Day #10: Plant Pathology

Plants have no immune system.


Plant disease is the rule rather than the exception.

Double yoicks!

What could go wrong with plants?

Judging from all the plants I’ve killed, apparently the list is endless. Just some of them are listed below in the Vocabulary section.

Lessons Learned

  • Best I can do is point to some useful resources:
  • Diagnose a Plant Problem via the University of Minnesota extension.
  • Pest Management Alerts from University of Maryland extension. Plant pest alerts posted weekly, or you can sign up for email notification.


  • Abiotic – Non-living.
  • Bacteria – Minute, single-celled organisms, much smaller and simpler than fungi.
  • Biotic – Living.
  • Blight – A general killing of the plant (twigs, limbs, leaves, flowers or shoots).
  • Blotch – Large, superficially discolored areas or irregular shapes leaves, shoots, fruits, and stems.
  • Canker – Dead areas in the bark of woody or herbaceous stems or twigs.
  • Codit – Compartmentalization of disease in trees.
  • Conk – Large, woody, shelf-like fruiting body of many the wood decay fungi.
  • Epinasty – Downward curve of leaves due to abnormal growth in part of the stalk that supports the leaf blade (petiole).
  • Fungi – Lower order of plants which contain no chlorophyll and do not form roots, stems, and leaves.
  • Gall – Localized abnormal enlargement of  plant parts.
  • Gummosis – Production or oozing of a thick gummy liquid in response to injury or disease.
  • Mildew – Grayish or whitish growth of fungus.
  • Mold – Similar to mildew but of different groups of fungi; commonly gray, white, black, blue or green.
  • Mushroom – Large fruiting body of certain fungi; few are pathogens.
  • Nematodes – Microscopic round worms.
  • Pathogens – Any organism that causes disease. Generally applied to bacteria, viruses, fungi, nematodes and parasitic plants.
  • Rot – Affected tissues discolored, disintegrated (decayed), and often softened.
  • Scorch – “Burning” of leaf edges.
  • Signs – Structures or products of the pathogen itself on a host plant, li mold fungal fruiting bodies, or bacterial slime/ooze. That’s gross.
  • Smut – Not what you think. Spore masses of certain fungi.
  • Symptoms – Physical expressions of disease in a plant, for instance, changes in color, appearance, integrity, etc.
  • Syndrome – Symptoms and signs that indicate or characterize the presence of disease or other abnormal condition.
  • Virus – Infectious molecules that take over plant metabolism and use it to produce more virus.


Topping a tree is about the worst thing you can do. … It’s going to ruin the plant growth forever.

Today’s Photo

Nothing wrong with that lovely bloom I found over by the gazebo.


Prior to our field trip October 13 to the Arlington National Cemetery Arboretum, read Handbook chapter on Woody Landscape Plants.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.