Bird Visitors to Winter Gardens

A few days ago a friend who lives in northern Rensselaer County mentioned  that he's noticed different kinds of birds now are showing up in and around his garden, and he was wondering what he might be seeing.  So, you can blame him for inspiring  this post.

Snowy Owl - Common visitor from the North

It is common for some birds from more northern ranges to move just a little south into our neck of the woods for at least part of the winter. Not all species undertake long migrations, and local newspapers bring attention to these visitors by  posting pictures from their readers of the larger species - snowy owls, snow geese etc.  Pine Siskins, Snow Buntings and  various Grosbeaks usually don't get as much attention because they tend to hangout   in secluded woody or shrubby areas.

Although gardeners living in the suburbs and rural areas will probably see more species, even in my urban backyard setting I have occasionally seen Lapland Longspurs and Cedar Waxwings. A few backyard gardeners might even be surprized to learn that some  of our regular Rensselaer County feathery friends such as Bluebirds, Gold Finches and Robins actually  are  wintering over in sheltered areas all around us.  

If you are wondering about what kind of birds are being seen in the Capital District, the best website may be the one maintained by the Hudson-Mohawk Bird Club. Many club members post their daily sightings year round, and anyone can take a look. On the club's homepage look for the heading, HMBirds, and click on the link labeled, To see the latest sightings. 

For gardeners who feel they could use help  with identifying birds,  Cornell's Laboratory of Ornithology  offers the free app, Merlin, for  smartphones or tablets.  This app guides users in selecting  important identifying characteristics and then offers suggestions with photos of the bird(s)   fitting that criteria.  Merlin covers about 3,000 species in North America; and once you confirm what you are seeing on the app, the sighting data  enters  the lab's database that compiles information about species ranges and migration patterns. - I never go for a walk without Merlin!

For  gardeners who might be looking for something more to do when not in the garden or while just waiting for the new seed catalogs to arrive, there is also   Cornell Lab's website, eBird.org. In addition to identifying birds, you can a find out about current research, create a lifelist of personal sightings, participate in a citizen science program by entering your daily sightings of even common birds into the Lab's  database, and  monitor ongoing migratory movements.

Another option is the Audobon Society's North American Bird Guide available through its website as well as via a mobile app.  From the website look for a drop down menu labeled, Birds. You can limit your searches to a region, but you do have to know a little something about the character of the bird you are attempting to identify.  The society's webpage  also offers extensive information about environmental and political developments impacting birds. And, in case you haven't heard of it or have been silently ruminating  about it, there is still time to get involved the Audobon Society's 119th Christmas Bird Count this year.

For those gardeners with more  traditional print-based propensities, there are a slew of handbooks for identifying birds. The leading ones continue to be the guides authored by Roger Tory Peterson, Donald & Lillian  Stokes (of NH) and David Allen Sibley. These authors also offer various web resources.  All   emphasize   educational topics  for both beginning and experienced birders.  Stokes offers an excellent birding blog; Peterson, in additionl to promoting his many publications,  offers podcasts, and Sibley seems to  focussing on developing  online  tutorials.

And remember:

"I value my garden more for being full of blackbirds than of cherries,

and very frankly give them fruit for their songs." - Joseph Addison, Essayist

Garden Preparation - December

Oh... No... December! For those of us without green houses, almost all our outside gardening work  in Rensselaer County, NY is past.  I still do have some curly leaf kale persisting in the garden, but that's all.  My other plants have succumbed to killing frosts. However, if you were conscientious last month and actually covered your carrots, beets and parsnips with a deep layer of straw, you may still may be harvesting. I hope you are.

In the mean time while you are waiting for next season's seed catalogs to start arriving in the mail, here are a few gardening related items you might consider doing to exercise that green thumb.

Culinary herbs

• Start a few culinary herbs indoors: The basic ones include chives, parsley, rosemary, thyme and basil. If you have space there is also oregano, cilantro, mint and lemon balm.  And, if you have even more space, you might want to try bay laurel (aka bay leaf) - actually a shrub that will work in a container.

• If you garden soil is still not frozen, check your carrots, and other root veggies. If they look alive, there is still time either to mulch them for later harvesting or you can simply dig them for storage indoors. If mulching, be sure to add a sheet of  plastic blanket over the mulch to help insulate the veggies from freezing.

• Don't wait any longer. Writing holiday cards can wait and get a jump on an early New Year's Resolution. Start that garden diary while you still remember a little bit of what you planted and how it did this year. You might even enter a note about what you want to do different next year.

And remember:

"The garden season officially begins January 1st and ends December 31." - Marie Huston, gardener and artist

Plant Pathology - Abiotic  Distress

A young pepper in distress from cool temperatures.

Recently, we enumerated the common causes of plant diseases in a post entitled  Plant Pathology. Now,  in keeping with the morbid greyness of November, we'll briefly review the character and sources of  "non-disease-related" problems.

Every gardener has encountered a sick looking plant. Some morning you cheerfully get up, grab a cup of coffee and then look at your flower box on the windowsill or maybe step into your sun porch to greet the newest pepper sprouts or marigolds and discover that overnight one, or some, suddenly are, to put it gently, 'failing to thrive.'   

What happened? Who did this? Don't jump to conclusions.

A  first reaction might be to think that some sneaky microbial pest has contaminated your private green domain. The plant  appears "sick," i.e. in some kind of  distress, but it may not be diseased; and the symptom appearing in front of you may be signaling a problem actually orginating in a different part of the plant. The plant's distress might not be caused by some other living thing at all...

Abiotic factors account for a lot more plant problems than you might think. Some experts attribute abiotic issues  as accounting for about 50% of plant problems while a few contend that it might be as much as 80%!  Many abiotic problems are readily remedied (or entirely avoided) by applying simple, good gardening practices - maintaining moisture levels, cultivating regularly to promote aeration and drainage, thinning plants, weeding etc. Some abiotic problems,  such as nutrient deficiencies, are harder to diagnose and require more time to correct; and some, like drought or monsoons, may not have readily available solutions. In my admittedly limited experience, containers, i.e. pots of any size or shape, seem to be prone to abiotic problems: they heat up and dry out fast,  salt residues from old fertilizers or hard water build up and soil fertility declines because soils or nutrients are not  replenished on a regular basis.  So - if you use a lot of containers, it's important that you be alert to the range abiotic problems that might develop.

Types of Abiotic Problems

Abiotic factors fall into several rather distinct, but unsexy,  categories:

Mechanical - These typically are simple breakages or abrasions that are usually caused by wind, hail, dogs, cats and other animals including small children.  [Tiny punctures in leaves or missing leaf tissue, however,  suggests some kind of  pest has been free loading.]

Beans showing some yellowing leaves.
Photo: NYSAES Geneva, NY

Chemical -  Nutritional deficiencies and toxicity frequently show up with disease-like symptoms. Too much of a good thing like fertilizer,  or, as in cases like road salt or pesticides - just a little too much of a bad thing, can cause yellowing (chlorosis) to varying degrees; but yellowing  can also  indicate  viral and bacterial  infestations.

How toxicity shows up depends upon whether a chemical is  absorbed by a plant  or comes into  direct foliar contact with some part of it, e.g. via careless spraying.  In the former case, symptoms may be general in nature, e.g. wilting or poor new shoot development; in the latter, leaf discoloration along with dead spots can rapidly occur.


[See earllier posts:  Macronutrients and Micronutrients about plant nutrition and how to recognize possible deficiences.]

Environmental - Plants, like many of us, typically do not respond well to sudden changes in their environment.  Temperature extremes, lighting,  air quality, oxygen and moisture levels will manifest themselves in various ways such as wilting, leaf drop, lack of flowering, inferior fruit, slow growth etc.  Note: oxygen and moisture levels can be related -- saturated soil that does not drain well will leave roots suffocating and that in turn can cause leaves to wilt, develop marginal browning and eventual dropping.  [And, of course, with respect to roots attacks by parasites and nematodes can also induce similiar symptoms.]  

Factors to Consider in Evaluating Problems

A wilted plant in a dried out pot is clearly distressed and easily resurrected by restoring the soil's moisture level, but a plant showing yellowing leaves as in the bean plants depicted above requires a more  systematic analysis to determine the cause.  Yellowing  leaves can be arise from a variety of factors:  nutrition, environment, parasites, fungi, bacteria,  viruses etc.

So after getting over the shock that your beloved rutabaga looks under the weather, switch on your situational awareness circuit and look at the unhappy specimen in front of you with an open mind and  begin thinking about  at leas some of the following before deciding on a  course of action:

• Does the symptom appear to be confined to just one plant, or are other plants also affected? 

• If more than one plant seems afflicted, is the symptom confined to a small area in your garden involving just a few plants or does it appear in a wider area? [Abiotic problems tend to be uniform in character and, in a garden setting, usually show up aross a wide area and are not limited to just one or a few plants. In fact, different types of plants may be affected.  Keep in mind, however,  that if you see multiple symptoms, there is a good chance that you may be dealing with multiple problems. ]

• If lately  you've been suspicious about the health of a plant, does the symptom seem to be changing over time?  

• Is the symptom spreading on this plant or are other plants showing lesser or greater degrees of the symptom?  [If yes, this implies a biotic cause.]

• Is just a specific variety of plant affected? [If yes, this also implies a biotic cause.]

• What part of the plant is affected?  Look at the whole plant -  check its stems, leaves, roots, blossoms, fruit. 

• Where is  the symptom located:  low or high on the stem.  

• Does the symptom appear to be confined to leaves, stems, blossoms or just to the tissue between leaf veins? 

• Consider the plant's setting. 

• Is the soil compacted,  loose, wet or dry;

• How much sunlight does the plant really get;

• Is the plant crowded? [Did you forget about thinning to the recommended spacing...]

• Has the weather been hot or cool?

• Are leaves or fruit touching the soil or other plants?

• If you are thinking that an insect or similar  pest is responsible, look on the underside of leaves and on stems for egg or spore clusters or  frass.  Snails (mullusks) may have left slime trails in their  retreat to a secure, remote daytime location.

• Finally, do you remember anything about  last year's garden problems?   Is what you are seeing  similar to anything that occured last year? Both abiotic and biotic problems tend to recur especially in small gardens.   

Be Your Own Plant Dr.

For gardener's who would like to minimize their reliance on the Internet and use a book to solve their plants' problems, I recommend "What's Wrong With My Plant (and how do I fix it?"   by David Deardorff and Kathryn Wadsworth (Timber Press, 2009).  The book served as one of the texts for my Master Gardener training program. The first half follows a decision tree format employing exceptionally  clear illustrations  -   you start with a symptom and then choose the next refining step from a choice of equally clear illustrations with accompanying text.

The second half of the  book discusses the diseases and disorders in detail as well as organic remedy options.  Deardorff is a plant pathologist at the U. Hawaii and serves as a consultant to the U. of Washington's Extension Service. The co-author is a professional photographer.  Both hardcover and paperback editions are available.


And remember:

"My green thumb came only as a result of the mistakes I made while learning 

to see things from the plant's point of view." - H. Fred Ale

What's in Your Garden Soil? - Nematodes

Nematode loa loa removed from eye.
Source: dated.org

I missed Halloween for this post; but given that it seems  horror movies are released year round, mentioning parasitic nematodes along with the beneficial ones seems okay to do. Most of us probably  have heard about diseases stemming from parasitic nematodes,  but hopefully have not suffered from ascariasis, trichinosis, hookworm or worse. we'll try  just to focus on what's in our garden's soil and not our guts...

Nematodes, named after their phylum, Nematoda, ["nema" means  "thread-like"] are unsegmented round worms that live in all the environments that other earthly lifeforms do.  They actually constitute the most numerous of animal lifeforms. In fact, for pratical purposes, nematodes are inseparable from other lifeforms... If you know what nematodes exist in a particular environment, you can predict what  other lifeforms will be also be found there.

According to the Wikipedia entry, about 25,000 species so far have been identified with probably tens of thousands more awaiting discovery.   They are typically described as being  just a "tube within a tube" with  a front and back end.  Their front ends are adopted for their feeding preferences. 'Herbaceous' types,  like  root feeders, insert long microstylets  into plant cells to syphon nourishment; fungal  feeders use shorter stylets to puncture cell walls; and  bacterial eaters have more recognizable mouth-like openings for collecting their lunches as they wiggle through  soil.  Most nematodes reproduce sexually, but a few are harmaphroditic; and many  are able to enter a dormant state to survive extreme environmental surprises like drought or extreme cold.

Cross section of typical  nematode.
Source: Biology Stack Exchange

Because nematodes closely co-exist with other lifeforms in their environments, their minescule wiggles are sufficient to meet their daily needs. Their greater travels depend upon outside factors such as wind, water or physical transport by some other agent -- animal, insect, garden tool or tractor tire for dispersal.

Soil nematodes are very small ranging in size between  1 mm and 50 ml; but some, like the parasitic ones that attack vertebrates,  can be large. One parasitic nematode that abides in the placenta of sperm whales   reaches 30+ feet!  

Minor carrot damage from root piecing nematodes.

Parasitic  nematodes can affect plants in several ways.  Some appear in foliar tissue (leaves); others burrow into roots or stems; while others just attach themselves externally to roots. Gardeners have probably encountered the effects of these latter pesty varieties on their cabbages and carrots. Small infestations of these "herbaceous" feeders cause carrots to respond with those little bumps, called 'root galls'.  Bigger infestations of this type of nematode (e.g. the NRK nematode - our local favorite) show up as "root knots" on cruciferous veggies like cabbage and broccoli, and they also can  cause serious crop damage to  legumes  like soy beans. Various root knot nematodes affect more than 2,000 agricultural  crops and ornamentals.

N.B. - Root knot nematodes also affect many common weeds such as lambsquarter, purslane, 

and dandelions -- Better keep weeding!

Severe root knot.

If you think that you have a root knot problem like the one pictured to the right, take a look at this visual assessment technique from Cornell Extension. You can probably use it as an initial guide for sizing up your  situation. Cornell's Plant Disease Diagnostic Clinic for a small fee will analyze soil samples for nematodes and other pathogens. There are also  commecial services that will analyze soil samples and identify what you've got.  Beneficial nematodes can be purchased to improve your soil if it turns out that you have a nematode deficiency or infestation.  Suppliers offer both  tailor made and  standard  mixes for particular crops and soils.

What Good Nematodes Do

Because nematodes occur naturally in the environment, their uses in pest control and sustaining soil health make them  important components in  organic farming practices.

Grasshopper demised by its parasetic nematode.
Photo: U. of Fl.

Nematodes in soil are particularly important  for protecting healthy young plants by controlling a lot of plant pests and pathogens. They also   increase soil fertility   by  making more nutrients available for plant use through their digestive processes. Among these is the ammonium cation (NH4+). Because ammonium is very soluble in water, it is easily taken up by plants - although too much of it, like all good things, is toxic. NH4+ is critical for plants. They convert it  into organic compounds like amino acids.  Animals, like us, and other creatures  depend on plants to supply us with these compounds.  Both plants and  us omnivores should be grateful for these beneficial nematodes. So, continue to tread lightly on your garden soil.

Although there are lots of potential nematode bad guys even in healthy soil, these are generally outnumbered by beneficial nematodes. Among the ranks of beneficial nematodes are the predatory   fellas that devour bacteria, fungi, protozoa along with other nematodes. Unfortunately, getting rid of an infestation of the bad dudes  using chemicals also  eleminates the good guys too. A balance of beneficial versus parasitic nematodes in healthy soil actually stimulates plant growth. Healthy plants simply  outgrow any nutrient challenge posed by low levels of parasite activity.  Finally, by their wiggling through  soil nematodes also promote soil fertility by redistributing both  good and bad bacteria and fungi.

What's a Normal Nematode Load in Soil? 

The US Dept. of Agriculture reports that a healthy census is around 100 nematodes in a teaspoon of dry garden soil. Given their microscopic size, this is a surprizingly low number.  But nematode populations can rapidly expand, e.g.  a rotten apple on the ground might contain 90,000+ nematodes while it still  vaguely resembles an apple.  Even this remains a low number compared with the  abounding nematode populations found in  sea beds that can reach 1,000,000 per square foot!

Good Gardening Practices 

Backyard gardeners can employ a number of techniques to minimize harmful nematodes. Among these are

Clean equipment and boots.
Source: Northville Dairy

• Using certified seeds and choosing nematode-resistant or tolerant varieties;

• Cleaning tools and equipment;

• Weeding as well as removal of infected stock;

• Rotating crops and allowing some areas to remain fallow during  growing seasons;

• Using cover crops and green manure along with compost both to keep up soil nutrient levels. 

Now stop worrying about what you might be walking on,  and remember to:

"...trust dirt. I don't trust diamonds and gold." - Eartha Kit

Vegetable Gardening Book Suggestions for the Holidays 

Sometimes I think my library is getting dated; and because it's nearing the gift giving season, I thought I would come up a list of relatively newer books about vegetable gardening that might be suitable for stuffing into  albeit very large holdiay stockings.

You will quickly notice that the titles in the below list are not spankingly brand new 2018 or 2019 books. Like any good book, they remain in print or readily available from used book dealers because they continue to  serve gardeners well. I compiled my list  from examining a number of  "best" book lists from various gardening sites that I trust, personal familiarity with some titles and the personal recommendations from gardener friends.  Most of the entries appeared on at least two lists, and a few titles appeared three or more times.

I did not use either Amazon or Barnes & Noble lists as sources although I did use these sites to view  sample pages of some titles.  The books are available from these sources, but if you do become motivated to give one or more to a friend, I  suggest that you also check used book sources such as abebooks.com, alibis.com or  bookfinder.com etc. for lower prices. Happy shopping...

• Brie Arthur - Foodscape Revolution: Finding a Better Way to Make Space for Food and Beauty in Your Garden. St Lynn's Press, 2017. 

• Susan Ashworth - Seed to Seed: Seed Saving and Growing Techniques for Vegetable Gardeners. 2nd ed. Seed Savers Exchange, 2002. [If you are unfamaliar with Seed Savers, find out about it now at seedsavers.org.]

• Mel Bartholomew - All New Square Foot Gardening: The Revolutionary Way to Grow More in Less Space. 2nd ed. Quarto Publishing Group, 2013. [Many a backyard gardener consider this to be their 'best' vegetable growing  bible. Actually, any edition will do.]

• Andrea Bellamy - Small Space Vegetable Gardens. Timber Press, 2014. [Don't have a yard or can't get to a community plot, then how about using a roof top, patio or windowsill - great ideas here.]

• Eliot Coleman -  Winter Harvest Handbook:  Year Round Vegetable Production Using Deep-Organic Techniques and Unheated Greenhouses. Chelsea Green Publishing, 2009. [n.b. Coleman  authored the classic, New Organic Grower (now in its 3rd edition). This one assumes you have a lot space for gardening.]

• Derek Fell - Vertical Gardening: Grow Up, Not Out for More Vegetables and Flowers in Much Less Space. Rodale Inc., 2011.

• Brad Halm & Craig McCrate - High Yield Vegetable Gardening: Grow More of What You Want in the Space You Have.  Storey Publishing, 2015.

• Toby Hemenway - Gaia's Garden: A Guide to Home Scale Permaculture. 2nd ed. Chelsea Green Publishing, 2009. [In case you are not familiar with the term, 'permaculture' is about establishing and using techniques that promote sustainable and self-sufficient agriculture.]

• Craig Le Houllier - Epic Tomatoes: How to Selet and Grow the Best Varieties of All Time. Storey Publishing, 2015. 

• Wendy Kiang-Spray - Chinese Kitchen Garden: Growing Techniques and Family Recipes from a Classic Cuisine. Timber Press, 2017. [This is specialized and (warning) includes recipes; but I like Chinese food and Timber Press is very selective in its offerings.  To learn a little more about the author and the cuisine, checkout her blog: greenishthumb.]

• Ron Kujawski and Jennifer Kujawski - Week-by-week Vegetable Gardener's Handbook. Storey Publishing, 2010. [Not on any list, but this is a personal recommendation. I reviewed it in February 2018, and now find myself referencing it regularly.]

• Bret Markham - Mini Farming: Self-sufficiency on 1/4 Acre. Skyhorse Publishing, 2010. [This might tempt you to buy that vacant lot next door...]

• Tara Nolan - Raised Bed Revolution: Build it, Fill it, Plant it - Gardening Anywhere. Cold Springs Press, 2016. [The author, a Canadian, founded Savvy Gardening that promotes innovative approaches to both ornamental and vegetable gardens.]

• The Organic Gardener's Handbook of Natural Pest and Disease Control: A Guide to Maintaining a Healthy Garden and Yard the Earth Friendly Way. Rodale Inc., 2009.

• Barbara Pleasant - Home Grown Pantry: A Gardener's Guide to Selecting the Best Varieties & Planting the Perfect Amounts For What You Want to Eat Year Round. Storey Publishing, 2017. [The author is a regular contributor to Mother Earth News and winner of three Golden Globe awards from the Garden Writers' Association.]

• Rodale's Ultimate Encyclopedia of Organic Gardening. Rodale Inc., 2009 ["Rodale's own  gardening bible has been a mainstay for organic vegetable growers since J. L. Rodale published the original in 1959.]

• Edward C. Smith - Vegetable Gardener's Bible. 2nd edition. Storey Publishing, 2009. [A Vermonter, Smith has been writing for 30+ years and gardening for more. He also has a "bible" on container growing published in 2011.]

• Jessica Walliser - Container Gardening Complete. Cool Springs Press, 2017. [The author is a regular contributor to Savvy Gardening, a women's owned company out of Canada covering  all aspects of gardening.]

And remember: 

"The more that you read, the more things you will know. The more things that you learn, the more places you'll go." - Dr. Seuss

GARDEN PREPARATION - NOVEMBER

For backyard gardeners the time spent in the garden amidst the last weeds and failing vegetables is rapidly diminishing, but there are still chores to do.  If you happen to think that you are  caught up outside, here are a few more chores to replenish your low guilt level; or,  you could go back and read the Garden Preparation - October  post to see what you may still need to do...

• Cleaning pots  - If you're really bored, wash and disinfect those stacked pots you put in the garage to get rid of any pests, fungi or bacteria. Fill a tub or utility sink with dish detergent and scrub the inside and outside of the pots.  To disinfect, you can either add vinegar to the detergent water or rinse the pots using a separate bleach solution.  If you  have terracotta  pots and notice a white powdery substance on them, don't worry... it's not biotic.  The stuff is just residue minerals that have leached out from fertilizer or water.

• Asparagus - If you are lucky enough to have room for asparagus in your garden, remember to cut down those dead shoots now.  

• Parsnips and leeks - Like garlic, you should mulch these. Mulching will help the parsnips through the winter, and the mulch will extend your access to fresh leeks into December.

• Bring in those plants - Want fresh herbs? Dig up rosemary, parsley, sage, chives etc. [Hint: you can use the pots that you just cleaned].  If you don't have a sun porch, maybe you can get  away with placing the plants near a south facing window; or, better yet, use your grow lights...

• Remember what you didn't like this year?  Did that plumb tomato  succomb too early to late blight? Did it taste bland? Make a note of it somewhere -- how about on that new 2019 calendar that you just received in the mail from the Friends of the Backyard Composting Society? A better idea maybe is to find one of your (very) old school notebooks and start that garden diary - winter lasts a  long time and your memory doesn't.  You might even decide to start  another gardening blog based on what you happen to remember!

• Spread your compost yet?  Missed October? - Shame. But you now have an opportunity to make amends. If you actually got a soil test done last month, November is now a good month to add any recommended amendments along with your compost.  Remember that it usually takes months for nutrient levels to change... Poisons work faster, but increasing or decreasing pH levels or the amount of magnesium etc. is a slower process.  

Source: Public domain

• Harvests: Jesrusalem archichokes - dig them now.  Kale, kale,  kale - just keep on cutting, cutting, cutting because it just keeps growing, growing,  growing.  I recently did a search on "kale" in the NY Times cooking database and found 294  recipes using kale. So it would appear that there might be just enough recipes to handle your kale's  bounty. Carrots & beets - you should pull them now before the really hard freezes occur. Neither carrots nor beets  handle  cold weather well. Remember to leave a little of their tops (about 1") when you store them.

• Got grow lights?  Start a crop of lettuce in your basement. Use up that leftover potting soil and the remaining seeds in the packet. And, if any of the plants that you dug up and brought indoors are leggy, you can also put them under the lights to become rejuvenated.

Hyposoter ebeninus on cabbage worm.
Source: Birdguides.com

• Leave it in the garden:  In an earlier post I suggested cutting off tomatoes and beans at the soil level to allow their roots to decompose because their roots have brought micronutrients that were deep in the soil closer to the surface.  With respect to beans and peas, the nitrogen fixing bacteria on their roots also will help to increase N levels.  Here's another  idea - leave your unharvested cabbages, broccoli, Brussel sprouts etc. in the garden over the winter.  This will allow the lava of the parasitic wasp, Hyposoter ebeninius, to over winter.  These chaps have a passion for the caterpillars of the white  butterflies that are attracted to Cruciferous veggies.  Not only do the  wasp  lava kill the caterpillars; but in response to the presence of the parasitized caterpillars, the plants actually emit an aroma that makes them less attractive to the "whites."  

And remember...

"I would rather sit on a pumpkin and have it all to myself than to be crowded 

on a velvet cushion." - Henry David Thoreau

Plant Pathology  

What better way to spend time on a cloudy, greyish October or November day than  reviewing a little  basic plant pathology - well, maybe thinking about  what EPA's latest predicted 7°F  global temperature rise  means for our species competes... Anyway, let's get started.

Bacteria canker. Now present on Long Island.
Photo: Cornell U.

What Indentifies a Sick Plant

There are many  sympthoms that backyard gardeners see; and just to keep us on our toes,  any given symptom can probably also be associtated with multiple  conditions.  Usually the symptons we  see on our plants are  caused by some kind of pathogen - a biological agent that  inteferes with a plant's basic  activities like transpiration, photosynthesis etc. But they can also be caused by environmental (i.e. abiotic) factors such as too much or too little of some type of nutrient, air pollution or just poor growing conditions [heat, cold, lack of sunlight, too little water, too much water etc].

Some of the most common symptoms of   plant diseases include: 

• Abnormal celluar growth - examples include motteled leaf coloration, an over  abundance of root hairs, galls (tissue enlargements on a plant's stems, leaves or roots), malformed petals etc.. 

• Cankers - a plant's response to some type of physical damage. The damage can allow fungal or bacterial infections to enter the plant before healing is completed. A good example of a canker is the smooth rounded bark that a tree grows trying to cover up  damage from a broken branch. 

• Chlorosis - yellow spots on leaves where chlorophyll  has been destroyed by a virus.

• Damping off - a seemingly sudden callapse and death of seedlings and young plants.  High moisture levels trigger various fungal diseases that overwhelm a stressed plant.

• Defoliation (leaf loss) - Innumerical causes: transplanting stress, climatic factors, pests and pathogens.

• Fruit drop - Commonly triggered by environmental conditions, but pests can also cause loss, and sometimes the plant itself maybe just self correcting  from having set too many fruit.

• Necrosis -  dead areas [not little tiny  spots] on leaves, stems etc. Typicaly caused by a bacteria.

Brown discoloration from root rot.
Photo: U Wisconsin Extension.

• Root rot - Commonly associated with house plants that get over loved and over watered.  It can happen out in the garden in very wet weather too. Too much moisture creates the conditions for several different fungi to activate. The plants may appear to wilt, turn yellow or be stunted. If you pull one up, you will probably see that the roots look very, very brown. Just get rid of such plants. Unfortunately, these  fungal spores can stay dormant in soil for a long time waiting for the right environmental conditions to reappear.

Grey mold on strawberry. Photo: OSU

• Fruit rot - Frequently called "molds" these are generally fungal infestations although some are bacterial. A very common one is "grey mold,"  Boytrytis cinerea, that affects many backyard favorites: tomatoes, cucumbers, peppers -- 200 plus in all. If you have seen clusters of grapes that appear  grown together and are covered with a brownish web, blame  grey mold.  To make matters worse, grey mold can affect different parts of a plant and appear different on different parts of it. Symptoms also can be different at different stages of plant growth.  

• Stunting  - A lot of environmental factors can affect plant growth, but sometimes  biotic sources, as will be noted below,  are to blame.

• Wilting - Lack of water, of course, is probably the most common cause, but over watering can also lead to wilt as the plant fails to get both moisture and nutrients because the roots are suffocating.   The drowned roots allow phytopthoria, a fungus, to get established; and the plant dies from root rot.   Just remember that there are  other fungal  and bacterial infections that can  also block water from reaching the rest of the plant causing it to wilt.

And now for a quick review of the nasty (but interesting) culprits responsible to creating the sympthoms...

Common Pathological Agents 

Bacterial leaf spot on peppers

• Bacteria - These are simple, single cell organisms without a recognizable nucleus. Bacteria usually  enter a plant by means of a wound, e.g. an insect piercing or stem breakage.  Different types of bacterial infections can cause galls, cankers, wilts  and rots; but a very common indicator of a very common type of a bacterial infection is the appearance of  leaf spots. Bacteial leaf spots first appear as   discoloration in  leaf tissue between a leaf's veins. Affected areas  appear dark and damp when held up to a light; eventually the tissue dies and  might even become smelly. Unlike viruses that enter and take over plant cells, bacteria stay in the tissue area between cells and absorb nutrients needed by the cells.There is also another class of bacteria, the phytoplasmas and spiroplasmas that infect plants.   Originally these were considered to be viruses, but  they are now viewed as bacterial.  Like regular bacteria, they lack a nucleus and, interestingly, they also lack a distinct cell wall. Because the 'plasmas'  and "spiros" congregate in a plant's phloem, they interfere with  nutrient transport throughout the plant.     Managing the risk posed by  bacteria involves selecting resistant plants, spraying for insect carriers, careful watering etc.  

• Fungi - Constituting a kingdom separate from those of animals or plants,  fungi derive their nutrients from other biotic sources and experience most of their [limited] mobility  by just growing in the environment they happen to occupy as well as occasional adventurous dispersals by sporing. Like other biotic entities, fungi have both beneficial and harmful actors; but fungal agents account for about 85% of all plant diseases according to MSU's Extension Service.  Most fungi are cylindrical in shape and grow at their tips by developing hyphae - thread-like structures that  can branch.  Hyphae have great penetrating ability, and it is through them that fungi  exude digestive chemicals whose resulting products are absorbed by the fungi.  For backyard gardeners, powdery mildew  and downy mildew along with rusts on apples and quinces (to say nothing of black spot on roses) might be the most commonly encountered  problems. Anthracnose is the another biggy - triggered by cool wet weather.  It shows up on  trees, shrubs and veggies by stunting young plants and leaves in the spring or spoiling fruit  and spotting leaves in the fall.  On the other hand, homebrewers and bakers are grateful for  the beneficial fungi that cause fermentation  and make bread rise. Control of harmful fungi requires selection of resistant plant varieties along with good gardening practices to remove infected plants or plant parts.  Sulphur can be employed as an effective fungicide; and, as a natural product, it  is permited in organic practices.

Tobacco Mosaic Virus on Tomato.
Source: American Phytopathological Society

• Viruses -  These are insidious, rogue pieces of DNA or RNA with only a surrounding protein coat that  only reproduce by injecting parts of themselves into other cells and using those cells to duplicate themselves. They are usually about l00x smaller than bacteria, and to complete the grim picture there are even viral agents called viroids that are smaller than your standard virus. Viroids lack the protein coat of their bigger cousins, and they seem to only exist on plants. All home gardeners have probably encountered the most common  viral infection, tobacco mosaic virus, that can infect many different plants.  Symptoms are variable -varying with the plant variety,  its age, the growing conditions and the viral strain. Leaves can be yellow, growth can be stunted, fruit can be miscolored -- to name just a few.  Control mainly consists trying to select resistant varieties combined with the removal and destruction of infected plants. In controlled environments such as greenhouses, sometimes contaminated soil is removed, and occasionally  young plants are even innoculated with known weak viral strains to spur natural resistance.  Giving asprin and making the plants go to bed doesn't work; but watering at soil level instead of spraying with a hose can minimize viral  diseases spreading between plants.

Nemotode cysts on potato roots.
Photo: Xiaohong Wang - USDA ARS

• Nematodes - Most backyard gardeners probably don't think about nematodes at all or just think that they mainly cause  root-knot on their cabbages. Nematodes are small to very small round worms; they are not earthworms. Nematodes usually range in size from .1 mm to 2.5 mm, but a few do reach 5 cm.  They exist in all environments. Half of them are parasitic; and as a life form, nematodes probably comprise about half of all the animals on and in the earth and sea! For humans, trichinosis is perhaps the  most familiar disease that is associated with nematodes.   In addition to root-knot, other notably harmful nematodes affect grapes by introducing a deadly virus, while another bad guy is the golden nemotode [Globodera rostochiensis] that affects  solanaceae (tomatoes, potatoes etc).  But, some nematodes are beneficial such as the ones that prey upon cutworms and corn ear worms.  There are various approaches to controlling nematodal damage.   You can plant marigolds, or you can even try steaming your soil. But, there are also a couple of other natural approaches. One involves chitosan, a type of polysaccharide that is derived from the shells of crustacians.   It  enhances both a plant's growth and resistance to infestations; the other  approach involves a friendly fungus, Clonostachys rosea f. rosea, also known as  Gliocladium roseum, that acts as a natural control.  If you really want to get into the detail of G. roseum, start with  this  journal article  by John C. Sutton in Plant Research.

Source: Missouri Botanical Garden

• Parasitic plants - Ever hear of "dodders?" I know about misteltoe; but, I've not experienced, or at least not recognized, dodders  attacking my vegetables - until now. Dodders are native to North America;   and, unfortunately,  they have become one of our really big unwanted exports to the rest of the world.   Field dodder (Cuscuta campestris)  and swamp dodder (Cuscuta gronovil) are two of the common ones you might encounter. They can seriously affect your carrots, tomatoes etc. Backyard gardeners can mostly control them by pulling, but dodders are much more challenging for farmers.  If a dodder finds your tomato, the vine will wrap itself around the stem, drop its leaves and live off of your plant by inserting haustoria (little root-like growths) into the tomatoe's tissue. Dodders are fast growing and  colored between yellow and orange. More detailed information on these beasts can be found on this data sheet from the Invasive Species Compendium of CABI (Center for Agriculgtural and Biosciences International).

That's all for now folks, but some of these fellas are so interesting that we will probably provide more details about a few of them during the upcoming dreary months...

And remember:

"Don't judge each day by the harvest you reap, but by the seeds that you plant." - Robert Louis Stevenson