Container Gardening Complete

Job:06-700309 Title: CPS - Container Gardening Complete

700309 - ContainerGardens_001-272_FINAL.indd 180 5/24/17 12:18 PM
Job:06-700309 Title: CPS - Container Gardening Complete
Job:06-700309 Title: CPS - Container Gardening Complete

700309 - ContainerGardens_001-272_FINAL.indd 181 5/24/17 12:18 PM

180 chapter 4

Fungus Gnats (Bradysia species

and Lycoriella species)

North American geographical range: All;

considered an indoor nuisance pest

Identification: Mature gnats are tiny black flies

that measure a mere^1 ⁄ 8 in.^ and live for about

2 weeks. During this time, females lay eggs in

soil fissures. The resulting translucent, minute

larvae feed largely on the assorted fungi growing

in potting soil, though they can also feed on

fine roots and plant debris. In a few weeks, they

pupate into adults within the soil and the cycle

continues with several generations occurring

together at any given time. When a cloud of tiny,

black flies rises from the pot of a houseplant, it’s

a clear sign of trouble. That cloud may consist

of hundreds of adult fungus gnats and, while

individually they are barely noticeable, in large

numbers they are hard to miss.

Plants affected: Any indoor plant is susceptible

Feeding habits and damage: Because fungus

gnat larvae feed primarily on fungi growing in the

potting soil, these insects typically don’t cause a

significant amount of damage to infested plants.

However, in extreme cases where the larvae also

feed on plant roots, the plant may wilt and show

signs of stunted growth.

Physical controls: Constantly damp soils promote

fungal growth, which serves as an excellent

food source for the larvae. Simply cut down on

watering to solve most fungus gnat issues. Water

infested houseplants deeply (but not frequently)

and only when the soil is dry. Be sure the pot itself

has good drainage and the saucer underneath

doesn’t hold standing water. If this doesn’t clear

up the problem, repot the plant with new, sterile

potting soil. You can also trap adult fungus gnats

on yellow or blue sticky cards placed vertically an

inch or two above the soil surface. Another option

is to remove the top half-inch of potting soil

completely and replace it with a small gravel-like

substance, such as Gnat Nix or chicken grit.

Product controls: Two biological control

products are highly effective: beneficial

nematodes (Steinernema feltiae) and Bti (Bacillus

thuringiensis va r. israelensis) can be applied

to the soil as a drench or spray. The first is a

microscopic nematode that burrows into the

soil and consumes the gnat larvae. The second

is a biological insecticide made from a strain of

bacteria that kills the gnat larvae. One popular

brand is named Gnatrol®.

Fungus gnats are a classic example of a nuisance pest.

Thankfully, they aren’t harmful to plants unless present

in large numbers, and they’re easy to trap on yellow

sticky cards.

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Troubleshooting 181

Japanese Beetle (Popillia japonica)

North American geographical range: Populations

are heaviest east of the Mississippi River and

north into the lower part of Canada, but they’re

found throughout most of the United States,

except in the extreme Southeast.

Identification: Metallic green with copper wing

covers, adult beetles are^1 ⁄ 2 in. long and^1 ⁄ 4 in. wide.

They stick up their two back legs when threatened

and drop off plants when disturbed. The ground-

dwelling larvae are C-shaped, plump, grayish-

white grubs with light brown heads.

Plants affected: Adults feed on over 300 different

landscape plants. Favorites include grapes,

raspberries, blueberries, roses, rhubarb, zinnias,

and many others. Grubs feed underground, on the

roots of turf grass and many ornamental plants.

Feeding habits and damage: Adults skeletonize

leaves and damage flower buds. They emerge in

midsummer and feed heaviest at temps between

85° and 95°F. Grub damage appears as irregular

brown patches in the lawn that peel back in a

carpet-like fashion.

Physical controls: Withhold water from the lawn

in summer when females are laying eggs and

allow your lawn to go dormant. The eggs need

moisture to survive, so doing so reduces next

year’s population. Knock adult beetles into a jar

of soapy water. Handpicking the adults early

and often limits the release of the congregating

pheromone the beetles release to lure in more

beetles for mating. Avoid using Japanese beetle

traps unless they’re placed far from your

container garden. Several studies have shown

these traps attract more beetles than they

actually trap.

Product controls: Beneficial nematodes

(Heterorhabditis species or Steinernema carporcapsae)

are incredibly effective against the grubs when

applied to the lawn every spring. Useful product

controls to battle adult Japanese beetles include

neem and spinosad.

Adult Japanese beetles skeletonize leaves and damage flower buds of over 300 dierent garden plants.

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