The Garden Professors™ – Page 40 – Advancing the science of gardening and other stuff since 2009

A new excuse for bad pruning

I spent last week in Orlando at the ISA annual meeting (that’s the International Society for Arboriculture). It’s a great venue for networking with colleagues and hearing about the latest tree research. And once in a while I’ll have a WTF moment. (That stands for Why Trees Fail in case you’re wondering.)

My WTF experience this year revolved around some new terminology and techniques. I learned there are now “environmental arborists” who practice “retrenchment pruning.” In the last few days I’ve tried mightily to find some standard definitions from reputable sources. I don’t know what an environmental arborist is, since it’s not a certification (like an ISA certified arborist) nor is it a university degree program (like urban forestry or environmental horticulture). It seems to be a self-anointed title.

This is what a mature oak should look like. — This is what a mature urban oak should look like.

But the real WTF issue is retrenchment pruning. I looked in vain for published research through my usual data bases and found nothing – other than two articles in Arboricultural Journal (which is not the same as ISA’s journal – Arboriculture and Urban Forestry). Neither of the articles presented experimental evidence to justify this radical approach to pruning trees. Instead, they are more philosophical in nature, with a smattering of ecological theory.

Fortunately, retrenchment pruning methods are easily found on the internet, along with horrific pictures illustrating the results. As described on various websites, retrenchment pruning imitates the natural process of aging. Practitioners remove live branches or partial trunks to reduce the size of the tree and prevent future failure. These aren’t clean cuts, either: they’re “coronet cuts” or “natural fractures.” The rationale described in one of the Arboricultural Journal articles is that these jagged broken branches and trunks “promote specialist habitats and enhance colonisation rates of niche species.” In other words, this technique creates large wounds that are easily colonized by various insects and microbes.

An example of natural fracture pruning (http://www.countytreesurgeons.co.uk/veteran.html)

So apparently we’re expected to ignore the well-established field of woody plant physiology (which happens to be my specialty) and related practical bodies of knowledge (e.g., formal and informal pruning techniques of said woody plants) and start hacking away at mature trees. In doing so, we’re removing live tissue and creating large wounds. This has the effect of both reducing photosynthetic potential of the tree as well as opening it up to possible pest or disease invasion. But nowhere are these possibilities discussed as part of the “natural aging process.” Nor was there mention about how to manage the epicormics shoots that result from improper pruning. And they do need to be managed.

These are epicormic shoots resulting from topping this tree.

I saw some very angry arborists at the ISA meeting who were incensed at the idea that we should deliberately malprune trees. But others seemed quite excited with this new philosophy. To paraphrase one of my plant physiology colleagues, “Give a bad arboricultural practice a catchy name and it magically becomes legitimate.”

Pollination strategies can lead to allergy woes

This article was originally published in my weekly newspaper column in the Charleston Gazette-Mail. Articles are archived at wvgardenguru.com.

A quick selfie with President Gee. He's perfected the art of the selfie. — A quick selfie with President Gee. He’s perfected the art of the selfie.

A few weeks ago I made my way to South Dakota for the annual meeting of the National Association of County Agricultural Agents (where fellow GP and I made the rounds at the trade show scrutinizing wacky products). It is a fun conference made even more special this year by the fact that WVU President E. Gordon Gee was in attendance as the conference co-keynote speaker and recipient of the Service to American/World Agriculture award. But I digress…..

Two days into the conference something wasn’t quite right. I kept feeling worse and worse, and by Wednesday I was confined to my hotel room (save for a venture out to the conference banquet for dinner). I would not have been functional for the rest of the trip save for the kindness of a co-worker who went through the pharmacy red tape to procure and deliver “the good stuff” to my hotel room.

I thought I had a sinus infection at best (I get them often) and the flu at worst (yes, it was really that bad). But guess what — I’m just really allergic to South Dakota. Two days after my return, I was nearly back to normal (well, my normal, anyway).

Those who know me know that I suffer from the occupational hazard of allergies. Irony dictates that my allergies are only to about two dozen plants and two molds (that occur in mulch/compost). Lucky me!

Lots of corn surrounding my hotel in the outskirts of Sioux Falls. — Lots of corn surrounding the outskirts of Sioux Falls.

My best guess is that I had a reaction to the corn pollen of South Dakota. It makes sense — while we do grow some corn here in West Virginia, the Mount Rushmore State boasts an estimated 4.75 million acres of corn. I don’t think I was tested for corn pollen allergies, but since corn is not a major crop here, it may not be part of the common test.

I tell this story not for sympathy (well, OK, maybe a little) but it brings up a good illustration about pollination strategies of plants.

Scanning electron microscope image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis).

You see, plants like corn rely on chance and wind to spread their genes around. In corn, the pollen drops from the male flowers (the tassel on the top) to the stigma of the female flower (the end of the silk sticking out of the cob). The process relies on lots of pollen being released into the air, since there is a good chance that a lot of it will miss the target. Corn pollen is usually heavy, therefore it doesn’t blow too far from the plant (unless there is lots of wind).

This is why you don’t get a good corn crop if you don’t have a big block of corn in the garden — just one or two rows doesn’t drop enough pollen to pollinate all the flowers. When the silks don’t get pollinated, you’ll end up with incomplete cobs missing kernels. This can also happen if the corn is in bloom during a long period of rain — the rain washes all of the pollen off before pollination can occur.

Most of the major allergen-producing plants are wind pollinators — trees, grasses, ragweed. They all release copious amounts of pollen into the air hoping for it to land in the right place.

Some plants still rely on pollen getting moved from plant to plant or flower to flower, but they remove the chance involved with wind pollination. These plants have a stickier pollen that stays on the flower and waits for something to come along and move it — a bee, a butterfly, a moth, a hummingbird, etc. These plants hold on to their pollen and have the more directed approach of getting a courier to make a direct delivery of their pollen between flowers.

Since these plants don’t leave the pollination to chance, they generally produce less pollen. Some good examples are fruit trees (apples, peaches, pears), sunflowers, squash, goldenrod and roses. Since they don’t release it into the air, they usually aren’t considered major allergens.

Still yet, some plants want to take no chance with their next generation. Self-pollinating plants don’t rely on pollen being spread to different flowers — they take care of business themselves. These plants are perfectly fine without crossbreeding with other plants.

Sometimes, these plants are so dedicated to self-fertilization that they make it difficult for the pollen to leave the flower. Bean flowers have a lower lip that curves upward to protect the reproductive parts inside. Tomato flowers are nearly completely enclosed. You may see bees going from flower to flower, but their search for food is in vain — they can’t get into the flower. Their buzzing does help dislodge the pollen inside the flower, but they don’t have access to spread it around. Producers that grow tomatoes in greenhouses where there is no wind to knock the pollen loose either buy boxes of bumblebees to release in the greenhouse, or use something like a vibrating toothbrush to help the flowers self-pollinate (no joke).

This is why you can plant two different tomatoes just a few feet apart and not have them crossbreed, but you would have to plant squash up to two miles apart (or protect the flowers) to guarantee that you get the same variety if you plan on saving seeds. This is why the most commonly saved seeds, at least in this area, are tomatoes and beans — they are easy to guarantee that you won’t get something other than what you plant.

So if you learn anything from this article, check out how plants pollinate before you save their seeds, and take plenty of allergy meds with you if you go to South Dakota.

Cool Plants for Late Summer

I thought today’s post would feature two awesome plants that are relatively new or unheard of in the industry. Both of these plants have performed well in my own garden and survived our two hardest winters recorded since the 1970’s. Many plants suffered severe winterburn or even death due to extremely low temperatures, but not these two plants. They may be harder to find in the nursery/garden center, but are well worth it and have huge ornamental impact all growing season.

The first is variegated fiveleaf aralia, Eleutherococcus sieboldianus ‘Variegatus’ (formerly Acanthopanax sieboldianus ‘Variegatus’). I know, a really horrible, long scientific name for such a great plant. Now before I go on about this particular cultivar, I need to let everyone know that this is the cultivar you want, NOT the species that has all green leaves. The straight species is weedy, grows too large for most landscapes and is not colorful. The variegated cultivar is a real showstopper! It is low maintenance, grows slowly and rarely needs pruning. This medium-sized shrub grows about 5-6’ tall and wide in the northern U.S. growing larger in the south. The natural form is upright, rounded with long, arching branches. Suckering at the base of the shrub is slow, hence the plant does not become a nuisance in the garden. Variegated fiveleaf aralia is adaptable to most soils and pH, tolerates sandy and poor, dry, clay-based soils, will stay variegated in shade and will not scorch in full sun. It is quite drought tolerant with no pest problems. Deer and rabbits seem to leave it alone.

The foliage is quite clean with 5-7, bright, cream to yellow variegated leaflets with an emerald green center. There is no fall color to talk about, however, the brightly colored leaves mix well with other yellow, white or purple flowering/foliaged plants. The stems do have 1-2 curved prickles on them at a node, but they are short. Unlike its straight species, ‘Variegatus’ rarely flowers or fruits so the plant does not become invasive.

This plant is native to Japan and was highly promoted as an outstanding urban tolerant plant by my former graduate advisor, the late Dr. J.C. Raulston of North Carolina State University. He tested and evaluated thousands of landscape plants for adaptability to the southeastern U.S. and a few of those plants are actually hardy up in zone 4b.

Another great plant that I am more and more impressed with each day is a relatively new release from Iseli Nursery, Boring, Oregon. It is NORTH WIND^® maple (Acer ‘IsINW’). This smaller, 15-20’ tall, ornamental maple is part of Iseli’s Jack Frost^® series of hardy, ornamental maples. Through testing across the country, this maple has proven hardy to zone 4a without any dieback, unlike Japanese maple (Acer palmatum). One of the parents of this great hybrid is the Korean maple (Acer pseudosieboldianum), which is also zone 4 hardy.

NORTH WIND® maple (Acer 'IsINW') — NORTH WIND® maple (*Acer* ‘IsINW’)

The beauty of NORTH WIND^® maple is that it combines the cold hardiness of Korean maple with the outstanding leaf qualities and deeper leaf lobes of the Japanese maple, one of the suspected parents, but with one exception. NORTH WIND^® maple new leaves are bright orange! The color of these leaves lasts longer in the growing season in cooler climates. I have a young tree in my yard and the leaves are still orange, even this late into August. The older leaves gradually fade to green in midsummer. The orange-red fall color is superb and makes a real eyestopper in the autumn landscape. For best color, plant the tree in full sun to partial shade.

Closeup of leaves of NORTH WIND® maple (Acer 'IsINW') — Closeup of leaves of NORTH WIND® maple (*Acer* ‘IsINW’)

NORTH WIND^® maple is pH adaptable and grows best in a moist, well-drained soil. I do not know yet how heat or drought tolerant this species is, but if anyone is growing this plant in southern climates, please let me know how it is doing.

Laura Jull, Ph.D. aka The Lorax

Don’t buy problems

Sometimes where you shop matters, because if you buy plants at the wrong place you run the risk of importing new problems into your garden. Those cheap plants you grab on a whim sometimes are far more trouble than they are worth.

I learned (or relearned…) this the hard way last year when I grabbed a bag of super cheap gladiolus corms at a box store. They were cheap, and pretty… and infested with gladiolus thrips.

gladiolusthrips — White marks on the flower are signs of an early infestation of gladiolus thrips. As the summer goes on, the damage gets worse and worse.

At first, they just caused a few small white marks and discolorations on my flowers, but by the end of the season the population was so high that almost every bloom was totally deformed and ugly.

The solution? Getting all my corms this year from a specialty grower who sends high quality corms which have been properly treated with cold temperatures to kill all the thrips. This particular thrips can’t survive my cold Michigan winters, so by buying clean stock this year my garden is totally gladiolus thrips free.

As an added bonus… the specialty growers have MUCH cooler varieties. Like this Gladiolus ‘Huron Mask’ which has become one of my all-time favorites.

Just like it said on the seed package!

I believe I’ve spent approximately $1,000,000 on seeds over the years. Plant and seed catalogs are usually addressed to “Gullible L. Scoggins.” I really suffer (on many levels) during the darkest days of winter; this makes me highly susceptible to seed catalogs filled with delicious descriptions and enhanced photos.

This spring, I sorted through my massive bin of partially used seed packets and ruthlessly (ruthlessly!!!) chucked everything dated prior to 2012 (like normal people do). A large portion of the expired packets were for squash and zucchini. I love squash of every ilk – glossy dark zukes, gold crooknecks, pattypan-anything. Squash and tomatoes are summer incarnate.

My absolute favorite is the heirloom Italian variety Costata Romenesco with its dense, nutty flesh – it really tastes like something on its own. The huge rambling vines put out relatively few fruit, so not the best for a compact garden.

But variety is the spice of life…so how to try several varieties and not end up with either a mountain of squash (as happened to me a while back) or a bunch of seeds left over? California seed purveyor Renee’s Garden does a very cool thing – one pack of seeds with three (3!) varieties – the “Tricolor Mix”. Brilliant! You get a gold-bar type (Golden Dawn), the dark green one that will go berserk (Raven), and a lovely pale gray-green Clarimore.

The zucchini trifecta from Renee's Garden seeds. That's Costata Romanesco on the far left. — The zucchini trifecta from Renee’s Garden seeds. Plus Costata Romanesco on the far left.

The seeds are color-coded with just good ol’ food coloring, so you know what you’ve planted. I got 100% germination (whoops) and a delightful variety and volume of zucchini. And NO LEFTOVER SEEDS – so I will feel completely justified next February when ordering more. Hurrah!

A Brief Announcement

Sometimes it’s fun to experience life unfolding around you. This past week I started my new position as the Director of the UNC Charlotte Botanical Gardens and am very excited to be working with my old friend (she’s not old – I’ve just known her a long time) Paula Gross, Assistant Director of the garden, a fantastic horticulturist, and one of the best people you could ever hope to meet. Together with our highly skilled staff we’re going to be working to bring the world of plants to people. It’s an exciting time in my life, and hopefully an exciting time for the gardens too.

That said, I’m sorry to be leaving Central Piedmont Community College. I have never seen instructors so devoted to their students as at this community college. So often at large universities professors teach because they have to, not because they want to. At community colleges, and particularly at CPCC, the opposite is true. These highly skilled instructors really care. If you are looking for a degree in horticulture I strongly recommend considering a two year school because of the cost, the attention to students, and the hands on education that most four year schools can’t compete with (I know that sounds silly, but speaking as someone who spent fifteen years working as a horticulture professor in a large university I can tell you that it’s simply the truth).

Here’s the official announcement. The only thing I’d like to add here is that we’d love to have you stop by! We are a wonderful little garden in the North of Charlotte with a lot of fascinating carnivorous plants, orchids, a great landscape collection, and a titan arum that just bloomed and which now appears to be setting seed. We hope to see you soon!

Jeff Gillman

The cardboard controversy

I’m not a fan of using corrugated cardboard as a mulch, which like other sheet mulches creates problems for the underlying soil. Long-time readers of this blog may remember several previous posts (1, 2, 3 and 4) on this topic and I won’t belabor the points made in those posts. Instead, today I’m doing to focus on cardboard itself.

First, cardboard is a generic term that can refer to many types of manufactured paper. The box you see delivered to your front door is more properly called corrugated board or containerboard. It consists of two layers of linerboard sandwiching a layer of accordion-like fluting material. The linerboard is made from sheets of pulp that may be coated to improve smoothness (more about this later). The finished linerboard is laminated using adhesives to both sides of the fluting material.

Corrugated boxes are built to be tough. — Corrugated boxes are built tough

These boxes are made to withstand rough handling and to protect the contents from the external environment. It’s tough stuff: while you might be able to bend a piece of corrugated board fairly easily, it’s more difficult to tear it in half. The more heavy duty the box, the more difficult it is to bend or tear its walls.

So let’s now consider using this tough material in your garden as a mulch. It may be coated as mentioned earlier to improve smoothness. That’s going to prevent it from absorbing moisture. The coating also reduces the ability for gases to move between the soil and the atmosphere. In fact, smoothness is measured using an air leak method – the smoothest materials have the least air leakage.

Photo credit vizpix at Flickr — Photo credit: vizpix at Flickr

A garden or landscape mulched with cardboard (or heaven forbid several layers of cardboard as part of the science-free lasagna mulch method) is now covered with a tough, relatively gas- and water-impermeable material that will take some time to break down. It’s hardly a mulch that’s going to nurture soil life.

But cardboard mulch fans swear that they find more earthworms under cardboard than anywhere else in their garden. This is almost always the first response I get from gardeners who don’t believe that cardboard causes problems. And this is where it’s important to consider earthworm behavior.

Photo credit: Kurt B. on Flicker — Photo credit: Kurt B. on Flickr

We’ve all observed that earthworms crawl to the soil surface during heavy rains; this is due in part to water filling their burrows and reducing oxygen availability (Chuang and Chen demonstrated this nicely in 2008). Likewise, the reduction in oxygen movement from the atmosphere into cardboard-covered soil would cause worms to crawl upwards in an effort to find oxygen at the soil surface.

So don’t assume your lasagna mulching draws earthworms to your garden. It’s more likely that you’re smothering their habitat.

***An update on cardboard gas permeability. We’ve just published an article comparing diffusion rates of different mulches. You can find the article here but it is behind a paywall. Here is a graphic comparing diffusion rates of various mulches. This is a logarithmic scale.
Now, until cardboard proponents publish evidence to the contrary, it’s pretty obvious that cardboard mulch interferes with gas diffusion.

***And another update on how our blog works. This post, by far, is the most popular. It generates a lot of comments. All comments must be approved before they’re posted, and I don’t approve comments that are derogatory or promote a belief in the absense of supporting science. If you want your comment to be published, be polite and provide evidence to support your statements. Otherwise, you are wasting your time.

***Another update on cardboard in your garden: A recent paper reports on PFAs (aka “forever chemicals”) in various products used for poultry bedding (among other things). Cardboard was one of the worst. The article is behind a paywall but I have access to it and was able to find the table shown here. So if you need yet another argument to NOT use cardboard as a mulch (like in “lasagna gardening), maybe “keep forever chemicals out of your garden” will do it.

**Look at the top line for shredded cardboard and then the last column which has the PFAs data. Not to mention all the other contaminants listed.**

FrankenFoodFacts

Sunset papaya cultivar — Public Domain Photo of GMO Papaya via Wikimedia Commons

The subject of Genetically Modified Organisms, or GMOs, first came to my attention sometime in the fall of 2009, not long after I started following the Garden Professors Blog.

I stumbled across a site called Biofortified, run (at the time) by a couple of grad students in the field, who were trying to accomplish the same thing that the GPs were, combatting myths and misconceptions about a subject, with research based information.

I spent about 2 years lurking there, because much of the information at the time was over my head, and seemed to be targeted to fellow scientists to help with getting the information out.

So I’m incredibly pleased to introduce you to the blog of Dr. Layla Katiraee, a scientist in a related field, but with little to no experience at all with the topic of GMOs, so spent time learning about it and sharing what she learned with the public.

She is now also a contributor to Biofortified.

One of the best things I like about the blog, is her continual checking with “the spouse” to see how her posts might be viewed from someone outside the field.

Here’s a great example:

So, the spouse has often complained that I don’t have a post with an overview of what transgenesis means and the transgenic (GMO) crops themselves. They’re scattered throughout the history of this blog, but not in a single place.

…

What does this mean? To explain, I have to go to the beginning: the working units within any cell are proteins. Proteins are made up by linking together amino acids in a given sequence. The exact amino acid sequence is defined in the cell’s DNA; the DNA blueprint for a specific protein is known as a gene for that protein. In general, one gene encodes for one protein (of course, there are exceptions). Since there are thousands of proteins, there are thousands of genes. We’re still figuring out what different genes/proteins accomplish.

Another great post on how the science of safety testing works …

The first thing to keep in mind is that there are many aspects to safety. In our example, we have to select an aspect of water safety that we want to examine: health impact, water transportation, water treatment, proper water storage, etc. For our example, we’re going to select “health impact”.

Then, we have to come up with a null hypothesis. Spouse, I know that it’s counter-intuitive and the double negatives in these statements suck, but unfortunately, it’s a key aspect of this whole article. The baseline for much of research is that there’s no impact or no difference. It’s the researcher’s responsibility to disprove that hypothesis, ie. to show that there is a difference or that there is an impact. So for our exercise, our hypothesis will be “Drinking water does not cause cancer”.

So follow her blog, FrankenFoodFacts, or follow her articles elsewhere on Biofortified, or her Twitter feed, and gain some better understanding about the science behind GMOs.

Why doesn’t my plant flower? Part 2

As promised last week, here is Part 2 of “Why doesn’t my plant flower?”. If any of you know of more reasons that are not listed here or in the previous week’s blog, please let me know. Happy gardening!

There may be several reasons why a landscape plant does not flower (see last week for more reasons):

Over fertilization caused leaf burn on Liriope spicata — Over fertilization caused leaf burn on creeping lilyturf (*Liriope spicata*)

1) Over fertilization may inhibit flowering.

Do not fertilize newly planted trees and shrubs the first 2-3 years after planting
Plants need to put their energy into establishing a healthy root system to support future shoot growth
Once the plant is established (2-3 years), fertilizers may be added if a soil test suggests fertilization is needed
Over fertilization with quick-release, high nitrogen (N) fertilizers can lead to excessive leaf growth at the expense of flower bud development
Avoid using lawn fertilizers around the base of your plants, as they are often high in nitrogen
More is not better; follow all fertilizer label directions and do not add more than is required
Your landscape plants might not even need fertilization, especially if compost is added or the soil conditions are favorable for plant growth

2) Poorly-drained, heavy clay soils can result in leggy, unhealthy looking plants that may not flower or will die.

Azaleas planted in poorly drained, heavy clay soil will not live long

Poor drainage will stunt growth, limit flowering, and may make plants more susceptible to root and crown rot
Before planting, assess soil for drainage
Dig a hole in the soil about 12 in. (30.5 cm) deep and 8-10 in. (20.3-25.4 cm) wide
Fill the hole with water to the top and let it drain for one hour
After an hour, measure the water depth with a ruler and record the new water level from the original level
If the water level drops less than 1 in. (2.5 cm) from the original water filled level, soil drainage is slow
The following day, if water is still in the hole, your soil needs much improvement
Desired range for water drainage is 2 to 6 in. (5.1-15.2 cm) per hour
Drainage can be improved by adding organic matter such as compost, composted leaf mulch, or other organic material; works well prior to planting
If possible, plant in raised planting beds amended with compost, topsoil and other organic amendments to improve drainage and root establishment

3) Under watering can cause a lack of flower buds or poor flower development.

Wilted hydrangea (*Hydrangea* spp.) source http://chatham.ces.ncsu.edu/2014/07/helping-your-yard-survive-drought/

Water immediately after planting for all landscape plants with a hose
Water trees, shrubs and perennials several times a week for the first month or two, depending on weather
Watering may be needed daily especially if windy, dry and hot
Check actual root ball/soil directly where the plants’ roots are located; insert your finger or soil probe as far as it can go
If you feel moisture, the plant may not need additional watering
Plants previously grown in soilless media in containers and bareroot plants require more frequent watering
Do not rely solely on rainfall as the amount may be inadequate to penetrate the root ball
If you see wilting of foliage, the plant is too dry
Plant establishment will take several years or more for trees, slightly less for shrubs and one to two years for herbaceous perennials
After establishment, 1 in. (2.5 cm) of water a week is recommended; check rainfall with rain gauge in yard
Avoid overhead irrigation as this keeps the foliage too wet and may increase foliar diseases
Water at the base of the plant using soaker hoses, drip irrigation or a hose set at a very slow flow rate to allow for percolation into the soil and avoid water runoff

4) Road salt injury can damage or destroy flower and vegetative buds

Winter road salt injury on eastern white pine (Pinus strobus) — Winter road salt injury on eastern white pine (*Pinus strobus*)

Fast-moving traffic and high winds from wet, salted roads accumulate on dormant plants in winter
Sodium chloride (NaCl) is most common deicing salt used and causes the most damage
Most damage occurs within 60-100 ft. from road
Desiccates and may kill buds, twigs; can burn foliage of evergreens; reduces water uptake by roots
Also accumulates on soil surface from melted, salted water from roads
Plant salt tolerant plants near roads, use physical burlap barriers to protect plants, leach soil in spring
Use of anti-transpirants and dormant oil sprays are ineffective in prevention of salt spray injury

5) Insects or diseases may be present which can reduce or eliminate flowering

Shoot death of TINY DANCER™ common lilac (Syringa vulgaris 'Elsdancer') from bacterial blight — Shoot death of TINY DANCER™ common lilac (*Syringa vulgaris* ‘Elsdancer’) from bacterial blight

Oystershell scale on 'Redwine' lilac [Syringa (Villosae Group) 'Redwine'] — Oystershell scale on ‘Redwine’ lilac [*Syringa* (Villosae Group) ‘Redwine’]

Plant is stressed and may not flower; more energy within a plant used for defense
Various bacterial pathogens can kill emerging buds and flower clusters, i.e. bacterial blight
Fungal pathogens can also do the same or reduce the size or quality of the flowers, i.e. powdery mildew, Botrytis
Certain insects, such as borers and scale, weaken a plant so it no longer flowers or flowering is reduced
Treatment for these pests needed or the plant may die
Improve plant health by watering and judicial pruning of infected/infested branches
Do not fertilize at this time as the plant is trying to recover from pests

6) Black walnut (Juglans nigra) and butternut (J. cinerea) trees can kill sensitive plants nearby.

Black walnut (Juglans nigra) tree roots, twigs, leaves and roots all contain juglone that can inhibit or kill nearby plants susceptible to juglone — Black walnut (*Juglans nigra*) tree roots, twigs, leaves, nut hulls and bark all contain juglone that can inhibit or kill nearby plants susceptible to juglone

Both of these trees and to a lesser extent hickories (Carya spp.) excrete juglone, a phytotoxic chemical produced in the leaves, twigs, bark, nut hulls, and particularly in the roots
Not all plants are sensitive to juglone, but those that are sensitive die either quickly (tomatoes, peppers) or over several years
Ornamentals sensitive to juglone include lilacs, crabapples, rhododendrons and azaleas, hydrangeas, etc.
Black walnut tree roots extend far beyond the drip line of a tree
Even if the tree is removed, roots remain in soil and continue to excrete juglone for several years

7) Deer or rabbits may be browsing on the flower buds.

Stems girdled by rabbit feeding on stems of burningbush (Euonymus alatus) — Stems girdled by rabbits feeding on stems of burningbush (*Euonymus alatus*)

During winter, deer and rabbits like to feed on the twigs, bark, and flower buds of many plants
Once the flower buds are destroyed, have to wait another year for flower bud set unless the plant flowers later in summer
Plants resistant to deer and rabbits are available, but if hungry enough, they will eat most any plant
Rabbits and voles chew on bark of shrubs and trees causing girdling of twigs or major stems/trunk
Girdled stems may die or barely flower or leaf out
Damaged branches should be pruned back to live wood

Laura Jull, Ph.D. aka The Lorax

Corny Ancestry

I love growing weird plants, and I’m endlessly fascinated by plant breeding and the extreme transformations humans have made in our crop plants over the history of agriculture.

Which is why growing teosinte, the wild ancestor of corn, was a no brainer. Even before I planted it, comparing the seeds is fascinating. teocornseed

Once growing you can see the similarity. Teosinte is on the left in the picture below, corn on the right.

The most dramatic difference between the two, I think, is the “ear” of teosinte, which is nothing more than a thin sprig of half-a-dozen seeds.

It is amazing to me that native Americans in Southern Mexico, with no knowledge of genetics, were able to transform this grass with a handful of tiny, rock-hard seeds into one of the single most productive crops in the world.