Author: Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - www.facebook.com/TheGardenProfessors "The Garden Professors" Facebook group - www.facebook.com/groups/GardenProfessors Books: http://www.sustainablelandscapesandgardens.com

When criticism becomes libelous

Dr. Cregg is on vacation for a few weeks so I thought I’d post something today by trolling the web for discussion of my horticultural myth columns. And when you go fishing, you know you might catch something you didn’t really want. In this case, personal and professional attacks.

Like the rest of the GPs, I relish vigorous debates on different horticultural practices and products. Ideally, these debates are based on science, so that we’re all friends afterwards and could go out for beer if we all lived in the same community. But when criticisms become personal, malicious, and in some cases out-and-out untruths, what should one do?

I have a relatively thick skin and ignore most of the nasty comments, but when my integrity as a scientist is challenged, I really have a problem. For instance, one blogger states “The fact that some – not all – of her articles have very little basis in reality and are widely disputed and even denounced in horticultural circles should be pointed out before anyone takes them immediately to heart.” Another blogger remarks “What little I’ve read about this Chalker-Smith person leads me to believe she is an “opinion for hire” much like some “expert witnesses” one sees in courtrooms.” How about this? “She tried to prove compost tea is bad by PURPOSELY using E.Coli infested compost (without telling anyone about it) and proclaimed it as unsafe product to use.” And so on.

I can guarantee you that if I didn’t base my publications in reality, or if I were an “opinion for hire” I would be in serious trouble with the university. The truth is I research the science behind topics and then have at least one colleague review them. (Sometimes that colleague is my husband, also a PhD in horticulture and one of my most honest critics.) The compost tea diatribe is so outlandish it took my breath away.

So onto my question: what should one do when one’s professional reputation is libeled? Do I continue to ignore it? Do I wade into these debates, thus giving credibility to the libeller? These people hide behind their anonymity – none have the courage to simply email me and voice their criticisms.

I’ll be curious to hear from my GP collaborators as well as non-academics.

(Hurry back, Bert. This was a painful experience.)

Five little lavenders – an update

Long-time readers of our blog might remember my August 12 column (linked here for your convenience). You saw my giant lavender plant devolve into 5 small plants with tiny spiraled root systems that put Marge Simpson’s beehive to shame. In any case, I promised to keep you up-to-date with their progress.

Transplanting in August is a risky proposition, especially when you prune out root defects. Nevertheless, all but one of the five survived the summer and here they are earlier this spring:

The one that didn’t make it was in the upper left corner of this south-facing landscape, where there is a lot of reflected heat from the nearby bricks and concrete. (You can see the empty spot where it was in this photo.)

If you haven’t tried corrective root pruning before, I’d encourage you to try it with an inexpensive shrub. Your best bet will be older containerized plants in the “sale” section of your nursery.

Clematis mystery solved

Friday’s quiz was a tough one. Bernadette and Lisa B. gave it a good shot, guessing that this might be a phosphorus deficiency. While they’re on the right track (it is a nutritional disorder), the mineral of interest is iron, and it’s a toxicity problem, not a deficiency.

Under wet conditions (the affected Clematis is in the part of our landscape with a perched water table – see the March 15 posting), iron is predominantly in the Fe⁺² form (ferrous) rather than the Fe⁺³ form (ferric). The ferrous form is easily taken up by roots, and when leaves accumulate too much iron they turn reddish-brown. This diagnostic characteristic is called bronzing, and it’s different than the reddening caused by anthocyanin accumulation. (As an aside, nonagricultural landscapes rarely have phosphorus deficiencies and are more likely to contain excessive levels of phosphorus.)

Finally, all this talk of iron has reminded me of one of my favorite chemistry puzzles – see if you can figure out what this is:

Give up? It’s a ferrous wheel!

Friday quiz – a tale of two clematis

These two Clematis are the same cultivar growing in my landscape about 15 feet apart. Both are growing on a fence facing north. Compare the leaves of the two:

Normal, happy Clematis

Not-so-happy or -normal Clematis

What do you think is causing the leaf discoloration? Very large hint: this is not a biotic stressor. Another hint: you’ve seen this part of our landscape before…back in March. For full credit, identify both direct and indirect environmental stress (in other words, [1] what is directly causing the discoloration in the leaves, and what is allowing [1] to occur, thereby causing stress indirectly)?

Answers on Monday – have a happy 4th of July.!

An interesting blog for science-loving oenophiles

There’s a new blog already generating a lot of discussion among wine aficionados. The not-so-subtly named “Biodynamics is a hoax” discusses all things related to Rudolph Steiner and his philosophies, including the pseudoscience of biodynamics.

Organic farming study at – gasp! – a research university

There is a common misperception among some that university researchers are in the pocket of Big Ag (see June 11 and 13 posts). So here’s a link to an article in today’s Seattle Times about the benefits of organic farming from a study at Washington State University. The research was published in Nature (one of the most revered of the scientific journals).

Cornmeal myth busted

As my colleague Fred Hoffman says, the horticultural silly season is upon us. This week I heard from one of our European readers, questioning the use of cornmeal as a fungicide. He referenced an online article entitled “Cornmeal has powerful fungicidal properties in the garden.” He hadn’t been able to find any reliable information and thought it might make a good topic for our blog. So Johannes, this rant’s for you!

If you’ve followed the link to column in question, you’ll see that the original “research” is attributed to one of Texas A&M’s research stations in Stephenville, TX. But it’s not really research – it’s just an observation on what happens when you don’t plant the same crop two years in a row; in this case, rotating corn and peanuts reduces peanut pathogens. This is hardly news – it’s one of the reasons agricultural scientists recommend crop rotation as part of an IPM program. And have for decades.

Then we’re referred to “further research” (at an undisclosed location) where cornmeal was shown to contain “beneficial organisms.” Well, no, cornmeal doesn’t contain organisms, beneficial or otherwise. Microbes can grow on cornmeal, and in fact cornmeal agar is commonly used in labs as a growth medium for many species of fungi. And has been for decades.

Nevertheless, we’re informed that a gardening personality has “continued the study and finds cornmeal effective on most everything from turf grass to black spot on roses.” This is directly refuted by Dr. Jerry Parsons, who by happy coincidence is an extension faculty specialist at Texas A&M. His informative (and hilarious) column on brown spots in lawns states “Lately there have been claims made that corn meal and a garlic extract is effective. This is absolutely false! Everyone trying to do the “environmentally friendly-to-a-fault” thing have been wasting their money. They would have been better off making corn bread and using their garlic for cooking purposes!”

Dr. Parsons continues: “Let me explain how these University tests and recommendations have been misrepresented in a desperate attempt to find an organic fungicide. The corn meal was investigated by a Texas A&M pathologist as a way to produce parasitic fungi used to control a fungus which occurs on peanuts.” (This directly relates to my earlier point that cornmeal agar has a long history of use in fungal culture.)

It boils down to this: if you have a healthy soil, it will probably contain diverse populations of beneficial microbes, including those that control pathogenic fungi. You don’t need to add cornmeal – it’s simply an expensive form of organic material. So you can ignore the directions in the article on how to incorporate cornmeal into the soil, or make “cornmeal juice” to spray on “susceptible plants.” Just nurture your soil with (repeat after me) a thick layer of coarse organic mulch.

(As a footnote, let me say how annoying it is when gardening personalities grant themselves advanced degrees or certifications in their titles. C’mon folks – if your information is so great, do you really need to pretend you’re someone else?)

(Another footnote: I discussed this myth more in 2012. Be sure to check this link out too.)

UPDATE: Since this is a myth that refuses to die, I’ve published a peer-reviewed fact sheet on the topic. Feel free to pass on to others.

Garden seminar coming to a place near you?

I just got back from British Columbia where I spoke to 2 garden club/Master Gardener groups. It’s always easy for me to do seminars in BC or along the west coast, but I rarely get a chance to go elsewhere. Many times it’s the expense that keeps groups, especially garden clubs and nonprofits, from bringing in speakers.

So here’s my idea: I keep a gift account budget here at WSU with the donations people make towards my educational program. Occasionaly I’ll make an equipment purchase, but for the most part it’s intact. And today it hit me – why not use it to help fund travel throughout the US (or elsewhere?) to give educational seminars?

So before I go any further with this thought, maybe some of you can give me feedback. Would your institution/garden club/or other group be interested in having me give a seminar on some aspect of sustainable urban horticulture? Just post a reply in the comments with your general location. I’ll see if there’s enough interest to pursue this further. I’d probably try to organize this trip for sometime in late February-early March of 2011.

Mystery berry revealed

You guys are just too smart – I was hoping to trap someone into guessing a Vaccinium species. But no, you all knew this was a Taxus spp. (yew):

Because Taxus is a gymnosperm, this reproductive structure is actually a cone. It’s botanically incorrect to call it a fruit of any sort, as the term "fruit" refers specifically to angiosperms. Taxus cones are modified for seed dispersal to include an edible, fleshy aril (very good, @GardenHoe!), whose taste and color are attractive to birds. The seed (which is toxic, like all vegetative parts of the plant – you’re right, Jimbo!) passes through the gut undigested.

The toxin in Taxus is the alkaloid taxine. Like many alkaloids, it’s a potent neurotoxin. Other alkaloids you’re more familiar with include caffeine, nicotine, and codeine.

Friday mystery

I just got back from Nanaimo BC, where I had gooseberries with my afternoon tea. Below is another "berry" found on a commonly used ornamental. (I use the term berry loosely – as you may know, the botanical definintion for berry excludes fruits like strawberry and raspberry, which are aggregate fruits.)

I’ve photoshopped this so that only the two "berries" are visible. On Monday I’ll post the entire photo, along with some botanical fun facts! See if you can guess what this is before then.