Pests and Diseases

 

CUCUMBER BEETLE, SPOTTED
(Diabrotica undecimpunctata howardi)

Adult spotted cucumber beetles are one of the most serious pests on cucurbits in many areas, and can eat a wide range of plants. Their larvae, which are known as Southern corn rootworms, typically like to eat corn.
DESCRIPTION

Adults are greenish-yellow, elongated beetles 1/4 inch (6 mm) long, with 11 black spots. The larvae are slender and white, and up to 3/4 inch (2 cm) long, with brown heads and brown patches on first and last segments.

LIFE CYCLE
Adults overwinter under crop debris, and emerge in the spring to lay eggs in the soil close to plants. When eggs hatch, larvae feed in the roots and crowns of plants for 2 to 4 weeks, then pupate. They typically have one or two generations per year in cooler climates, and up to three generations in warmer climates.


PLANTS MOST AFFECTED
Corn, cucumber, peanut, potato and several other plants including many ornamentals.


DAMAGE
Larvae feed on roots, often killing young plants. Older plants are weakened and fall down easily. Adult beetles eat holes in leaves and chew on fruit skin. Larvae and adults transmit cucumber mosaic virus and bacterial wilt diseases.
MEANS OF CONTROL
Prevention:
Plant resistant cucumber, squash, and melon cultivars.
Rotate garden crops with cover crops.
Remove and destroy crop debris to get rid of overwintering sites.
Cover plants with floating row covers.
Heavy mulching can deter cucumber beetles from laying eggs in the ground near plant stems and may hinder feeding by larvae migrating to fruits
Companion plant with oregano, radish, tansy, and nasturtium
Control:NEEM OIL
Controls both fungal and bacterial infections
Over the last few years we have talked about how great neem oil is as an insecticide and mitacide, but we don't want to forget the many fungal and bacterial problems neem oil can also solve.
Neem oil is pressed from the fruits and seeds of Neem (Azadirachta indica), an evergreen tree which is native to India, and is used as a broad spectrum insecticide, miticide, and fungicide, which is used on vegetables, fruit trees, ornamentals, and more.
It is used commonly as an effective fungicide for the prevention and control of various fungal diseases including:
powdery mildew
black spot
mildew and scab
anthracnose
rust
leaf spot
botrytis
needle rust
tip blight
alternaria
It also controls bacterial diseases such as fire blight.
As a preventative: neem oil should be applied on a 7 to 14 day schedule until the potential for disease development is no longer present.
To control disease already present: apply neem oil on a 7 day schedule until disease pressure is eliminated. Then continue spraying on a 14 day schedule to prevent the disease from reoccurring.
Directions for Use:
Mix at the rate of 2 tablespoons (30 ml) per gallon (3.8 l) of water. Thoroughly mix solution and spray all plant surfaces, including the undersides of the leaves, until completely wet. Frequently shake the solution as you spray to keep it mixed.
Spot treat with botanical insecticides such as Bon-neem, an insecticidal soap with neem tree oil
Use sticky traps to monitor populations and slow feeding adults
Apply insect parasitic nematodes to soil weekly to control larvae.