Transcript Pests and diseases - Wilson County Master Gardener Association

In the Vegetable Garden
PESTS AND DISEASES
DISEASES IN THE VEGETABLE GARDEN
Symptoms
Plant will wilt and die quickly
Early on center of stem appears
water-soaked
Later it stem appears brown and
may hollow
Affects tomatoes, potatoes,
eggplants & peppers &
cucumbers
BACTERIAL WILT
Favorable Conditions
Warm, wet weather of late spring &
early fall
Management Practices
Rotate Crops
Remove and destroy plants
Replace soil surrounding plant
BLOSSOM END ROT

Symptoms
Brown to black, leathery rot
near the blossom end of the
fruit
 Lesion gets bigger as the
disease worsens


Management Practices
Make sure plants are
fertilized and watered
properly
 Mulch

Caused by lack of sufficient calcium
Most severe following extremes in soil
moisture (either too dry or too wet)
Applying too much fertilizer at one time
can result in blossom end rot
EARLY BLIGHT

Symptoms






Spots are dark brown to black.
Concentric rings develop in the
spot forming a bulls eye. Leaf
eventually turns yellow.
Starts on the lower leaves
Overwinters on old tomato vines
Occurs during cool, rainy weather
Also affects peppers
Management Practices






Rotate crops
Plant disease free seeds
Use resistant cultivars
At season end clean up garden
thoroughly
Avoid getting the leaves wet
Apply fungicides as
appropriate(before the disease
first appears)
LATE BLIGHT

Symptoms
Lesions that are large,
irregular and gray with
white mold
 Fruit will be firm and rotted


Management Practices
Use disease free plants and
seeds & resistant varieties
 At the end of the season be
sure to clean up the garden
thoroughly
 Apply fungicides containing
copper as appropriate
(before disease appears)

Thrives in cool, moist conditions, or high humidity
levels.
OTHER TOMATO PROBLEMS

Leaf Roll



Happens when there is a
period of heavy rainfall that
keeps the soil constantly
moist.
Keep soil well drained &
well aerated
Edges of leaves curl up to
form cups; then the edges
overlap & the leaves
become firm & leathery to
the touch.

Fruit with cracks




Cracks radiate from stems
and around the shoulders
Caused by hot, rainy weather
To avoid do not overwater
Blossom Drop


Prevalent in cool rainy
weather or where soil
moisture is low and winds
are hot & dry.
Large fruited tomatoes are
particularly vulnerable
ANTHRACNOSE

Symptoms



Sunken, reddish to black
lesions on the bean pods,
leaves & stems
Also affects peppers,
cucumbers & squash
Management Practice






Avoid working when leaves
are wet
Avoid overhead irrigation
Crop Rotation
Destroy crop residue
Encourage air movement
Plant disease free & resistant
plants
BACTERIAL BLIGHT

Symptoms
Large, brown, circular spots
on leaves & bean pods
 Lesions may be surrounded
by a yellow halo


Management Practices
Avoid working when leaves
are wet
 Avoid overhead irrigation
 Crop rotation
 Destroy crop residue
 Encourage air movement
 Plant disease free &
resistant plants

POWDERY MILDEW

Symptoms


Small, round & whitish
spots on the lower leaves
Management Practices
Encourage air movement
 Plant resistant cultivars


Conditions Favorable for
Development


Cool, moist conditions
Time of Year it Appears

March thru September
DOWNY MILDEW

Symptoms
Yellow to brown spots on
the upper surfaces of
leaves
 Fuzzy white patches on the
fruit
 Infected leaves may die
 Effects beans, cucumbers &
melons


Management Practices
Rotate Crops
 Plant resistant varieties
 Spray fungicides

FUSARIUM WILT

Symptoms
Plants wilt, turn yellow and
die (starts from bottom)
 Often confused with lack of
water
 Cucumber, squash,
broccoli, & cabbage is also
affected


Management Practices
Plant resistant varieties
 Rotate crops
 Remove and destroy plant

MOSAIC VIRUS

Symptoms
Leaf blades become long &
skinny
 Leaves may be mottled
 Cucumbers, squash &
beans are affected


Management Practices

Control aphids
PESTS
COMMON PESTS IN THE VEGETABLE GARDEN
JAPANESE BEETLE

Damage

Adults



Larvae


Grow borage as a trap crop
White geranium, garlic & rue are
Repellents
Larkspur not only attracts them, but it is
Fatal to them.
Apply milky spore to your lawn to kill the grubs
Eat flowers
Skeletonize leaves of a broad
range of plants
Feeds on roots of lawn
grasses & vegetable plants
Management Practices




Hand pick and place in bottle
with soapy water
Cover plants with floating row
cover
Apply parasitic nematodes to
sod to kill larvae
Parasitic wasps & flies
REDBANDED LEAFHOPPER

Damage







Adults & nymphs suck juices
from stems & undersides of
leaves of most fuit &
vegetable crops
Toxic saliva distorts & stunts
plants
Causes tipburn & yellowed,
curled leaves with white
spots on undersides
Spread viral diseases as they
feed
Wash plants with stiff sprays
of water
Spray with insecticidal soap
Last resort spray with neem
or pyrethrin
APHIDS







Usually green although some
species are yellow, pink, brown or
black.
Most prevalent during cool, dry
weather on small plants.
They suck the plant sap, causing
foliage to distort & leaves to drop.
Feeding spreads diseases.
Treatments for aphid control should
begin at any time colonies are
found.
Spray foliage with soapy water, then
rinse with clear water or use
insecticidal soaps.
Once the weather warms up,
natural enemies usually control
aphids
CORN EARWORM




Affects tomato, pepper, beans,
cabbage and corn.
Plant corn as early as possible
Apply mineral oil on corn silks
five to six days after silk
emergence.
Mixing a Bacillus thuringiensis
(B.t.) product with mineral oil
can improve control of
earworms. With liquid B.t.
products, use a ratio of 1 part
B.t.to 20 parts oil. One
application of ¼ teaspoon or
five drops of the oil mixture
should be applied to the silk at
the tip of the ear.
CUTWORM






They chew through stems at ground
level
May completely devour small plants
Most damaging in May & June
Place a collar of stiff paper, cardboard,
or aluminum foil around each plant for
protection after transplanting to the
garden.
At the first sign of cutworm moths,
spray the plant stems and leaves with
Bacillus thuringiensis (B.t.) to kill the
larvae.
A bait can be made by mixing B.t. with
bran until the liquid is absorbed by the
bran, and then adding a small amount
of molasses. Crumbled pieces can be
scattered around the base of the plants
to protect them. Cultivating the soil can
kill cutworms.
MEXICAN BEAN BEETLE





Adults and larvae chew on
leaves from beneath, leaving
a lacy appearance
Plants are defoliated & killed
Since most damage occurs
during July and August, quickmaturing varieties of green
beans planted very early or
during late summer may
escape damage.
Handpick and destroy beetles
and egg masses.
Spray with neem
SPIDER MITE





Adults and immature stages appear as
tiny specks on the undersides of leaves
where they pierce the leaf surface and
suck sap.
Lightly infested leaves develop tiny
whitish speckled spots, while heavily
infested leaves turn pale yellow or
bronze-colored and dry up.
The undersurfaces of leaves usually
are covered with silken webs over
which the mites crawl.
Spider mites develop rapidly during hot,
dry weather and one generation can be
completed in as few as eight days.
Insecticidal soaps generally offer
adequate control when applied before
the numbers are too high. Mites can be
removed with a strong spray of water.
Natural enemies such as lady bugs are
important natural controls.
STINK BUG




Stink bugs feed on over 52 plants,
including native and ornamental trees,
shrubs, vines, weeds and many
cultivated crops
Nymphs and adults of both kinds of
bugs pierce plants with their needlelike
mouthparts and suck sap from pods,
buds, blossoms and seeds.
The degree of damage depends, to
some extent, on the developmental
stage of the plant when the stink bug
pierces it. Immature fruits and pods
punctured by bugs become deformed
as they develop. Seeds are often
flattened and shriveled, and
germination is reduce
Insecticides such as permethrin,
effective in controlling stink bugs.
CUCUMBER BEETLE







Harmful to cucurbits (members of
the gourd family, including
cucumbers, melons, pumpkins and
squashes), particularly young
plants.
They feed on plants as soon as they
emerge and either kill the plants or
greatly slow their growth.
Transmits bacterial wilt of
cucurbits.
Control measures include the use
of fabric row covers.
Handpicking to remove the beetles
is effective.
Eliminate weeds in and around the
garden.
Last resort apply pyrethrins
FLEA BEETLE








Adults chew numerous small,
round holes in leaves
Larvae feeds on plant roots
Most damaging to young
plants
Adults are very small (1/16
inch or so) black or dark
brown insect
Severe infestations stunt
plants and reduce yields
Apply floating row covers
Apply parasitic nematodes to
soil
Spray neem
CABBAGE LOOPER






Feeds on cabbage, broccoli &
cauliflower
Young larvae feed between veins on
the underside of the lower leaves.
Large larvae make ragged holes in the
foliage and move to the center of the
plant.
Large loopers can also burrow through
3 to 6 layers of tightly wrapped head
leaves in cabbage.
Plants can be severely defoliated and
stunted, producing no heads or
becoming unfit for consumption.
Large amounts of dark green pellets
excreted by the feeding
Bacillus thuringiensis, Bt can be used
along with row covers and diamaceous
earth
HARLEQUIN BUG




Feeds on squash, corn, bean,
asparagus, cabbage, okra,
and tomato
Adults and nymphs pierce
stalks, leaves, and veins with
their needle-like mouthparts
and extract plant juices.
Stems and leaves injured in
this manner develop irregular
cloudy spots around the
puncture wound.
Control by handpicking or
using insecticidal soap
WHITEFLY






Feeds on bean, melon, lettuce,
cucumber, tomato, squash,
potato, eggplant, strawberry
Nymphs and adults extract plant
sap through their needle-like
mouthparts, the adults
preferring to feed on tender new
growth.
Leaves turn yellow and drop
from infested plants.
Spray with insecticidal soap
Check plants bought from the
nursery
Nasturtiums & marigolds repel
them
COLORADO POTATO BEETLE





Serious pest of tomato, eggplant,
peppers & potatoes
Notorious for its ability to rapidly
develop resistance to insecticides
that are used repeatedly for control
Bacillius thuringiensis (Bt) is
effective against small larvae (less
than 1/4 inch) and should be
applied at egg hatch or when
larvae are first seen
Hand picking of adult beetles and
immature stages is encouraged
Hand picking can be particularly
effective in reducing the numbers
of overwintering beetles coming to
the young plants in the spring
Floating row covers
SQUASH BUG


Radishes, tansy, marigolds &
nasturtiums interplanted with squash
help repel
Trellising gets foliage off the ground,
reducing the moist, covered areas
they seek




Squash plants frequently are killed by
this sap-feeding pest. Leaves wilt
rapidly and become brittle.
Adults and nymphs may be found
clustered about the crown of the plant,
beneath damaged leaves, and under
clods or any other protective ground
cover.
This can be used to your advantage in
controlling these pests. Place a small,
square piece of old shingle or heavy
cardboard under each squash plant. As
bugs congregate under it for protection,
simply lift the trap and smash them
with your hoe (or shoe).
Other control methods include early
planting and removing eggs and
nymphs by hand.
SQUASH VINE BORER

Radishes interplanted helps repel
them






Damage is caused by larvae
(immature forms) tunneling into
stems. This tunneling often kills
plants
Sudden wilting of a vine and
sawdust-like insect waste coming
from holes in the stem are
evidence of attack
Till the soil in late winter to expose
overwintering insects.
Rotate squash to another location
in the garden each season.
Destroy vines that have been killed
to break the life cycle.
Cut a slit along afflicted stem and
remove the borer or inject the stem
with Bt
THE GOOD GUYS
LADY BUGS

Feed on small, soft pests
such as




Aphids
Mealybugs
Spider Mites
Purchase the larvae not
the adult
LACEWINGS

Feed on the following:







Aphids
Caterpillars
Small beetles
Leafhoppers
Thrips
Mites
and they sometimes eat
each other
PARASITIC WASPS


Injects its eggs inside
host insects
Controls the following



Aphids
Whiteflies
Caterpillars
SOLDIER BEETLE



Larvae feed on insects in
the soil
Adults feed on
caterpillars, aphids
And other soft bodied
insects
PEST & DISEASE PREVENTION

Grow strong, healthy plants that can resist attack



Plant in fertile soil



Check your garden daily
Be careful when handling plants. Do not damage the stems or leaves.
This will stress the plant and weaken them.
Plants are like humans


Plants are able to find the nutrients easily in healthy soil
Daily Vigilance


Starts in the nursery
Pest & Diseases prefer plants that are weak and injured
Never let them go short of food or water
Sanitation


Disease-causing organisms can live through the winter
Equipment used on diseased plants should be washed with a bleach solution
PREVENTION CONT’D
Rotate Crops
 Avoid Monocultures

Don’t just plant one variety in a large area.
 Diversity

Encourage Natural Predators
 Plant Resistant Varieties
 Use Barriers

Floating Row Covers
 Bird Netting

ORGANIC CHEMICALS FOR PEST CONTROL



Even though they are organic follow the instructions on the
label
Spray when bees are not active
Types:

Insecticidal Soap



Bt (bacillus thuringienses)



Potassium-salt soap
Control can only be achieved by hitting the insect
Bacteria that produces crystals & spores that paralyze the digestive
tract
Nontoxic to mammals
Neem


Broad spectrum
Nontoxic to mammals
REFERENCES




Southeastern US 2011 Vegetable Crop Handbook
www.utextension.utk.edu
http://vegetables.tennessee.edu
Organic Gardening


Bugs, Slugs, & Other Thugs


Rodales
The Organic Gardener’s Handbook of Natural Insect & Disease
Control


Rhonda Massingham Hart
All-New Encyclopedia of Organic Gardening


Geoff Hamilton
Barbara W. Ellis & Fern Marshall Bradley
Rodale’s Garden Problem Solver

Jeff Ball