Least Favorite Plant: Bidens

14856148_1192325424191374_6246555258212959974_oBeware the Bidens! Kelly and I were naive when it came to this common plant. It looked innocuous so we let a few grow. We’ve never seen it before in our yard and had to post a picture to Facebook’s only useful group, Plant Identification, in order to identify it.

Bidens is in the Asteraceae family which includes sunflowers, daisies and asters. There are many different varieties of Bidens and an equal number of popular names, according to Wikipedia: “beggarticks, black jack, burr marigolds, cobbler’s pegs, Spanish needles, stickseeds, tickseeds and tickseed sunflowers.”

Those popular names should give some clues as to the plant’s behavior. Brush up against it and this happens:

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It turns out that nature has brilliantly designed these seeds to hitch a ride on mammals. Just touch or lightly brush up against the seed pods, which resemble mid-century chandeliers, and you’ll be picking out seeds for the next hour. Plants can’t move on their own so they’ve got to enlist helpers. In the case of Bidens, we’re the Uber.

Do you have Bidens in your garden?

Paper Wasps: Your New BFFs

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We don’t spend nearly enough time admiring the works of nature, because we are too busy admiring ourselves. Sure, humans invented smartphones, but what is a smartphone compared to an acorn? The thing is, the more you learn about nature, the more you learn about it, the more it blows your mind.

All this summer I’ve been fascinated with Polistes dominula, the European paper wasp. In North America there is a native paper wasp, which is quite similar, but the non-native European variant is more the wasp you will  likely be dealing with in urban/suburban North America, because unlike their native counterparts, Euro wasps aren’t shy. They are the ones who will build a nest by your back door, or on the side of your mailbox. Paper wasps build those distinctive, easy to recognize papery nests made of many cells. There are other types of native wasps which build with different materials, such as mud. Honeybee colonies, of course, are made of wax, and in cold climates you’ll never see those just hanging out in the open air. Honeybees like to build inside cavities.

Polistes dominula really like our front porch, and every year we host a colony out there. The nest rarely exceeds the size of a tennis ball. This year, though, it is more than twice that size. This is our fault. We did not knock down the previous year’s empty nest, so they were able to reuse it and get a real jump start in terms of colony size. (Generally they don’t like to reuse nests, but can do so– in this case the queen started a new nest next to the old nest and annexed it as she built).

img_7454So the population of wasps is accordingly quite large, and perhaps a bit worrisome to visitors, who make it up our stairs only to be confronted with a large wasp nest by the door. Yet we have not had any bad encounters with our waspish neighbors. In fact, we’ve never had a single problem with our porch wasps ever, not one sting, despite the fact the like to nest a couple feet from our front door, despite the fact I hang laundry all around them, despite the fact that Erik’s favorite chair is just beneath them

They truly are peaceable creatures, which is why it saddens me when I hear that someone panicking about a wasp nest, calling the exterminator or heading off to the big box store for a can of poison. When I hear about this, I always want to bring up a few points:

  1. Paper wasps are, as I’ve said, peaceable unless their nest is disturbed. The process of trying to get rid of them is what makes them ornery.
  2. They should not be confused with yellow jackets, those reviled picnic crashers who are attracted to meat and like to hang out on the lips of your soda can. Those guys live in underground nests. Your resident paper wasps will not hassle you if you’re doing backyard grilling or enjoying lemonade on the porch. They don’t like our food.
  3. Wasps are seasonal creatures. They build their nests in the spring and the colony disperses in the fall. You can solve your wasp “problem” by simply waiting it out. If you don’t bother them, they won’t bother you! Wait til they die off in the fall, knock the old nest down, and next spring, keep your eye out for any single wasps trying to establish nests in your space. That would be a queen trying to start a new colony. It is a lot easier to discourage a single wasp than to wait and deal with a full populated nest. But I never discourage them, because…
  4. Wasps are a gardener’s best friend! Sure, ladybugs are cute and all, but wasps are stone cold killers working for your benefit, like your own army of mini Dexters. Their favorite prey is caterpillars, e.g. your arch enemies the cabbage lopers and hornworms, but they are also fond of aphids. They swoop down on garden pests like tiny eagles–or flying monkeys–or homicidal Amazon drones– and drag their ravaged bodies back to the nest to the nest to feed their babies. Only the larvae are carnivorous. The adults live on nectar, so wasps are both pest hunters AND valuable pollinators. You want a healthy garden? Host a paper wasp colony.

These are my arguments for adopting a tolerant attitude for paper wasps around your house. Here are some more cool things to know about them:

Only fertile queens survive the winter. The rest of the colony disperses and dies. The fertile queens mate one last time in the fall, and then find some little nook in which to hibernate over the winter (this is amazing to me and I haven’t found any details about it yet.)  In the early spring she emerges and builds a tiny nest, like maybe six cells, to generate a first generation of workers to help her out.

These workers are female, as with the bees, and as soon as they hatch they get to work on enlarging the nest and feeding and tending the next generation of workers. So when you look at a paper wasp nest, this is what they are doing. The wasp nest is a fairly mellow place compared to the extremely crowded, restless interior of the honeybee hive. If you watch a wasp nest, mostly they just seem to be hanging out there, while a few come and go. What they are actually doing, as far as I can figure, is slowly masticating wood pulp to make new cells, or stuffing caterpillars down larvae mouths.  They are daylight creatures, so during the day the nest will only have a few wasps on it, whereas in the evening they will all come home and every inch will be covered with huddled bodies.

I’d love to take a closer look at all this, but as mellow as our relationship might be, I’m not sticking my nose inches from their nest! Someday, though, maybe we can set up a spy camera.

Here is one of those jaw dropping natural science facts: wasps choose the destiny of the developing larvae in the nest– whether will they be workers or “founders” — that is, fertile wasps. They influence this by vibration, by drumming with their antennae. These vibrations alter the gene expression of the larvae, pushing them one way or the other.

If I’ve got my facts right, the males are produced only with the purpose of breeding–like honeybee drones, they do not work. The wasp queen is mobile, so she can choose to mate with males in her own nest, or to go out on the town looking for love– and more often she chooses non-nestmates. Which I understand, because more than likely their nestmates leave the toilet seat up all the time.  Freewheeling males attract fertile queens by staking out key landmarks, such as trees, and marking the leaves and stems with scent. I believe they prefer Drakkar Noir.

I’m feeling a little bittersweet, sitting on the couch, admiring our wasps and knowing that their days are numbered by winter–even a winter as insubstatial as the one we have here in LA. The other day something unusual happened at the nest: suddenly, most of them were airborne and swirling in circles around our porch. This is something I’ve never seen before. I only noticed because I heard the “tip-tap” of wasp bodies hitting the glass of our front door. At first I thought they might have been attacked by a bird or something, and were all riled up, but after watching for a while, I realized they didn’t seem angry, and in fact, it reminded me of something the honeybees do called orientation. Whenever a new batch of workers is hatched in a hive, they all flow out of the hive and circle around it in a big cloud for a few minutes. They are learning how to recognize the hive so they can locate it when they go out in the world. It looks crazy for a couple of minutes, and then ends as abruptly as it started. It was the same case with the wasps– the party (?) lasted for only 15 minutes or so, but was pretty impressive while it lasted. I imagined it might terrify some folks, who would assume the wasps were swarming and up to no good. I wondered if perhaps they’d just hatched their batch of males for their fall mating, the last party of the year. Maybe those males were orienting, or maybe they were all dancing their last, joyous dance before the quiet of winter sends them all to sleep.

For a complete run down of the wasp life-cycle, the University of Michigan’s Animal Diversity Web provides a really detailed read.

What Does California’s Prop 64 Say About Home Marijuana Cultivation?

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After our fist book, The Urban Homestead, came out we visited a big-box bookstore to see what category it ended up in. This was before bookstores created separate shelves for urban homesteading. Unsurprisingly, we found it in the gardening section. What did surprise me was the other books in the garden category. The overwhelming majority were about growing marijuana. There were lavish coffee table books of bud porn, detailed encyclopedias edited by huge teams of experts and countless tomes covering the technical details indoor lights, fertilizers and growing mediums.

Marijuana is the elephant in the gardening bedroom. I strongly suspect that the majority of money spent on fertilizers and gardening related products are for growing pot not petunias. This November, Californians will vote on Proposition 64 which will legalize marijuana for adults over 21. I thought I’d take a look at the text of the law to see what it says about home cultivation.

Currently, qualified patients can use and grow marijuana for medical purposes. In practice anyone can “qualify” by handing over some cash to a storefront doctor and claiming some vague symptoms. This is an exact repeat of what happened during prohibition when a shady doctor could write you a prescription for a shot of whiskey. Under the present law, according to NORML,

Qualified patients are exempt from the state permit program if cultivating less than 100 square feet for personal medical use.  Primary caregivers with five or fewer patients are allowed up to 500 square feet (AB 243, 11362.777(g) and SB 643, 19319). Exemption under this section does not prevent a local government from further restricting or banning the cultivation, provision, etc. of medical cannabis by individual patients or caregivers in accordance with its constitutional police powers under Section 7, Article XI of the CA Constitution (11362.777(g))

In other words, right now there’s a confusing patchwork of regulation when it comes to personal cultivation.

Here’s the text of Proposition 64 relating to home cultivation:

11362.2. (a) Personal cultivation of marijuana under paragraph (3) of subdivision (a) a/Section 11362.1 is subject to the following restrictions:
(1) A person shall plant, cultivate, harvest, dry, or process plants in accordance with local ordinances, if any, adopted in accordance with subdivision (b) of this section.
(2) The living plants and any marijuana produced by the plants in excess of 28.5 grams are kept within the person’s private residence, or upon the grounds of that private residence (e.g., in an outdoor garden area), are in a locked space, and are not visible by normal unaided vision from a public place.
(3) Not more than six living plants may be planted, cultivated, harvested, dried, or processed within a single private residence, or upon the grounds of that private residence, at one time. (b)(l) A city, county, or city and county may enact and enforce reasonable regulations to reasonably regulate the actions and conduct in paragraph (3) of subdivision (a) of Section 11362.1. (2) Notwithstanding paragraph (1), no city, county, or city and county may completely prohibit persons engaging in the actions and conduct under paragraph (3) of subdivision (a) of Section 11362.1 inside a private residence, or inside an accessory structure to a private residence located upon the grounds of a private residence that is fully enclosed and secure. (3) Notwithstanding paragraph (3) of subdivision (a) of Section 113 62.1, a city, county, or city and county may completely prohibit persons from engaging in actions and conduct under paragraph (3) of subdivision (a) of Section 11362.1 outdoors upon the grounds of a private residence.
(4) Paragraph (3) of this subdivision shall become inoperable upon a determination by the California Attorney General that nonmedical use of marijuana is lawful in the State of California under federal law, and an act taken by a city, county, or city and county under paragraph (3) shall be deemed repealed upon the date of such determination by the California Attorney General.
(5) For purposes of this section, ”private residence” means a house, an apartment unit, a mobile home, or other similar dwelling.

In short, the proposition will prevent municipalities from forbidding indoor growing while allowing the regulation of outdoor growing. I’m not going to address what the proposition says about larger growing operations since this involves a complex maze of yet to evolve state and local laws that are hugely controversial.

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In my perfect world marijuana is just another plant, no more or less exciting that a grape vine. As a consequence of marijuana prohibition, illegal outdoor growing operations have been the cause of a lot of environmental damage and violence. Indoor growing is energy intensive and inefficient. It’s my hope that Proposition 64 will improve the current situation by legalizing personal growing (though I wish that municipalities did not have so much control over outdoor growing). Enacting laws against plants seems arrogant, and reminds me of King Canute’s demonstration of the futility of willing the tide not to come in. I have no interest in growing pot, but I think it should be legal to do so.

That said, I realize this proposition is hugely controversial and depends a lot on what will happen when the legislature and local municipalities start building up a regulatory structure surrounding the use, taxation and production of marijuana. I’m interested in hearing your opinions. To those of you who already live where pot is legal–Alaska, Colorado, Oregon and Washington: what has legalization meant in terms of home growing operations? If you’re in California, will you be voting for or against Prop 64? If you’re not in California do you think is should be legal to grow pot? Why or why not?

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Polyphagous Shot Hole Borer and Avocados

Multiple entry holes on avocado trunk. Photo credit: Eskalen Lab, UC Riverside.

Multiple entry holes on avocado trunk. Photo credit: Eskalen Lab, UC Riverside.

Of all the plants in our yard the one I care most about is our avocado tree. I’d be despondent if anything happened to it. Which is why I panicked when I first heard about the Polyphagous Shot Hole Borer (PSHB), a beetle that spreads a fungus Fusarium euwallacea. First noticed in 2003 here in Southern California, the PSHB seems to damage some trees more than others.

Concerned about losing my avocado tree I wrote Akif Eskalen, a plant pathologist at the University of California, Riverside. Dr/ Eskalen’s lab has done a lot of work on the PSHB and what to do about it. I asked him specifically about avocados and here’s what he had to say in an email,

My lab has been conducting a continuous survey on PSHB on infested and non-infested avocados in California since 2012. Based on the preliminary results from our survey the beetle PSHB seems to be attacking and causing damages on primary and secondary branches of avocado only. We have also seen attacks on the trunk of the trees but somehow the beetle is not successful establishing galleries there which could cause of quick death of the tree. I believe with a proper orchard sanitation you can reduce the damage of the beetle and also keep the beetle population down in the orchard . . . we are still continuing experiments with different insecticide and fungicides on avocado against this beetle and their fungi. An insecticide (Hero) has already registered under Section 18 that could be used by growers in CA.

He provided a link to a short publication his lab put out on orchard sanitation best practices as well as a link to information for avocado growers on the use of Hero. Hero is a pyrethroid-based pesticide.

For my own backyard tree I’m going to:

  • Make sure pruning tools are disinfected before use. This is one of the main reasons we use a qualified arborist.
  • Avoid moving firewood around. I’m going to have to think carefully about the wood I import for my pizza oven.
  • Use mulch that has been chipped to less than 1 inch.

I’d sure hate to lose a tree that provides six months worth of free and delicious Fuerte avocados.

Attractive Ornamental Flowering Trees

As I mentioned yesterday, I attended a class a tree identification class at the Arboretum taught by LA County plant pathologist Dr. Jerrold Turney. During the course of the lecture Dr. Turney recommended a number of striking, flowering ornamental trees. I thought I’d list a few of those remarkable trees in case you’re considering planting one. While this list is Southern California-centric, many of these trees can be grown in other climates. All images are courtesy of Wikimedia.

800px-magnolia_stellata_in_the_jardin_de_plantes_de_paris_001Magnolia stellata (Star Magnolia)
Small trees go with small houses like gin goes with tonic water. Small trees are also easy to maintain and don’t break the bank when it comes time to call an arborist. This tree is from Japan and will grow all over North America and Europe.

754px-cornus_florida_02_by_line1Cornus florida (flowering dogwood)
One catch with this pretty tree is that it’s susceptible to anthracnose.

800px-ipe%cc%82_roxo_ype-tabebuia_impetiginosa_cemiterio_sa%cc%83o_paulo_brazilTabebuia impetiginosa (pink trumpet tree)
A tough and beautiful tree that’s great for urban locations.

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Tabebuia chrysotricha
Of all the trees Dr. Turney showed, I think this one was my favorite. The yellow flowers really pop out against a blue sky.

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Brachychiton acerifolius (Australian Flame Tree)
Speaking of popping out, red flowers are also really dramatic.

chionanthus_retusus_-_chinese_fringetree_-_3Chionanthus retusus
Another good urban tree.

To these suggestions I’d add one of my own that also produces a tasty fruit:

redbaronRed Baron Peach
Plant one of these as a bare root tree this spring and you’ll have an attractive small tree and peaches!

Thanks to Dr. Turney for a great lecture. If you’d like to attend the other three parts of his tree identification class you can sign up here.