Riding the storm out

This past weekend marked our first real bout with severe thunderstorms here in Mid-Michigan.  Several lines of storms moved through the mid and southern part of the state and northern Ohio.  The storms in southern Michigan and Ohio also spawned some tornadoes.  Around here, storm damage was confined mainly to downed trees causing power outrages and some damage to homes and buildings.

Severe weather outbreaks provide some opportunities to observe tree failures and gain insights into how they can be prevented.  Or, as Yogi Berra put it, “You can observe a lot just by watching”. I was at a little disadvantage in scouting out tree damage from out most recent storm because we were traveling over the weekend and  I wasn’t able to get out and about to survey damage until Monday evening.  As it turns out the area most heavily affected by the storm is also fairly affluent.  Folks in these neighborhoods don’t tolerate downed trees lying around very long.  Nevertheless, I did make a couple of interesting finds.

 


A common sight after a storm in this area is wind-throw in shallow-rooted species, such as spruce and pines. We didn’t see a lot after the current storm, which was probably due to the fact that the storm moved through quickly – most of the high winds lasted only a few minutes – and the storm was not preceded by prolonged heavy rains.

I don’t have any specific data but I have seen several cases where wind-throw was occurred on trees in which mulch was underlain with landscape fabric.  Perhaps coincidence, but another strike against the stuff in my mind.

 


This maple provided one of the best (or worst) examples I have seen of planting too deep.  The tree snapped off about 6” below ground line.

Note that there are plenty of pretty stout roots that look like structural roots near the surface, but none of these originated near the current ground line.  The tree was on private property and time constraints prevented me from getting permission to do an excavation, nevertheless, it would be interesting to try to find the original root flare.

 


By far the most common problem in this storm, and most of our typical thunderstorms, was large limb breakage associated with narrow crotches.  This occurred in a variety of species; oaks, maples, elms, pines.  Narrow branch angles often form from multiple leaders, which results in weak branch attachment as included bark forms and gradually reduce the proportion of wood attaching the branch to the tree.  The encouraging thing, or maybe discouraging depending on your point of view, is that this is one of the most easily preventable tree defects.  Pruning double leaders or multiple leaders back to single leaders and eliminating other poor branch angles when small can easily prevent this type of breakage.  For most of our garden-variety thunderstorms, eliminating narrow crotches would probably eliminate 50% or more of our tree-related storm damage.

Morphology quiz answers

As Jason rightly guessed, this is a Schlumbergera species, specifically S. truncata, also known as the Thanksgiving cactus (which has toothed edges as shown). It’s related to the Christmas cactus (S. bridgesii – scalloped edges) and the Easter cactus (S. gaertneri, whose segments are three-sided rather than flattened). [Disclaimer: the nomenclature of this genus and its species is a mess. Even the university websites disagree on whether it’s Schlumbergera, Hatiora, or Rhipsalidopsis. Now you know why I am not a taxonomist.]

On to the more interesting question – those hairs. The green segments you see on these plants are not leaves, but flattened stems, called phylloclades (or cladodes). Phylloclade comes from the Latin word for leaf (phyllo-) and the Greek word for branch (-clade). These leaf-like branches are the primary photosynthetic organs for the plant.

So where, you may ask, are the leaves? That’s what those hairs are! And if you look at your Christmas/Easter/Thanksgiving cactus when it begins to set buds, you’ll see that the buds arise from the leaf axils – that point where the leaf joins the stem. This distinction is why these hairs are, morphologically, the true leaves of the plant.

Dirty Dozen?

Nobody in their right mind considers pesticides safe.  They are, after all, poisons which we have created to kill things, be those things plants, insects, fungi, rats, or whatever.  The idea that we could have foods with no pesticides on them is attractive.  Now I’ve got to admit that, as a general rule, I don’t think that the levels at which most pesticides are found on foods is concerning.  Our methods of detecting poisons are just too sensitive today and so we end up saying that a poison is “present” on a tomato or whatever even if it’s there at a harmless parts-per-trillion level.  Still, I won’t deny that I’d prefer it if there were no synthetic pesticides on any food.

A couple of days ago a report came out from CNN about the “dirty-dozen.”  http://www.cnn.com/2010/HEALTH/06/01/dirty.dozen.produce.pesticide/index.html This is a list of the twelve fruits and vegetables which are most likely to have detectible levels of synthetic pesticide residues.  Along with this list there is a suggestion that, when purchasing these fruits and veggies, you should select those that are organically produced whenever possible.  I don’t have a problem with this list being reported.  In fact, I think it’s a good idea to give people all of the information that we can about pesticides.  While I, personally, am not particularly afraid of conventionally produced fruits and veggies because of the synthetic chemicals which they may contain I appreciate the fact that others might be.  I do, however, have a major problem with the idea that organically produced fruits and veggies are necessarily safer than those produced with synthetics.  You see, organically produced food is not tested for residues of potentially damaging organic pesticides, and those same foods that are slathered by synthetic pesticides in non-organic growing systems are typically slathered by organic pesticides in organic systems, particularly if you’re dealing with foods produced using what has become known as “industrial organic production” which fill most of our large grocery stores with USDA Certified Organic Produce nowadays.  These organic pesticides may be present at higher concentrations than synthetic pesticides and may have similar effects on humans, and even worse effects on the environment than synthetics (though it depends on the exact pesticides used and how often they are used of course).

The myth that organic foods don’t have pesticides used on them is one that really needs to die.  No farmer, organic or non-organic, wants to use pesticides, and sometimes they can get away without using them.  Certain crops are rarely sprayed regardless of whether they’re produced organically or not.  Pesticides cost money and are dangerous, but when faced with the potential loss of a crop producers will do what they need to do to avoid losing their crop, and if that means applying pesticides then so be it.  Organic farmers may choose to use different pesticides, and they might wait longer before they spray (although often they spray sooner because the relative efficacy of their sprays are inferior to synthetic sprays) but let’s not say that organically produced foods are free of pesticide reside.  Just because we’re not testing for it doesn’t mean it isn’t there.

How to get rid of your lawn

With increasing interest in reducing monocultural swaths of turf, summer water consumption, and the drudgery of mowing, many people are eliminating part or all of their lawns.  We did this at home some years ago and can attest to the tangible benefit of reduced water bills during our dry summer months.

The question I often get is – how? Do you dig up the turf and throw it out, then fill in with topsoil? Or do you cut it, flip it, and then plant on top of it? Or do you cover it up with cardboard to kill it?

We’ve tried all of these methods over the years (except sheet mulch, because you already know what I think about that).  What I now recommend is the easiest, cheapest, and most effective way to both remove turf and protect the soil. Here it is in four easy steps:

1) Mow your lawn as close to the ground as possible. Scalp it. If you can wait until it’s not actively growing (summer here in the west), that’s even better. Don’t water it!

2) Cover it up with – yes, you guessed it – a really thick layer of arborist wood chips.  They need to be at least 8″ thick and can be as much as 12-18″ deep without negative effects. They will settle quickly, so you do need to put enough down to maintain a 6-8″ depth after a few weeks. The depth is important to suppress the turf as well as any persistant weeds (like those you can see in the above photo).

3) Wait. Turf decomposition will depend on temperature and water availability – warm and moist conditions are optimal. After 2-4 weeks, pull part of the mulch back and check out what’s underneath. When it’s easy enough to dig through, then you can…

4) Plant. Be sure to move the mulch aside and plant into the soil. Replace the mulch to cover the disturbed soil and keep the weeds down. It only needs to be 3-4″ deep at this point.

It’s that easy.

Duty Calls

As retirements have decimated our Horticulture Department’s faculty ranks, I find myself in the interesting position of teaching a course in small fruit production next fall semester. I’m working on the syllabus as was speak (hence this post).  If you’ve read my bio (“About Us”), you’ll see that this is not my bag.  But our students are clamoring for fruit and vegetable production courses, so someone’s got to do it. We are also  currently without on-campus vegetable faculty, if you can believe it. Though I know a few full professors that could pass as vegetables – HA!!!.

Anyhoo, I volunteered because I know just enough to be dangerous, and am willing to learn more.  I’ve been an avid home vegetable gardener
for years. My partner has a Ph.D. in small fruit breeding and genetics, and I helped him with some experiments back in our grad school days (and his field sampling/taste trials made me doubt my specialization in ornamentals).  We now  have a you-pick blueberry farm where I’m learning the finer points of blueberry culture (the pH thing is a really huge deal).  All this vast experience obviously qualifies me to teach fruit production at the college level. I say this tongue-in-cheek, but many Horticulture departments are in the same boat, with early retirements used to meet budget shortfalls, compounded by hiring freezes (since 2007 here). Research staff, grad students, and hired instructors are picking up the teaching load and helping  the already-spread-too-thin teaching faculty.  I mentioned in a previous post about our brilliant state legislatures’ desire to eliminate urban Extension programs,  leaving only the agriculturally–related specialists and offices.

This is depressing on many fronts, but what bothers me most is that I feel we’re missing the boat – just when Horticulture is getting sexy again.  Think of how frequently this discipline is mentioned in the media, whether in the form of community gardens, safe food production, the popularity of native plants, sustainability, organics, etc….unfortunately, the writers/broadcasters rarely say the “Horticulture” word.  But horticulture is exactly what they’re talking about: small-scale gardening and the art and science thereof.  People want to do it, they’re thirsty for good information, and now, with the spotlight on us, we can’t meet their needs.

Nice tomato!

I can’t really think of an image appropriate to this rambling post, so will end this with a more cheerful photo of one of my tomatoes from last summer (variety is ‘Kellogg’s Breakfast’).

Good to the last drop

As part of our discussion of the relative merits of fall planting, Linda mentioned an article in Arboriculture and Urban Forestry that suggests that frequent, light irrigation might be better for landscape trees then the usual recommendation of infrequent soakings.  While I will withhold final judgment until I see the article (I did a scan of the last two year’s table of contents for A&UF but missed the article in question), here’s my rational for following the standard recommendation.

 

First, the context.  In discussing landscape tree irrigation I am talking about watering trees during establishment, typically during the first year after planting and maybe the second if the tree is lucky.  The goal of watering in this case is ensuring survival.  The questions are whether deep soakings are more likely to encourage deeper rooting where water availability is less variable than near the surface after irrigation ceases and whether infrequent watering increases drought tolerance over more frequent irrigation.

 

Roots follow resources
As my Woody Plant Phys students quickly learn, we avoid the teleological ‘roots seek out water’; nevertheless, roots do proliferate where resources are available.  A couple of illustrations.  As a Tree Physiology Project Leader with International Paper I supervised a 25 acre hardwood fertigation trial.   Trees were watered daily via drip irrigation system with emitters spaced every 3’ down a row.  As part of the study we did periodic root harvests.  My technicians quickly learned it was an easy job: just look for the drip emitters – every three feet there was a mop of roots right next to the drippers.  The notion of roots following resources is also widely reported in the ecology literature on tree utilization of ‘patchy resources’ (e.g. Gloser et al. 2008 Tree Phys 28:37-44 ).  Other factors being equal deeper watering should result in deeper rooting.

 

Trees habituate to frequent irrigation
Another short rotation forestry example.  In eastern Washington and Oregon forestry companies Potlatch and Boise Cascade operated intensively managed ‘fiber farms’ which grew 70’ tall, 7” diameter hybrid poplars on a 7 year rotation.  To maintain these growth rates, trees were irrigated daily.  But there was a downside: If one day’s irrigation was missed the leaders to the trees would start to wilt.  Three days without water would result in leaf drop. The daily irrigation was great for growth but it turned the trees into physiological wusses.

 

Periodic water stress improves drought tolerance and survival
A common adaptation for trees to tolerate drought is osmotic adjustment, which is an active accumulation of solutes that enables plant cells to maintain turgor pressure during dehydration.  Plants that have acclimated to stress via osmotic adjustments and other physiological adjustments are able to survive better during prolonged drought than plants that have not been pre-conditioned.  For example ponderosa pine seedlings that had been subjected to brief drought events survived a terminal dry-down two weeks longer than seedlings that had been watered 3 times a week before the final dry-down (Cregg 1994 Tree Phys. 14:883-898.

 

What would it take to change my mind?
Obviously some of my examples here are anecdotal (though there’s plenty of hard data on osmotic adjustment and other drought conditioning effects on trees).  To recommend frequent (2 or 3 times a week), shallow irrigation I would need to see: a well designed and executed experiment that compared frequent irrigation to periodic (once every 7-10 days) applying the same amount of water weekly (0.5 to 1” per week) for the first year and then documented improved survival of the trees after irrigation had been discontinued.  I’m not saying it’s not possible but it goes against my personal observations with irrigated trees in a variety of settings and relevant data with which I’m familiar.

Flower demystification

As Paul suspected, this is a Phalaenoposis flower.  Here it is again, shown next to another flower on the same plant (but different stalk):

  

As to the second question – why does it look this way – there could be a number of reasons.  I’m leaning toward environmental.  This particular flower stalk is an old one – after it had bloomed initially (with normal flowers), we left it on after the flowers fell.  As often happens, new flower buds appeared, but all of them have been abnormal.  Some were completely fused and never opened.  This one is missing most of its petals.

Other reasons could include viral infection (as Sheila suggested) or somaclonal variation (common in tissue cultured plants, which is how many orchids are propagated).  But this flower stalk is perpetually colder than the rest of the plant as it’s closest to the window.  And since its first crop of flowers were normal, I think this variation is due to cold temperature interference during flower development.

If you have other ideas, be sure to post them!

Right and Left

Just got a picture of the cover of a new book I’ve got coming up soon.  It’s a collaborative project with an old friend of mine who is a political science professor at UNC Charlotte.  We look at a bunch of different environmental issues, different things that the government could do about these issues, and then we rate these options by how the well the right and left wingers would like them.  Sure to tick people off!  The book won’t be out till next January — It’s typically over a year between when something is first turned in and when it comes out — that’s just publishing.