Trivia Hoedown #4 May 29, 2007

1. The smell of rich soil – that delicious smell reminiscent of gardening and fresh mulch and recent rain – is courtesy of Actinomycetes, a filamentous gram-positive bacteria. It’s usually treated like a fungus in study because it acts like one, forming hyphae and breaking down organic matter in soils.

Actinomycetes in Soil

2. It is possible for a dead wasp to sting you. Repeatedly. Don’t touch the pointy part; alternately, stop touching the pointy part after the first time.

3. Red Osier Dogwood, Cornus sericea, looks an awful lot like a Viburnum. It’s not though, and don’t let your botany TA tell you that it is.

4. The bulk of agricultural pests are in one of five orders of insects: Hemiptera (true bugs), Homoptera (leafhoppers, aphids, scales), Coleoptera (beetles), Lepidoptera (butterflies and moths, or rather, their larvae), and Diptera (flies). The bulk of beneficials are in Hymenoptera (wasps, ants, and bees) and again, Coleoptera.

5. Several important (meaning here “significant”) agricultural pests experience an increase in proliferation in the presence of an overabundance of nitrogen. You don’t want to overfeed because it’s expensive and wasteful, but it also kicks some insects’ reproduction cycles into high gear. Plants that are overfed are also more susceptible to disease and live in a constant state of low grade stress, meaning dwarfed growth in the longterm and smaller yields (fewer flowers).

6. Speaking of reproductive cycles, here in the PNW the temps are projected to be above 80 every day this week. Warmer weather also shortens reproductive cycles. More bugs in half the time! Rose gardeners, gird yourselves.

7. Another reason to abandon overhead watering of plants: only 30% of the water reaches the soil in container plants.

8. Every mature Cryptomeria I have ever met had a distinct lean. Planted alone, it leaned toward the sun; planted against structures, it usually leaned away from the structure. I’ve just discovered that the reason for this is that Cryptomeria are very sensitive to reflected light; reflected light means nearby competition, so the trees lean away to try to intercept light on as much of their surface area as possible. Likewise in full sun, they situate themselves to get as much of the light as possible.

9. It is possible to isolate bacteria and fungus from a 95% solution of EtOH. Don’t rely on it for sterilzation, unless you’re following up with a trip through the burner.

10. Roosevelt Elk carcasses are an excellent source of carrion beetles for your entomology collection, as you might imagine.

11. The smell of said carcass will be with you for hours. Longer, if you keep mistaking the rancid stench of those hoof treats you gave the dogs for the rancid stench of elk hooves when you foolishly wandered downwind.

12. It’s true: nothing is wasted in nature.

13. When peeing out of doors, the sound of your pee making contact with the underbrush is a critical component of ensuring that you are not peeing on the cuff of your pants.

14. Your closed car, parked in the sun, makes an excellent dryer for your field press. The smells that greet you when you open the door are nothing to worry about.

15. Mosquitos love to bite you where it’s least appropriate to scratch in public.

16. Word of the week: Ichneumonidae.
a) That’s a beautiful Ichneumonidae specimen, 10 points for perfect curation.
b) Ichneumonidae! I can’t believe you eat haggis!

Arabidopsis Thwarts Land Mines May 29, 2007

A Copenhagen biotech firm has modified a common Arabidopsis to detect nitrogen dioxide and express red leaves instead of green in its presence.  Over 100 million landmines worldwide are a danger to humans and animals and leave prime agricultural land fallow.  Now the nitrogen dioxide that they outgas can be detected by this lowly thale-cress which is seeded by air.  When the plants grow and express the red color, mine removal teams know exactly where to direct their efforts.  The red color will also serve as a warning to passersby who can avoid stepping on the mines.  Very exciting news.

 Overview from the Landmine Survivors Network here.

Literature Review: Biennial Bearing May 25, 2007

Dennis, Frank G. and Neilsen, John C. 1999. Physiological Factors Affecting Biennial Bearing in Tree Fruit: The Role of Seeds in Apple. HortTechnology 9(3): 317-322.

This article, rather than a publication of new research, is a review of the existing research to date on the biennial bearing patterns of apples and pears. Research has been aimed at discovering why some varieties exhibit biennial, or every other year, bearing: during “on” years, there is a full fruit crop but floral initiation for the following growing season is inhibited; during “off” years, there is no fruit crop as a result of the previous season’s failure to initiate flowers, but floral initiation proceeds normally during the current year for a full fruit crop the following year, and so on. The idea that flowering inhibition is a result of nutrient partitioning to developing fruit rather than initiating flowers is set aside in favor of two hypotheses that link developing seed-bearing fruit to inhibition of floral initiation.

 

Chronologically, the referenced research is as follows: in 1918, Kraus and Kraybill’s work with carbohydrates and nitrogen concentrations in Lycopersicon suggested that nutrient aviailability was a factor in flowering, and subsequent studies probed this hypothesis with inconclusive results. Roberts ‘1920 study suggested that “flowering is greatest when shoot length is intermediate,” which was untrue for strongly biennial varieties. Chan and Cain (1967) showed that it was the developing seeded fruit that was inhibitory towards floral initiation unless the flowers/fruit were removed within a few weeks of bloom. In 1996, bourse shoot length was revisited and the Michigan grown, commercial, biennial and seeded ‘Paulared’ was evaluated. The authors reported inconsistent effects of shoot length on flowering, and in this particular variety, floral inhibition was also not consistently correlated with developing fruit. However, it is accepted that in general, parthenocarpic varieties exhibit floral initiation inhibition in the presence of seeded fruit. Two hypotheses roughly fit these existing data and are good candidates for further study: the export of biochemical inhibitors from developing fruit, and priority for florigen, the hypothetical floral promoting hormone.

 

For the first hypothesis, Luckwill (1969) demonstrated that “seeds contain[ed] relatively high concentrations of gibberellins,” and he proposed diffusion of GAs into the bourse shoot, which was supported by higher concentrations in the bourse shoot tissue adjacent to developing seed. This would explain the apparent relationship advanced by Roberts between floral initiation and shoot length (in some varieties). Though this conclusion is widely accepted, it is not equivocally supported by subsequent research. In fact, there is a disconnect between increased GA concentration in shoots and unexpected lower concentration of GA in developing seeds. In some cases, the GA exudates in the bourse shoot were in another form of GA (GA₄) which is sometimes floral inducing. How GA is distributed or diffused between seeds and bourse tissue remains unclear even after studies where GA was radiolabeled for tracking. Green (1987) showed that less than 0.01% of labeled GA was transported, even when accompanied by hypothetical biochemical precursors. Subsequent studies produced similarly small percentages of transport, though there was relatively more GA diffusion from seeded than unseeded varieties, and GA₄ levels were found to be lesser during floral initiation.

 

Additional factors may play significant roles. Callejas and Bangerth (1997) suggested that IAA might be a “secondary messenger in the inhibition of flowering,” but no appreciable differences in IAA levels in tissues were demonstrated between annual and biennial varieties. Additionally, naphthaleneacetic acid (NAA), a thinning agent that also has been shown to stimulate flowering, could possibly produce results that mimic floral initiation at fruit removal. Neither substance’s role is well understood at this time.

 

The second hypothesis is based on Ryogo’s hypothesis that “seeds have priority for florigen,” referring to the hypothetical hormone thought to promote flower induction (1988). In this scenario, instead of carbohydrate partitioninig or prioritizing, the substance that reproductive tissues might be vying for is florigen, which is thought to be produced by leaves and available relative to leaf area. Adequately long bourse shoot length and adequate leaf area could diffuse enough florigen to make flower initiation possible even with adjacent development of seeded fruit, which fits with Roberts’ findings. The authors also note that this hypothesis “might explain the failure of seeded ‘Bartlett’ pear fruit to prevent flowering in California, where water and sunlight are abundant and growth is vigorous.” This supports the idea that increased leaf area would result in increased concentrations of its assimilate, florigen – enough for seeded fruit development and floral initiation to be concurrent. Substituting “florigen” for “nutrients” in the previous hypothesis of carbohydrate partitioning (Kraus & Kraybill) would corroborate those findings.

 

At this stage of researching the physiology of biennial bearing, it isn’t clear what the research question is or what mechanism or substance is being sought. In discussing the inhibitor export theory and IAA/NAA effects, the authors acknowledge that inconclusivity may reflect the limits of technology at the time of these referenced studies. Possibly none of the existing scenarios is a good approximation. Luckwill has posited that a balance of phytohormones involving cytokinins may be play a role, as might antagonistic reactions between substances. Practically speaking, complex and as yet understood chemical balances and relationships are certainly germane. Additionally, this article does not discuss other factors outside the scope of completed research, such as why some trees can be induced to biennial bearing after a hard frost. There have been insufficient comparisons among species and cultivars, an aspect of the research that may have to wait until a firmer hypothesis is in place.

 

In conclusion, what is known with some confidence is that “seeded fruit of biennial cultivars of apple and pear [does] inhibit flowering, whereas seedless [fruit] do not,” and for now, the “effect of the seeds declines as bourse shoot length and/or leaf surface per bourse increases.” This article is a good starting off point for future research, provided inquirers agreed with these hypotheses, but it also shows that previous studies attempting to answer the same question have addressed it in very different ways. As technology and funding are available, it might be possible to answer the questions of inhibitor export and florigen priority.

 

Trivia Hoedown #3 May 18, 2007

1. Insects that congregate together to feed or sleep or just hang out are termed ‘gregarious.’

2. Domesticated honey bees cannot pollinate alfalfa because the keel of the alfalfa flower pops up and hits the bee in the subesophageal ganglion, rendering it either trapped in the flower or very cranky or both.

3. Volumes of EtOH and water are not additive – 50 mL of EtOH and 50 mL of H2O do not equal 100 mL, but a little less: around 97-98 mL.

4. It’s never a good idea to give a landscape design client the original, solitary copy of their new landscape plan. This isn’t trivia so much as it is common sense. You would think.

5. The dreaded female Ginkgo tree: those stank bombs are not fruit, they are the seedcoat and seed. Ginkgo do not bear fruit.

6. Forensic entomology As Seen on TV is a truism. The ability to determine approximate time of death based on the date of insect oviposition relies on a biofix: a first date when the adult insect is present. The remainder of the sleuthing is done with degree days by adding up the cumulative degrees above a threshold over a period of days. With a biofix and temperature data, you can easily determine when insect eggs were laid and when they should hatch.
7. An orchard without apples represents an absence of Malus. I love pome humor.

8. If you’re looking for a good container mix that will drain well, act as a pH buffer, hold nutrients efficiently, and let plants’ roots breath, you can’t do a whole lot better than plain old Doug fir bark.

9. The difference between a bee and a wasp? Hairy eyes. Bees have fuzzy ommatidia.

10. Word of the week: equilibrate (v). Which sentence best represents:

a.) Let the solution spin down and equilibrate before you pour the plates; or
b.) I got a D on the midterm but have a solid B in lab, so I’m hoping it will all equilibrate.

Rhododendron ‘peptus bismolicus’ May 11, 2007

This week I discovered that the course list for my option in horticulture is less of a list of courses to be ticked off and more of a series of suggestions.

Excellent news as I’m discovering that my original option is limiting, and I’ve been thinking of ways to tweak my course listing to be more of a generalist. As soon as the landscape advisor is back in his office, I’m ready to pounce on him for permission to take classes in the design option.

It would be…ironic if I ended up going back into design as that’s where I started. Oh, yeah, and I didn’t need a degree to do that. But I did need the degree to not feel like a charlatan.

The plant ID midterm was today, ever so slightly reminiscent of a death march. We all trotted along behind the instructor who dragged us all over campus, and I was silently urging him, “No! Do not stop in front of another pink Rhonodendron! Don’t do it!” or “Yes!! Stop in front of the Photinia davidiana or Fagus sylvatica ‘Purpurea’ or Aesculus x carnea.” He did his own thing however, and it was funny the contrast between traipsing through brush and behind buildings and down in culverts and having test terror while we marched. It was not unlike your first driving test.

Personally, I do not see the need for 6 varieties of pink Rhododendrons, in life or on exams.

Trivia Hoedown #2 May 3, 2007

This week is less of a hoedown and more of a little soft-shoe.

1. Putting gravel or broken pottery at the bottom of a container before you put in the soil and plant does not improve drainage. What it does do is raise the perched water table in the pot, making more of the container volume saturated and anaerobic. If you’ve been putting things in the bottom of your pots to keep out insects, use screen instead. If you’ve been doing it to improve drainage, stop it.

2. Turkey’s Law: if you skip class, you’re sure to cross paths with the professor within 4 hours.

3. Pipettes vary by volume and dialing “5″ on the 200 microliter pipette delivers 50 microliters of solution, while dialing “5″ on the 20 microliter pipette delivers the expected 5 microliters. When your contamination indexes grow nothing after 24 hours and more of nothing 24 hours after that, it’s entirely possible that you pipetted 50 microliters of Rifampicin onto your agar and not the proscribed 5, thereby snuffing out any bacteria that dared try to colonize. Really clean petri dishes after you’ve smeared and incubated them are super embarrassing. In other news, Rifampicin is a pretty broad spectrum concoction.

4. When you splash said Rifampicin onto your hands while opening the aliquot and then note that it was put into solution with DMSO, you can rest assured that have just mainlined plant antibiotics.

5. The best Blattodea collection site is in the bathroom right outside entomology lecture hall.

6. Phrase of the week: phenotypic plasticity. Which sentence is correct?

• The more deeply lobed leaves of Acer macrophyllum in warmer climates are an example of phenotypic plasticity.
• Does everyone in your family have a hunchback and hairy moles, or is that just phenotypic plasticity?

The Dreaded Colibrina Marsditzia May 3, 2007

The Dreaded Colibrina Marsditzia is code for “I don’t know what it is, but it’s very bad,” usually applied to situations where one is feeling poorly, has an outcropping of skin or tissue, a mysterious rash, contusion, ominous neurological symptom, or general malaise. The diagnosis of Dreaded Colibrina Marsditzia was profferred by my father with utter seriousness and the slightest hint of horror. And it really pissed me off because there’s a semantic undertone to the DCM: hypochondria.

To make a fairly short story even shorter, let’s just say that hypochondria blooms in the absence of medical insurance.

I wish I could discover the true origins of the phrase – it doesn’t even show up on Google. I will trade you my best guess at a diagnosis of your bizarre physical manifestations for an origin of this phrase.