Plant Symptoms & Solutions
for South Florida

Here is a listing of typical South Florida plant symptoms (including some for lawns), their likely cause, and ways to treat for each.

This is meant as a reference only. Take bagged cuttings to your local plant nursery for actual diagnosis of any plant symptoms...and the treatments to alleviate the problem and restore health.

Symptoms may indicate more than one possible cause, and plant symptoms can vary from one variety of plant to another - even with the same type of insect.

SYMPTOM: Black residue on leaves

CAUSE: This is sooty mold, which forms on the secretions of insects, meaning your plant is infested with a bug - often mealybug, aphids, scale or whitefly.

TREATMENT: Apply neem oil or another insecticide spray.

SYMPTOM: Ants crawling on stems

CAUSE: Same as above - ants feed on the secretions of insects (called "honeydew"). So your plant has an insect problem like mealybug, scale or aphids.

TREATMENT: Apply neem oil or another insecticide spray.

SYMPTOM: Mounds or trails in the lawn

CAUSE: One of the most annoying plant symptoms is moles in the lawn, where they're dining on grubs (and sometimes mole crickets for dessert).

TREATMENT: Getting rid of moles requires getting rid of them and their food source.

First, treat the lawn with an insecticide containing permethrin. READ THE LABEL - the curative amount of insecticide is usually double the preventative amount.

Then use a stick to make a hole in an active trail, shake in mole bait and tamp down with your foot. Don't use your hands - moles have an excellent sense of smell.

SYMPTOM: The plant just sits there and won't grow

CAUSE: The plant may be planted too deeply, settled after planting, or have too much mulch around its base.

TREATMENT: Remove any excess mulch and keep it at least 6 to 8 inches away from the plant's base.

If mulch isn't the issue, pull back soil to see if the trunk has been sitting below the soil level.

If it's situated too deep, dig it up and replant at the proper height. It may be necessary to cut it back as well. Treat as a new planting with soil amendments and TLC (see Planting Tips.)

SYMPTOM: Yellow leaves

CAUSE: The sudden appearance of bright yellow leaves is one of the most common plant symptoms, usually indicating stress from an inconsistency in water or climate. An overall leaf yellowing indicates a nutritional deficiency.

TREATMENT: If, for instance, we've had several days of rain after a dry spell, the appearance of some yellow leaves is normal. You can spray with a fungicide if the discoloration persists.

If the overall look of your plant is yellowed, apply fertilizer. With palms, you may need to apply a fertilizer with more of a focus on micronutrients.

SYMPTOM: Flowering plant won't bloom

CAUSE: It could be lack of needed sunlight - or it's not the right season for that type of plant - or it's between bloom cycles - or the plant needs a bloom-boosting fertilizer.

TREATMENT: If the plant needs more sun, you may need to move it to a sunnier area.

If fertilizer is the issue, apply liquid 15-30-15 or 12-48-8 and/or bone meal. (See Plant Fertilization.) If it's newly planted, give it some time to settle in before producing flowers.

SYMPTOM: Curling leaves

CAUSE: Your plant has been invaded by sucking insects such as spider mites, scale, aphids or mealybug, which are literally sucking the life out of the leaves.

TREATMENT: Apply neem oil or another insecticide spray. If it's mites, be on the lookout for fungus - mites can cause fungus, too - and in that case use a combination spray of neem oil or another miticide and a fungicide.

SYMPTOM: Chewed or notched edges of leaves

CAUSE: Chewing insects such as caterpillars or leaf notcher weevil are munching on your plant.

TREATMENT: For leaf notcher weevil, apply insecticide spray containing bifenthrin. For caterpillars, use thuracide or a product which contains spinosad.

SYMPTOM: Gray or green moldy growth on trunk

CAUSE: This is lichen, formed when algae and fungi join forces to grow upon woody trunks of plants.

TREATMENT: No treatment is necessary - lichen won't hurt a plant because it's not actually feeding off it.

Lichen needs a certain amount of sunlight, so keeping foliage denser can discourage it - and it may be taken care of naturally by the next bug on our list.

SYMPTOM: White, webby stuff appears suddenly, covering the trunk

CAUSE: Wood louse is a BENEFICIAL INSECT that eats lichen off bark.

TREATMENT: This is one of the few plant symptoms where no treatment is necessary (and the web will disappear on its own by the next day).

SYMPTOM: Little brown spots on leaves

CAUSE: Brown spots that go all the way through the leaf usually indicates fungus, which is caused by stress.

TREATMENT: Treat with a fungicide spray or drench - and, if possible, fix the root cause of the stress.

SYMPTOM: Tiny white bugs fly up when you approach a plant

CAUSE: Whitefly is a sucking insect that can outsmart humans unless you know how to deal with it.

TREATMENT: You must sneak up on the affected plant, moving very slowly as you approach. Whiteflies will fly up from the plant when you get close, so wait until they've settled back down. Then spray with neem oil - directing the spray ABOVE the plant to hit any insects that fly up again.

SYMPTOM: Circular or oval holes in the leaf

CAUSE: These plant symptoms are from the leaf notcher weevil or from the leaf cutter bee, a wasp that takes the leaf pieces to another location to build a nest.

TREATMENT: Apply neem oil or another insecticide spray.

SYMPTOM: Flower buds drop before opening

CAUSE: Midges, a sucking insect, may have infested your plant (often hibiscus and gardenia) - open the fallen bud and look for little "worms."

OR you may have fertilized your azaleas or gardenias at the wrong time...fertilizing should only be done on these plants no later than October and then after their spring bloom is over.

TREATMENT: If midges are the problem, apply a non-oil systemic insecticide containing imidacloprid or acephate.

SYMPTOM: Hanging moss or mossy balls on stems

CAUSE: Spanish moss and/or ball moss, both epiphytes (air plants that don't need soil to live).

TREATMENT: Remove by hand, if you can reach it. If you can't, and don't want to climb ladders or hire someone to physically pull the moss off, spray with neutral copper.

The best time to do this is late winter when moss is at its weakest. IMPORTANT! you MUST protect other air plants like bromeliads, orchids and staghorn ferns from the spray.

SYMPTOM: New growth is dying or deformed

CAUSE: Plant symptoms like these can be caused by several completely different things:

1) Check for insects - sucking insects like spider mites, mealybug, etc., go after tender new growth.

2) New growth wilting or dying could be from root damage caused by fungus.

3) Deformed and discolored new growth may indicate witches broom, a not uncommon plant virus.

TREATMENT: 1) Insects - spray with neem oil.

2) Fungus - treat with a systemic fungicide as a drench around the roots.

3) Witches broom - generally fatal, but you can try to save the plant by cutting off affected areas well beneath the damage, sterilizing your pruners in a bucket of bleach solution between each cut, and immediately bagging clippings.

If discarding the plant, dig it up and immediately bag it for trash. Be sure to wash and disinfect your hands before touching any other plants, and clean with bleach any garden tools that have touched the infected plant.

SYMPTOM: Most or all the leaves have fallen off

CAUSE: Leaf drop can be due to stress (lack of or too much water, cold weather, planting too deep, even rough treatment during planting), or a weed killer or animal urine spray.

TREATMENT: If lack of water is the issue, soak the roots and set up a better watering schedule.

For any stress situation, remove the cause of the stress (if possible) and treat with a systemic fungicide.

In most cases, cut the plant back (see the page on Plant Trimming) and apply a water-soluble fertilizer to encourage new growth.

SYMPTOM: Brown patches on the lawn

CAUSE: Dead lawn patches can indicate chinch bugs (on St. Augustine) or fungus.

TREATMENT: To find out which cause, cut an 8" square patch of lawn, half brown and half green, and take to your nursery for inspection.

If your grass has chinch bugs, treat with a lawn insecticide...if fungus, spray a liquid fungicide and change the situation causing the fungus (usually watering frequency is the problem).

SYMPTOM: Color variations on plant leaves

CAUSE: Lots of choices for this one, such as viral, nutritional, or even leaf miner insects.

TREATMENT: If your nursery diagnoses the problem as leaf miner, spray with neem oil. If it's a nutrition deficiency and your fertilization has been on schedule, apply a supplemental feeding such as minor elements.

SYMPTOM: Leaves and/or stems have white (or another color) bumps

CAUSE: Bumps are usually a type of scale. Scale is an insect that builds a hard-shelled house to live in. Sometimes you'll see "crawlers" (residents of the little houses) moving around on the leaves, as well.

These plant symptoms can also indicate galls, where an insect lays an egg and the plant grows over it...just cut off the affected part.

TREATMENT: For scale, spray with neem oil. NOTE: Some forms of scale look different - see the next symptom.

SYMPTOM: White "snowy" substance on leaves or stems

CAUSE: Mealybug or snowy scale or possibly cottony cushion scale (an egg mass with a cotton-like cover). Check to see if the leaves (usually roses and crape myrtles) have a powdery underside, it may be powdery mildew.

TREATMENT: Spray with neem oil for all but powdery mildew. For that, use a systemic fungicide.

SYMPTOM: Tips of leaves are brown

CAUSE: Quite a few possibilities: the lack of adequate water, leaf burn from winter winds, fertilizer burn, many more. This is one of those plant symptoms that require an accurate diagnosis at your nursery.

TREATMENT: If the plant's been kept too dry, change the watering schedule. For either water or cold stress, treat with a systemic fungicide. Your plant nursery will recommend treatments for these and other causes.

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