Troubles with Plant Pests – Part Two

This is a continuation of my first post about plant pests.

Introduction – Did you know that there are over 1,000,00 insect species, 250,000 weeds, and 10,000 different plant diseases in the world, and because of Florida’s geographic location and our weather conditions, our plants are vulnerable to many of them?

What is a plant pest?

A simple answer is that it’s an annoyance that may be detrimental to plants by disrupting growth cycles, cause plant stress, etc., etc.  Usually when we think of pests, we think of insects, diseases, or weeds, but there are others as well, including other animals, such as slugs/snails, spider mites, nematodes (microscopic wire worms), and man and physiological disorders (non-infectious injuries usually due to improper care or are weather related.)

Is it possible to determine what type of pest your plant has by becoming familiar with plant symptoms?  Yes, but in many cases there may be a combination of pests or 1 type of pest may mimic another.  In general:

Insects either chew plant parts, usually beginning at the edge of a leaf, (examples: grasshoppers, caterpillars), or suck sap from plant parts (examples: aphids, (which attack new plant growth), thrips, (which attack flowers or leaves causing distortion in shape, color, etc.), and scale insects (usually attach to underside of leaves or stems).  Spider mites, although not a true insect, also sucks nutrients from various plant parts resulting in discoloration or abnormal growth.  They are particularly bad during hot, dry weather, when populations build up rapidly and spider-like webs can be visibly seen.

Diseases, which are actually microscopic plants, (fungi, bacteria, or a virus), cause deterioration/discoloration of plant tissue.  For a disease to occur, 3 things must be present.

A susceptible plant host

A favorable environment (usually warm and damp)

And the presence of a disease organism (usually found in the air around us.

Weeds are defined as a mislocated plant – that is, growing somewhere that you don’t want them to.  There are 3 basic types:

Broadleaf – leaves have net-like veins and often showy flowers.

Grasses – hollow rounded stems with nodes and leaves with parallel veins.

Sedges – solid triangular stems usually found in moist areas.

You really don’t need to know the name of a specific weed to control/eradicate it.  What you should know is what type of weed it is, and which, if in your lawn, what type of grass you have.

Slugs/Snails – typically nocturnal (night feeders), they tend to eat succulent growth.  Key to identification is to look for silvery slime trail.

Nematodes – Usually found living in the soil or within the plant.  Typical symptoms include stunted growth, reduced yield, etc.  If you have sandy soil, you most likely will have nematodes within.  What’s important is knowing what kind and size of population your soil has.  Very difficult to control.

Physiological Disorders are typically due to extremes in weather, sunlight, or failure to provide good culture.

How to Handle a Pest Problem:

Know your plants.  Learn as much as you can about each of them, including their cultural needs, problems that you can anticipate and when, and inspect them regularly (via scouting).

Don’t panic – identify the problem and determine what caused it.  How serious is it?

Consider the options for control:

  • Provide good culture (best)
  • Use pest resistant varieties if available
  • Mechanical control
  • Sanitation
  • Soil drench
  • Dusting (seldom used anymore)
  • Applying baits or traps or use of pheromones  (this will also help determine extent of pest problem)
  • Fumigation (no longer recommended)
  • Use of sticky tape  (for insects)
  • Biological control
  • Use a pesticide  (last resort)

Determine safest and best way to control pest.  If you must apply a pesticide, always read and follow label direction.  Don’t spray wilting plants or when temperature is above 90⁰ (best to apply in early morning or just before darkness).  Spray to the point of run-off starting from the bottom of the plant and proceed upwards.  Practice safety – remember pesticides are poisons.  Don’t keep re-using the same pesticide.  Use others that will take care of the pest to avoid development of pest resistance.

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About AskthePlantMaster

I have 50 years of horticultural experience, am currently a Master Gardener in Central Florida. In addition, I'm a Horticulture Instructor and retired Parks Manager and Arborist. I love plants and would love to help you with yours!
This entry was posted in Aphids, Caterpillars, grasshoppers, Insects, Nematodes, Plant Diseases, Plant Pests, Slugs and snails, Spider Mites, Weeds and tagged , , , , , , , , , . Bookmark the permalink.

2 Responses to Troubles with Plant Pests – Part Two

  1. Janet says:

    Can you really kill slugs/snails by placing a saucer of beer on the ground by the affected plants?

  2. Yes. You can also kill them by dusting them with common table salt. Thank you for your question.

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