Soil has Many Names, Just Not the “D-word”

Soil has Many Names, Just Not the “D-word”

For all my years in the classroom, I never let students say the “d-word” when discussing soil science.  In some instances, we had a “d-word” swear collection jar of a quarter when you used the term and even today, I hesitate from spelling the word out in text due to feedback from all those I have corrected.  In case you still need a clue on the “d-word”, it ends in irt.

As a horticulturist for 46 years, I have read, heard, and been told many secrets to growing good plants.  I still hold firm that without proper knowledge of how soil works, most of what we do is by chance.  Soil is a living entity comprised of parent material (sand, silt, and clay), air, water, organic matter (OM), and microorganisms.  It is this last item which makes our soils come to life.  If you have pets, then you know they need shelter, warmth, air, water, and food.  From this point forward think of soil microorganisms as the pets in your soil.  If you take care of them, they will take care of your plants.

Sandy Soil

Sandy soil without any organic matter at the Wakulla County Extension office.

There is a huge difference in habitat from a sandy soil to a healthy soil with a good percentage of OM (5% – 10%).  In one gram of healthy soil (the weight of one standard paper clip), you can have bacteria (100,000,000 to 1,000,000,000), actinomycetes (10,000,000 to 100,000,000), fungi (100,000 to 1,000,000), protozoa (10,000 to 100,000), algae (10,000 to 100,000), and nematodes (10 to 100) (1).  A teaspoon of healthy soil can contain over four billion organisms (2).  These microorganisms are part of the soil food web and they form a relationship between soil and your plants.  They help convert nutrients to useable forms and assist with other plant functions.

The question becomes how to take care of your soil pets.  For years we have performed practices that compromise these populations.  Growing up we put all of our grass clippings in the weekly trash.  We know now how valuable those clippings are and to leave them be.  Two practices still common today though are tilling and raking leaves.

OM Soil

Master Gardener Volunteer vegetable bed with organic matter added.

Tilling has a limited purpose.  If I place a layer of organic matter on top of the ground, then tilling incorporates the OM which feeds my pets.  Excess tilling of soil introduces large amounts of oxygen which accelerates the breakdown of OM thus reducing our pet populations over time.  Another adverse result from tilling is disturbing the soil structure (how the parent materials are arranged) which can reduce pore spaces thus limiting water percolation and root growth.  There is a reason agriculture has adapted no-till practices.

Raking leaves (supposedly the sign of a well-kept yard) is removing large amounts of OM.  Do you ever wonder why trees in a forest thrive?  All of their leaves fall to the ground and are recycled by the microorganisms.  Each of those leaves contains macronutrients (carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, sulfur, and magnesium) and micronutrients (boron, copper, chlorine, iron, manganese, molybdenum, nickel, and zinc) which are necessary for plant growth.  You would be hard pressed to find all those nutrients in one fertilizer bag.  So recycle (compost) your leaves versus having them removed from the property.

We are in our off season and tasks such as improving soil health should be considered now for soils to be ready in spring.  Remember a little organic matter at a time and never work wet soils.  As your OM levels build over the years, remember to change your watering and fertilizing schedules as the soil will be better adapted at holding water and nutrients.  Soil tests are still recommended before fertilizing.

If you would like more tips on improving your soil, contact me or your local county horticulture extension agents.  For a more in depth look at caring for your soils, read The Importance of Soil Health in Residential Landscapes by Sally Scalera MS, Dr. A.J. Reisinger and Dr. Mark Lusk (https://edis.ifas.ufl.edu/ss664).

  1. Chapter 2: Soils, Water, and Plant Nutrients.  Texas Master Gardener Training Manual.
  2. The Importance of Soil Health in Residential Landscapes. 2019.
Clean Up for the Fall Vegetable Garden

Clean Up for the Fall Vegetable Garden

A common question for gardeners at the end of the season is if one should till the soil or use no till practices.  Opinions vary regarding this question, even among Extension Agents.  However old crops harbor insects, both good and bad.  This phenomenon was noticed on some recently cut back tomato plants.  The intention was to cut the leftover spring garden tomatoes back to encourage fall production.  Instead, a host plant for mealybugs was provided.

Whitefly larvae on a tomato plant.

Mealybugs on a tomato plant. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

Mealybugs are soft-bodied insects that possess a covering of flocculent, white, waxy filaments.  They are about 1/8 inch in length and usually pinkish or yellowish in color.  Mealybugs have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental and vegetable plants.  Mealybug damage produces discolored, wilted, and deformed leaves.

One very common example of an insect pest likely to claim residence in your garden’s crop residue, are squash bugs. They like to overwinter on squash, cucumber, and other cucurbit crop residue.  If you choose to not till your garden and leave a portion of last seasons crop in your garden, then you should consider applying an insecticide to your spent crop at the end of the season.  A product containing a pyrethrin or pyrethroid as an active ingredient would be a good broad spectrum insecticide to control any pest that may reside on plant residue.  More information on pyrethrins and pyrehtroids can be found at the EPA webpage: Pyrethrins and Pyrethroids.  If you choose to apply an insecticide, it is important that you follow the information on the label regarding pollinator protection.  Another option is to plant a trap crop on the edge of your garden to help attract pest insects away from your desired crops.  More information on trap crops can be found in the EDIS PublicationIntercropping, Pest Management and Crop Diversity.

An adult squash bug on a zucchini leaf.

An adult squash bug on a zucchini leaf. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County

So the answer to the till or no till question is…it depends.  It is really up to the gardener.  Yes, the residue from crops will add nutrients and organic matter to your soil, but it could also increase pest pressure in your garden.  If you don’t plan to remove crop residue and don’t plan to till, then keep an eye out for what could be hiding in your garden.

False Potato Beetle:  An Overlooked, Destructive Pest of Eggplant

False Potato Beetle:  An Overlooked, Destructive Pest of Eggplant

August is awful.  Its heat makes one miss the relative cool of July.  Its rain is so sporadic that it invokes nostalgia for the rainy afternoons of early summer.  But if there is a silver lining in August for gardeners, it is the simplicity that it brings.  The weaker spring crops, tomatoes, squash and the rest, are all gone now, destroyed or rendered fruitless by insects, disease, and heat.  This leaves only the hardened, usually pest and disease-free survivors Okra, Pepper, Sweet Potato and Eggplant.  I say usually because, this year, my eggplant bed is under attack by a new-to-me pest, the False Potato Beetle!

I’ve dealt with Colorado Potato Beetles (CPB) before.  Those orangish, black-striped terrors often attack my spring potato crops and occasionally bother early tomatoes.  However, I’ve never seen them in late summer on Eggplant.  This raised suspicion.  Also, I spotted unusual, round, whitish purple creatures munching on leaves from the same plants; these appeared to be the larval stage of the unidentified beetle. A little digging led me to identify these garden pests as the lesser known, lookalike cousin of CPB, the False Potato Beetle.

False Potato Beetle munching on an Eggplant leaf in the author’s garden.

False Potato Beetle (FPB) looks nearly identical to its cousin in the adult stage.  They are similarly shaped and colored, though a close look reveals subtle differences between species.  While both have yellowish-orange heads and pale-yellow backs with dark stripes, the FPB’s back is slightly lighter hued, more of a whitish, cream color.  Also, the CPB’s underside and legs are a very dark orange to brown, with the False Potato Beetle having lighter colored legs and underside.  If you’re saying, “These old eyes will never be able to tell the difference, County Agent.  Cream and light-yellow look the same to me.”, I get it.  Fortunately for those of us with poor vision, the larval stage (babies) of the two beetles looks very different and is the key to correct ID!  FPB larvae are larger and have a whitish coloration.  CPB larvae, in contrast, are a similar burnt orange color to the adult beetle.  I promise, the difference is very distinguishable!

False Potato Beetle is considered a minor garden and agronomic pest as they typically only bother Eggplant, and they don’t usually destroy entire plants.  However, if you get a FPB outbreak in your Eggplant garden, they can still be pretty destructive.  These beetles feed in the same manner as caterpillar pests, chewing away entire sections of leaves and stems.  Unchecked infestations can defoliate entire sections of plants.  So, if you find these little beetles eating away at your eggplant garden, what can you do?

False Potato Beetle larvae. Photo courtesy of the author.

First, if you scout regularly, you’ll notice the beetles and their larvae in relatively small numbers before outbreaks become widespread.  I had pretty good success this year just catching infestations early and picking off the beetles I saw and squishing them.  Continue scouting and squishing for a few days and pretty soon,  the population is reduced to a manageable level.  However, if squishing makes you squeamish, you also have some common pesticide options at your disposal.  I normally encourage clients to start their chemical pest control strategy with “softer” products like Pyganic, a pyrethrin make from an extract from the Chrysanthemum plant.  Pyganic works great but is a little harder to find; you may have to order online or ask your local retailer if they can get it for you.  If you are unable to find Pyganic or it doesn’t perform for you, the old standby products with carbaryl or pyrethroids (Sevin, Ortho Bug-B-Gone, and others) also work well.

False Potato Beetle can be a late summer garden pain, but with regular scouting, proper insect ID, lots of squishing, and maybe a timely pesticide application or two, you should be able to continue to harvest eggplant deep into fall!  If you have FPB in your garden or have another horticultural question, give your local UF/IFAS County Extension office a call!  Happy Gardening!

Armyworms Attacking Your Garden?

Armyworms Attacking Your Garden?

It’s been a challenging spring in this guy’s garden!  Despite getting the normal early start required for successful gardening in Florida, I’ve been affected by Bacterial Leaf Spot stunting my tomatoes, cutworms that reduced my watermelon plantings by half, and an eternal test of my patience in the form of a dog that seems to think my raised beds are merely a shortcut to a destination further out in the yard.  My latest adversary is the most potentially destructive yet, an outbreak of Southern Armyworm (Spodoptera eridania).

Early Southern Armyworm damage on Okra seedlings. Photo courtesy of the author.

Unlike some serious garden pests that wait until the heat of summer to emerge, Southern Armyworms begin appearing in spring gardens around the end of April.  Adult moths can survive mildly cold weather and venture into the Panhandle as soon as warmer spring weather arrives.   Once the adult moths arrive, egg masses are then laid on the undersides of leaves and hatch in a little under a week.  Once loosed upon the world, Southern Armyworm larvae (caterpillars) become indiscriminate, voracious feeders and congregate in extremely large numbers, allowing them to destroy small, developing garden vegetable plants in a manner of days.  Young larvae feed on the undersides of leaves and leave little but a skeleton.  As larvae grow larger, they become solitary and begin to bore into fruit.  Once they’ve eaten the good stuff (leaves and fruit), large larvae turn to branches and even plant stems!

Southern Armyworm larvae feeding on Okra leaves. Photo courtesy of the author.

The good news for gardeners is that Southern Armyworm, and most other caterpillar pests, are easily controlled if outbreaks are caught early.   Scouting is critical for early detection and good control.  Armyworm damage generally appears from above as brownish-gray sections of affected leaves with a yellowish ring surrounding these sections, this ring indicates the current feeding zone.  Affected areas will appear transparent and “lacy” due to the skeletonizing effects of larval feeding.  If you see leaves that look “off” in the manner just described, check underneath for the presence of a horde of tiny greenish worms.

If found in this early stage, an application of Bacillus thuringiensis (Bt), a biological pesticide utilizing a bacterium destructive to caterpillars, is extremely effective.  Bt has to be ingested by caterpillars with leaf tissue to work; thorough coverage of leaf surfaces is critical for maximum control.  I generally follow up with a sequential application of Bt a day later to ensure that I achieved good coverage of the plant surfaces and, therefore, good control.  Unfortunately, Bt is much less effective on older larvae.  Infestations not caught early require harsher chemistries like carbamates, pyrethroids and organophosphates for adequate control.

Don’t let armyworms or other caterpillar pests destroy your garden, get out there daily and scout!  You have a short window for easy caterpillar control with a harmless to people, natural product, Bt.  Don’t waste it!

For more information about Southern Armyworm, other caterpillar pests, Bt, or any other horticultural topic, please consult your local UF/IFAS Extension Agent.  Happy Gardening!