|
Leaf
Symptoms
Examine leaves carefully.
Look for holes, general discoloration, spots. Note size, shape, and edges
of holes, and color or patterns of spots.
Leaves appear eaten | Large
areas of foliage discolored | Spots
on leaves | Other symptoms |
|
Symptom |
Suspects |
What
to Look For |
Plants
Most Commonly Affected |
Controls |
Notes and additional photos |
|
Leaves
appear eaten |
|
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|
|
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|
Ragged holes |
slugs and snails
|
Look for silvery
slime trail.
|
many plants, esp. hosta
|
Concern® Diatomaceous
Earth Crawling Insect Killer
Slug & Snail
Copper Barrier Tape |
Start control measures early in the season to minimize
the slug and snail populations.
|
caterpillars
|
Look for dark-colored fecal pellets (droppings) |
many plants |
SaferŪ Brand Caterpillar Killer with BT
|
Remember that caterpillars are butterfly and moth larvae,
so use controls judiciously so as not to harm desirable insects.
cabbageworm
swallowtail
larva |
beetles |
Visit the garden in the morning to look for beetles --
they're sluggish in cool temps. |
many plants |
Safer® Brand
BioNEEM® Insecticide & Repellent |
Japanese beetles are a common culprit, but there are many
others, too. Note that not all beetles are pests, though!
Colorado
potato beetle |
|
Perfectly
round
or semicircular holes |
leafcutter
bees |
|
|
|
Leafcutter bees are important as
pollinators and are NOT pests. The damage they cause is negligible. SImply
stand back and marvel that an insect can cut such perfect, circular holes. |
|
Numerous small holes |
flea beetles |
Look closely for shiny, black insects that jump when disturbed. |
radishes, cole crops |
Safer® Brand
BioNEEM® Insecticide & Repellent |
Most common in early spring; most plants will outgrow
damage. Use tightly secured row covers to exclude flea beetles.
covering
plants to exclude insects |
|
Leaves appear shredded or torn |
mechanical damage |
Heavy winds, torrential rain, and hail will tear plant
leaves, as will string trimmers.
|
|
|
Plants will outgrow damage to foliage; however, fruits,
such as tomatoes and apples, may be ruined.
hail damage |
|
Large areas of foliage discolored |
|
|
|
|
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Blackened areas, especially tops of plants
|
frost or chill damage
|
If the upper, exposed leaves are damaged, but interior foliage is
fine, and you've experienced a recent cold snap, suspect frost damage.
|
basil, tomatoes, peppers
|
|
Remove affected foliage and plant will probably recover.
|
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Black, powdery substance all over leaves
|
sooty mold
|
Sooty mold will cover large areas of the leaf; touch affected leaves
and see if any parts are sticky.
|
houseplants
|
Control insects with Safer® Brand
Insect Killing Soap |
Certain insects,
such as aphids, secrete a sticky "honeydew." Sometimes black
sooty mold develops on the honeydew. By controlling the insect infestation,
you'll control the sooty mold.
|
|
Bleached or white areas on the leaves of new transplants
|
sunburn
|
If indoor or greenhouse-grown plants were recently set out in the
garden and the weather has been sunny, suspect sunburn.
|
new transplants
|
|
Unless damage is severe, plant will probably recover.
In the future, harden off transplants by gradually exposing them to outd style="border: solid 1px black"oor
conditions.
|
|
White or gray powdery substance on leaves
|
powdery mildew
|
|
lilacs, roses, bee balm
|
Safer® Brand
Garden Fungicide |
Minor infection won't harm plants, but a serious attack can cause
stunting and misshapen blooms. |
| 
|
Overall bronze tint
to foliage |
spider mites |
Spray a fine mist of water on the new growth; if spider mites are
present, the droplets will cling to the fine webbing. Look closely and
you may see the red, pinhead-sized mites.
|
houseplants
|
Safer® Brand
Insect Killing Soap |
Common on houseplants, spider mites flourish in hot, dry conditions.
Occasionally washing plants and daily misting with water can control
minor infestations.
|
 |
White stippling on leaves |
mites, leafhoppers |
|
roses, citrus |
Safer® Brand
Insect Killing Soap |
These small insects are difficult to see. |
| |
Yellow leaves
|
insufficient water
|
Check soil moisture
|
many plants
|
|
Both too little and too much water can cause yellow
foliage.
|
nutrient deficiency |
Fertilize indoor and container plants; have garden soil
tested for nutrients and pH |
many plants |
|
Nutrient deficiencies can cause various symptoms, from
weakened growth to yellowing leaves. |
disease |
Diseases usually show up as patches of discoloration. |
many plants |
|
Rule out above factors before suspecting disease. |
|
Spots on leaves |
|
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Leaves finely speckled with yellow spots
|
thrips
|
Look for black specks -- these aren't the actual thrips, they are
the thrips' fecal matter. Since thrips are so small, these are a good
identifier.
|
many plants
|
Safer® Brand
Insect Killing Soap
Safer® Brand
Sticky Whitefly Trap |
Because they are small, hide in plant crevices, and are very mobile,
thrips are challenging to control. Although the damage they cause is
often
cosmetic, they can transmit harmful plant viruses.
|
|
Fuzzy spots;
target-like spots;
rust-colored spots or bumps; watery-looking areas |
various foliar diseases, such as rust |
Different diseases cause different types of damage, so
noting the shape, size, and color can help determine the specific culprit. |
many plants |
Safer® Brand
Garden Fungicide |
Good air circulation, keep foliage dry |
|
Black spots, often accompanied by yellowing leaves |
black spot disease |
|
roses |
Safer® Brand
Rose Care Kit |
If just a few leaves are showing symptoms, pick them
off and throw them in the trash. This task, plus raking up leaves in
fall, can go a long way to controlling this common disease. |
|
Other symptoms |
|
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| |
Narrow, winding paths or tunnels on leaves. |
leaf miners |
Try splitting the leaf open to look for the small larvae. |
columbine, birch |
|
Leaf miners are the larvae of a number of insects.
They
live
and feed
between the upper and lower leaf surfaces, making them difficult to control.
Fortunately, the damage they cause is mostly cosmetic. |
| |
Sticky
substance on leaves; leaves may be distorted or discolored. |
aphids
|
Look for slow-moving aphids congregating on new growth.
They are about 1/8" long and oval-shaped. |
many plants
|
Safer® Brand
Insect Killing Soap
|
Aphids, scale, and whiteflies are similar
in the way they attack plants: They suck on plant juices and leaves become
distorted. The insects all secrete a sticky
"honeydew," which may eventually lead to a covering of black
sooty mold.
ladybugs eating aphids |
scale
|
Scale look like tiny turtle shells attached to stems and
leaves, especially leaf veins. They don't move, and you can scratch them
off with your fingernail. |
houseplants, citrus
|
Safer® Brand
Insect Killing Soap |
Gently scrape scale off. |
whiteflies |
Tap the foliage; if whiteflies are present you'll see a
flurry of tiny, white, mothlike insects flying away. |
houseplants, tomatoes |
Safer® Brand
Sticky Whitefly Trap
Safer® Brand
Insect Killing Soap |
The damage whiteflies cause is often mostly cosmetic;
however, they can transmit harmful plant viruses. |
|
Leaves that are curled,
puckered, and discolored |
aphids, scale, or whiteflies; see above |
|
many plants |
Safer® Brand
Sticky Whitefly Trap
Safer® Brand
Insect Killing Soap
|
|
|
Cottony white masses on underside of leaves, and esp. in leaf axils |
mealybugs |
|
houseplants, citrus |
Safer® Brand
Insect Killing Soap |
You might also see the sticky honeydew secretion if infestation is severe. |
|
Foliage wilted |
dessication; stem damage; root damage
|
Dry soil or dry, windy weather can cause wilting.
|
many plants |
|
Anything that affects a plant's ability to take up
water can cause wilting. Check soil moisture first. Note that even some
healthy plants will wilt slightly during very sunny,
hot, and/or windy days, but will recover at dusk.
|
Small holes in stems, especially near the soil line, indicate
borers. |
many plants |
|
Insects, such as borers, create small holes in stems and
inhibit water update. If you find holes, try inserting a paper clip into
the hole to impale and remove the caterpillar. |
Overwatering can damage roots, as can certain diseases. |
many plants |
|
Overwatering results in root rot. Plant may recover
if moved to a spot with better drainage..
|
Rule out other options before suspecting diseases |
many plants |
|
Some diseases affect water uptake. These can be difficult
to diagnose. |
|
Overall lack of vigor |
|
Insufficient water;
check soil moisture
Nutrient deficiency
Improper soil pH |
many plants |
|
If soil pH (a measure of acidity/alkalinity) is too high or too low,
nutrient update is inhibited. If you've recently fertilized and plant is
still stunted, test your soil pH. |
| Flower
Symptoms |
| |
Flower buds distorted; flower petals flecked
with white; flower buds fail to open.
|
thrips |
|
|
Safer® Brand
Sticky Whitefly Trap |
|
| Fruit
Symptoms |
|
Asymmetrical or misshapen
fruit |
poor pollination, chill damage to flowers, insect attack during early
fruit development
|
If
part of the fruit looks fine, but another part is underdeveloped, suspect
a pollination problem.
If the damage more widespread it may be due to weather or insect attack
during development.look or holes or scars from insect feeding |
squash, apples, cucumbers, corn |
|
Bees don't fly
in cold, rainy weather, and the population of bees is dwindling. Encourage
pollinators by using pesticides judiciously, and never on flowers. Plant
pollinator-friendly
flowers to encourage bees to visit your yard. Become a beekeeper!
Once the damage to the developing fruit occurs, there's no way to fix
it.
tomato |
|
Bottom (blossom end) of fruit is blackened |
blossom-end rot
|
If damage is confined to the blossom end and the rest of the fruit
is unaffected, assume blossom end rot.
|
summer squash, cucumbers, tomatoes |
|
Blossom-end rot may be caused by several factors, including fluctuating
soil moisture levels and low soil calcium. Keeping soil evenly moist
and mulching tomatoes will help prevent the problem.
|
| Root/Soil
Symptoms |
| |
Small,
black "fruit flies" flying around soil of houseplants. |
fungus gnats |
|
houseplants |
Safer® Brand
Sticky Whitefly Trap |
Fungus
gnats are a nuisance but are usually not harmful to plants. Their
larvae feeds
mostly on organic debris but may also damage roots of young seedlings. |
| Beneficial Insects |
| ladybug larva |
ladybugs eating aphids |
lacewing larva |
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