Knock It Off – Page 8 – The Garden Professors™

Out of the lead frying pan and into the phosphate fire

A recent NYT post reports that adding fish meal to lead-contaminated soils will cause the lead to bind to phosphate found in fish bones. As the article explains, this chemical reaction results in the formation of pyromorphite, “a crystalline mineral that will not harm anyone even if consumed.”

Given my concerns about excessive phosphate loading in urban soils, I contacted Dr. Rich Koenig, an urban soil scientist and chair of WSU’s Crop and Soil Science department. I wondered, at least, if the article should have directed people to have a soil test done first to determine how much phosphate was already in the soil before adding more.

Dr. Koenig was likewise concerned that the application rate of fish meal was probably far higher than what plants would require, thus increasing the risk of phosphorus leaching and runoff. He also referred my question to Dr. Jim Harsh, a soil chemist in his department familiar with the process described in the article.

And as Dr. Harsh pointed out, it’s important to make lead less susceptible to uptake by people and other animals exposed to contaminated soils. However, he’s unconvinced that phosphate is the best choice; in fact, research by Dr. Sally Brown (cited in the NYT article) and others (including Dr. Harsh) have found that compost containing iron is also able to bind and immobilize lead. The advantage of high iron compost is that iron will not leach into nearby waterways, nor cause the same kinds of plant toxicity problems, as phosphate can.

Thanks to both Dr. Koenig and Dr. Harsh for their quick and informative responses on this topic.

Consternation in the You-Pick Field

It’s high season at our blueberry farm. Each morning, the yard fills with cars (at 7:00 a.m. – aargh) and eager blueberry pickers hit our four acres of Northern Highbush berries. No late freezes, lots of hard work by our honey bees, and good rainfall have added up to a blockbuster crop. Certainly helps with the mortgage.

Running a you-pick ( U-Pick makes me itch) farm is an …interesting experience. Upside – you do the picking, we weigh the buckets, we take the money – $2.40/lb + tax. Very reasonable for big, fat berries. Our average sale is right around 10 lbs. I’d (theoretically) invite 90% of our customers to stick around for dinner – they’re that nice. Downside, besides hot, grumpy children, bee stings, and porta-potties: some people literally eat their way across the field. We absolutely expect pickers to taste a few as they go. That’s part of the you-pick experience. But I have witnessed some remarkable acts of blatant face-stuffing. Kids, I can kind of understand, but adults? I mean, do you eat your way through the produce section of the grocery store? The truly noble customer recognizes this and offers an extra dollar or two (“Gosh, I may have eaten a lot”). But the clueless #%$& who eats with both hands for an hour and then pays for a pound makes us a bit queasy. We get reports all the time from concerned customers i.e. “See that guy in the brown hat? He’s eating more than he’s picking.” One incident that comes to mind is a lady that completely denuded a 6′ plant; encouraging her daughter to eat the whole time, and then paid for less than a pound.

We try not to sweat it – maybe it’s a compliment as to how good our blueberries are – but it still puzzles me. What am I missing here? Why is this acceptable? Taking a tip from another local farm, we put out a jar near the register last week. They call it a “sin jar” but that’s a little too judgmental for us. We call it “munch money” and note that the contents of the jar goes to our local woefully-underfunded animal rescue and shelter. We make a donation yearly anyway; now it’s more fun (and satisfying), served up as a gentle nudge – we raised $120 for the shelter over the 4th of July weekend alone!

Right Plant, Wrong Place?

It’s (apparently) Dead Tree week here on the GP!

[To my GP colleagues…we should make “Right Plant, Wrong Place” one of our categories, sort of like “Knock it Off.” Or maybe just “Dead Plants in Action.”]

Exhibit A:

Some unhappy little Magnolias. Drip irrigation was running, which leads me to believe salt spray is the culprit.

I was pedaling my sweet Electra beach cruiser down the sidewalk on Cape San Blas, Florida (or Cape San Blarrrgh, if you caught my post last week) and happened upon this tragedy. In the background is natural coastal sand pine scrub including saw palmetto and myrtle oak. Growing on nothing but sand and a bit of decaying organic matter, 300 yards from the ocean, these are tough plants. Pretty darn salt tolerant. Cabbage palms, also very salt tolerant, marched along the sidewalk. Southern magnolias had been planted in between, and they weren’t faring as well.

Just like “deer resistant,” “salt tolerant” is a rather vaguely-defined grouping of plants. You can find list after list on the interwebs and in the back of nursery catalogs and reference books. The source of the information is rarely confirmed, and if so, it’s the same Extension publication that has been cut and pasted to death. Degrees of salt tolerance are further described as “high,” “moderate” and sometimes “low” without any quantitative parameters (a range of soil electrical conductivity perhaps?). There are tremendous scientific resources (including funding) devoted to breeding for salt tolerance of food crops like rice, barley, and soybeans. Ornamental plants are pretty unimportant in the grand scheme of things (like the global food supply) thus the mere smattering of practically unfunded research out there, leaving us with only anecdotal evidence. Though some lists have M. grandiflora listed a “moderately” salt tolerant, I vote to move it to “low.”

Vinegar: A Garden Miracle!

I’ve been working with homemade garden remedies in one context or another for about 10 years now. As someone who has spent days searching for odd cures to garden problems I consider myself qualified to say that, of all of the remedies I’ve seen, vinegar seems to be the product with the most (supposed) uses. You can kill weeds with it, as well as plant diseases and insects. You can also use it as a fertilizer or even to acidify your soil. It’s amazing! But which of these uses are real and which are just someone flapping their jaws?

Vinegar as an herbicide: White vinegar which is about 5% acetic acid and does a nice job of burning the tops of plants, but not their roots – so a larger weed will live right through a spray even though it will look bad right after the spray. You can buy 20% acetic acid. It works faster, but it has essentially the same problem killing larger weeds that that 5% acetic acid does. Besides efficacy issues there are safety issues also. I’ve used 20% acetic acid and I think that this stuff is too dangerous for the average person. A little in the eyes could cause permanent injury. Just a little whiff of it is enough to make the nose start running (in other words it’s not good for mucous membranes).

Vinegar as a disease control: What a great idea! Spray something that kills plants onto your prized petunias to control disease! OK, when you use vinegar as a plant disease control you do use a lower concentration which shouldn’t hurt the plant. But vinegar has never proven to be particularly effective at controlling plant diseases.

Vinegar as a fertilizer: Nope, doesn’t work. Acetic acid only contains carbon hydrogen and oxygen – stuff the plant can get from the air. The other things that may be in vinegar could be good for a plant – but it seems an expensive method of applying an unknown amount of nutrition.

Vinegar as a soil acidifier: This is one that I’ve seen a lot – and so I tried it. In a nutshell, it just doesn’t work that well. It takes a lot of vinegar and the pH change is brief at best. Use something like sulfur instead.

So to summarize, despite a lot of recommendations, the only thing that vinegar has really proven to be good at is killing weeds – and then only if the weeds are young.

Upside: I’m Two Pounds Lighter!

Cape San Blas
mullet and bass
cheap sunglass
sand flea and crabgrass
beachy landmass*

Had big, relaxing fun last week in the greater Port St. Joe/Cape San Blas/Apalachicola region of the Florida panhandle (billed as the "Forgotten Coast" or more locally "Florida’s Last Stand"). The bays are filled with fishies, the gulf is turquoise and rimmed with soft white sand. Highly under-developed, it’s truly paradise for anyone who likes to boat, fish, kayak, and run with your hounds on empty, wide, dog-friendly beaches. I’ve got fodder for a couple of posts, but will postpone the flora/landscape observations until next week.

The news of the awful outbreak of a particularly virulent and dangerous strain of Escherichia coli in Europe coincided with my own mid-vacation, not-so-pleasant experience. Twenty-four hours of bed-bound, trash-can-gripping, don’t stray far from bathroom non-activity while paying for a beach house and boat rental gave me some time to think deep thoughts about food safety. Salad, meat, seafood, and cream sauces were all involved. I could have ingested one of any number of sweat-and-barf-inducing microorganisms. Being off food and drink for another couple of days wasn’t ideal either. I didn’t go on vacation intending to detox (rather, "to tox"). But at least I was up and about. Renal failure and death takes the E. coli strain O104 to a whole ‘nother level.

In digging for a bit more information, the usual safe food handling advice has been trotted out in regards to this vicious beast; wash, peel, cook, etc. But a microbiologist at a Scottish agricultural research center (The James Hutton Institute) has noted there are strains of E. coli “associated with plants, not animals.” Dr. Nicola Holden says that the bacteria “are not simply sitting on the surface of the plants and are particularly difficult to remove post-harvest.” She goes on to state that these particular bacteria colonize the root system and then “have the opportunity to move to the edible foliage or fruits.” Yes, E. coli is a motile organism; that’s one way to get from the soil to your salad, but there is evidence it can invade the tissue and move within the plant; no amount of peeling or washing will help. Dr. Jeff LeJeune’s lab at Ohio State was taking a look at this several years ago, especially how E.coli can enter through points of damage from mechanical injury or plant pathogens. Haven’t had a chance to dig any deeper, but will be having a chat with a friend from our Food Science and Technology Department to find out more.

*apologies to the Car Talk guys, but I always wanted to do that.

Exploding watermelons and exploding hysteria

One of our loyal blog readers passed on this interesting article about exploding watermelons in China. Seems that Chinese farmers have been overapplying a synthetic growth regulator which has led to the of proliferation of plump pepos (gotta love alliteration!). Of course the media has “blown” this out of proportion with action verbs like “explode” and “erupt”, when what’s actually happening is that the melons are merely splitting. (It’s a pretty boring video if you take time to watch it.)

Ok. This isn’t to defend the practice of misapplying any chemical. But the fear generated is obvious in the comments on this video – just scroll through them. The growth regulator in question is forchlorfenuron – a cytokinin legal in the United States and approved for use in very low concentrations on kiwifruit and grapes to enhance fruit size, fruit set, and cluster weight. It’s been approved for use in the US since 2004 and has been tested extensively prior to that approval for human and environmental safety.

Fruit split happens all the time during ripening. I’m sure most of you have seen this yourself, like when your tomatoes are overirrigated or cherries get unseasonal rain. And it can happen when growth regulators – natural or synthetic – are misapplied. But the fruit isn’t dangerous. It just looks bad, and might not taste that great, either.

There are lots of things to worry about out there. But growth regulators used in fruit production really aren’t one of them.

A rant about urban farming

(I know this one will get me into trouble…but hey, if I don’t tick someone off I’m not doing my job.)

I have mixed feelings about the increased popularity of urban farming. On one hand, I love the idea that people are becoming more involved in producing their own food. But on the other hand, the naivety of many urban farmers is scary – because they assume that home-grown food is safer and/or healthier than what they can buy at the market.

I give a lot of seminars every year, on a lot of different topics. At the end I usually have a room full of happy people, asking lots of questions and eager to go apply the new knowledge that they’ve gained. But one talk I’ve done has exactly the opposite effect. It’s the seminar I give on vegetable gardens and heavy metal contamination of urban soils. The audiences are subdued and worried. It doesn’t make me feel very good, but on the other hand I know I’ve got people thinking.

Heavy metal contamination of soils is insidious. Like the iocane powder in The Princess Bride, these compounds can be odorless and tasteless…and deadly. Lead, arsenic, cadmium, and a handful of other heavy metals are the legacy of centuries of “civilized” living. Mining, smelting, manufacturing, and driving all contribute to localized toxic hot spots. Unlike organic contaminants, heavy metals are elemental. They don’t break down and go away. The lead from gasoline fumes of the past is still found along roadsides; the arsenic from early pesticides still lingers in soil used for field and orchard crops. Many plants not only take up heavy metals, but accumulate them in their tissues.

It’s easy to avoid heavy metal problems: soil tests are the logical first step. If soils are contaminated, you can build raised beds or use containers with clean, imported topsoil or other growing media for vegetable gardens. Likewise, you might want to take care in buying produce from farmer’s markets – ask questions about possible soil contamination.

So by all means, grow your own vegetables – save money and take satisfaction in producing your own food. But be careful out there.

Tuesday Quiz!

I think I’ll stay on the invasive species track. And in honor of finals week, here’s a wee quiz for you.

1) What do we have here?*

hint – it’s a naughty plant

2) Why can’t federal/state designations be somewhat uniform?**

Exempli gratia:

“[This plant] is listed by the U.S. federal government or a state…" – USDA Plants Database

Connecticut: Invasive, banned

Massachusetts: Prohibited

Montana: Category 3 noxious weed

New Hampshire: Prohibited invasive Species

Oregon: "B" designated weed; Quarantine

Washington: Class C noxious weed

*scroll down for answers…

[scroll]

[a bit more]

* Iris pseudacorus. Yellow flag iris. Loves wetlands. Spreads like crazy via rhizomes and seeds. Possible inspiration for the fleur-de-lis.

** I don’t know. It’s very confusing. "Banned" seems more alarming than "prohibited", I suppose. Is "B designated" less a concern than "Class C"? Feel free to weigh in.

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.

Mulch much?

[Try to say post title three times fast. Heh.]

Here on the GP blogski, we’ve discussed both the merits and shortcomings of many non-traditional forms of mulch; rather, stuff that covers the ground that is referred to as mulch. Shredded rubber, marble chips, lava stone, dyed lava stone (ick), etc.

But this is a new one on me:

Naturally, I immediately shoved my hand in the biggest tub of glass (part of the Scientific Method). It was not…super smooth. A couple of pieces stuck, and there was a bit of sparkly-dust residue. I tried to remember not to rub my eyes for the rest of the day. Not sure I’m buying the recommendation to “use in pathways.”

"Aaargh! My Eyes!"

Pretty colors…soooo shiny. And recycled!

What’s this? A warning label on the aqua mulch: “Parents, please watch your children’s hands around the glass mulch.”Whoops.