The Garden Professors™ – Page 91 – Advancing the science of gardening and other stuff since 2009

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.

Trees: Dead or Alive

In light of the comments on Dr. Jeff’s latest post (When Trees Don’t Know They’re Dead), especially those by Shawn, Ed, and Dr. Linda, I absolutely have to post this.

To the best of my knowledge, the number of stand-up comedian bits related to tree health can be counted on one finger. Here it is, transcribed, as close as I can without having Linda ban me from the blog/WSU server.

Ron White is a big, bawdy, laid-back Texan, permanently armed with a cigar, glass of scotch, and high-beam smile. I think he got thrown off the Blue Collar Comedy tour for not being red-necky enough. However, not recommended for the easily or moderately offendable. Anyhoo, here goes, and it suffers without the drawl…

****
From Ron White’s You Can’t Fix Stupid recording
(verbatim, mostly):

I was having a fight with the landscape guy because, like, half the plants died…you know it cost tons of money and half the plants died. And the guy is fighting with me over whether or not a tree is alive or dead. Can you believe that bleep? We walk over to two trees, there’s not one leaf on either one of them except [you look toward the] timber [where the] the forest is a-blooooom.

I said “those two trees are dead right there.”

He goes over to one of the trees and scratches the trunk with his thumb and comes back and says this, and I quote: “The core of this tree… is still alive”. [Long pause]

I said “Let me tell you what I’m looking for in a bleeping tree.”

[lotsa laffs]

I’m looking for tree that you can tell is alive even if you don’t know bleep about trees.

I don’t want to spend the next two years every time somebody comes over to our house “… oh no, those trees are fine right there – go scratch the trunk with your thumbnail. You will find a vibrant core. Just beneath the bark.”

******

Science Education and Lichens

Seemingly once a week we see a report in the news about how Science and Math education in the US lags behind many developed countries around the world. http://articles.cnn.com/2011-05-15/us/education.obrien.response_1_math-and-science-national-robotics-competition-education?_s=PM:US

While we typically think of Chemistry and Physics when discussing science education, biology is in there too.

I bring this up because I am continually amazed at how little many people know about basic biology. Some of this funnels its way into extension calls and e-mails. A couple of weeks ago I got a call from a distraught homeowner in a Detroit suburb. “My maple trees are dying”, he told me sincerely. “There are growths all over them. They’re big trees. What do I need to do to save them?”

I tried to get as much information as I could over the phone: How old are the trees? What kind of maple? Describe the site. Describe the symptoms. I told him the problem didn’t sound like typical issues with maples in our area (i.e., not manganese chlorosis, tar spot, gall mites, or verticillium wilt). Diagnosing problems sight unseen is difficult so I asked if he could get me some digital photos. “Yeah, my son has a digital camera. We can do that.” Later that week I got a series of digital photos like the one below.

Lichens on maple

I informed him the growths on the trees were lichens, a combination of a fungus and algae; they’re normal and they don’t harm trees. I gave him a quick biology lesson on lichens and pointed out that some of the pictures he sent were of lichens growing on the sidewalk. The algae part of the lichen is photosynthetic so they just need a place to hang out – a tree, a sidewalk or a piece of wood all work fine.

British soldier lichens

One of my all time favorite bumper stickers says, “If you think education is expensive, try ignorance”. I suspect if this homeowner had happened to call an unscrupulous tree service instead of MSU Extension, they would have been more than happy to ‘treat’ the problem and sign him up for their deluxe 8-step pest and micro-nutrient maintenance plan. Sometimes a little knowledge can go a long ways.

When Trees Don’t Know They’re Dead.

Last week a neighbor of mine called me up to ask how likely it was that their 4 year old (or so) crab apple tree was dead. Sometime over the course of the winter cute fuzzy bunnies had decided that the tree’s bark was tasty and decided to eat it. Naturally they ate it all the way around the circumference of the tree with the exception of a strip about an inch wide. At this point you’re probably asking yourself why the neighbors suspected the tree might be alive. The reason they were calling me was that the tree was leafing out– so they figured that maybe the tree would make it — that maybe, just maybe, it wasn’t as bad as it looked. My answer — Sorry, the tree is dead, it just doesn’t know it yet. As a rule of thumb you can have up to a third of the circumference of a young tree girdled and the tree has a decent chance of growing out of it. More than that and, though the tree might live for a few years, you’re dealing with so much damage to the vascular tissue that you’re just putting off the inevitable by not cutting it down. A tree with as much damage as my neighbors tree had was just going through the motions.

When bark is eaten what is destroyed is the phloem — the tissue which carries the carbohydrates made by the leaves down the plant’s stem. The cambium — which creates new phloem and xylem — is also destroyed. But the xylem — the innermost tissue which transports water and nutrients up the stem — is left largely intact. So girdled trees will flush out in the spring (using resources provided by the xylem), perhaps even two springs, but ultimately the tree will succumb.

But there is an up-side! Girdled trees will be under a lot of stress. Stressed trees tend to flower heavily — so enjoy the show first, then cut down the tree.

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.

Creating a sense of place

As many GP readers know I’m originally from Olympia, WA. Once a week or so I troll through the on-line version of my hometown newspaper, the Daily Olympian (“the Daily ‘O’” for short or, more commonly, “the Daily Zero”) to keep up with latest happenings back home and to see if any of my high school classmates are on their way to jail. While none of the Olympia High Class of ’78 made the news recently, my interest was piqued the other day by the headline “Saving the world – from weeds”. The article described the Earth day efforts of local grade-schoolers to eradicate Scotch broom from a local nature trail.

http://www.theolympian.com/2011/04/23/1626461/saving-the-world-from-weeds.html#storylink=misearch

For those that are not familiar, Scotch broom is an exotic shrub that commonly invades disturbed areas throughout the Northwest. It’s been a problem for years and, even as a kid 40 years ago, I remember every cutbank around town covered with the nasty yellow blossoms. In doing a little trolling on the internet I was surprised (stunned is probably a better word) to learn that there are parts of the country where Scotch broom is still sold as an ornamental shrub – named cultivars and all. There are commercial cultivars of dandelion after all, so why not?

As we’ve noted here on the GP blog, there are lots of layers of complexity to the native/non-native discussion. In many cases I think native advocates have over-sold the ecological side to the argument. But the Daily O article got my dander up; not because 4^th graders were pulling up Scotch broom – good riddance and keep up the good work kids – but because the Scotch broom was replaced with trees and shrubs that were all exotics in that part of the Northwest.

Native plant advocates often downplay the ‘sense of place’ argument in promoting natives. I suppose they feel the ecological arguments are based on ‘harder science’ and therefore more convincing. While it can be argued that native plants have adapted to the environment in which they evolved; it’s not always a given that the native conditions still exists, particularly in the built environment. What’s beyond argument, however, is that trees and other plants provide a connection to the natural world around us and, for lack of a better term, do give us a sense of place. From my personal experience, I have a visceral reaction to the sight of Scotch broom or English ivy in the Northwest where I’m native. Here in Michigan, on the other hand, I’m less bothered by exotics – even some that may be considered invasive. I suspect many native-born Michiganders have the opposite reaction.

I’m sure part of my connection to all things Washington stems from lessons learned in school (I still know all the lyrics to ‘Washington my Home’ and my plant collection form Mr. Chance’s high school Botany class is still somewhere in the attic of my parent’s house). Which is why I was flummoxed by the schoolkids planting tulip poplars and sequoias instead of big leaf maples and western redcedars. Wouldn’t this exercise have been a great opportunity to teach these young people about the great trees and shrubs that are native to the Northwest and to give these kids a sense of place?

Solution to Friday’s flower fuddlement

Ed and Gayle correctly pointed out that short day plants (those that bloom in the spring or the fall) can sometimes do both. The asters probably experienced some transplant shock in the fall, which would have suspended floral bud development. This phenomenon could also be due to mild winter conditions (as Ed and Gayle also mentioned), which could have spared flower buds normally killed by freezing temperatures.

In any case, as spring daylengths approached those found in the fall, flower development continued and voila! Asters in the spring! Likewise, there are a number of spring bloomers that sometimes have a second (usually reduced) floral display in the fall.

Thanks again to Ginny for sharing her photographs and information!

Floral fuddlement

Gardeners love asters as part of their autumn floral palette. Yet these native asters are blooming now – in the spring!

These specimens were purchased last summer and planted in the fall in Florida. Why might they be blooming out of season?

Reader Ginny Stibolt contributed today’s puzzle. If you’d like to be a guest inquisitor on our blog, send photos and explanatory text to Linda Chalker-Scott.

This ‘n That

Grading finals, looking at roots, and planting seeds is consuming my time this spring, but I have just a few things to share today which might be interesting.

So, as those of you who follow this blog know, I love peanuts. This year we’re planting out a bunch of new varieties, a few of which are extremely interesting. Believe it or not there are not only red and pink peanuts but also black, white, and mottled peanuts. We have these on order — when they come in I’ll post a picture. When we introduce Minnesota Boiled Peanuts at the State Fair in a few years (that’s the goal anyway) the plan is to introduce a wide variety of really unique looking peanuts. Fingers crossed they can live here!

Here, at the University of Minnesota, we do a really great job of telling people that, when they fertilize their grass, they should keep the fertilizer on the grass and not on the sidewalk — SO WHY CAN’T THE UNIVERSITY TEACH THE KIDS WHO APPLY THE FERTILIZER TO THE UNIVERSITY’S LAWNS TO KEEP THE DARN FERTILIZER OFF OF THE PAVEMENT?!? Last week as I walked in I heard a crunching sound coming from my feet. When I looked down there was a little pile of fertilizer on the sidewalk.

Believe it or not, judiciously fertilizing your grass actually helps prevent fertilizer run-off. That’s because grass with a weak root system (as occurs in the typical lawn when you don’t fertilize at all) won’t be able to hold the soil as well — so you get more erosion. So do fertilize your lawn, just don’t go nuts.

About that whole tree in the lung thing which I posted last week? Yeah — It’s BS. How do we know it’s BS? No obvious roots on the tree and the tree’s needles were green (you don’t get green plants without sunlight). Personally I think this is some kind of odd cry for attention, but I guess it’s possible that the guy swallowed a cutting while he was shearing/pruning trees. HOWEVER, there are documented cases where seeds will germinate in a persons lung — Usually the person has a compromised immune system.