Starting Seeds with Success: Best Practices

As we edge closer to spring it is time to start getting ready for the active growing season.   Many gardeners kick off their gardening year early with indoor seed starting to prepare for the upcoming season.

Starting your own seeds is an excellent, and often economical way to prepare for your year of gardening. Whether you grow vegetables or flowers (or both), starting from seeds can offer many benefits. Of course, there are some dos and don’ts for getting the most mileage from your seed starting endeavors.

I recently connected with Joe Lamp’l, host of the Growing a Greener World show on public television and the more recent The Joe Gardener Show podcast to talk about advanced seed starting techniques and technology.

You can follow the link below to listen to the show on your computer, or find it on Stitcher or iTunes (links included on the show page, too).  In addition to the podcast, the show page features extension notes on everything we chatted about with links to good reading materials.

Seed Starting Indoors: The Joe Gardener Show featuring GP John Porter

Here are a few of my best seed starting tips:

  • Be economical. One of the great benefits of starting plants from seeds is saving money. A packet of several (even hundreds) of seeds is often around the same price you’ll pay for one plant at the garden center. Of course, if you go out and splurge on the fancy (and expensive) seed-starting systems you see in your garden store or favorite catalog you may end up investing more than you planned. Instead of fancy seed starting trays or peat pellets and pots, use low-cost or recycled items such as takeout containers or shallow disposable aluminum baking pans to start your plants.  Remember that if you are reusing containers, especially ones that have had plants grown in them before, that sterilization is key in reducing disease.  Thoroughly wash the containers, then dip in a solution of 10% household bleach (1 part bleach : 9 parts water) to disinfect.  There are some horticultural disinfectants out there, but bleach is usually the easiest for home gardeners to get since you can pick it up at the local store.
  • Start seeds in clean, sterile seed-starting mix. This is one area where I don’t skimp. You’ll want to use a sterile mix that is primarily made of peat or coconut coir. It is lightweight and pathogen free and also low in fertility, so you will be less likely to lose plants to such issues as damping off (a fungus that rots the seedlings off at the base). Using regular potting mix may work, but increases your chances of such issues. Plus, seeds are equipped with enough nutrients to make it to their first set of true leaves before they need anything from the soil. I know that some sources say to use mixes with compost in them, but unless you know 100% that the compost got hot enough to kill all pathogens (140 degrees plus for several days) you could be introducing diseases to your plants that could affect them in the seedling stage or in the future.
  • Once the seedling has its first set of true leaves (the second leaves that appear), you should transfer it to an individual container/cell/pot with regular potting soil. At this point, the plant will need to have nutrients from the soil to grow healthy. You’ll want to loosen the plant from the seedling mix (I use a chopstick) and lift it by the leaves (not the stem). Temperature control is key.
  • Heat is usually the most important factor in coaxing your seeds to germinate, so placing your newly sown seeds in a warm (around 75 degrees F) place will help them germinate faster. Fast germination is key for making sure you get the optimal number of seeds sprouting. However, moving the seedlings to a cooler place (around 65 degrees) after they’re germinated will make them grow sturdier and keep them from getting thin and leggy. Most people laugh when I tell them, but one great warm place to start seeds is on top of the refrigerator.
  • Light is necessary for good plant growth. Most seeds don’t require light until they get their first true leaves, but after that you’ll want light to keep your plant healthy. Some people are lucky to have a good, sunny (usually south facing) window with plenty of light. Otherwise you’ll need to invest in some lighting. The most economical option is a basic shop light fixture from the hardware store. You can buy plant lights, or full spectrum lamps for it, but if they prove too difficult (or expensive) to find, use a regular warm fluorescent and cool fluorescent bulb to get the right light spectra. You’ll want light on for about 16 hours per day. If you are using a window, be sure to turn the plants regularly to keep them from
    Image result for led plant lights
    Blue and Red LEDs Source: Wikimedia Commons

    growing in one direction.  As LED lights become less expensive, many home gardeners are checking them out for home seed starting.  You can use a full spectrum white LED bank, but plants primarily use red and blue light so you can also find high-intensity LED banks for plant production that are blue and red (makes purple!).  Some research is emerging that a tiny bit of green light helps growth, so some newer systems are incorporating a touch of green, too.

  • Don’t get started too early.  Look at the packet for the number of days/weeks before last frost to start your seeds.  If you start them too early, you could end up with spindly, leggy plants or ones that have grown too large for their containers. Even if you have good lighting, your plants will not thrive being cooped up in the house too long.
  • What about fertilizer? Up until the first set of true leaves, seedlings don’t need much in the way of fertility.  When they’re put in larger containers or cells, a good potting mix (usually containing some type of fertilizer or nutrients) will get you most everything you need….to a point.  If you’re growing in small containers, say those cell packs where you have very limited soil, you may find that you need to provide supplemental fertility after a few weeks.  There’s only so many nutrients in that potting mix in small amounts, so if you are holding your plants for longer than, say, six weeks you may need to apply a water-soluble fertilizer or start off with a slow-release fertilizer.  Larger containers, say a 3 or 4 inch pot, may have enough soil to have sufficient nutrients to get you to the point of transplanting.

Translating the Language of Seed Packets: Hybrid, Heirloom, non-GMO, and more

Hybrid, heirloom, organic, non-GMO, natural….there’s lots of labels on those seed packets or plants you pick up at the garden center or from your favorite catalog.  Since the seed-starting season is upon us, let’s take a minute to look at some of the information – and mis-information – you might find on those seed packets.

For a brief overview, here’s a short video segment I recently shot for the Backyard Farmer Show, a popular public TV offering for Nebraska Extension:

Hybrid vs. Heirloom vs. Open Pollinated

Just what is a hybrid anyway?

Source: http://www.biology.arizona.edu

Simply put, a hybrid is a plant (or any living organism, technically) with two different parents. Take for example the Celebrity variety of tomato, which is very popular among home gardeners. In order to get seeds of Celebrity tomatoes, whoever produces the seeds must always cross two specific parent plants to get those specific seeds, called an F1 hybrid.

These parents have been developed through traditional breeding programs (read: the birds and the bees — no genetic engineering here) from many different crosses. Hybridization has occurred naturally ever since there were plants. Man has been directing this process throughout most of his agricultural history to get better crop plants. How else would we have many of the vegetables and fruits that we take for granted today?

Crops like corn have very little resemblance to its wild counterpart, many thanks to selection and even crossing of superior plants by humans over the centuries. University researchers and seed developers use this natural ability of plants to cross to direct the formation of new varieties that improve our ability to produce food.

What is an heirloom?

Perhaps the first question we should ask is, what is an open-pollinated seed? An open-pollinated variety is one whose genetics are stable enough that there is no need for specific parent plants, because the seeds produced from either self-pollination (as in the case of beans and tomatoes) or cross-pollination with the same variety will produce the same variety.

An “heirloom” plant is basically an open-pollinated plant that has a history, either through age (50-plus years) or through heritage (it has a family story).

Take for example the Mortgage Lifter tomato.

Mortgage Lifter Tomato Source: https://www.flickr.com/photos/blewsdawg

It was developed by a gentleman living in West Virginia (my native state -there are two competing stories as to who developed it). For all intents and purposes, the Mortgage Lifter started out as a hybrid, since the gardener in question developed the tomato by crossing many different varieties to find one that he liked.  He sold so many of them to his neighbors that he was able to pay off the mortgage…thus its interesting moniker.

It just so happened that the genetics of this tomato were stable enough that its offspring had the same characteristics, so seeds could be saved.  Therefore, it was technically an Open-Pollinated variety. Over time, the tomato became considered an heirloom because of both its age and unique story. This story has played out many times, in many gardens and in many research plots at universities.

There are some trying to revive the practice of plant breeding for the home gardener. If you’re interested, check out the book “Plant Breeding for the Home Gardener” by Garden Professor emeritus Joseph Tychonievich. Who knows? Maybe in 50 years we will be celebrating your plant as a distinctive heirloom.

So which is better – Heirlooms or Hybrids?

There are pros and cons to hybrid plants and heirlooms both, so there really isn’t an answer as to which one you should plant. It really boils down to personal choice. Hybrid plants tend to have more resistance to diseases and pests, due to the fact that breeders are actively trying to boost resistance. This means that there will be higher-quality produce fewer inputs. This is why hybrids are popular with farmers — nicer, cleaner-looking fruits with fewer pesticides. Many times hybrids are also on the more productive side, thanks to a phenomenon called hybrid vigor.

Heirlooms, on the other hand, help preserve our genetic diversity and even tell our cultural story. Heirlooms do not require a breeding program, so there is built-in resilience, knowing that we can produce these seeds well into the future with little intervention. But we do have a trade-off with typically less disease-resistance and less consistency on things like yield.  Since they are open-pollinated, they are often a good choice for people who enjoy or rely on saving seeds from year to year.

GMO-Free or Non-GMO

As we have pointed out several times before, when it comes to seeds for home gardeners, the label of GMO-Free is largely meaningless and sometimes mis-leading.  Whether or not you believe the prevailing science that shows that genetically engineered plants are safe for human consumption, you can rest assured that there are currently no genetically engineered seeds or plants available to home gardeners.  Not on the seed rack at the box store nor your local garden center.  Not in a catalog or online.

Here are two assurances to that statement:  A majority of the things that you grow in the home garden don’t have a genetically engineered counterpart. Only

Source: USDA Animal and Health Inspection Service

12 genetically engineered crops have been approved in the US, and only 10 of those are currently produced.  Most of these are commodity crops that home gardeners would not even produce, such as cotton, sugar beet, canola, and alfalfa.  A few more have counterparts that are grown by home gardeners, but are vastly different from those grown by commodity producers (soybeans vs. edamame soy).  And some just aren’t that very widespread (there are some GE sweet corn cultivars and squash cultivars, but they aren’t widespread on the market).

So for the most part, there aren’t any “GMO” counterparts to the crops you’d grow in the home garden.  They don’t exist.

The other assurance is that genetically engineered crops are not marketed or sold to home gardeners as a matter of business practice or law.  In order to purchase genetically engineered seeds or plants, it is current practice in the United States that you must sign an agreement with the company that holds the patent stating that you will not misuse the crop or propagate it (and before we get into the whole intellectual property argument – plant patents and agreements like this have been around since the early 1900s – it isn’t new).  So you know that you aren’t buying genetically engineered seeds since you aren’t being asked to sign an agreement.  Plus, these companies make their money by selling large quantities of seeds, they just aren’t interested in selling you a packet of lettuce seeds for $2.

So since there aren’t any GMOs available to home gardeners, why do all these seed companies slap that label on their packets?  Marketing, my dear!  It started off with just a few companies, mainly using the label to compete in a crowded market.  And fear sells.  The label has spread to more and more companies as this fear and anti-science based marketing ploy has spread…both by companies who jumped on the fear bandwagon and by those who took so much harassment from the followers of the non-GMO crowd or they lost sales to people sold on the non-GMO label that they finally gave in.  Unfortunately for some companies, slapping the non-GMO label on a product seems to give them permission to charge more, even if has no real meaning….so buyer beware.

Treated vs Non-Treated

Image result for treated seed
Treated seed Source: pesticidestewardship.org

Seed treatment usually involves the application of one or more pesticide such as a fungicide or insecticide to protect against pathogens or pests, mainly in the early stages of growth.  A good example would be if you’ve ever seen corn, pea, or bean seeds at the local feed or farm store that are bright pink or orange in color.  These seeds have been treated with a fungicide to offer short-term protection against damping off.  Some crops are also treated with systemic insecticides, such as imidacloprid, to protect against insect damage. There’s been a big emergence of organic seed treatments, so treatment doesn’t necessarily mean the crop can’t be labeled organic.

Treated crops are most-commonly found at farm supply stores and aren’t generally marketed directly to home gardeners. You’ll likely not find them at most box stores or garden centers catering exclusively to gardeners. Many packets will specify whether they are non-treated or treated.

Organic and Natural

In seeds, the term Organic largely refers to seeds harvested from plants that were certified organic.  Generally speaking, these seeds were produced on plants that received no synthetically produced fertilizers or pesticide sprays.  However, it does not mean that the plants were not treated with pesticides.  There’s a great misunderstanding about organic production – there are a number of pesticides and even seed treatments approved for use on organic crops.  Typically, they are produced from a plant or microorganism extract, naturally occurring mineral, or other organic derivative.  So organic does not equal pesticide free (on the seed rack or on the grocery shelf).

There are a few different levels of “organic,” too.

Sometimes small producers use the label in a general sense to mean that they follow organic practices, but aren’t certified.  The process for certification is often onerous and costly for small producers, so they often opt to not get it.  This is especially true for producers that market exclusively to a local clientele, like at the farmers market, where they can rely on their relationship with customers and reputation to speak for their practices. Some food companies may also use a simple “organic” label – either as a design choice, or because their product wouldn’t qualify for a certification.

"Certified Organic" Label“Certified organic” means that the producers practices have been certified to meet the requirements laid down by a certifying agency.  A certifying agency could be a non-profit or a state department of agriculture.  The requirements and practices vary from entity to entity.

Image result for certified organicUSDA Certified Organic” means that the producer has been certified by the USDA as a follower of the guidelines set forth by the National Organic Program (NOP).  This is usually seen as the most stringent of the certifications, and is standardized nation-wide.

 

For certified organic producers, a requirement for production is that all seeds or plant sources are organic.  For home gardeners, I often question the need for organic seed, even if organic methods are followed.  A quick literature search turned up no evidence that garden seeds contain pesticide residues.  There’s been no evidence that plants translocate systemic pesticides to their seeds or fruits(Though it is impossible to prove a negative).  Since seeds are located inside some sort of fruit, there would be little chance of residue on the seed from a pesticide application.  And even if there was some sort of residue, it would be such a small amount in the seed that it would be so dilute in the mature plant that it would likely be well below any threshold of threat to human or wildlife health…or even measurability.

Personally, I may opt for the organic seed at home if it were the same price of the “conventional” on offer…but that organic label often includes a pretty good price differential.  Knowing that there likely isn’t a huge difference in what is in the packages….my penny-pinching self will reach for the conventional, cheaper option.

And what about “natural.”  That one’s easy….there is no recognized definition of natural by the USDA or any other body.  Companies use that term to mean whatever they want it to mean….meaning that it is relatively meaningless in the grand scheme of things.

Where to find me on the web:

Twitter

Facebook

Personal Blog

Work Blog: GROBigRed

Love notes of genetics and physiology for Valentine’s Day

A St. Valentine meme compliments of my "friend" the self-styled Rev. Apostle, and Bishop to the Stars, Joel L. Watts.
A St. Valentine meme compliments of my “friend” the self-styled Rev. Apostle, and Bishop to the Stars, Joel L. Watts.

Ahhh….’Tis the time of year when we celebrate romantic love in homage to a 3rd Century priest who came up a head short for performing unsanctioned Christian weddings.  (It is also of note that St. Valentine, or Valentinius as his friends called him, is the patron saint of bee keepers but, strangely, not of birds, flowers, or trees).

In celebration, many suitors, partners, spouses, fling-seekers, and woo-wishers will flock to florists, grocery floral counters, and even gas stations to purchase flowers, namely roses, that have likewise been beheaded.

Those roses, with all of their tightly wound petals, look nothing wild-type roses. Modern roses are the product of many centuries of breeding that started independently in China and the Mediterranean region.

So if the wild-type rose has a single row of five petals, how do breeders get all of those extra petals?  They can just come from nowhere, you know.

The simple answer is that tissue that turns into stamens in the wild-type flower are converted to petal tissue.  While early (and even contemporary) plant breeders may not understand the mechanism responsible for the doubling (gene expression), research is showing that the same gene is responsible for the doubling in both the Chinese and Mediterranean set of species/subspecies.

In a nutshell, what happens is that the different regions of the flower – sepals, petals, stamens, carpel – develop in response to the expression of a set of genes.  It isn’t just the genes acting alone, though; it is their interaction in the tissues that makes the difference.  These genes are grouped by the floral part they affect and are grouped as A-Function, B-Function, C-Function, and E-Function.

If you want to learn a whole lot more about it than I can ‘splain (it has been a few years since my last plant physiology class), this paper thoroughly explains the gene expression and evolution of the flower.  Their figure depicting the flower model is informative, yet simple.  I’ve included it (and its accompanying caption) below.

The ABCE model of floral organ identity. Sepals are produced where A function acts alone, petals where A and B functions overlap, stamens where B and C functions combine, and carpels where C function acts alone. In the eudicot genetic model Arabidopsis thaliana, APETALA1 (AP1) and APETALA2 (AP2) are the A-function genes, APETALA3 (AP3) and PISTILLATA (PI) together specify B function, C function is specified by AGAMOUS (AG), and multiple SEPALLATA genes provide E function
The ABCE model of floral organ identity. Sepals are produced where A function acts alone, petals where A and B functions overlap, stamens where B and C functions combine, and carpels where C function acts alone. In the eudicot genetic model Arabidopsis thaliana, APETALA1 (AP1) and APETALA2 (AP2) are the A-function genes, APETALA3 (AP3) and PISTILLATA (PI) together specify B function, C function is specified by AGAMOUS (AG), and multiple SEPALLATA genes provide E function.  http://www.pnas.org/content/107/52/22570

 

In the paper “Tinkering with the C-Function: A Molecular Frame for the Selection of Double Flowers in Cultivated Roses” researchers show that in lines from both regions of the world produced double flowers as a result in a reduction of expression of the C-Function gene AGAMOUS (RhAG) leads to double flowers.  In Arabidopsis (every plant lab bench jockey’s favorite model plant), this reduction shifts expression of the A-Function genes toward the center of the plant, turning stamens into petals and carpels into sepals.

Now, one question I get from time to time is “why don’t these roses smell like the old-fashioned roses?”  One answer is that as we breed for looks, we are breeding out genes responsible for scent oil production.  So Shakespeare was actually wrong when he said that “a rose by any other name would smell as sweet.”  That isn’t true these days.

So, I wish you a perfectly lovely Valentine’s Day, no matter how you celebrate. Just remember to whisper sweet nothings of floral gene expressions in your sweetheart’s ear.  And remember to stop and smell the roses – if it is a variety that has a decent scent.

Of potatoes and blue roses: be a mad plant tinkerer

A few weeks ago, I saw an interesting article in the Wall Street Journal (of all places) talking about people who are bioengineering plants at home to develop, among other things, a true blue rose.   I love to see this.  “Tinkerers” have long been a proud tradition of people who make true impacts and discoveries.  I think of the ultimate plant “mad tinkerer” Luther Burbank who established himself as a foremost expert on developing new plants all from his crazy tinkering that developed the potato that you’ll find at nearly every fast food joint and created plants such as the shasta daisy and the wonderberry.  I also think of a contemporary plant tinkerer – my friend and fellow GP Joseph Tychonievich.  I love seeing all of his new plants and envy his creativity.

I can only hope that more and more people, and younger people especially, have an interest in amateur plant science. We live in a time when science education has reached a fervor, with about every school and youth program focused on STEM education.  We even have 4-H clubs that meet in our office that are completely focused on robotics and coding.  While this focus on science is great, my issue is that it focuses mainly on the “sexy” disciplines (engineering, chemistry, physics, etc) and little on life sciences like plant biology.

I’m heartened to see many many schools adding gardens to incorporate into the curriculum.  Here in my county we’ve helped build and advise over two dozen school gardens.  I’ve also seen some new tools to inspire young plant scientists, including an online community of scientist mentors who give guidance to budding plant science students (Planting Science). Who knows, maybe we’ll inspire a new generation of Luther Burbanks.  We can only hope.

Not raking leaves: Too good to be true?

Rejoice, gardeners and homeowners, for your deliverance from the drudgery of raking leaves has arrived. Or so goes the proclamation from a viral article that popped up on social media this past fall.

The article in question was posted on the Woman’s Day magazine website based on information from the National Wildlife Federation As the article points out, leaving piles of leaves on the lawn are good “habitat” and homeowners should just let the leaves fall where they may for the sake of supporting critters in the lawn. Of course, you can always believe everything you see online, right?  Let’s take a look at what research can tell us.

Not so fast. There are a few issues with this new proclamation. Not that I am a great fan of the rites of autumn that dictate that we remove leaves from the lawn. It is one of my least favorite garden tasks, as evidenced by the fact that I wait until every last leaf has fallen before I get the leaf blower out so I’m certain that I don’t have to do it more than once.

Many people rake up leaves in the lawn because of aesthetics — we don’t want our neighbors to see a messy lawn. But there are lots of other issues that leaving leaves on the lawn can cause. Let’s take a look at all the reasons why leaving a layer of leaves on the lawn may not be the best idea.

First, the claim that leaving leaves where the fall on the lawn provides “habitat” for wildlife. What wildlife? The original source suggests small mammals, butterflies, and moths — specifically providing a place for overwintering. While I’m sure that there are some perfectly nice little critters that will make their home in the leaf litter, I have a name for what a lot of those things that find their home in your new “habitat” may be— pests.

Plant debris provides excellent overwintering opportunities for many garden pests. I also suspect that some of the wildlife that would find a comfy abode in the leaf litter would be small rodents, like mice and voles, that would enjoy nothing more than to snack upon some of the woody plants in your landscape. I also found some research that says removing leaf litter from residential areas reduces populations of ticks (article). Definitely something I wouldn’t want to welcome with open arms to my lawn.

Now let’s think about how plants make their food — they use sunlight for the process of photosynthesis. The article in question advocates letting leaves pile up where they fall on the lawn.  This means piling up on the grass (or in my case, whatever passes for green).  A layer of leaves on top of the grass will inhibit the plants from making their own food. While grass may not be actively growing in the winter, as long as it is green, it can still perform photosynthesis and store the food for spring. Even if you have a species of grass that turns brown in the winter, a pile of leaves would become an issue when things warm up in the spring.

It also turns out that a thick layer of matted leaves on top of the soil can create a barrier that reduces oxygen in the soil — thus creating an anoxic condition that will reduce or damage roots. Not only do the leaves create a barrier, but research has shown that the rapid consumption of oxygen by leaf litter bacteria lead to anaerobic conditions in the leaf litter itself (article).

Give the reduction in sunlight and soil oxygen, grass can have a difficult time thriving in areas of heavy leaf litter. Some other research results I found indicate a layer of leaf litter reduces the amount of herbaceous plants (in woodland) (in a field study). If you think about it, you don’t see many small herbaceous understory plants in forests with lots of trees — it isn’t just the shade from the trees that causes a problem.

I’ll also point out that for dog owners, leaving a layer in the yard can make it much easier to fall prey to what we refer to as “yard bombs.” I’m sure other dog owners have felt this pain.

Now, I’ll be the first to tell you that leaves are a valuable resource for lawn and gardener, so don’t think that I’m anti-leaf. I put all of the leaves that fall in my yard to work for me. While leaving the leaves to pile up into layers on the lawn is not a good idea, using a mower to chip them up and leave them in place will provide valuable organic matter and nutrients for the soil. So if you don’t want to rake them up, run over them with the lawnmower so they will break down quickly into the soil (and don’t smother out the grass).

If you do rake up (or vacuum up) the leaves, there are a few things you can do with them. First, the shredded leaves make a good winter mulch for landscape beds (put the plant suppressing power to work controlling weeds). You can also bag them up and store them for use in composting next spring and summer when you have fresh green plants to add to them.

This article originally appeared in the Charleston Gazette-Mail on November 15 (sans citations).  

You can find my other articles online at wvgardenguru.com

@wvgardenguru

Allelopathy Helps Black Walnuts Compete

A walk through the woods can be one of the most peaceful and calming experiences — a place where you can find quiet for reflection and marvel at the beauty of nature. Little do most people know that some plants, especially one specific tree, wage chemical warfare against other plants to keep away potential neighbors that would compete for nutrients and sunlight. In the Appalachian Mountains, the tree most skilled at chemical warfare is the black walnut.

The black walnut tree (Juglans nigra) is a useful, yet often misunderstood tree. Prized for its excellent wood qualities for lumber and furniture, the nuts it produces are either loved or reviled by those who try them.

The flavor of black walnuts is hard to describe. I would say that they have an almost astringent flavor, mainly due to the high level of tannins in them. They aren’t my favorite, but I don’t mind them either. I’ve learned to accept them, unlike during my childhood when you knew which church lady’s cake to avoid at the potluck because you knew that she put black walnuts in everything she baked.

My appreciation for black walnuts grew the year that I was the official nut judge (no joke) for the Black Walnut Festival in Spencer, WV. It was quite an experience — examining and weighing all the entries with a team of high school FFA students who cracked more than a few inappropriate jokes about the situation.

You could tell when someone was picking or cracking black walnuts, thanks to the tannin stains on their hands that just wouldn’t wash off. Black walnuts are a tough nut to crack (literally), so I also remember my grandmother cracking them “the easy way.” She would just pile them up in the driveway and run over them a time or two with her behemoth of an Oldsmobile (you know, the one that had full seats front and back and could hold half the neighborhood).

Black walnut trees have the interesting ability to excrete a chemical called juglone, which makes it nearly impossible for a number of plants to grow anywhere in its root zone. Juglone works by damaging the tiny root hairs on roots that are responsible for taking up a great majority of the water and nutrients the plants use. Research shows that it also interferes with the interaction of the roots with mycorrhizal fungi that aid the plant in taking up nutrients.

This process is not just specific to black walnuts. There are several other plants that do this. The phenomenon, called allelopathy, occurs when an organism excretes something that inhibits the growth of other things around it. You could equate it to the Penicillium fungus excreting a chemical that kills bacteria around it. We harness that chemical to use as penicillin.

Some plants are especially sensitive to the chemical. Many vegetable plants, especially tomatoes, are sensitive. Some plants, mainly those that would grow wild in the woods, are not susceptible. Many grasses also have a hard time growing beneath black walnut trees (tall fescue and Kentucky bluegrass being the exception, except during periods of drought).

Publication with lists of plants tolerant and damaged by juglone

All parts of the tree produce the juglone chemical, so the effects could spread beyond the perimeter of the tree from fallen leaves and branches. I would also suggest that you make sure any fresh woodchip mulch that you use (specifically that from local tree cutters) is free of black walnut. The juglone may break down after composting the wood chips for six months to a year, but I would still be cautious about its use. The wood will release the chemical, killing susceptible plants for a few years in the area where it is applied. Studies suggest that juglone will break down during the composting process, but I would check to make sure by starting a few tomato seeds on the batch of compost to see what happens.

—Garden Professor John Porter is a county extension agent for West Virginia University and writes the weekly Sunday garden column for the Charleston Gazette-Mail Newspaper.  This article was originally published October 2, 2015.

You can find John’s writing at wvgardenguru.com and on Facebook and Twitter.

When Plants Attack! (each other)

When you talk about killer plants, your mind may conjure images of a man-eating plant in “Little Shop of Horrors,” insect-eating Venus flytraps or poisonous plants like deadly nightshade.

While all of those scenarios are interesting in and of themselves, what about plants that attack other plants?

I’m talking, of course, about parasitic plants. These plants thrive on stealing nutrients from other plants, either weakening them or, quite possibly, killing them.

Parasitic plants connect themselves to a host plant and siphon off the sugars that plant produces and the nutrients it pulls from the soil. These plants often bend the definition we have in our heads of plants, since they don’t have to behave like other plants that make their own food.

Probably the most well-known (and beloved) parasitic plant is mistletoe. The plant that gives us the warm fuzzies and romantic feelings around the holidays makes its living by feeding off of the trees in which it lives. They don’t talk about that aspect of the plant in all those Christmas songs. It doesn’t kill the tree, but a heavy infestation can weaken a tree and slow its growth.

Indian pipe (Monotropa uniflora). Photo courtesy GP Raymond Eckhart

While they are few in number, there are some parasitic plants you may run into. Another parasitic plant in our part of the world is the Indian pipe (Monotropa uniflora), a white, chlorophyll-free plant that resembles a smoking pipe as it unfurls from the forest floor. Without chlorophyll, it can’t make its own food, so it connects itself to a nearby tree (usually beech) for nutrients.

Another plant, called a beech drop (Epifagus americana), also makes its living in the same manner. A plant called squaw root or bear corn (Conopholis americana), because it resembles an ear of corn growing out of the forest floor, is a parasitic plant that connects with the roots of oak trees.

An infestation of dodder beginning in an annual bed. Photo courtesy Ann Berry.
An infestation of dodder beginning in an annual bed. Photo courtesy Ann Berry.

These plants may cause a little damage to their host plants. This week, though, there seems to be something more sinister afoot. I received two different calls about the same parasitic plant this week, from different parts of West Virginia (one of which came from Ann Berry, associate vice president for marketing and outreach at WVU). It seems that the problem here was with a parasitic plant called dodder (Cuscuta sp.). Despite the name, I assure you that this plant does not dodder around when it comes to feeding off other plants. This plant can severely infect and potentially kill any plant it touches.

 

Seeds of the plant germinate in the soil, so it starts life just like any other plant. Once germinated, though, the seedling has about 10 days to find a host plant to attach to and begin feeding. But this is not left to chance — it seems that dodder is a pretty good hunter. Scientists have determined that dodder can, in a way, sense chemical signals from nearby plants and grow directly toward them.

Dodder is an odd-looking plant, and many people don’t even know to classify it as a plant. It grows in long strings, often without leaves (or only having inconspicuous ones). Different species can be different colors. The one that is most common here is often a yellow-orange color.

cuscuta Haustorium
Dodder, above, inserts a haustorium into its host plant.

Once the dodder touches the soft tissue of a plant (leaves or stems), it inserts a structure called a haustorium into the plant. Haustoria insert themselves into the plants vascular tissue (veins) and siphons off the water, sugars and nutrients. After the connection is made, the dodder plant detaches its roots from the ground and becomes completely reliant upon the host plant. Luckily it has trouble attacking woody plants, so it mainly goes after herbaceous ones.

One connection is bad enough, but the dodder twines its way around the plant as it grows, resembling what some would call “silly string.” Everywhere the dodder touches the host, it sends in new haustoria to strengthen its connection. If other plants are close enough, the dodder will grow outward through the air to ensnare another host. It can easily grow to encompass many plants, covering them completely and eventually strangling them or starving them out.

My advice to both of the callers this week was to remove as much of the plant as possible, as soon as possible. Unfortunately, the plant can regrow from the connections it makes with the host plant, so you often need to remove whole parts of the plant or the whole plant itself. If it has only made one or two connections, you may be able to control it just by removing the dodder from the plant.

Dodder is hard to see on the ground as it germinates, so it is only usually spotted after it has attached and grown on a plant. If you do happen to catch it before it attaches to a plant, cultivating the soil to break it up and removing as much by hand as possible will help. Unfortunately, there is no spray or control method that will kill the dodder without killing the host.

Dodder is definitely a bizarre plant that many have not seen. Keep an eye out for it this year, since it seems to be cropping up in unexpected places. It just goes to show you that sometimes it’s a plant-eat-plant world out there.

This article was originally published 08.09.15 in the Charleston Gazette-Mail.  You can find more article at wvgardenguru.com.