Saturday, June 25, 2011

Six Interesting Things About Garlic

I spent the better part of a day harvesting garlic yesterday.  It is a pleasing job made even better by the garlic aroma that ebbs and flows around your head while you work.  At one point, the farm owner was harvesting basil upwind, and I had a wonderful aromatic pesto experience.  I have always wanted to grow garlic in my home garden, and I learned enough yesterday to try it this year.

To grow garlic, you plant a clove in the late summer and let it grow.  It grows a stalk with leaves above ground and begins to build a large bulb underground.  When the above-ground leaves start to die off, you know the bulb is ready to be harvested.  To harvest, stick a pitchfork into the ground a few inches away from the bulb and pull up the bulb and soil.  Gently brush off much of the soil and pull a leaf or two off if they are mushy and dead.  The fresh garlic is fabulous - mild and slightly green tasting, but you can cure it and keep it to use throughout the year.  To cure the garlic, let the whole stalk and bulb dry outdoors for two weeks or so.  Then you can cut off the top of the stalk and roots and store the whole thing in a cool, dry location.

Here is a row of garlic and one fifth of my garlic harvest ready to go to the drying racks:



Garlic is an amazing and powerful plant.  In no particular order, here are some interesting things about garlic:

1. Eating two cloves of garlic a day reduces your risk of cancer.  (reference)  If you crush the cloves, let them sit for 15 minutes, then cook with them, they will cause your body to produce more of its own antioxidant, hydrogen sulfide.  Antioxidants reduce the risk of cancer. 

2. Garlic also helps maintain elasticity of the blood vessels, reducing the risk of cardiovascular disease.  It also has many other health benefits that are less rigorously demonstrated.  Garlic is anti-viral, anti-parasitic, antibacterial and anti-fungal. 

3. Garlic makes any savory dish taste better.  It helps bring out the other flavors in food even as it adds its own richness.  It is good lightly sauteed (don't burn it), roasted whole, cooked in broth, or even crushed raw into hummus or pesto or salad dressing.  To avoid burning garlic when sauteeing, add it as you finish sauteeing the onions and 1-2 minutes before you add the major ingredients to the pan.

4. Garlic scapes are delicious and only available for a flash in the spring.  Garlic scapes are the flower stalks of the garlic plant.  They have a gentle garlic flavor.  They can be stir-fried or sauteed.  Another farm worker brought in pesto made from only garlic scapes, olive oil and pine nuts, and it was fantastic.

5. Garlic is in the onion family, which includes all types of onions, chives, leeks, ramps and shallots.  These plants grow all over the world and are used in almost all cultures' cuisines and medicines.

6. Garlic plants are mostly all clones of each other.  Garlic seeds are not usually planted, and seeds would be the offspring of two garlic plants.  Cloves are parts of one plant, so when they are separated off and planted, they are genetically identical to the plant they came from - clones.  Garlic is very easy to grow from cloves, and the results are predictable.  Seeds take much longer to grow, and each seed results in a plant that may be bigger, smaller, less pungent or otherwise different than the parent plants. 

I'll leave you with my foot - toes looking fabulous from a recent trip to New York and lots of mud from harvesting after a good rain.

Wednesday, June 22, 2011

Mmmmantis!

My favorite game to play with idle high school students was Stupid Ninja.  In Stupid Ninja, players each perform ninja moves, and the top move is always 'Mantis' because mantises are sooo bad (by which I mean fierce - high school terminology here).

Praying mantises are the voracious tigers of the bug world.  They are crafty, patient hunters that stalk their prey then pounce and chew.  They will hunt and eat anything they can catch - mostly other insects, but also birds and even reptiles, depending on the relative sizes of the parties involved.  They are indiscriminate carnivores, even eating their own siblings soon after hatching.  Their copulatory cannibalism behavior was a source of endless questions and freak-outs by my students.  One well-informed student:  "The female eats the male after mating!!!"......Everyone else in chorus:"Ewwwwwwwwwwwww!!!!!!"

There are a couple of going hypotheses to explain this infamous afterglow routine.  Some say that the female will be more tolerant of mating behavior by the male if she is to get a meal out of the deal.  For smaller males who cannot escape or battle competitors, this may be the price of passing on their genes.  It's the mantis version of the fancy dinner date with expectations, I suppose.  Others point out that a female who is well-nourished will be able to produce better eggs and egg-cases, thus helping to ensure the offspring of the sacrificed male.

Mantises are very useful bugs on the farm.  Predators in general help keep numbers of prey organisms lower.  The presence of predator insects help keep all the other insects in check.  They are part of this balanced ecosystem.  One aspect of Optimal Foraging Theory says that generalist predators tend to hunt for the most common species they encounter as their preferred prey species.  At any given time on a farm, the most common insect species is likely to be a crop pest, therefore predatory insects are always good to have around.

The farm owner and her 9-year-old son are delighted to welcome this year's group of bright green mantises to their farm.  They saved egg cases and shepherded the little hatchlings into their fields.  The son can easily find them upon request, which is quite impressive to me, since my much older students were unable to collect them for their insect collections for the past couple of years.  Mantises are known for their camouflage, so they can be tricky to find even when they are abundant unless you have spent enough time outside to be able to really notice what lives around you.

The egg cases are strange clumps of tough dried mucus filled with eggs.  Mantises overwinter as eggs inside the egg cases, and baby mantids hatch out in the spring.  They grow all summer long, and mate and lay eggs (or get eaten) by the end of summer.

You can go on a mini-safari if mantises are around.  Bring a camera, wear long pants, and sit in the weeds near a praying mantis.  They love to sit under flowers, since flowers attract flying food.  Be patient and watch carefully with your camera poised - he hunt is already on.  The mantis will sit and wait for its prey.  Then, when something buzzing comes near, the mantis will ambush in a flash.  One moment there will be two insects, and the next there will be only a mantis holding its lunch and chewing happily.  It's thrilling and slightly scary to watch, and you will learn some bad Stupid Ninja moves.

Here's a young adult mantis hiding in the seedlings:

Tuesday, June 21, 2011

Hail, Mary!





What you see here is not only my first picture posted to this blog but also the largest hail I have ever seen.  It fell on my house, and it is officially called, "golf ball-sized hail".  The coin in the picture is a quarter.  The house is fine.  The car has a little cellulite now.  The garden is licking a few wounds, but really OK.

This rather charismatic weather event got me thinking more about weather on the farm.  A co-worker on the farm remarked that she would not like do farming as her primary profession because she didn't want her job to be at the mercy of the weather.  While all are livelihoods are linked to weather at some level (try doing any work in a tornado), she clearly has a point.  Great weather means healthy, productive crops, which in turn means income.  Drought, hail, flood, tornado and hurricane are the dreaded words that mean an entire season's income could be down the drain (or evaporated, as the case may be).  Farmers can buy crop insurance for these unpredictable events, but it is only a safety net, not a satisfying season's income.

Fortune has smiled on the farm this spring, with ample rain, early warmth to start the crops, later cool to work in and no hail or tornadoes.  The crops are growing as fast as the weeds.  The hail that fell on my house thirty miles away would have been disastrous for the farm.  It would have destroyed all the greens (chard, kale and lettuce) and would have seriously stunted the ornamental flowers and tomatoes.  The leaves would have been shot through with holes, like those on the leaves of my zucchini plant at home.  The tomatoes would have been dented badly, with bruises that rot in a day or two.

Hail is a very poorly understood weather phenomenon, but it has a lot in common with tornadoes, which are well-known here in Nashville.  Conditions that create tornadoes are also likely to create hail - the clouds pile high (cumulonimbus clouds), often with thunder and lightning, ominous winds, massive rain and a greenish tint to the sky.

Hail and tornadoes tend to occur on the leading edge of a thunderhead as it enters the area.  A cumulonimbus cloud indicates a tall pile of cool to cold air over an area of warmer air.  Think about it - it's summer and you're standing outside in the heat.  Next a thundercloud comes up and does it's thing.  After the storm, the air that has moved in with the storm is cooler.  A big mixing of air has occurred, usually squeezing the water out of the air as some form of precipitation.  When the temperature difference is larger, for example when it's hot on the ground and freezing in the cloud, the air mixes very fast (tornado), and the precipitation freezes (hail).  If it's cold on at ground level, for example in winter, hail doesn't form because the water in the air doesn't form liquid water droplets that can freeze into solid balls, instead water molecules in the air collide and grow onto crystals of water, forming snow.  We will all probably become more familiar with this process as the Earth warms, since climate change is increasing the severity of storms. 

The strangest thing about precipitation of any form is that it doesn't just automatically fall out of the air when it forms.  We all know that water or ice are denser than air, so they fall to the earth when we drop them.  But they don't fall when there are updrafts blowing them higher up in the clouds or when they are so small they are pulled more strongly by the air molecules than by gravity.  A cumulonimbus cloud is tall because it has updrafts.  If it has updrafts and downdrafts and is very, very cold, a piece of hail can form and grow on the updraft, fall and melt a little, blow back up and grow, etc. until it grows to the size of a dime, a golf ball, or even a grapefruit.  Next time it hails golf balls near you, observe the hail balls and you will probably see layers from the hail freezing differently as it rises and falls in the clouds.  You will probably also notice that the hail is irregular in shape due to multiple hail pieces freezing together somewhere above your head.

Today is the first day of summer.  Precipitation will be less predictable for  the next few months.  I know I'll be paying a lot more attention to the weather than I normally do - you can't help it when you grow plants outside.  Even without checking the rain gauge, you notice the dampness of the soil, the color of the ground, the turbidity of the leaves and stems and the dustiness of the air.  With a little luck, it'll be a good crop.

Wednesday, June 15, 2011

Japanese Beetles Put their Thumbs on the Scales

The stability of any ecosystem depends on having a multitude of species playing different roles in that ecosystem.  Some are producers, some are decomposers, some are predators, and no one gets out of hand.  The predators don't take over because there are bigger predators, disease organisms, and competitors for food and other limiting factors. 

Invasive species are the newcomer species that upset the fine balance, altering ecosystems and even causing extinctions.  For example, entire food chains have collapsed in the Great Lakes due to the invasion and overgrowth of the zebra mussel.  The zebra mussel eats all available algae, and other species starve.

Invasive species arrive in many ways - sometimes by expanding their range but usually because they have been carried from one place to another by humans.  Our species of the day, the Japanese beetle (Popilla japonica) (picture), was accidentally brought into the United States from Japan as grubs in soil of ornamental plants.  The new species was detected in New Jersey in 1917 and quickly traced to a plant nursery in the area.

Because invasive species are new to an ecosystem, they are neighbors with other species to which they have not evolved.  That means their neighbors have not had a chance to adapt to eating the invasive species, or competing with it or infecting it.  That's how you end up with entire mountains covered in kudzu.  Or the entire eastern United States covered in Japanese beetles (range map), despite massive federal, state and private efforts to destroy this aggressive farm pest.

But even invasive species are fascinating.  Japanese beetles are beautiful, metallic beetles.  Also, they might just be the only insect capable of growing one body part at a time, according to Dr. Hans-Willi Honegger, an entomologist who also works on the farm.  Dr. H thinks they might be able to grow their jaws, which would make sense since they are such voracious feeders.  Japanese beetles' life cycles are also very interesting.  They emerge in late spring, feed like crazy on leaves of their favorite plants, mate and lay their eggs in the soil.  Most of the adults die off by late August, but the larvae are just starting to get busy.  They burrow in the upper layers of soil throughout the fall, eating roots and organic matter in the soil.  When the temperatures start to drop, the beetles burrow deeper and deeper to stay warm only to come back up when the spring thaw comes again.

On the farm, the beetles are just starting to emerge.  According to the farm owner, the beetles have gotten a little worse over the past few years as their range has expanded.  Now that they are here, they are probably already laying eggs here for next year, and their numbers may increase.  Once beetles establish themselves, they are really impossible to get rid of, but several strategies can help.  A soil drought during early larval stages can kill many larvae; parasitic wasps, worms or bacteria can be released into the area to help kill beetles; traps do attract beetles, but they don't seem to help the overall problem; and insecticides are of course used on non-organic farms.  A surefire way to control Japanese beetles would be to simply wait around long enough for evolution to take its course.  All those Japanese beetles are a great food source for any animal that could evolve to eat them.  Given the rate of evolution, we might only have to wait about 20,000 years for Japanese beetles to become a part of our balanced ecosystem.

Saturday, June 11, 2011

Vegetarian Vampires

There is a particularly interesting killer on the farm. It creeps silently toward its prey, searching victims by their shadows and their smell. It kills its victims gradually, sometimes over months, slowly drinking their fluids until there are none left and the dessicated victims expire from exhaustion.

Terrified? Don’t be. These predators are vegetarians – vegans even. They are actually parasitic plants called dodder, in the genus Cuscuta. picture They are the ghostly bleached cousins of morning glories. Dodders comprise approximately 150 closely-related species of flowering vines with no green chlorophyll. Their appearance reminds me of a childhood poem I once loved about spaghetti trees, because they drape over their victims with vast quantities of whitish-yellow strands.

Dodder produces flowers, fruits and seeds like any normal plant. Their flowers are small white clusters that develop in to fruits with multiple seeds. The seeds drop in groups onto the soil to germinate up to 5 years later. Even as the seeds germinate, the plant seems normal. The seedlings grow using the energy stored inside the seed by the mother plant. Since seedlings of most plant species grow from stored energy, it is common for seedlings to be white or yellow like those of dodder. Most plants quickly grow leaves that fill up with chlorophyll, and they start making their own food before they run out of what’s stored in the seed. But here is where dodder is unique.

If dodder seedlings don’t find a victim within 10 days of germination, they will starve. They are somewhat picky eaters, as dodder won’t parasitize grasses or corn. Fortunately, they have evolved the ability to find their preferred foods. The seeds germinate faster when a preferred host is near. They grow toward host stems by growing toward shade (most plants grow toward light), and by curling when they touch something. The most amazing feature of dodder is that it can find its hosts by smell. Dodder can detect and grow toward the volatile compounds produced by its food. Ever smell a tomato plant? Dodder has too!

When dodder finds a host, it punctures the stem and grows into the food veins, or phloem, of the plant. It absorbs water, sugar, minerals and everything else it needs straight from the plant. It discards its own stem and root connecting it to the ground and goes completely airborne as it quickly covers its host plant with spaghetti stems.

Dodders are annuals, meaning they die back each year and regrow from seeds. Some, however, have figured out another way to survive the winter. If they colonize a host plant that survives the winter, the dodder growing inside the host stem can survive and resprout the next spring.

The best parasites don’t usually kill their hosts, because then they would be out of a food source. This is usually true with dodder too. It may kill some of the plants it is in contact with, but it usually maintains at least one live host. It certainly reduces host plant size, which is a problem for farmers when the host plant is a crop plant. Farmers don’t like dodder, and they often have to work hard to get rid of it. On the farm where I work, we hand-pull the dodder and throw it onto mowed grass, where it can’t regrow. Desperate farms can switch to non-host plants for a few years in particularly infested fields.

As much as I know I should hate the plant, I can’t quite. It’s just so darn strange. There are very few truly parasitic plants, and this is one. People always think Venus Fly Traps are the consumers of the plant world, since their little traps look so much like mouths, and they move (!), but sadly, they are not consumers. They are green, indicating chlorophyll, and they get all their energy from the sunlight. They do, however, absorb nitrogen, which is like a plant vitamin, from the flies they trap. Dodder, though, has discarded its ability to photosynthesize. The loss of a trait is fascinating from an evolutionary perspective. Organisms evolve new traits all the time, but they don’t usually lose them. Of course, dodder probably still has most of the genes necessary for photosynthesis, because it is so closely related to and descended from photosynthesizing plants. But there is really no need to spend the energy to maintain those genes. The dodder plants that spent more energy parasitizing host plants and less energy maintaining their ability to photosynthesize found the successful strategy.

Are their any plants that are parasitic on animals? No. But the laws of natural selection say that will be is variation. Doubtless there is some dodder plant out there that might just maybe be able to puncture human flesh and collect its energy from me. So you’ll find me moving just a little bit faster past the dodder plants!

Wednesday, June 8, 2011

Weedy Strategies

The onions have weeds. LOTS of weeds. As we weeded for a couple of hours, I contemplated the varying successful strategies of the primary weeds we pulled. Weeds are any organism humans have deemed annoying, and we are annoyed by lots of organisms! Usually weeds compete with humans for food. For example, Monks and Schultheis (1) demonstrated that for every week crabgrass was allowed to grow alongside watermelons, the watermelon yield per hectare (2) was reduced by 716 watermelons (that's almost 4000 kg, or 8800 pounds, equivalent 2 average American cars)! So weeds GREATLY decrease productivity.

Why do weeds decrease productivity? Well, they are the greedy kids that grab the most M&M's at snack time. They are better at using available resources quickly. Resources for plants include sunlight, water and soil nutrients. Weeds out-compete crop plants for some or all of those resources. Crop plants are usually somewhat wimpy competitors. Plant breeders have selected for tender, juicy fruits or pretty flours or large seeds, which often come at the expense of defensive or offensive plant growth strategies.

Our hours of weeding enabled us to become intimately familiar with three weeds: crab grass (3), yellow wood sorrel (4) and spiny amaranth (5). Oddly enough, each of these weeds has a different strategy for success as a weed.

Most of us know crab grass, even if we don't realize it. Crab grass is a vicious, ubiquitous, nonnative weed found throughout most of North America. It is a weed of agriculture, lawns, sidewalks, and vacant lots. Crab grass's strategy is to dominate territory throughout the summer. It puts as much energy into roots as it does leaves as it develops its death grip on the soil. It is an annual that leaves holes in lawns when it dies back in the Fall after it has deprived all neighboring plants from all necessary resources. Removal of crabgrass requires tough hands and strong muscles and also a strong tolerance of soil disturbance by neighboring plants as the crabgrass clings to the soil even as it leaves the earth.

Wood sorrel is ironically the sweetest of the three weeds to pull. While it would taste sour due to its oxalic acid content, it comes out of the ground as smooth as honey - a great relief to a weeder who is fed up with crab grass. Wood sorrel grows quickly, and it puts little energy into maintaining its turf. It just needs a little patch of soil to get in, grow some seeds and get out. It is done with its life cycle early in the summer.

Spiny amaranth blends strategies of the other two plants and adds its own twist to the mix. It grows quickly but also holds on tightly to the soil. For a little flourish, it grows sharp spines all along it's stems discouraging predators and pullers.

From an evolutionary perspective, each of these plants has found a successful strategy. Their growth patterns yielded plants that could use available resources to produce offspring with similar characteristics to the parent plants. Each survives in a similar habitat with a different answer the the ultimate biological question, "How do I survive and pass on my DNA?". After yesterday, at least a few of those weeds lost the evolutionary battle to their wimpier onion competitors. Onions, though, have their own secret weapon. They have managed to be useful and appealing enough to humans that humans are willing to fight off their competitors for them!



(1)
David W. Monks and Jonathan R. Schultheis, 1998. Critical Weed-Free Period for Large Crabgrass (Digitaria sanguinalis) in Transplanted Watermelon (Citrullus lanatus)
Weed Science. Vol. 46, No. 5 (Sep. - Oct., 1998), pp. 530-532
(2) A hectare is about 2.5 acres, which would take about 5 hours to mow with a push mower. No breaks.
(3) http://plants.usda.gov/java/profile?symbol=DISA
(4) http://plants.usda.gov/java/profile?symbol=OXST
(5) http://plants.usda.gov/java/profile?symbol=AMSP

Saturday, June 4, 2011

Sound Exchange

The sounds changed even in the car on my way out of the city, well, I changed the sound anyway. For some reason, NPR's reports on the daily movements of Al Quaeda grated more than usual, and I switched to music. My poor little car radio has been waiting for years to play something other than news.

As I neared the little farm where I'll be working this summer, I opened the windows and let the country smells and sounds in. The air shifted as I got off the highway. Southern country air is thick, dense and sweet in the summer. When you step out of air conditioning, it feels a little syrupy for the first few breaths until your lungs relax. Southern city air is also thick and dense in summer, but it has a sticky sour quality to it, perhaps from the additional particulates or ozone.

It's not technically summer yet, but you can be fooled into thinking it's summer in the daytime heat. At night, the air is still cool and dry - a sure sign of spring.

The farm itself turned out to be everything I had imagined a picturesque organic farm to be. It has gorgeous rows of greens and flowers, edges of grasses and rural weeds, a sturdy old barn leftover from the last farm, two hoop houses and the owners' house complete with skylights.

I quickly fell into the old familiar rhythms of farm work. In college, I worked on the state of Florida's research farm assisting a plant geneticist. The job was long days of transplanting, mixing soil, watering, fertilizing and spraying pesticides. There is a kind of zone that the body goes into when actively working all day in the heat. It is almost surprising to be quick and strong in intense heat. It was satisfying to revisit those sensations from a younger age with the perspective I have now.

Since I enjoy the work and the atmosphere, the stretching of time that happens with a pleasing repetitive task gives way to thoughts. It was my first day, so there was a lot of conversation with the farm owner and the other worker. I hope that will continue, but I also know we'll all fade into long stretches of nothing but farm sounds and our own thoughts. The contrast with my old job in these aspects is almost comical. The pace of high school teaching is like a car race - constant, hectic, loud and inconsiderate. I enjoyed the excitement of quick decisions and rapid-fire intellectual problem solving, but there was never time to reflect or converse at length with colleagues, and the repetitive work required all one's attention, or one would be embarrassedly fixing idiotic grading errors the students noticed. Time passes not in minutes but in weeks at school. Each glance at the calendar requires the crossing-out of a shocking number of boxes.

I wasn't sure I'd still be up to the task of laboring all day in the sun, but I made it through easily. Next time, I'll bring a little more water, as water becomes much more appealing than even my favorite dessert when I'm sweating like that. I'll also bring my own big straw hat and a handkerchief - two essential items of comfort. One provides an umbrella of shade, and the other provides passing moments of dry skin. Sweat cools best when there is just a little of it on the skin, but for some reason, my sweat glands seems to increase their output in a linear fashion with the temperature, so I need to mop it off to have a few moments of cooling as the next batch of sweat starts to pour out.

As I drove home, I was thankful to have completed my first First of the next phase of life. Quitting my teaching job required giving notice in March, telling students and colleagues in April, and doing things for the last time since I knew I would be leaving. It's been months of sad goodbyes and well-wishing. I am satisfied with the work I did, and I hate to lose that truly wonderful community. Since it had to happen, I must admit I've been a little antsy to get on with it. Yesterday, I finally cleared out my classroom and surrendered my keys to the school, and from now on, my days are about building my next life. I know I'll find ways to weave threads of my teaching life into my future life. My nomadic childhood taught me that old friendships must be maintained intentionally, so I'll put in the effort to make it happen. But now, I'm doing everything for the first time again - first day on the new job, first blog post, first time designing my future with intention.