Hidden Herbicides Damaging Your Roses?

A few weekends ago I stopped by Wayne and Deb Geltz’s home and rose garden in the wonderful little town of Lititz, PA (2013 Budget Travel’s America’s Coolest Small Town) located just north of Lancaster, PA.  Wayne grows exceptional rose bushes– mainly hybrid teas with a handful of miniatures and mini-flora roses.  You will not find one fallen leaf or dropped petal in Wayne’s rose beds.  During my visit he even picked a dropped petal up and put it in his pocket for later disposal!  Wayne is one of Penn-Jersey District’s top exhibitors and won the Queen and King of Hybrid Teas at the Reading-Berks Rose Show this spring with ‘Randy Scott’ and ‘Snuffy’, respectively.

Minor damage on Rrose bush suffering from herbicide toxicity

Minor damage on Rose bush suffering from herbicide toxicity.

Despite rose show success, a new problem this spring has unfortunately occurred in approximately 1/4 of Wayne’s rose garden.  He showed me the affected bushes to ask my opinion about the problem.  Upon observation I noticed the foliage was small, curled upwards, and had exaggerated serrated elongated leaves.  I observed that most of the affected bushes had two or less canes with the deformed foliage and completely healthy vigorous canes would grow right next to affected canes. Additionally,  the canes in question had no real loss of vigor or stem length other than the ugly deformed foliage.  I never saw the blooms atop the affected canes; however, prior to pruning Wayne told me the flowers were small and deformed.  Wayne initially suspected the dreaded Rose Rosette Disease because of the symptoms in the foliage described during the growing stage.  After much discussion we both concluded his garden was not affected with Rose Rosette Disease as the symptoms did not fit the criteria of the virus.

Moderate damage of rose stem and foliage due to herbicide toxicity

Moderate damage of rose stem and foliage due to herbicide toxicity.

Wayne contacted Steve Bogash, Professor of Botany at Penn State University and Cooperative Extension Educator for Horticulture/Small Fruit.  When the symptoms of the rose damage were described over the phone and the foliage was then examined in person, Mr. Bogash recognized the damage as symptoms of Auxin herbicide damage.   It should be noted the symptoms in the roses are very similar to the tomato problems reported by various extension agencies across the country. Professor Bogash is currently studying similar plant damage occurring in commercial tomato farms and grape vineyards. The common ground with the tomato farms, grape vineyards and Wayne’s rose garden was the use of mushroom compost.  Thus the conclusion was Wayne’s roses are suffering from a form of Auxin herbicide damage through the use of mushroom compost.

Synthetic Auxin herbicides (also known as growth regulators as they disrupt the natural balance of hormones in plants) are used to kill broad leaf weeds and thistle in turf, grass farms, pastures and hay fields and can be safely consumed by horses and livestock . The fecal matter produced by the horses may contain trace amounts of the Auxin herbicide. Horse manure and hay are two of many items used in the manufacturing of mushroom soil. Professor Bogash explains that although the mushroom soil goes through several transformations before it is used as compost, small amounts of the Auxin herbicide can remain in the mushroom compost. Wayne was informed that research of this class of chemical herbicide can potentially become deactivated within a month under ideal conditions; however, various reports state complete degradation may unfortunately take several years. Complete degradation of the herbicide appears to be slow in manure and compost.

Talking with another avid mushroom compost user, Ken Bormmann has also noticed some very minor symptoms similar to Wayne on three of his rose bushes.   Why Ken has seen less damage in his garden than Wayne may be due to the fact the compost itself was bought from a different vendor and therefore contains a lesser amount of herbicide.  It should be noted that I observed the worst area of affected roses in Wayne’s garden was on the bottom portion of his front yard slope, thus possibly enhancing the amount of contaminated mushroom compost leaching into the soil due to run off.

While compost can be examined by laboratories, the tests can be expensive.  It has been suggested that the easiest and most “economical” way to test compost is to perform your own bioassays with vegetables that are sensitive to herbicides.  This can be performed in pots in soil mediums with and without compost in a controlled setting. Professor Bogash suggested to Wayne the use of kelp/seaweed in either the liquid or meal form to help “counteract” the effect of the herbicide.  Kelp/seaweed has many good nutrients and growth hormones that does more for a rose or plant than the low N-P-K would suggest.  Wayne will use kelp as a foliar feed and use it around the drip line of the roses for the remainder of the 2013 growing season as what he calls “Kelp Therapy”.  If no improvement is noticed Wayne told me he will attempt excavating the soil from around the affected bushes knowing that mushroom compost will have been leaching into the soil.  Wayne will be providing me information on the progress of his roses affected by the herbicide damage.

I would like to thank Wayne Geltz for his contribution and information he has provided with his conversation with Professor Steve Bogash.

Additional Information:




5 thoughts on “Hidden Herbicides Damaging Your Roses?

  1. I would have thought the mushroom industry would be quite wary of where the mulch is sourced from. My 1st concern…..can this effect the edible viability of fresh mushrooms.? Do elements of herbicide exist in the produce.? A VA. Organic grower lost their entire early roster of of crops due to hay mulch laced w/ herbicide. They wondered why the hay was so affordable. Lawsuits were pending I heard. The use of herbicide is so widespread . Is a concern for all. I doubt seriously if a lot of the applicators are qualified to use & apply the specific herbicides in our area. I do horticultural consulting & get my fair share of herbicide effected plants. . Carelessness w/ applying & wind drift are the usual sources of the problem. Sometimes it’s not a herbicide, I had an Estate rose garden damaged from other sprays applied to adjacent shrubs & trees. Contained a toxin in the spray material w/ a warning NOT to apply around certain other listed plants. Roses were one of them. And….. It was quite breezy that day. Spraying shouldn’t have occurred .TIP— a tomato plant will not tolerate any type of herbicide. They are a good “spotter.”.Good Luck all. Bill Blevins, VA.

  2. Are experts saying that rose growers should not use mushroom compost? I apply 35 bags around my 250 roses every spring and am concerned.

    • This appears to be am ongoing problem with compost and mushroom compost across the country. Certain states have banned the sale of compost that have had known sources of herbicide sprayed material used in the compost. Is the problem worse in compost bought by the load versus by the bag out of Home Depot or Lowes is not known at this time. A new research paper is supposed to come out maybe soon about further study of compost. Trying to grow items sensitive to herbicide before applying to your garden or already in your garden such tomatoes in small pots is the easiest ans moat ecomincal way to see if you have compost with herbicide traces.

      • Also, this revised study from NC State that’s soon to be published recommends that the mushroom compost vendors/distributors should verify/certify with the source that no herbicides were used and include this on the label. Whether this is accepted and becomes industry standard, only time will tell; however, as with most things, if there is a drop off in sales, they may want to rethink their practices and go that route.

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