Eggplants getting their buzz on

I was checking my eggplants today, and watching the bumble bees getting busy with the large purple flowers. As they flew in, buzzing away, they landed on the flower and kept buzzing — but the note changed, dropping in pitch. The bumble bee hummed away for a while, then flew off to the next flower.

I was watching buzz pollination at work. Egg plants, and a lot of other flowers, don’t leave their pollen hanging out in the open where any ant or fly that happens by could eat it. Rather they wrap them up in little packages that, when vibrated at just the right rate by a buzzing bumble bee, sends the pollen shooting out, so that bumble bees, which pollinate effectively, can access the pollen, but other insects, that would just eat it all, can’t.

In the garden, it isn’t easy to catch a glimpse of the pollen spewing forth, but luckily there are videos. Thank goodness for youtube. Watch it, and next time you are in your garden and hear a bee land in the flower and suddenly change the tone of its buzz, know you are seeing — and hearing — buzz pollination at work.

Observations regarding you-pick blueberries…

We just finished up with our 8^th season of welcoming you-pickers to our back yard, which happens to include three acres of northern highbush blueberries. This has been an interesting venture – helps pay for our farm, obviously, but also presents an opportunity to connect with the “general public” outside of academia [that probably wouldn’t happen otherwise, considering we are both introverts]. Ninety-nine-point-nine percent of the folks that take the trouble to come to a you-pick are fabulous, functional human beings. We are very, very grateful for their patronage, especially since blueberries from Canada are on sale for $1.50/pint at the grocery store and take 5 seconds to plop in your cart. We do, as you might expect, get some interesting questions and comments, and the “OMG! Nature!” thing has come up a few times.

Here’s a selection of our [reasonably patient] responses to not-so-frequently-asked questions and comments that occur while handing out buckets and ringing up sales:

“No, we don’t have to plant them every year like potatoes. They are perennial shrubs.”
“The berries do indeed taste better if they are blue. Green and pink, not so much.”
“No, I cannot weigh you before and after picking to tell how many you’ve eaten in the field. Ha, ha, I’ve not heard that one before.”
“I’m sorry you saw a Japanese beetle.”
“Alas, we do not provide Wi-Fi out in the field.”
“I can’t go pick for you while you watch the sales stand. Sorry.”
“I know the picking season started one week earlier than last year, even though you were on vacation. It’s kind of a weather thing.”
“Nope, there will not be more berries ‘appearing’ later. This is sort of a one-shot deal, they flower in the spring, and that’s what you see here.”
“Yes, there may be some bees around. It’s a farm. We have bees. The name of our business is Bee Berry Farm.”
“No, we cannot put a net over three acres.” (People are very concerned as to how we are not overwhelmed with deer, birds, bears, etc.)
“I’m so sorry your child was stung while poking a stick in a yellow jacket’s nest.” (indeed very scary for all of us involved…especially the poor little guy with the stick.)
“We do not apply chemicals other than water and fertilizer. Pardon? Yes, water is a chemical.”
“Unfortunately, you cannot make your own bushes by planting these blueberries. And no, I’m not familiar with that website.”
“No ma’am, I do not know who placed excess zucchini in your unlocked car.”

Other observations made and behaviors noted:

Small children are usually not excited about roaming through a hot sunny field at 11:30 a.m. Though we salute the parents who think this might be a good experience for them.
Please do not send said hot and annoyed children to stand unattended under the sales tent, staring at the proprietor.
You would be amazed at how sound travels across a hillside; other pickers may or may not want to hear exactly what you think of your mother-in-law.
Please don’t park IN our perennial border.
It’s not fun to find a dirty diaper hiding in the bushes.

Jumping genes!

This spring, I noticed this striped flower in a stand of feral Hesperis matronis
Stripey flowers! And like almost all striped flower variants, almost certainly caused by transposons, aka jumping genes.

To understand transposons, you can think of genes as instructions. So when making a flower, a plant may be following a gene that says:

MAKE PURPLE PIGMENT

And so it does, and the flower is purple.

You can think of a transposon as a gene that says:

COPY ME!

And so the cell makes a copy of the transposon, and then that copy gets dropped somewhere else in the genome. And sometimes, that new copy of the transposon lands in the middle of a gene that does something important. Like, for example, a gene involved in pigment production. So you get this:

MAKE PUR COPY ME! LE PIGMENT

Which doesn’t make any sense. So now the gene for making the purple pigment doesn’t work. And if that happens in a cell in a flower petal, that part of the flower will be white. And as that cell divides, the new cells resulting from it will also have the transposon in place, making more white cells, producing a white patch or stripe in the flower.

When transposons were first discovered in corn by the great geneticist Barbara McClintock, they were thought to be an oddity, something unusual. As we’ve learned more, it turns out they are ubiquitous. Some 40% of the human genome is thought to be transposons. Usually they are invisible, and have been silenced to prevent their moving around and disrupting other genes. But sometimes they pop up in a flower and make themselves visible, in a beautiful, interesting way.

Joseph Tychonievich

Are Soaker Hoses Safe?

By Cynthia Lee Riskin

With drought predicted for the west, southwest, and south through June 2015 (National Weather Service March 2015), many conscientious vegetable gardeners will try to conserve water by using soaker-hoses, those bumpy black hoses that weep water onto the soil through tiny pores.

Soaker hoses are made from fine-crumb rubber, usually recycled from vehicle tires. Research strongly establishes that tire particles leach heavy metals, carcinogens, and mutagenics, among other toxins. Yet soaker hoses have not been studied for potentially increasing the toxicity of edible plants. Are they really safe to use safe on our edible plants?

Soil in the City
Urban soils already contain high levels of heavy metals (Murray et al. 2011) from years of household runoffs—chemicals from pesticides, cars, painting, cleaning, and more. Adding soaker hoses made of crumb tires might exacerbate the problem.

Whether plants take up enough heavy metals to be toxic, however, is a complex equation, depending on a slew of interrelated factors, including:
• Soil pH (Costello 2003) and texture (Singh and Kumar 2006; Murray et al. 2011)
• Temperature (Murray et al. 2011; Lim and Walker 2009)
• The size of the rubber particles (Gaultieri et al. 2004)
• Chemical composition of irrigation water (Singh and Kumar 2006)
Furthermore, the plant species and even the cultivar can affect a plant’s uptake of zinc and other heavy metals (Murray et al. 2009 and 2011).

Growing Healthy Food
If you’re looking for the key to ensuring that your vegetable patch grows healthy food, however, I’m sorry to disappoint you. Too many factors are involved to predict the toxicity of what we grow in our gardens.

A good way to get more information is to contact your local extension agent for a list of laboratories that test soils not only for nutrient composition but for heavy metals. Although this information won’t guarantee you’ll be able to grow heavy-metal-free produce, it’s a step in the right direction while we wait for more research to be done.

Cindy Riskin is a Master of Environmental Horticulture and freelance journalist raising edible plants, an unkempt ornamental garden, and elderly mutts in Seattle, Washington.

NOTE: This article is excerpted from a longer one soon to appear in Cindy Riskin’s upcoming blog, tentatively named Muddy Fingers Northwest. Please contact Cindy Riskin at cindyri@q.com for an advance copy or the blog’s web address.

REFERENCES
1. Costello, Laurence Raleigh. 2003. Abiotic disorders of landscape plants: A diagnostic guide. Oakland, Calif.: University of California, Agriculture and Natural Resources. P. 117.
2. Gualtieri M., M. Andrioletti, C. Vismara, M. Milani, and M. Camatini. 2005. Toxicity of tire debris leachates. Environment International 31 (5): 723–30.
3. Lim, Ly, and Randi Walker. 2009. An assessment of chemical leaching releases to air and temperature at crumb-rubber infilled synthetic turf fields. Albany, N.Y.: New York State Department of Environmental Conservation. http://www.dec.ny.gov/docs/materials_minerals_pdf/crumbrubfr.pdf.
4. Murray, H., T.A. Pinchin, and S.M. Macfie. 2011. Compost application affects metal uptake in plants grown in urban garden soils and potential human health risk. Journal of Soils and Sediments 11 (5):815–829.
5. Murray, Hollydawn, Karen Thompson, and Sheila M. Macfie. 2009. Site- and species-specific patterns of metal bioavailability in edible plants. Botany 87:702–711.
6. National Weather Service Climate Prediction Center. March 19, 2015. U.S. Seasonal Drought Outlook. NOAA/National Weather Service National Centers for Environmental Prediction. http://www.cpc.ncep.noaa.gov/products/expert_assessment/sdo_summary.html.
7. Singh, S., and M. Kumar. 2006. Heavy metal load of soil, water and vegetables in peri-urban Delhi. Environmental Monitoring and Assessment 120 (1-3):1–3.

Spec errors mount

For years I subscribed to Consumer Reports. I appreciated their objective approach to product testing and lack of advertising. In their own words, their policy is to “maintain our independence and impartiality… [so that] CU has no agenda other than the interests of consumers.” But recently they’ve veered off the science-based trail – at least the one running through our gardens. Their approach to plant and soil sciences is more pseudo than science. And last year, after 30+ years of loyal membership, I quit my subscription when Consumer Reports began partnering with Dr. Oz (see here for instance ).

So until today I’ve been blissfully unaware of whatever CR has published on gardening and garden products. Then this post appeared on our Garden Professors blog group page ). I’ve included some of the article below along with my italicized comments in brackets.

“Lawn care without the chemicals: rid your yard of weeds and pests with these mostly organic solutions”
“…Here are 10 common weeds and pests that plague homeowners nationwide, along with chemical-free measures [“chemical-free?” Well, we shall see.] that should be effective in bringing them under control. For more information, go to the websites of Beyond Pesticides and the Great Healthy Yard Project. [Neither of these two sites is remotely scientific or objective.]

“Dandelion – what is it? A perennial weed whose common yellow flowers turn to windblown seed. Telltale signs. Though a handful of dandelions is no big deal, a lawn that’s ablaze in yellow has underlying problems that need to be addressed. How to treat. Like many broadleaf weeds, dandelions prefer compacted soil, so going over the lawn with a core aerator (available for rent at home centers) might eradicate them. [Like many broadleaf weeds, dandelions will grow anywhere. That’s why they’re called weeds.] It also helps to correct soil imbalances, especially low calcium.” [I’m curious how CR determined a “soil imbalance.” And did they test their hypothesis experimentally?]

Dandelions obviously suffering in a calcium rich soil

“Barberry – what is it? An invasive shrub with green leaves and yellow flowers, often found in yards near wooded areas. Telltale signs. Left unchecked, the shrub’s dense thickets will start to choke off native trees and plants. How to treat. Cut back the stems and paint their tips with horticultural vinegar or clove oil (repeated -applications may be needed). Burning the tips with a weed torch might also work.” [Yes! Chemical free vinegar and clove oil! By the way, clove oil has NO demonstrated efficacy for this application. And I’m sorry, but “burning the tips” of barberry is just going to stimulate lots of new growth below the damage. Just out of curiosity, how many people have problems with barberry in their lawn?]

I think you’d notice this in your lawn…

“Crabgrass – what is it? An annual weed with a spreading growth habit. It’s common in the Northeast, in lawns with poor soil conditions. Telltale signs. Lots of bald spots, especially after the first freeze, when crabgrass dies off. How to treat. Have your soil tested. Lime or sulfur may be needed to adjust the pH. Aeration is also recommended. Corn-gluten meal, applied in early spring, can be an effective natural pre-emergent herbicide. [Corn gluten meal, applied in early spring in climates where it rains, is an effective fertilizer for crab grass.]

Crabgrass with increasing levels of corn gluten meal.
Courtesy of Tom Cook, Oregon State University.

“Kudzu – what is it? An aggressive climbing vine that’s common in parts of the Southeast and the Midwest. Telltale signs. The thick vine forms a canopy over trees and shrubs, killing them by blocking out sunlight. How to treat. Pull out the vine and, if possible, its taproot. Be sure to bag and destroy the plant or its vines will regerminate. If the root is too thick, paint the stump with horticultural vinegar or clove oil repeatedly, or burn it with a weed torch.” [Ditto the comments for barberry.]

Have fun painting stumps. (Wikimedia)

“Canadian Thistle – what is it? An aggressive creeping perennial weed that’s found throughout the U.S. Telltale signs. Look for outbreaks in vegetable gardens, particularly those with peas and beans. [I have no idea where this little nugget of nonsense came from. It’s a weed! It will grow ANYWHERE! It doesn’t need peas and beans!] How to treat. Repeated hand weeding and tilling of the soil will weaken its extensive root system. [Because tilling the soil is such a great way of suppressing weed seed germination. And it’s really good for your lawn, too.] Planting competitive crops, such as alfalfa and forage grasses, will keep it from returning.” [Yes, do replace your lawn with alfalfa and forage grasses.]

Your new, improved lawn (Wikimedia)

“Fig Buttercup – what is it? A perennial weed with yellow flowers and shiny, dark green leaves. It’s common in many parts of the East, Midwest, and Pacific Northwest. Telltale signs. The weed will start to crowd out other spring-flowering plants. It can also spread rapidly over a lawn, forming a solid blanket in place of your turfgrass. How to treat. Remove small infestations by hand, taking up the entire plant and tubers. For larger outbreaks, apply lemongrass oil or horticultural vinegar once per week when the weeds first emerge. It might take up to six weeks to eradicate.” [Now in addition to pouring vinegar on your lawn, we’ll try lemongrass oil instead of clove oil. Another unsubstantiated application – maybe lemongrass because buttercups are yellow? Makes about as much sense as anything else. It smells nice though.]

Color coordinated weed control

“Phragmites – what is it? An invasive grass species found nationwide, especially in coastal wetlands [where so many of us have lawns]. Telltale signs. Dense weeds can crowd out other plant species without providing value to wildlife. How to treat. Cut back the stalks and cover the area with clear plastic tarps, a process known as solarizing. Then replant the area with native grasses.” [Solarizing pretty much nukes everything that’s covered – not just the weeds. In fact, the rhizomes of this weed are so pernicious I’m not sure that solarization would work. Am still waiting for CR to test their hypothesis in an objective and scientific manner.]

Phragmites rhizome (Wikimedia)

So, Consumer Reports, I’d love to come back to you. But until you start applying your own standard of objective rigor to everything you cover, I’ll have to pass.

Walnut warfare

Recently, a question about using black walnut chips for mulch was posted on our Garden Professors Facebook group page. As gardeners know, black walnut has a reputation as a chemical warfare species that will kill anything growing underneath it – a phenomenon called allelopathy. So it’s logical to wonder about the lethality of walnut chip mulches.

To get a good feel for the science behind black walnut’s allelopathic abilities, I was fortunate to find a relatively recent review on the topic (Willis, R.J. 2000. Juglans spp., juglone and allelopathy. Allelopathy Journal 7(1):1-55.). This well-written review includes a fascinating section on the historical background of walnut allelopathy, which was first mentioned in 36 BC by the Roman author Varro. But the science of allelopathy really started less than 100 years ago, when a Virginia researcher noticed the injury caused to tomato plants growing near black walnut (Juglans nigra) in his home garden. Subsequent experiments by him and others suggested that the orangish hydroquinone juglone leaching primarily from leaf litter and hulls.

Source: Wikipedia.

The research results on walnut, juglone, and allelopathy have been nothing if not inconsistent. For every report of toxicity in an exposed species, another report found no effect. In fact, much of the supposed allelopathy might instead be due to walnut’s highly competitive root systems, which could suck up available water and nutrients over a vast expanse of soil.

Source: Flickr user davidburn

There are a number of other factors that help account for ambiguous results:

1) Juglone is not the only secondary metabolite produced by walnut species. They are loaded with a number of untested phenolics, flavonoids, alkaloids, terpenes and other quinones which could have allelopathic activity.
2) Juglone concentrations vary greatly among walnut species. They also have seasonal variability in the same individual.
3) Light conditions, rainfall, soil chemistry, and many other abiotic factors can influence juglone levels.
4) Organic matter and clay particles in soils can bind juglone, reducing its movement within the soil.
5) Microbial activity breaks down juglone.

Carefully controlled laboratory experiments can demonstrate juglone allelopathy to a number of plant species, especially at the seedling stage. However, there is little evidence from landscape level research to suggest that allelopathy is the reason that plants are damaged by being in proximity to walnut trees. In fact, the author of the review study concludes that even though Juglans species provides the best known and most widely accepted example of allelopathy, there is “still is no unambiguous demonstration of its effect” as “no one has as yet demonstrated that juglone is actually taken up by plant roots.”

Source: Wikipedia

Where does this lead us in our discussion of walnut mulch toxicity? Fresh hulls and leaves appear to be the primary source of allelopathy, but not the wood. And even these sources may be quickly neutralized by soil conditions. Therefore, a walnut chip wood mulch should pose no danger at all to landscape plantings.

Cross-pollination making you cross?

No, your cucumbers have not hybridized with your melons.

I’ve been fielding different versions of the same question a LOT lately.
Three different people have sent pictures of “cucumelons” telling me they planted cucumbers next to their melons, and now the cucumbers look strange, so they’re concerned that they have cross pollinated with the melons. One person planted what was supposed to be a red raspberry next to their yellow raspberry, but the new plant is producing yellow fruit, so they think that it must be cross pollinating with their yellow plant, causing the fruits to turn yellow. Not to mention similar queries about tomatoes, peppers, and watermelons. It seems like every time a piece of produce turns out looking differently than what people expect, they blame pollen from the plant next to it.

I’m sure the highly educated readers of The Garden Professors know this already, but to clarify, there is a very simple reason why you don’t need to worry about one plant pollinating another plant and changing the quality of your produce UNLESS you are planning on saving seeds to grow for the next year.

When a flower is pollinated and starts developing into a fruit full of seeds, it is only the seeds themselves that combine the genetics of the two parents to develop into something new. Everything else – the flesh of a tomato, or cucumber or melon or raspberry – is produced solely by the mother plant, and the daddy of those seeds inside doesn’t matter a bit. Think about when a woman is pregnant… the identity of the father of the child inside her doesn’t change the character of the skin of her belly.

If you want to save seeds of your plant for next year, it is another matter, and you should be sure to isolate or (better yet) hand pollinate different varieties of the same species from each other to make sure they don’t hybridize unintentionally. You still don’t need to worry about your cucumbers and melons, however – they won’t hybridize by chance in your garden. If a plant doesn’t produce the right colored fruit or flower, most likely it was just mislabeled at the nursery. Grow a strange looking cucumber, chances are it was left on the plant too long. Cucumbers are harvested and eaten when young and immature, leave them too long and they get… strange looking. No need to blame it on the melons next to them.

There IS one exception to this, one common plant in the garden where the source of pollen makes a huge difference in what you harvest: Corn. Corn is the exception because what we’re eating is the seed itself, not the fruit produced by the mother plant surrounding the seed. That’s why if your sweet corn gets a dose of pollen from the field corn the farmer is grown next door, it comes out starchy and not sweet.

It also makes breeding colorful corn for fall decorations REALLY fun… Because when you see a multicolored ears of corn like this from my garden last year:

You can carefully pick out just the seeds showing the colors you like best, say the palest blues and pinks, sow them together the next year, and get something looking like this:

Or plant all the darkest kernels together and get this:

Spring = really?

You've got to be kidding... — Bebe the Wonder Dog says “You’ve got to be kidding…”

I’m sorry I’ve been so quiet, but I am not feeling SPRING. Here in the Blue Ridge of Virginia (Zone 6), March is averaging 10 F below average. Snow and ice is piled up on the north side of buildings. My Herbaceous Landscape Plants class is not impressed by the inch-tall Mertensia and the fact that the only thing we can call a cool-season annual (pansies/violas) is brown mush. All the delightful Zone 7 things I’ve been pushing on people for several years here – er, whoops. This is as far north as I’ve ever lived (please don’t mock me Bert). I’m tired of bales of laundry. Flannel sheets, corduroy, fleece…I am NOT good with winter. I admit I am at my best with only one layer on. And if one more person says “at least we’ll have fewer ticks”…
*snap*

Re-using containers? A cautionary tale.

I attempted to clean up our little home greenhouse over the holiday break. There’s no good place to recycle pots around here, and I hate throwing them away…so I suffer from container build-up. Figured I’d sort through the haphazard pile in the corner of the greenhouse, wash and re-stack the useable ones, and finally ditch the busted ones.

As I started separating the first stack, I noted a tiny flash of red. It is well-known and oft-reported among my gardening and grower buddies that the Southern Black Widow (Latrodectus mactans) really enjoys a nice stack of grubby pots. But I hadn’t seen one in quite a while, and not at our current location.

Boy, did I hit the jackpot.

I’m not afraid of spiders. At all. Quite fond of them, actually – they are immensely useful and fascinating critters. And only a very few pose any kind of danger.
In the case of the Black Widow, a bite injects a neurotoxic venom (latrotoxin). The bites and ensuing symptoms are allegedly quite painful, though rarely fatal. In this instance, I chose not to sacrifice my comfort for our collective edification, i.e. “How Bad Can it Hurt?” (see Blister Beetle post).

So, I squished her. But felt pretty bad about it.
As I worked through the stacks, I found another.

Shook her to the floor and did some more tap-dancing. Perhaps it was time to stop taking pictures and put some gloves on.

By the time I got through the entire pile, I’d found and mushed thirteen of them, sized small through pretty darn large. The landscape fabric on the greenhouse floor was peppered with little beige, black, and red blobs (you don’t need to see that photo).

There were none in the stacks of shiny new nursery pots I’d ordered for our blueberry transplants. But if there was some growing media or plant debris still stuck inside, there was a high probability of finding a spider.

Moral of this story? Think twice about leaving a bunch of dirty plant containers piled up. A simple hosing out before I’d stacked them would have probably prevented such a large infestation.

There’s also a significant chance that I will forget all about the need for caution the next time I’m potting up stuff. Which may lead to an even more educational and entertaining blog post, where I describe “Adventures In Lactrodectism.” Because I’m sure I missed a couple, or they’re hiding in the gravel. As the old saying goes,

“Seeing a spider isn’t a problem. It’s a problem when it disappears.”

Sheep-eating flowers?!

I was planning to follow up on Jeff’s phosphorus post with a bit more “phun with phosphorous.” However, I was completely derailed by Ray Eckhart’s message and link left for me on our GP facebook page with this headline:

RHS ‘sheep-eating’ plant about to bloom in Surrey

“The Royal Horticultural Society (RHS) at Wisley said the Puya
chilensis, a native of Chile, would bloom in the next few days and last
about a week.

In the Andes it uses its sharp spines to snare and trap sheep and other animals, which slowly starve to death.”

“The animals then decay at the base of the plant, acting as a fertiliser.”

[Dear BBC News: “Snare” and “Eat” are not really interchangeable]

How…have I not heard of this before.

I’ve posted previously on my Puya fixation. I asked readers to bet on how long it would take for me to kill my wee Puya bertoniana, mail-ordered from Annie’s Annuals. I am happy to report that it made through the winter (greenhouse) and is now sunning itself on our deck.

Now this really ups the ante – it captures sheep! Maybe P. bertoniana isn’t as robust as P. chilensis though. Perhaps…a vole or rabbit?