An Apple a Day

Landin_apples_web

I grew up in the great apple-producing state of Michigan. If you haven’t been to an apple cider mill during October in the mitten state, you are missing out on one of the great joys of life.

Thousands of apple varieties grew in agricultural fields when nation’s founders declared independence. Today, 80% of that diversity is gone and with it, the genetic variation that can save apples from pests, weather, and disease.

Santayana said, “Those who cannot remember the past are condemned to repeat it.” The consequences of low crop diversity were felt during the Irish potato famine in the 1840s which caused the death or emigration of a quarter of Ireland’s citizens. A pathogen entered the potato fields and spread. Since the potatoes were genetically identical, a disease that affected one could infect them all.

Today, cost and transportation constraints benefit massive agricultural operations. The efficiency of monocultures, though, threatens our food and our health. To fight off disease in genetically-similar apples, we turn to pesticides. Apples are continually cited as worst offenders for chemical coatings (fyi, the American Chemical Society recommends a baking soda solution for washing). Today, about half of apples grown in the U.S. are Red Delicious (despite tasting like wood pulp).

Consider trying some local heritage apple varieties. Apple season starts in August!

P.S. An informative Smithsonian blog post about heritage varieties of apple includes a reference to an apple sleuth who lives just down the road from me!

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Of Leaves & Worms

leavesEvery autumn, vibrant leaves float down from the tree tops to stitch a patchwork quilt resting on the forest floor.

Over time, leaves are broken down by fungi, bacteria and other detrivores (organisms that eat dead stuff) like earthworms. The superpower of the earthworm (Lumbricus terrestris) is its ability to compost vegetation and return vital nutrients to the soil.

Charles Darwin was fascinated by earthworms, conducting wonderful experiments to determine how much soil they moved and whether worms preferred to collect leaves from the broad end or pointed end. Worms pull leaves into their burrows (narrow end first) to plug the opening and protect themselves from ‘early birds’.

In much of North America, earthworms were killed off in the last ice age (~10,000 years ago). The worms you see now in Michigan, Maine and Minnesota are all invaders. Sounds great, right? More nutrients in the soil? Unfortunately, the northern hardwood forest ecosystem is adapted to a thicker leaf litter layer and slower release of nutrients. So now, the introduction of the earthworm changes which seeds can germinate (and which trees will continue to survive), nutrient run-off, and which animals live in the new, de-littered forest. (1)

If you’re interested in appreciating the awesome recycling power of the worm, check out a delightful little book by Amy Stewart – “The Earth Moved: On the Remarkable Achievements of Earthworms”.

Want to read more specifics about leaf-earthworm experiments? Natural History Magazine has an entertaining write-up.

  1. Hale CM et al. 2008. Exotic earthworm effects on hardword forest floor, nutrient availability and native plants a mesochosm study. Oecologia. 155:509-518.