Category: Amusing Facts

Mortal Kombat – garden version

Soil solarization is regarded as an environmentally friendly alternative to pesticides for controlling nematodes, weeds and disease.  Sheets of plastic (generally clear) are spread over the ground and solar energy heats the soil underneath to temperatures as high as 55C (or 131F).  Since the soil environment is usually insulated from temperature extremes, the organisms that live there are unlikely to be resistant to heat stress.

This is a practice best suited to agricultural production, where monocultures of plants have attracted their specific diseases and pests.  Decades of research have shown success in controlling pests in greenhouses, nurseries, and fields.  But there’s a down side to this chemical-free means of pest control.

It shouldn’t be surprising that beneficial soil organisms, in addition to pests and pathogens, are killed by solarization.  Studies have found that soil solarization wipes out native mycorrhizal fungi and nitrogen-fixing bacteria.  One expects that other beneficial microbes, predacious insects, and parasitoids living in the soil (but so far unstudied) would be eliminated as well.

This may be an acceptable loss to those who are producing crops; soil can be reinoculated with mycorrhizal fungi, for example.  But for those of us caring for our own gardens and landscapes, this is literally overkill.  (And consider that most of us probably have trees and shrubs whose fine roots extend over our entire property.)

So this spring, instead of solarizing your soil, consider some less drastic measures of pest and disease control. Minimize soil disruption to preserve populations of desirable microbes. Plant polycultures (more than one species) in your vegetable garden, or at least practice crop rotation.  Protect and nourish vegetable gardens with compost.  Use coarse organic mulches, which provide habitat for beneficial insects and spiders, in landscaped areas.  Above all, try to treat your soil as the living ecosystem it is, rather than a war zone.

Bordeaux Mix

One of my favorite stories about pesticides is the story of Bordeaux mix.  It’s a story of France in the 1800s (so it must be pretty romantic, right?) and how they were suffering from a shortage of grapes.  Don’t feel sorry for them — it was really their own doing.  Over the course of the 19th century grape vines were brought from the United States to test their merits against European grapes.  It was quickly discovered that, for the most part, American grapes were not the equal of European grapes for winemaking.  Unfortunately for the French, however, along with the grapes came a disease: downy mildew.  This mildew absolutely ravaged grape vines across Europe, and particularly France from the time that it was introduced, around 1878.

Meanwhile there was another problem for grapes growing in France.  People.  People like to eat grapes beside the side of the road and so, throughout France’s grape growing regions, grapes on the sides of the road were typically bare.  Unlike downy mildew, however, grape growers had a pretty good idea what to do about people.  They sprayed nasty stuff on the grapes.  This nasty stuff took many forms, but the one which was most effective was a mixture of copper sulfate (basically you dissolve copper in sulfuric acid) mixed with lime.  Brushed on a plant’s foliage, it was darn ugly.

Then came 1882; a terrible year for downy mildew.  Grape vines were losing their leaves all over Europe, except for those vines beside the sides of the road.  There the grape vines were doing just fine.  The reason was the copper in the lime/copper sulfate mixture which was eventually dubbed Bordeaux mixture because of where it was first used.  Bordeaux mixture is still available today, and is one of the most important tools in the organic grower’s pesticide arsenal.  Unfortunately it’s nasty stuff – it builds up in the soil and it’s toxic to earthworms and a wide variety of different plants and aquatic organisms.  Using this stuff once in a while – such as once a year – isn’t terrible, but regular use is a good way to ruin your plot of land.

One final thought – Those American vines which originally brought in mildew?  They eventually became very important to French wines because of another introduced pest, phylloxera.  They were used as rootstocks because they were resistant to this pest — unlike European grapes.

A salt bath for your tomatoes?

This morning I got an email from one of my gardening colleagues, wondering about the wisdom of watering tomato plants with salt water.  He had a link to a UC Davis website which tacitly endorses spraying tomato plants with 10% salt water “to increase their nutritional value and taste.” Unreferenced “worldwide studies” are mentioned, along with the “major potential benefit of providing irrigation for crops in areas with freshwater restrictions.”

Before we deal with the impracticalities and out-and-out harm of using salt water for irrigation, let’s look at why this practice would work on tomatoes.  By training I’m a plant stress physiologist (and I’m well versed in the primary literature on this topic).  Watering tomato plants with a salt solution imposes a drought stress on the entire plant, as less water is taken up under these conditions.  So leaves and fruits are smaller and they may produce stress-induced biochemical compounds in response.  The upshot is that you have smaller tomatoes with a higher concentration of various solutes, some of which might be tastier or more beneficial to humans.

Guess what?  You can do the same thing by decreasing irrigation during fruit set!  Less water means smaller fruit and increased concentrations of sugars and other plant compounds, and voila!  So you can skip that step of adding salt water and just cut back on irrigation to induce a mild drought stress.

So…why in the world would you dump salt water on your garden soil?  The article blithely dismisses this:  “Many are still concerned about salt causing soil degradation and rendering some seawater-treated tomatoes inedible, but scientists cite that plants thrive in balanced soil containing both macro- and micronutrients.”  Sorry, but sodium is NOT a micronutrient for most plants and does NOT contribute to a “balanced soil” in one’s vegetable garden.

An ironic twist to this whole article is that most of the research that’s been done is relevant to arid parts of the world (the Middle East, primarily) where saline soil conditions and limited water are common.  I can’t imagine what they would think about people who would deliberately contaminate good soil by adding salt water to it.

Jeff Gillman a.k.a. Dr. Unbiased!

“Everyone’s taking stands, and unfortunately, some of those taking the strongest stands have the least information.”
– Dr. Jeff Gillman, on “How the government got in your backyard”, co-authored with Eric Heberlig

Fine Gardening did a fine job in a recent interview that was linked to their e-mail update.  FG Editor Steve Aitken brings some humor as he quizzes Dr. Jeff. about his new book.  Check it out here.

Steve opens with “Is the government really in my backyard? And if so, can I get them to pull some weeds?”

Hee!!!  The interview awesomeness continues as herbicides, nudity, tofu dogs, and  poo-pooing are all discussed. I just may renew my subscription, if Steve can promise more of the same. I gave up on Garden Design years ago – since I don’t have a gravel garden with infinity pool overlooking a canyon in California, nor am I interested in $5000 lawn chairs. Reading it just made me feel dowdy.

“I can practically guarantee that you’ll find something in this book that
you don’t like.”  Way to sell a book, Dr. Jeff!

Despite waiting pensively by the mailbox for my Complimentary Copy which has yet to arrive, I can safely say there’s already a kerfuffle brewing over the book. As Jeff noted in his post last week, folks have already weighed in DISAGREEING with his position. Wait! He has no position! That’s the whole bloody point. It seems an alarming number of people aren’t sure what to do with the 1,350 grams of gray stuff between their ears.

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Relative to last weeks “trivia” post: I’m apparently the tallest Garden Professor, at 72 + 5/8 inches.

The roots of the rhody problem

There were several good shots at analyzing Friday’s unhappy rhododendron.  Mature leaf size can be determined by light levels, as both Lisa B and Tom &  Paul suggested.  Moving a plant from a low to high light environment could cause this change in leaf size.  This rhododendron hasn’t been recently transplanted, however, so we can eliminate light levels as a cause.  (And there was no other impediment to light, such as the presence of shading plants.)

Lack of nitrogen was mentioned as well; but a lack of nitrogen would have resulted in chlorosis in newer leaves as well as smaller leaf size.  In this case, the new leaves are not chlorotic.  (The chlorosis on the older leaves is probably a phosphate-induced iron or manganese deficiency.)

Foy alluded to issues with water…and indeed that’s what I believe is happening with this rhododendron.  Plants that exhibit smaller mature leaves in subsequent years are often limited by water.  Full turgor is needed to force leaves to expand fully; without this physical pressure from inside, leaves fail to expand and once cell walls have lignified, leaf expanion ceases. 

Lack of sufficient water during leaf expansion could be related to irrigation, though in our wet spring climate this is rarely a factor.  More likely is a problem with the roots themselves.  Definitive diagnosis would require digging up the plant to find out whether its roots are still encased in clay and burlap (my guess) or if something else is restricting their ability to grow beyond the planting hole. 

Friday puzzle: unhappy rhododendron

Today we have a diagnosis question. Consider this unhappy rhododendron:

While there is more than one problem with this poor thing, the one I’d like you to think about is why the newer leaves are smaller than the old leaves. (They are fully mature.) There are two parts to this question:

1) What is the physiological reason that the leaves are smaller? (In other words, what is directly causing this difference?)
2) Knowing this, what does this tell you about the underlying problem? (This is related to diagnosing what’s happening in the landscape that you could actually see if you knew where to look.)

I hope that’s not too confusing! I’ll monitor the blog over the weekend and add clarification if I need to.

Answer on Monday!

Breaking up Tree Week with an Important Announcement! (Or Not — depending on how you feel about shameless plugs)

OK, here it is, my one and only shameless plug — because my publisher says: Hey! You need to at least let people know that the book exists!

So — I’m excited to say that my next book, How The Government Got In Your Backyard, which I co-wrote with my good friend (and old college roommate) Eric Heberlig, who is an Associate Professor of Political Science at UNC Charlotte, is finally out.

In case it isn’t immediately obvious, I love to write. This is my fourth book — and in many ways I think it’s my best.  In it Eric and I look at the science and politics behind a number of environmental issues — everything from Plant Patents and Illegal Plants (think marijuana) to Organic Food, Global Warming and Biotechnology.  We look at the political right and left, investigate the science behind what they believe, and try to give unbiased opinions.  Some people have already let us know that we’re wrong!  (Which we find amusing — but that’s another story).

What we don’t try to do in this book is make up your mind for you — that’s your job based on your priorities.

Blog Survey Results, Part 1

I was gently reminded last week that I never published the results of our survey, asking our readers for feedback on the first full year of posting on The Garden Professors. All four of us are extremely grateful to those of you that participated, as we could use this information in our annual reporting and reviews.  Thank you all for taking the time.

To keep this from being too long for our blog, I’m going to just cover the first two questions today.  I’ll continue with this next week, where we’ll consider possible improvements to content and structure.

On the date we ran our analysis, 119 people had responded (the final number was 140).

Reason for reading

Science based information: 107 (90.0%)
Interesting and relevant topics: 101 (84.9%)
Ability to engage bloggers in Q&A: 39 (32.8%)
Usefulness as a CE resource: 75 (63.0%)
Entertaining approach: 78 (65.5%)

Some of the other reasons (you sent us lots!) included:

  • Friday quiz/mystery photos
  • Trusted source of information
  • Balanced and intelligent content
  • Diverse subjects
  • Ability to get feedback
  • Smart, funny, well-written, and challenging
  • Fun science fix

Behavior changes attributed to information on blog

Reduce use of chemicals, including fertilizers and pesticides: 52 (43.7%)
Reduced use of potentially invasive species: 40 (33.6%)
Improved ability to protect soil, including reducing erosion: 47 (39.5%)

Some of the other reasons included:

  • Stopped promulgating horticulture myths
  • Reduced use of peat moss
  • Improved ability to plant trees and shrubs
  • Improved ability to educate others
  • Improved ability to diagnose plant problems
  • More informed decision making about plant selection, gardening methods
  • Less work using better practices

[Sadly for some of you, I did not include the snide personal comments (about me) from trolls, irrationalists and/or the disgruntled. And to be honest, there were only 1 or 2 of these. But if you’re one of this little group, feel free to send your thoughts on to my supervisors! You’ll need to include your actual name and contact information, however, if you want your comments to be taken seriously.]

Valentine’s Day, yet again…

We make fun and call it “National Forced Affection Day” (NFAD) around
our house. But it’s big business.

The National Retail Federation did a survey of 8900+ consumers in their 2011 Valentine’s Day Consumer Intentions and Actions Survey They found that the
average person will shell out $116.21 on traditional Valentine’s Day merchandise this year, up 11 percent over last year’s $103.00. Men spend twice
as much as women. Total holiday spending is expected to reach $15.7 billion. The main categories of consumer spending include $3.5 billion on jewelry, $1.6 billion on clothing (didn’t say what kind, heh!), $1.5 billion on candy and $1.1 billion on greeting cards. $3.4 billion will be spent on dining out. With $1.7 billion worth of  flowers sold, it is, by far, the most important (and stressful) holiday for the floral industry, including growers, wholesalers, and florists.

If you do choose to participate in NFAD,  please spend your dollars in the floriculture sector, but take a look at some of the alternatives to red roses.
Plant-based alternatives, that is. You can choose to follow the herd and cough up $39.95 for a dozen scentless, soon-to-be lifeless red roses. Nothing is more depressing than a vase full of roses with bent neck – that signature wilt that indicates water is not making it all the way to the flower – usually due to a bacterial clog in the pipes.

Alternative: for $19.95, thrill him/ her with a lovely Phalaenopsis (moth orchid) to grace a desk or windowsill. Now, I’ve killed my share of orchids, but this symbol of your affection will last a LOT longer than roses with just a bit of care (indirect light and do not overwater!).


from www.orchidweb.com

Or perhaps a florist Cyclamen – comes in all the requisite VD colors of pink, white, and red. Really tough little plants – if you forget to water them for several weeks, they’ll often just go dormant. Let them rest for a while longer, pull off the dead leaves, and commence reviving them with frequent waterings and a little bit of fertilizer – they will bloom again.

Just some suggestions for those so inclined.  Alas, I know what I’ll be getting…squat, with a big red bow.

Proposed phosphate fertilizer ban – a dissection of the criticisms

A few brave souls gave Friday’s homework assignment a good shot.  Ryan did a nice critique of the bullet points; Kenny did a little digging on WFFF, the organization behind the email; and Tom chimed in with the fact that Israel managed to do this a long time ago without impairing plant health.  Gold stars for all!

Here’s my initial analysis of the statements made, based on reading the bill (which you should do if you haven’t yet; it’s neither long nor difficult to understand):

WFFF: 1) The intent section contains scientifically inaccurate statements, creating a false precedent that turf fertilizer is a significant surface water pollutant and is not necessary for a healthy lawn.

The bill: The legislature finds that: (a) Phosphorus loading of surface waters can stimulate the growth of weeds and algae and that this growth can have adverse environmental, health, and aesthetic effects; (b) Lawn fertilizer contributes to phosphorus loading. Limits on fertilizer containing phosphorus can significantly reduce the discharge of phosphorus into the state’s ground and surface waters; (c) Fertilizer containing no or very low amounts of phosphorus is readily available and maintaining established turf in a healthy and green condition is not dependent upon the addition of phosphorus fertilizer; and (d) While significant reductions of phosphorus from laundry detergent and dishwashing detergent have been achieved, similar progress in reducing phosphorus contributions from fertilizer has not been accomplished.

LCS:There is no identification of the “scientifically inaccurate statements” in the intent section, and as far as I can tell the statements are accurate.  The WFFF statement also misdirects the reader into believing that the intent section states that “turf fertilizer…is not necessary for a healthy lawn” when in fact the section (point c) states that healthy lawns can be maintained with low phosphorus fertilizers.

WFFF: 2) It grants the authority to regulate fertilizer sales and use to the Department of Ecology (Currently, the Department of Agriculture regulates fertilizer content and registers it for sale.)

LCS:  It is unclear why this is a problem; both are state agencies.

WFFF:  3) It changes the definition of fertilizer used by the Department of Agriculture, creating confusion.

LCS:  Where is the confusion?

WFFF:  4) It is inconsistent and will be ineffective because it exempts “natural organic sources.” Organic products are high in phosphorous. The ecosystem cannot tell the difference. All fertilizer should be regulated equally.

LCS:  This is misleading.  Not all organic products are “high in phosphorus”.  Furthermore, the phosphorus in organic matter is usually bound up in compounds that must be degraded before the phosphorus is available, making organic matter more of a slow release material.

WFFF:  5) It fails to recognize the expertise of trained lawn care professionals, who should not be prohibited from providing quality service to their customers, including publicly owned golf courses, parks, and sports fields.

LCS: How is the “expertise of trained lawn care professionals” relevant to the bill, and how is this expertise not being recognized?  In fact, the bill creates increased expert oversight by working with Washington State University Extension specialists (faculty) in setting standards for applying phosphorus fertilizers based on soil test results.

WFFF:  6) As written, it bans the use of phosphorous fertilizer for forestry, house plants, shrub beds, golf courses, sports fields and other uses. It is unclear as to private commercial property.

LCS: Unless there is a demonstrated need for phosphorus fertilizer (i.e. a deficiency verified by soil testing), there is no need to use it.  The routine use of phosphorus fertilizer without establishing a need is the behavior this bill seeks to limit.

WFFF: 7) It bans the sale of phosphorous fertilizer for flower and vegetable gardens, forestry, house plants, shrub beds, golf courses, sports fields, and many other uses.

LCS: Again, unless there is a demonstrated need for phosphorus, it should not be routinely added to any garden or landscape.

WFFF: 8) It bans retailers, including farm stores and ag dealers, from displaying any type of fertilizer containing phosphorous.

LCS: This does not preclude people from purchasing it.

WFFF: 9) It fails to address the primary causes of impaired water quality. Regulating something because it’s easy without addressing root causes of the problem accomplishes nothing.

LCS: This statement fails to inform us what the “primary causes of impaired water quality” are. How do we know that fertilizer runoff is not one of these causes?