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Beets - Diseases, Pests and Problems





Basic Information



Problem: Beet Leafminer
Affected Area: Leaf

Description: Small whitish maggots feed between the leaf surfaces. Damage appears as winding trails in leaf tissue. As mines enlarge, they may merge and from large, light-colored blotched areas. Feeding lasts 1 to 3 weeks. They may pupate in the leaf or in the soil and 1/4" long, gray, flies emerge in 2 to 4 weeks. Control: Remove and dispose of infested leaves. Floating row covers may screen out the fly. Control host weeds like lambs quarter to reduce local populations.

Control: Remove and dispose of infested leaves. Floating row covers may screen out the fly. Control host weeds like lambs quarter to reduce local populations.


Problem: Leaf Hoppers
Affected Area: Leaf

Description: Yellowish green, wedge shaped, winged adults and their nymphs feed on plant foliage by piercing leaves and sucking on sap. On severe infestations, leaves may become crinkled and curled. They also spread virus diseases.

Control: Control weed patches where pests may hide. Sprays are not generally useful for light populations. * Malathion, Diazinon, and Sevin may offer some control. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Flea Beetle
Affected Area: Leaf

Description: Small 1/16 ? brown jumping beetle. Causes leaves to have a ?shot-hole? appearance.

Control: * Sevin, Diazinon or Rotenone are effective. Spray early for best control. Allow 3 days between sevin application and harvest for root consumption. Allow 14 days between sevin application and harvest for leaf consumption. Allow 1 day between rotenone application and harvest. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Aphids
Affected Area: Leaf

Description: Small green, red, black or white sucking insects less than 3/16" long. Aphids live by sucking plant fluids which causes curled or twisted, yellow leaves. Leaves generally become sticky from the honeydew substance they excrete.

Control: With time, aphids may be controlled by predator insects such as ladybugs and lace wings. Treat with Insecticidal soaps or a strong stream of water. * Sevin, diazinon, malathion, and rotenone are also effective. Allow 3 days between sevin application and harvest for root consumption. Allow 14 days between sevin application and harvest for leaf consumption. Allow 1 day between rotenone application and harvest. Allow 14 days between diazinon application and harvest. * Pesticide use and recommendations for various areas are constantly changing. Check with your County agent for current recommendations.


Problem: Damping Off
Affected Area: Seedling

Description: Seedlings develop blackened stems, wilt and die

Control: Rotate crop location each year. Use treated seeds.


Problem: Curly Top
Affected Area: Leaf and Root

Description: Young plants die quickly. Young leaves roll inward, pucker, develop blister-like thickenings, veins appear clear and swell, then wilt. The tap root is covered with many fine rootlets.

Control: Leafhoppers spread the curly top virus. Remove infected plants and control weeds which harbor leaf-hopper. Crops planted and harvested early often escape leaf-hopper flights.


Problem: Alternaria Leaf Spot
Affected Area: Leaf

Description: This disease is characterized by lesions that develop on the leaves and are circular to irregularly shaped, dark brown to black, frequently zonate, and may be covered by fungal growth and conidia.

Control: Experts find that it is not necessary to have control measures.


Problem: Aphid
Affected Area: Leaf and Crown Feeders

Description: The aphids damage sugar beet by sucking plant sap, retarding growth and causing the leaves to turn yellow. Both the bean aphid and the green peach aphid have many natural enemies, such as lady beetles, lacewings, syrphid larvae, predacious hemipterans, and braconid parasites.

Control: The best form of control is to apply insecticides in areas of heavy infestation.


Problem: Armyworms
Affected Area: Leaf and Crown

Description: Plants infected with armyworms are damaged by feeding by larvae, mostly at night and much of the foliage is destroyed in a very short time due to caterpillar consumption.

Control: The best form of control is to apply insecticides where available and plow and disk deep to reduce the damage to the sugar beet.


Problem: Beet Leafhopper
Affected Area: Leaf and Crown

Description: The severity of the damage to sugar beet from the virus infection depends on the size and proportion of the leafhopper population carrying the virus from its winter breeding sites.

Control: The best form of control is to apply insecticides.


Problem: Beet Mosaic
Affected Area: Leaf

Description: This disease is characterized by yellow spots that develop on young leaves and are circular with sharply defined margins. These spots often appear as yellow rings with green centers.

Control: The best form of control is to avoid planting in infested fields or fields where wild varieties of beets have been grown.


Problem: Beet Petiole Borer
Affected Area: Leaf and Crown

Description: Plants infected with the beet petiole borer have punctured petioles and leaf veins. Warty growths develop at the site of many of these punctures, which often turn darker than the surrounding area.

Control: There are no control measures available.


Problem: Beet Western Yellows
Affected Area: Leaf

Description: This disease is characterized by mild yellow spotting of interveinal areas, most often at the leaf tips on older plants. As the disease progresses, the yellowing becomes more intense, and more of the interveinal tissue turns yellow. Older infected leaves become thickened, brittle, and almost completely yellow except for green areas adjacent to the veins.

Control: The best form of control is to use resistant cultivars where available and separate new plantings from infected crops by as much space and time as possible.


Problem: Beet Yellow Net
Affected Area: Leaf

Description: This disease is characterized by one to several scattered yellow spots on a leaf blade and uniform yellowing of veins and veinlets occurs.

Control: There are no control measures available at this time.


Problem: Beet Yellow Stunt
Affected Area: Leaf and Petioles

Description: This disease is characterized by severe twisting, cupping, and increased leaf growth of one or two leaves of intermediate age. Petioles are shortened and the leaves become spotted and yellow with the youngest leaves becoming dwarfed, malformed, twisted, and slightly spotted.

Control: The best form of control is to avoid planting in clean fields and those free from large areas of weeds.


Problem: Beet Yellow Vein
Affected Area: Leaf and Growth

Description: This disease is characterized by dwarfing and vein yellowing of young leaves of infected plants causing the main vein to turn yellow. Dwarfing usually occurs on only one side of the plant, causing a stunted, asymmetric growth pattern.

Control: There are no control measures available at this time.


Problem: Black Root
Affected Area: Root

Description: This disease is characterized by plants that show yellowing and wilting of foliage and unthrifty top growth. Lateral rootlets are produced in abundance, many appearing shriveled, black, and dry.

Control: The best forms of control include using resistant cultivars where available, rotating crops with something other than sugar beet, maintaining well-drained soil, and controlling weed hosts.


Problem: Blister Beetles
Affected Area: Leaf and Crown

Description: The adult beetles injure sugar beet by feeding on the leaves leaving only the petiole portions of the plant.

Control: Parathion is the only control measure, where it is available.


Problem: Carrion Beetles
Affected Area: Leaf and Crown

Description: Carrion beetles typically eat the edges of leaves, leaving numerous projections around the leaves. The adults cause some damage to sugar beet, but heavier damage is done by the larvae at thinning time, usually along the edges of beet fields.

Control: Destroying weed hosts along ditches, fence rows, and roadsides where carrion beetles overwinter helps to reduce the insect populations.


Problem: Cercospora Leaf Spot
Affected Area: Leaf

Description: This disease is characterized by spots that develop on the leaves that are nearly circular and are tan to light brown with dark brown to reddish purple borders. Blighted leaves soon collapse and fall to the ground but remain attached to the crown. The heart leaves remain green and are less severely affected or lesion-free.

Control: The best forms of control are to use resistant cultivars, a two to three year rotation with nonhosts, and clean plowing practices to turn under crop residues.


Problem: Crusting
Affected Area: Seedlings

Description: In crusted soil, seedlings fail to emerge, or they grow parallel to the soil surface below the crust and emerge through cracks or cause upheavals of soil plates.

Control: NA


Problem: Cutworms
Affected Area: Leaf and Crown

Description: The most severe damage to sugar beet is caused in the spring by first generation cutworms, which typically cut plants at or just below the soil surface.

Control: The best form of control is to apply insecticides and exercise certain cultural practices, such as spring plowing and disking, to help reduce damage to the sugar beet.


Problem: Dodder
Affected Area: Entire Plant

Description: Dodder is a parasitic plant with slender, threadlike, leafless, yellowish or orange stems. Dodder spreads from plant to plant if not controlled.

Control: The infection center should be burned or controlled by chemicals and seed of the parasite should not be allowed to be produced there.


Problem: Downy Mildew
Affected Area: Leaf

Description: The fungus attacks young heart leaves of the crown and creates small, distorted, light green, thickened, puckered leaves with downward-curled margins.

Control: The best form of control is the use of resistant cultivars and allowing a beet-free period before planting the next crop.


Problem: Empoasca Leafhoppers
Affected Area: Leaf and Crown

Description: Large populations can cause hopperburn, speckling, and yellowing of affected leaves.

Control: The best form of control is to apply insecticides.


Problem: False Chinch Bug
Affected Area: Leaf and Crown

Description: The false chinch bug tends to congregate in large numbers, and its feeding desiccates and kills the beet. The insect damages both leaves and seedstalks but rarely causes economic losses in sugar beets.

Control: No insecticide is registered for control of this insect.


Problem: Flea Beetles
Affected Area: Leaf and Crown

Description: Damage to leaves is caused by adults, which eat numerous small holes in the leaves.

Control: The best form of control is to apply insecticides and eliminate field bindweed and wild mustard since they are two of the preferred weed hosts of flea beetles.


Problem: Freezing Damage
Affected Area: Seedlings

Description: Aboveground frost damage in seedlings, causing plant parts to be dry, may resemble damping-off. The primary difference is that below the frost line the roots of frost-damaged plants appear healthy, whereas damping-off plants are diseased belowground.

Control: NA


Problem: Fusarium Yellows
Affected Area: Root

Description: The older leaves show yellowing between the larger veins and become dry, brittle, and heaped around the crown.

Control: The best form of control is rotation with other crops for a few years.


Problem: Garden Symphylan
Affected Area: Roots

Description: The garden symphylan damages sugar beet by feeding on germinating seed and on taproots and feeder roots of young and old plants.

Control: Soil fumigation with 1,3-dichloropropene helps to control it and restores land to full productivity for several years.


Problem: Grasshoppers
Affected Area: Leaf and Crown

Description: The insects feed on sugar beet leaves and in heavy infestations they will attack the leaf petioles late in the season. Certain cultural practices, such as plowing, disking, and harrowing, can destroy grasshopper eggs in the soil and reduce the population of the insects.

Control: Insecticides available for control of grasshoppers on sugar beet are diazinon, malathion, parathion, and carbaryl.


Problem: Hail Damage
Affected Area: Entire Plant

Description: Hail may cause moderate damage, perforating or tearing sugar beet leaves, in a storm of short duration. However, complete defoliation may occur in a hailstorm that continues for a long time.

Control: NA


Problem: Lettuce Infectious Yellows
Affected Area: Leaf

Description: Interveinal yellowing or reddening and stunting of affected plants are characteristic of lettuce infectious yellows on a wide range of commercial and weed hosts. The early symptom is very mild spotting, which develops into interveinal yellowing.

Control: The best forms of control include reducing whitefly populations, avoid planting in infected areas, destroy infected plantings of cucurbits and lettuce immediately after harvest, and weed control in crops and in nearby fields.


Problem: Lygus Bugs
Affected Area: Leaf and Crown

Description: On sugar beet grown for roots, Lygus bugs cause injuries by puncturing leaf surfaces with their beaks and sucking plant juice from new succulent leaves. Affected areas turn yellow to brown, and occasionally all beet plants in a field have discolored leaf tips. Injured plants wilt more easily than healthy ones do. The destruction of all overwintering sites along the banks of ditches, fence rows, and roadsides helps to reduce populations of Lygus bugs and the damage they cause.

Control: Parathion is the only insecticide approved for control of these insects on sugar beet.


Problem: Magnesium Deficiency
Affected Area: Entire Plant

Description: Plants suffering from magnesium deficiency become yellow and interveinal tissue becomes scorched. Dry spots form within the scorched areas and gradually expand to include most of the interveinal tissue except for a green triangular area, in the shape of an arrowhead.

Control: NA


Problem: Manganese Deficiency
Affected Area: Leaf

Description: As the severity of the symptoms increases, leaf blades of manganese-deficient plants gradually fade from green to a uniform yellow. As manganese deficiency increases, a gray, metallic, sometimes purplish luster develops on the upper blade surface. This symptom is followed by gray to black freckling along the veins.

Control: NA


Problem: Molybdenum Deficiency
Affected Area: Leaf

Description: Symptoms of molybdenum deficiency first appear as a general yellowing. The center leaves are light green to yellow and as the symptoms increase in severity, pitting develops along leaf veins.

Control: NA


Problem: Nitrogen Deficiency
Affected Area: Leaf

Description: Overall yellowing of leaves occurs when a plant first becomes nitrogen-deficient. With nitrate depletion, these leaves become light green, turning yellow. Yellowing continues as the plant ages, accompanied by wilting and an accelerated death rate of the older leaves. Newly formed leaves in the center of the plant are much smaller and narrower than older leaves and turn an intense green.

Control: NA


Problem: Pale-Stripped Flea Beetle
Affected Area: Root

Description: The damage to roots often resembles the injury caused by black root. If possible, sugar beet should not be planted in fields that were heavily infested with the adult beetles and larvae during the previous year.

Control: Most insecticides used to control the sugar beet root maggot are also effective against larvae of the pale-stripped flea beetle.


Problem: Phoma Leaf Spot
Affected Area: Leaf

Description: Individual leaf spots are usually light brown and round to oval and have dark, concentric rings near the perimeter. Small, spherical, black pycnidia develop in the dark rings, and conidia are produced within the pycnidia.

Control: A four-year rotation with crops other than hosts and fungicide seed treatment are the only recommended controls.


Problem: Phosphorus Deficiency
Affected Area: Leaf and Growth

Description: Phosphorus deficiency is by far the most difficult deficiency to recognize. An overall stunting of the plant and a gradual deepening of the green color of foliage are the only visible symptoms. As the deficiency becomes more severe, the deep green color often assumes a metallic luster, ranging from dull grayish green to almost bluish green.

Control: NA


Problem: Powdery Mildew
Affected Area: Leaf

Description: When field-grown sugar beet plants are two to six months old, mildew first appears as small, disperse, radiating, whitish mats of hyphae and conidia on older, lower leaves. The underlying leaf tissue may become yellowed, then purplish brown, and a field of heavily infected plants may take on a bluish cast.

Control: The best form of control is to use fungicides.


Problem: Ramularia Leaf Spot
Affected Area: Leaf

Description: Typical leaf spots are light brown, large and angular. Mature lesions may have a dark brown to reddish brown margin, and the dry centers of the leaf spots become silvery gray to white when the fungus sporulates.

Control: There are no control measures because of its minor importance.


Problem: Rhizoctonia
Affected Area: Leaf

Description: The fungus commonly attacks heart leaves of sugar beet causing them to become stubs of petiole with malformed portions of leaf blades and blackened fragments of diseased tissue. Shallow, brown to black cankers occur on petioles.

Control: A four to five year rotation of sugar beet with corn or small grains is the only recommended control.


Problem: Rhizoctonia Root and Crown Rot
Affected Area: Root

Description: The first aboveground symptoms are sudden wilting, yellowing of foliage and black drying of petioles near the crown. Wilted leaves subsequently collapse and die, forming a dry, brown or black rosette, which persists through the growing season. On the root surface, infected areas are dark brown to black.

Control: The best forms of control include tilling and fertilizing that promote good crop growth and adequate soil drainage, crop rotation with corn or small grains, avoidance of hilling-up of plants with cultivated soil, and control of weed hosts, such as pigweed.


Problem: Rodents
Affected Area: NA

Description: NA

Control: The use of bait has been effective for the control of some rodents.


Problem: Salt Injury
Affected Area: Entire Plant

Description: Injury may occur in arid and semiarid regions where silts accumulate in the root zone of sensitive plants, including sugar beet. If such accumulation occurs, plants are stunted, fail to emerge, or die. Salt accumulation on the soil surface or in the root zone also interferes with nutrient uptake, water absorption, and photosynthesis. Seedlings are more sensitive to salt damage than are older plants.

Control: NA


Problem: Seedling Diseases
Affected Area: Seed and Seedlings

Description: Infection primarily causes preemergence damping-off. Postemergence damping-off may follow under moist conditions. Pythium aphanidermatum attacks seedlings only in warm soils with abundant soil moisture. Rhizoctonia inflicts most of its damage on emerged seedlings and infection is initiated below the soil surface extending up the hypocotyl, with a sharp margin between infected and healthy tissue. A. cochlioides causes very little preemergence damping-off, but soon after emergence the fungus invades the cortex of the hypocotyl, causing a brown discoloration, which may extend up to the base of the cotyledons. Severely infected seedlings seldom produce normal mature plants, and yields are strikingly reduced. Phoma betae. After seedlings emerge, severe infection of the hypocotyl may appear, resulting in retarded growth and a dark brown discoloration.

Control: The severity of damping-off can be minimized by shallow planting of seed and by managing soil moisture, where possible, to encourage rapid emergence.


Problem: Spinach Leaf Miner
Affected Area: Leaf and Crown

Description: The spinach leaf miner feeds inside leaves making slender, winding mines, which become enlarged and form blotches as the maggots grow. Destruction of alternate hosts, such as lambsquarters, reduces infestations of the spinach leaf miner on sugar beet.

Control: Insecticides approved for control of this pest are diazinon, trichlorfon, parathion, aldicarb, and phorate.


Problem: Stem and Bulb Nematodes
Affected Area: Roots and Crown

Description: This disease is characterized by swelling of most plant parts in young seedlings. These plants will be severely stunted and develop a multiple crowned appearance. Infected scars may encourage crown canker and girdling at the crown.

Control: The best forms of control include rotating crops and using good sanitary practices.


Problem: Sulfur Deficiency
Affected Area: Leaf

Description: Leaves of entire plants change gradually from green to light green, then to light yellow with a faint tinge of green remaining. The new center leaves of sulfur-deficient plants become light green to almost yellow. The leaves of sulfur-deficient plants remain erect as their center leaves change from green to yellow and the petioles and blades are brittle and break readily if compressed by the hand.

Control: NA


Problem: Sweet-Potato Whitefly
Affected Area: Leaf and Crown

Description: Plants infected with sweet-potato whitefly have the sap sucked out from the undersides of the leaves. In addition, the insect transmits lettuce infectious yellows virus, which causes yellowing and stunting of infected plants and thus reduces yields.

Control: There are no control measures available at this time.


Problem: Verticillium Wilt
Affected Area: Root

Description: Initially, foliage turns straw-colored and the outer leaves wilt and become dry with the inner leaves becoming twisted and deformed.

Control: Rotation with crops other than sugar beet has been recommended as a means of preventing a buildup in the soil of strains that attack sugar beet.


Problem: Webworms
Affected Area: Leaf and Crown

Description: Webworm larvae, moving rapidly up and down and forward and backward, spin webs over beet leaves, usually near the leaf base. They consume leaves at such speed that they can completely defoliate a beet field in a very short time. Weed control is extremely important, since webworms prefer weedy fields and deposit eggs on such weeds as lambsquarters and Russian thistle.

Control: Some insecticide control is available.


Problem: White Grubs
Affected Area: Root

Description: White grubs damage sugar beet by chewing off small roots and eating into large roots. Taproots are often severed so that plants wilt and eventually die.

Control: Sugar beet and other crops that are susceptible to white grubs should not be planted in fields that were previously planted with sod.


Problem: Wireworms
Affected Area: Root

Description: Wireworms damage sugar beet by feeding on seed and seedlings, chewing off small roots, and tunneling through large roots.

Control: Certain cultural practices, such as crop rotation and deep plowing of infested fields, help to reduce the wireworm population. Diazinon and fonofos are currently approved for control of these pests.


Problem: Yellow Wilt Leafhopper
Affected Area: Leaf and Crown

Description: The yellow wilt organism causes more severe damage to sugar beet than the yellowing produced by the insect's feeding. A wide range of symptoms may be produced, from stunting and yellowing to wilting and rapid collapse of plants.

Control: The best forms of control include using resistant cultivars, applying insecticides, and avoid planting in infested areas.






Beets

Tips

Plant 1/4" deep and cover with compost, sand or vermiculite if soil caking is a problem.

 

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