Pests and diseases

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 Favorable Conditions Warm, wet weather of late spring & early fall Management Practices Rotate Crops Remove and destroy plants Replace soil surrounding plant Bacterial wilt

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 • Eat flowers • Skeletonize leaves of a broad range of plants • Larvae • 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 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

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, quick-maturing 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 • Bacilliusthuringiensis (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

Grow strong, healthy plants that can resist attack • Starts in the nursery • Pest & Diseases prefer plants that are weak and injured • Plant in fertile soil • Plants are able to find the nutrients easily in healthy soil • Daily Vigilance • 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 • 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 Pest & Disease prevention

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 Prevention Cont’d

Even though they are organic follow the instructions on the label • Spray when bees are not active • Types: • Insecticidal Soap • Potassium-salt soap • Control can only be achieved by hitting the insect • Bt (bacillus thuringienses) • Bacteria that produces crystals & spores that paralyze the digestive tract • Nontoxic to mammals • Neem • Broad spectrum • Nontoxic to mammals Organic chemicals for Pest control

Southeastern US 2011 Vegetable Crop Handbook • www.utextension.utk.edu • http://vegetables.tennessee.edu • Organic Gardening • Geoff Hamilton • Bugs, Slugs, & Other Thugs • Rhonda Massingham Hart • All-New Encyclopedia of Organic Gardening • Rodales • The Organic Gardener’s Handbook of Natural Insect & Disease Control • Barbara W. Ellis & Fern Marshall Bradley • Rodale’s Garden Problem Solver • Jeff Ball References

Pests and diseases