The Case of the Dead Zoysia in Southern Indiana

Zoysia grass is a warm-season grass that is being more frequently used in warm, humid and transitional regions. As zoysia is becoming more frequent in our state we are learning more about the pests that attack it. The photograph below was taken of a stand of zoysia in the southern part of Indiana. It was clearly killed by something – but what? Damage was evident in the late fall and got even worse this spring. We went through the usual bank of questions; diseases, winter kill, billbugs, but came up with no certain cause of decline.
At last, a sample was run through a Berlese funnel that uses heat and light as a method to extract live insects. In addition to the myriad of mites that are found in nearly every soil sample, we extracted many small red insects with white stripes across their backs (photo below).

These were identified as newly hatched chinch bugs. Looking back at the weather conditions last fall, it became apparent that this zoysia lawn occurred right in the middle of the drought affected region of the state. Interestingly, chinch bugs are also known to occur most in times of drought.

Putting two and two together allowed us to make a tentative diagnosis of a difficult problem. Certainly, the drought must have played a part in the decline of the turfgrass, but finding the chinch bugs also allowed us to say with certainty that they also contributed, AND are continuing to contribute to this damage.

Chinch bugs have piercing-sucking mouth parts and suck juices from the crowns and stems of grasses. Adults are black and have shiny white wings that are held flat across the back. The newly hatched nymphs (1st and 2nd instars) are bright red in color and have a characteristic white strip across their back. As they grow they slowly change to a brown, and eventually black, color and the white stripe vanishes.

Natural controls often hold these pests in check, however, when conditions (including weather) are just right, populations can build up and damage may be manifest.

Chemical control should only be considered when the chinch bugs are confirmed in high numbers and damage begins to become apparent. Otherwise, insecticides often take out the very predatory insects that keep chinch bugs in check.

Insecticides recommended for chinch bug control include any of the pyrethroids labeled for use in turf.

Tim Gibb, Turfgrass Entomologist

Doug Richmond, Turfgrass Entomologist

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Brown Patch--initial outbreaks

A new posting has been added to Turfcast. See Turfcast (http://btny.agriculture.purdue.edu/turfcast/ ) to read more about brown patch and for a daily summary of risk for several turfgrass diseases.

Rick Latin, Turfgrass Pathologist

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Drought Damage on Zoysiagrass Lawns

Last summer and fall we experienced some widespread drought throughout the state which we documented with turf tips in July, September, and November as well as tips on reestablishment this March (click here for an archive of these tips). Most were uncertain as to what the extent of the damage would be until the turf began to green-up this spring. Many areas came back surprisingly well although many other areas (typically southern slopes, and poor, shallow, compacted or sandy soils) did not do as well. For some warm-season grasses, especially zoysiagrass we are only now able to ascertain the full extent of the damage since these grasses do not fully green-up until late April or May in Indiana. I have fielded a few calls regarding damage to zoysiagrass lawns this spring. Consistent in all these cases the damage seems to occur on unirrigated areas with sandy, shallow, or compacted soils. Most of the damage is limited to small spots or small portions of the lawn.

Although zoysiagrass is a warm-season grass and drought tolerant compared to cool-season grasses, it is still susceptible to drought injury. Meyer (also called Amazoy or Z-52) zoysiagrass is used throughout much of the state because it is the most cold hardy of all the zoysiagrass cultivars, but it only has moderate drought tolerance compared to other zoysiagrasses which can predispose it to drought injury under severe drought conditions as we experienced last summer/fall. Of the turfgrasses grown in Indiana bermudagrass will require less irrigation than ‘Meyer’ zoysiagrass although both are more drought tolerant than cool-season grasses with tall fescue being more drought resistant that Kentucky bluegrass. However, because bermudagrass is not as cold hardy as zoysiagrass we are limited to growing bermudagrass in the southernmost part of the state.

Should drought strike in the future, limit traffic (including mowing) to minimize damage to the turfgrass leaves and crowns and apply irrigation once every 4 weeks with ½ inch of water to keep turf plant crowns hydrated. This amount of water should not green up the turf, but it will increase its long-term survival.

For those with zoysiagrass that was damaged from last summer’s drought and in need of repair, there are three options for reestablishment.

  1. Resodding with Meyer zoysiagrass. Zoysiagrass is available from sod farms in SW Indiana. Homeowners may be able to get sod directly from the grower but some prefer to work through a local landscape companies and you might need to contract out this work.

  2. Seeding zoysiagrass is also an option. Seeding zoysiagrass is only for patient people and will require herbicide applications for best results as weeds easily outcompete zoysiagrass seedlings even though there are few weeds in established zoysiagrass. More information on seeding zoysiagrass is available on our website at this link. NOTE: If a preemergence herbicide application was made this spring then seeding will not be an option for these lawns as the preemergence herbicide will prevent weeds seeds from germinating as well as desirable turfgrass.

  3. Plug zoysiagrass. Using a hand spade or small shovel, cut pieces of sod approximately 3 x 3 inches or larger from healthy portions of your zoysiagrass lawn and plant them on 1 foot centers (using an imaginary grid) in the dead areas. These newly planted plugs will spread and fill in over time (1 year or so) and fill in the bad spots. Be sure to water the new plugs for the first month after planting and don’t forget to fill the holes you made in the rest of your lawn.

Regardless of the method of reestablishment, it is important to first obtain a soil test (soil test instructions, soil testing laboratories) in the area and fix any nutrient or pH problems prior to planting as well as any soil compaction or other limiting soil problems.

Aaron Patton, Assistant Professor/Turfgrass Extension Specialist

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