Beets:Diagnostics

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BEET PESTS AND NUTRITIONAL DISORDERS


Contents

ALTERNARIA LEAF SPOT (ALTERNARIA ALTERNATA)

‘‘‘Alternaria Leaf Spot (Alternaria alternata) ‘‘‘ 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. Experts find that it is not necessary to have control measures. (Leaf Disease Caused by Fungi)


APHIDS

‘‘‘Aphids: ‘‘‘ 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. The best form of control is to apply insecticides in areas of heavy infestation. (Insects and Arthropods -- Leaf and Crown Feeders)


ARMYWORMS

‘‘‘Armyworms: ‘‘‘ 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. The best form of control is to apply insecticides where available and plow and disk deep to reduce the damage to the sugar beet. (Insects and Arthropods -- Leaf and Crown Feeders)


BACTERIAL LEAF SPOT (PSEUDOMONAS SYRINGAE)

‘‘‘Bacterial Leaf Spot (Pseudomonas syringae) ‘‘‘ The symptoms of bacterial leaf spot are dark brown to black streaks and spots on leaf blades and occasionally on petioles and seedstalks. The best form of control is it plant pathogen-free seed. (Disease Caused by Bacteria and Bacterialike Organisms)


BACTERIAL VASCULAR NECROSIS AND ROT (ERWINIA CAROTOVORA PV BETAVASCULORUM)

‘‘‘Bacterial Vascular Necrosis and Rot (Erwinia carotovora pv betavasculorum) ‘‘‘ This disease is characterized by inconsistent dark, black streaks running up petioles, froth in the centers of crowns, and wilt if the roots becomes severely affected. Some severely infected plants do not die from the disease, but their roots become hollowed-out cavities. The best form of control is the use of resistant cultivars. (Disease Caused by Bacteria and Bacterialike Organisms)


BEET CURLY TOP (BCTV)

‘‘‘Beet Curly Top (BCTV) ‘‘‘ This disease is characterized by leaves that are dwarfed, crinkled, and rolled upward and inward. The roots are also affected and are dwarfed, with twisted and distorted rootlets. Dark areas of dry tissue can usually be observed in root sections of diseased plants. The best form of control is to use resistant cultivars and to practice good cultural controls. (Disease Caused by Viruses and Viruslike Entities)


BEET LATENT ROSETTE

‘‘‘Beet Latent Rosette: ‘‘‘ This disease is characterized by leaf twisting, turning down of leaf tips, and yellowing of young leaves. There are no control measures available. (Disease Caused by Bacteria and Bacterialike Organisms)


BEET LEAF CURL (BLCV)

‘‘‘Beet Leaf Curl (BLCV) ‘‘‘ This disease is characterized by veinclearing of the youngest leaves and crinkled, dwarfed inwardly curled older leaves. All parts of the plant are significantly stunted. The best form of control is to plant away from infected areas and to apply chemical treatments. (Disease Caused by Viruses and Viruslike Entities)


BEET LEAFHOPPER (CIRCULIFER TENELLUS)

‘‘‘Beet Leafhopper (Circulifer tenellus) ‘‘‘ 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. The best form of control is to apply insecticides. (Insects and Arthropods -- Leaf and Crown Feeders)


BEET MOSAIC (BMV)

‘‘‘Beet Mosaic (BMV) ‘‘‘ 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. The best form of control is to avoid planting in infested fields or fields where wild varieties of beets have been grown. (Disease Caused by Viruses and Viruslike Entities)


BEET NECROTIC YELLOW VEIN OR RHIZOMANIA (BNYVV)

‘‘‘Rhizomania (Beet Necrotic Yellow Vein) (BNYVV) ‘‘‘ The symptoms of rhizomania are root stunting and proliferation of lateral rootlets on the main taproot, giving it a bearded look. Leaves can be mildly yellowed and have an upright posture. Leaves may also become flabby and wilt without discoloration. Efforts should be made to prevent the spread of the pathogen to other beet fields and growing areas. (Disease Caused by Viruses and Viruslike Entities)


BEET PETIOLE BORER (COSMOBARIS AMERICANA)

‘‘‘Beet Petiole Borer (Cosmobaris americana) ‘‘‘ 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. There are no control measures available. (Insects and Arthropods -- Leaf and Crown Feeders)


BEET RUST AND SEEDLING RUST (UROMYCES BETAE AND PUCCINIA SUBNITENS)

‘‘‘Beet Rust and Seedling Rust (Uromyces betae and Puccinia subnitens) ‘‘‘ Beet rust develops on seedstalks, petioles, and both leaf surfaces as slightly raised, circular pustules, randomly dispersed or aggregated in rings and usually surrounded by a yellow halo. As urediospores form within the pustules, the host epidermis ruptures to reveal the reddish brown spore masses. Seedling rust generally occurs only on the lower surface of cotyledons and occasionally on the first true leaves of sugar beet seedlings as bright yellowish orange aecial pustules aggregated in rings. Most sugar beet cultivars developed for the coastal valleys of the Pacific coast are resistant and no other control measures are available because of its lack of economic importance. (Leaf Disease Caused by Fungi)


BEET SAVOY

‘‘‘Beet Savoy: ‘‘‘ This disease is characterized by veinlet clearing, vein thickening and growth retardation, which gives the lower leaf surface a netted appearance. The leaves are dwarfed and curled downward at the edges. The best form of control is to eliminate the vector or its hosts near beet fields. (Disease Caused by Viruses and Viruslike Entities)


BEET TUMOR, OR CROWN WART (UROPHLYCTIS LEPROIDES)

‘‘‘Beet Tumor, or Crown Wart (Urophlyctis leproides) ‘‘‘ Galls on leaf blades and petioles are greenish brown and rough. Affected leaves are stunted and malformed. Galls also occur on beet crowns but do not form on taproots. No control measures have been developed for beet tumor. (Leaf Disease Caused by Fungi)


BEET WESTERN YELLOWS (BWYV)

‘‘‘Beet Western Yellows (BWYV) ‘‘‘ 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. 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. (Disease Caused by Viruses and Viruslike Entities)


BEET YELLOW NET (BYN)

‘‘‘Beet Yellow Net (BYN) ‘‘‘ This disease is characterized by one to several scattered yellow spots on a leaf blade and uniform yellowing of veins and veinlets occurs. There are no control measures available at this time. (Disease Caused by Viruses and Viruslike Entities)


BEET YELLOW STUNT (BYSV)

‘‘‘Beet Yellow Stunt (BYSV) ‘‘‘ 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. The best form of control is to avoid planting in clean fields and those free from large areas of weeds. (Disease Caused by Viruses and Viruslike Entities)


BEET YELLOW VEIN

‘‘‘Beet Yellow Vein: ‘‘‘ 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. There are no control measures available at this time. (Disease Caused by Viruses and Viruslike Entities)


BEET YELLOWS (BYV)

‘‘‘Beet Yellows (BYV) ‘‘‘ This disease is characterized by veinclearing that may be very bright yellow or have a dry appearance. The best form of control is to plant in clean fields that do not have any wild varieties growing. (Disease Caused by Viruses and Viruslike Entities)


BLACK ROOT (APHANOMYCES COCHLIOIDES)

‘‘‘Black Root (Aphanomyces cochlioides) ‘‘‘ 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. 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. (Root Diseases Caused by Fungi)


BLISTER BEETLES (EPICAUTA SPP)

‘‘‘Blister Beetles (Epicauta spp.) ‘‘‘ The adult beetles injure sugar beet by feeding on the leaves leaving only the petiole portions of the plant. Parathion is the only control measure, where it is available. (Insects and Arthropods -- Leaf and Crown Feeders)


BORON DEFICIENCY

‘‘‘Boron Deficiency: ‘‘‘ Plants suffering from boron deficiency exhibit a white, netted chapping of the upper surface of leaf blades, wilted tops, crinkling leaf blades, and darkening and cracking of petioles. (Nutritional Disorder)


CALCIUM DEFICIENCY

‘‘‘Growing-Point Damage: ‘‘‘ Plants suffering from calcium deficiency have crinkled and downward cupped of young leaf blades. As these leaves develop, the blades crinkle and fail to develop to full size. (Nutritional Disorder)


CARRION BEETLES (SILPHA BITUBEROSA)

‘‘‘Carrion Beetles (Silpha bituberosa) ‘‘‘ 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. Destroying weed hosts along ditches, fence rows, and roadsides where carrion beetles overwinter helps to reduce the insect populations. (Insects and Arthropods -- Leaf and Crown Feeders)


CERCOSPORA LEAF SPOT (CERCOSPORA BETICOLA)

‘‘‘Cercospora Leaf Spot (Cercospora beticola) ‘‘‘ 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. 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. (Leaf Disease Caused by Fungi)


CHARCOAL ROT (MACROPHOMINA PHASEOLINA)

‘‘‘Charcoal Rot (Macrophomina phaseolina) ‘‘‘ Initially, infection is indicated by pronounced wilting of the foliage, which turns brown and dies. Brownish black, irregular lesions appear externally in the crown region and later rupture to expose masses of charcoal-colored sclerotia. There are no control measures available. (Root Diseases Caused by Fungi)


CHLORINE DEFICIENCY

‘‘‘Chlorine Deficiency: ‘‘‘ Plants suffering from chlorine deficiency have yellow blades of the younger leaves near the center of the plant. The interveinal areas of the leaf blades become light green to yellow while the main veins remain green and become raised. (Nutritional Disorder)


CLOVER CYST NEMATODE (HETERODERA TRIFOLII)

‘‘‘Clover Cyst Nematode (Heterodera trifolii) ‘‘‘ Symptoms include loss of resistance, uneven growth, yellowing of outer leaves, and severe wilting. Infected beets lack well-formed storage roots, have branched root systems, and excessive fibrous root growth. The best form of control is rotation of sugar beet with nonhost crops. (Nematode Parasites)


COPPER DEFICIENCY

‘‘‘Copper Deficiency: ‘‘‘ Plants suffering from copper deficiency develop mild yellowing of the young, center leaves and only a small amount of copper is required for growth. (Nutritional Disorder)


CRUSTING

‘‘‘Crusting: ‘‘‘ 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. (Environmental Disorders)


CUCUMBER MOSAIC (CMV)

‘‘‘Cucumber Mosaic (CMV) ‘‘‘ Leaves of young plants appear spotted, with yellow spots of various shapes and sizes. As the disease progresses, spotting continues, and leaves may be dwarfed and distorted, developing green blisters. The best form of control is to eliminate weeds in the area planted with sugar beets. (Disease Caused by Viruses and Viruslike Entities)


CUTWORMS

‘‘‘Cutworms: ‘‘‘ 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. 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. (Insects and Arthropods -- Leaf and Crown Feeders)


DODDER (CUSCUTA SPP)

‘‘‘Dodder (Cuscuta spp.) ‘‘‘ Dodder is a parasitic plant with slender, threadlike, leafless, yellowish or orange stems. Dodder spreads from plant to plant if not controlled. The infection center should be burned or controlled by chemicals and seed of the parasite should not be allowed to be produced there. (Dodder)


DOWNY MILDEW (PERONOSPORA FARINOSA PV BETAE)

‘‘‘Downy Mildew (Peronospora farinosa pv betae) ‘‘‘ The fungus attacks young heart leaves of the crown and creates small, distorted, light green, thickened, puckered leaves with downward-curled margins. The best form of control is the use of resistant cultivars and allowing a beet-free period before planting the next crop. (Leaf Disease Caused by Fungi)


DROUGHT

‘‘‘Drought: ‘‘‘ Drought occurs when plants are unable to extract water from the soil as rapidly as it is lost by transpiration. If the condition is temporary, only wilting occurs. If the condition persists, older leaves die prematurely and turn brown. In irrigated areas of beet production, water should be applied when the soil becomes too dry. (Environmental Disorders)


EMPOASCA LEAFHOPPERS (EMPOASCA SPP)

‘‘‘Empoasca Leafhoppers (Empoasca spp.) ‘‘‘ Large populations can cause hopperburn, speckling, and yellowing of affected leaves. The best form of control is to apply insecticides. (Insects and Arthropods -- Leaf and Crown Feeders)


FALSE CHINCH BUG (NYSIUS ERICAE)

‘‘‘False Chinch Bug (Nysius ericae) ‘‘‘ 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. No insecticide is registered for control of this insect. (Insects and Arthropods -- Leaf and Crown Feeders)


FALSE ROOT-KNOT NEMATODES (NACOBBUS ABERRANS)

‘‘‘False Root-Knot Nematodes (Nacobbus aberrans) ‘‘‘ Developing nematodes usually invade the cortical tissue of sugar beet, creating large cavities that extend into the stele. They frequently feed on root hairs as well as fibrous and storage roots. (Nematode Parasites)


FLEA BEETLES

‘‘‘Flea Beetles: ‘‘‘ Damage to leaves is caused by adults which eat numerous small holes in the leaves. 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. (Insects and Arthropods -- Leaf and Crown Feeders)


FREEZING DAMAGE

‘‘‘Freezing Damage: ‘‘‘ 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. (Environmental Disorders)


FUSARIUM YELLOWS (FUSARIUM OXYSPORUM PV BETAE)

‘‘‘Fusarium Yellows (Fusarium oxysporum pv betae) ‘‘‘ The older leaves show yellowing between the larger veins and become dry, brittle, and heaped around the crown. The best form of control is rotation with other crops for a few years. (Root Diseases Caused by Fungi)


GARDEN SYMPHYLAN (SCUTIGERELLA IMMACULATA)

‘‘‘Garden Symphylan (Scutigerella immaculata) ‘‘‘ The garden symphylan damages sugar beet by feeding on germinating seed and on taproots and feeder roots of young and old plants. Soil fumigation with 1,3-dichloropropene helps to control it and restores land to full productivity for several years. (Insects and Arthropods -- Root Feeders)


GENETIC DISORDERS

‘‘‘Genetic Disorders: ‘‘‘ Genetic aberrations or anomalies occurring in beet include chimeras and leaf spotting or yellowing. Neither causes any great harm.


GRASSHOPPERS (MELANOPLUS SPP)

‘‘‘Grasshoppers (Melanoplus spp.) ‘‘‘ 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. Insecticides available for control of grasshoppers on sugar beet are diazinon, malathion, parathion, and carbaryl. (Insects and Arthropods -- Leaf and Crown Feeders)


HAIL DAMAGE

‘‘‘Hail Damage: ‘‘‘ 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. (Environmental Disorders)


HERBICIDE SOIL RESIDUES

‘‘‘Herbicide Soil Residues: ‘‘‘ The growth and development of sugar beet plants can be retarded, or the plants can be killed, by carryover soil residues. Early symptoms of atrazine injury are slight yellowing and browning of leaf tips. (Herbicide Damage)


IRON DEFICIENCY

‘‘‘Iron Deficiency: ‘‘‘ The younger leaves change from green to light green and finally to a uniform light yellow. The veins remain green at first, but later they become bleached. As the symptoms progress in new leaves, older leaves are also gradually affected by the same pattern of yellowing. (Nutritional Disorder)


LEAF AND STEM ABNORMALITIES

‘‘‘Leaf and Stem Abnormalities: ‘‘‘ Increased leaf growth, twisting, bending, and curling of stems is a common symptom of injury from auxinic herbicides. Photosynthesis-inhibiting herbicides can cause yellowing followed by drying of sugar beet leaves. (Herbicide Damage)


LETTUCE INFECTIOUS YELLOWS (LIYV)

‘‘‘Lettuce Infectious Yellows (LIYV) ‘‘‘ 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. 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. (Disease Caused by Viruses and Viruslike Entities)


LIGHTNING

‘‘‘Lightning: ‘‘‘ Death of plants usually occurs in a circular pattern around the site of a lightning strike with the severity of the damage being greatest at the center and decreases as the distance from the center increases. (Environmental Disorders)


LYGUS BUGS (LYGUS SPP)

‘‘‘Lygus Bugs (Lygus spp.) ‘‘‘ 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. Parathion is the only insecticide approved for control of these insects on sugar beet. (Insects and Arthropods -- Leaf and Crown Feeders)


MAGNESIUM DEFICIENCY

‘‘‘Magnesium Deficiency: ‘‘‘ 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. (Nutritional Disorder)


MANGANESE DEFICIENCY

‘‘‘Manganese Deficiency: ‘‘‘ 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. (Nutritional Disorder)


MOLYBDENUM DEFICIENCY

‘‘‘Molybdenum Deficiency: ‘‘‘ 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. (Nutritional Disorder)


NEMATODE PARASITES OF SUGAR BEET (HETERODERA SCHACHTII)

‘‘‘Nematode Parasites of Sugar Beet (Heterodera schachtii) ‘‘‘ Plants infected with nematode parasites may cause seedlings to have a delayed emergence, be killed before they emerge, or plants may die after emergence from direct attack by the nematode or from pathogenic soil fungi. Leaves of affected plants may remain green or have pronounced yellowing, depending on the severity of the attack. Affected plants usually have underdeveloped storage roots and excessive formation of fibrous roots, which may have slight swellings with localized lesions at sites of penetration by the nematode. The best form of control is rotation of sugar beet with nonhost crops. (Nematode Parasites)


NITROGEN DEFICIENCY

‘‘‘Nitrogen Deficiency: ‘‘‘ 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. (Nutritional Disorder)


PALE-STRIPPED FLEA BEETLE (SYSTENA BLANDA)

‘‘‘Pale-Stripped Flea Beetle (Systena blanda) ‘‘‘ 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. Most insecticides used to control the sugar beet root maggot are also effective against larvae of the pale-stripped flea beetle. (Insects and Arthropods -- Root Feeders)


PHOMA LEAF SPOT (PHOMA BETAE)

‘‘‘Phoma Leaf Spot (Phoma betae) ‘‘‘ 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. A four-year rotation with crops other than hosts and fungicide seed treatment are the only recommended controls. (Leaf Disease Caused by Fungi)


PHOMA ROOT ROT (PHOMA BETAE)

‘‘‘Phoma Root Rot (Phoma betae) ‘‘‘ Initial symptoms include wilting and the occurrence of small, dark brown, depressed spots on the root surface near the crown. Rotted tissue is usually dark brown to black with prominent black lines. Cultural operations that promote vigorous growth of the host are recommended, including use of fertilizers, timely irrigation, and adequate cultivation. (Root Diseases Caused by Fungi)


PHOSPHORUS DEFICIENCY

‘‘‘Phosphorus Deficiency: ‘‘‘ 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. (Nutritional Disorder)


PHYMATOTRICHUM ROOT ROT (PHYMATOTRICHUM OMNIVORUM)

‘‘‘Phymatotrichum Root Rot (Phymatotrichum omnivorum) ‘‘‘ The first symptom is a slight yellowing or bronzing of leaves followed by sudden wilting of the plants. A thin, felt-like layer of yellowish mycelium develops on the root surface developing into a yellow to tan rot. There are no control measures available other then avoiding infested fields. (Root Diseases Caused by Fungi)


PHYTOPHTHORA ROOT ROT (PHYTOPHTHORA DRECHSLERI)

‘‘‘Phytophthora Root Rot (Phytophthora drechsleri) ‘‘‘ This disease is characterized by dry spots that appear toward the bases of the roots which become rotted, turn brown, and develops a blackish margin adjacent to healthy tissue. The best forms of control are proper field drainage, subsoil plowing, sprinkler irrigation, and planting in raised beds. (Root Diseases Caused by Fungi)


POTASSIUM DEFICIENCY

‘‘‘Potassium Deficiency: ‘‘‘ A leathery tan color on the edges of recently matured leaves is the first symptom of potassium deficiency. This marginal discoloration spreads between the veins to the midrib. Bright sunlight intensifies the tanning to a brown scorch. Large leaf blades with symptoms of potassium deficiency have a faint but distinct putrid odor similar to the smell of decaying vegetable matter. (Nutritional Disorder)


POWDERY MILDEW (ERYSIPHE POLYGONI)

‘‘‘Powdery Mildew (Erysiphe polygoni) ‘‘‘ 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. The best form of control is to use fungicides. (Leaf Disease Caused by Fungi)


PYTHIUM ROOT ROT (PYTHIUM APHANIDERMATUM)

‘‘‘Pythium Root Rot (Pythium aphanidermatum) ‘‘‘ Aboveground symptoms include wilting, yellowing, death of lower leaves and a water-soaked black rot of petiole bases. The best forms of control are proper field drainage, subsoil plowing, sprinkler irrigation, and planting in raised beds. (Root Diseases Caused by Fungi)


RAMULARIA LEAF SPOT (RAMULARIA BETICOLA)

‘‘‘Ramularia Leaf Spot (Ramularia beticola) ‘‘‘ 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. There are no control measures because of its minor importance. (Leaf Disease Caused by Fungi)


RHIZOCTONIA FOLIAR BLIGHT (RHIZOCTONIA SOLANI)

‘‘‘Rhizoctonia Foliar Blight (Rhizoctonia solani) ‘‘‘ 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. A four to five year rotation of sugar beet with corn or small grains is the only recommended control. (Leaf Disease Caused by Fungi)


RHIZOCTONIA ROOT AND CROWN ROT (RHIZOCTONIA SOLANI)

‘‘‘Rhizoctonia Root and Crown Rot (Rhizoctonia solani) ‘‘‘ 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. 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. (Root Diseases Caused by Fungi)


RHIZOPUS ROOT ROT (RHIZOPUS STOLONIFER)

‘‘‘Rhizopus Root Rot (Rhizopus stolonifer) ‘‘‘ The most characteristic symptom is permanent wilting that creates a dry, brittle rosette and the entire root system turns black. Avoidance of excessive injury and insect damage are suggested control measures. (Root Diseases Caused by Fungi)


RODENTS

‘‘‘Rodents: ‘‘‘ The use of bait has been effective for the control of some rodents. (Rodents)


ROOT ABNORMALITIES

‘‘‘Root Abnormalities: ‘‘‘ The growth and development of sugar beet roots have been affected by dinitroaniline compounds, such as trifluralin and nitralin, more than any other class of herbicides. Some injuries of young roots of sugar beet have actually been caused by nematodes. (Herbicide Damage)


ROOT-KNOT NEMATODES (MELOIDOGYNE SPP)

‘‘‘Root-Knot Nematodes (Meloidogyne spp.) ‘‘‘ Infected plants may have yellow leaves, become stunted, or fail to emerge. Root-knot nematodes usually attack small fibrous roots and taproots, inducing the formation of galls, which may contain one to several nematodes. The best control is using fumigants containing 1,3-dichloropropenes. (Nematode Parasites)


SALT INJURY

‘‘‘Salt Injury: ‘‘‘ 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. (Environmental Disorders)


SEEDLING DISEASES

‘‘‘Seedling Diseases: ‘‘‘ Pythium ultimum Trow. 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. The severity of damping-off can be minimized by shallow planting of seed and by managing soil moisture, where possible, to encourage rapid emergence. (Seed and Seedling Disorders)


SOIL COMPACTION

‘‘‘Soil Compaction: ‘‘‘ A layer of compact soil may restrict the growth of taproots or cause the initiation of secondary roots, which grow at a right angle to the axis of the plant. (Environmental Disorders)


SOUTHERN SCLEROTIUM ROOT ROT (SCLEROTIUM ROLFSII)

‘‘‘Southern Sclerotium Root Rot (Sclerotium rolfsii) ‘‘‘ Initial symptoms include unthrifty top growth and wilting, which later becomes permanent. Infected roots are covered with thick, white strands of cottony mycelium which contain a vast number of spherical sclerotia. The sclerotia are initially white and then turn tan to dark brown. Control is difficult, because no method exists for eradicating the pathogen from infested soils. Application of nitrogenous fertilizers, which promote vigorous root and top growth, can reduce losses. (Root Diseases Caused by Fungi)


SPINACH LEAF MINER (PEGOMYA HYOSCYAMI)

‘‘‘Spinach Leaf Miner (Pegomya hyoscyami) ‘‘‘ 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. Insecticides approved for control of this pest are diazinon, trichlorfon, parathion, aldicarb, and phorate. (Insects and Arthropods -- Leaf and Crown Feeders)


STEM AND BULB NEMATODES (DITYLENCHUS DIPSACI)

‘‘‘Stem and Bulb Nematodes (Ditylenchus dipsaci) ‘‘‘ 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. The best forms of control include rotating crops and using good sanitary practices.


STUBBY ROOT AND NEEDLE NEMATODES (TRICHODORUS PRIMITIVUS AND LONGIDORUS SPP)

‘‘‘Stubby Root and Needle Nematodes (Trichodorus primitivus and Longidorus spp.) ‘‘‘ This disease is characterized by dead taproot tips and stubby-ended lateral roots. Roots that survive thicken and divide creating a short, branched root system. Patches in the field may demonstrate lack of uniformity and size among plants and develop symptoms after wet springs or during the period of seed germination.

SUGAR BEET CROWN BORER (HULSTIA UNDULATELLA)

‘‘‘Sugar Beet Crown Borer (Hulstia undulatella) ‘‘‘ Most severe damage occurs about thinning time, when first-generation larvae cut off leaves and kill the young plants. Parathion is approved for control of this pest. (Insects and Arthropods -- Leaf and Crown Feeders)


SUGAR BEET ROOT APHID (PEMPHIGUS POPULIVENAE)

‘‘‘Sugar Beet Root Aphid (Pemphigus populivenae) ‘‘‘ The surface of colonized roots is characteristically covered with a white, waxy material secreted by the insect. In very heavy infestations, beet leaves turn from dark green to yellowish green, and affected plants wilt and actually shrink in size. The best forms of control are to plant resistant cultivars where available, rotate the crop, and plowing deep to reduce infestations. (Insects and Arthropods -- Root Feeders)


SUGAR BEET ROOT MAGGOT (TETANOPS MYOPAEFORMIS)

‘‘‘Sugar Beet Root Maggot (Tetanops myopaeformis) ‘‘‘ The maggots scrape the root surface with their mouth hooks, causing irregular scars, which later become darkened from sap escaping from the injured root. Small taproots of some plants are completely severed by the larvae, and such plants usually wilt and eventually die. Most growers rely on insecticides to control the sugar beet root maggots and crop rotation can help to reduce the root maggot population to some extent, but this practice is not totally dependable. (Insects and Arthropods -- Root Feeders)


SULFUR DEFICIENCY

‘‘‘Sulfur Deficiency: ‘‘‘ 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. (Nutritional Disorder)


SWEET-POTATO WHITEFLY (BEMISIA TABACI)

‘‘‘Sweet-Potato Whitefly (Bemisia tabaci) ‘‘‘ 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. There are no control measures available at this time. (Insects and Arthropods -- Leaf and Crown Feeders)


VERTICILLIUM WILT (VERTICILLIUM ALBO ATRUM)

‘‘‘Verticillium Wilt (Verticillium albo atrum) ‘‘‘ Initially, foliage turns straw-colored and the outer leaves wilt and become dry with the inner leaves becoming twisted and deformed. 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. (Root Diseases Caused by Fungi)


VIOLET ROOT ROT (RHIZOCTONIA CROCORUM)

‘‘‘Violet Root Rot (Rhizoctonia crocorum) ‘‘‘ Characteristic symptoms include purplish spots on the root surface, reddish purple, felt-like mycelial growth that advances over the root surface from the rib toward the crown, and occasional wilting. The best forms of control include crop rotation, soil aeration, and eradication of susceptible weed hosts. (Root Diseases Caused by Fungi)


WEBWORMS (LOXOSTEGE SPP)

‘‘‘Webworms (Loxostege spp.) ‘‘‘ 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. Some insecticide control is available. (Insects and Arthropods -- Leaf and Crown Feeders)


WHITE GRUBS

‘‘‘White Grubs: ‘‘‘ 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. Sugar beet and other crops that are susceptible to white grubs should not be planted in fields that were previously planted with sod. (Insects and Arthropods -- Root Feeders)


WIND DAMAGE

‘‘‘Wind Damage: ‘‘‘ The damage may be associated with the blowing of soil, which acts as an abrasive, or wind and rain together may cause plants to fall over and adhere to the soil. (Environmental Disorders)


WIREWORMS

‘‘‘Wireworms: ‘‘‘ Wireworms damage sugar beet by feeding on seed and seedlings, chewing off small roots, and tunneling through large roots. 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. (Insects and Arthropods -- Root Feeders)


YELLOW WILT (PARATANUS EXITIOSUS)

‘‘‘Yellow Wilt (Paratanus exitiosus) ‘‘‘ The symptoms are yellowing of leaves or wilting and collapse of infected plants. These symptoms may be accompanied by dwarfing of new leaves, which often turn downward at their tips. In some cases, only sectors of leaves turn yellow, and the veins of some leaves may show distinct yellowing. The best form of control is to use resistant varieties and avoid planting where the disease has caused significant losses. (Disease Caused by Bacteria and Bacterialike Organisms)


YELLOW WILT LEAFHOPPER (PARATANUS EXITIOSUS)

‘‘‘Yellow Wilt Leafhopper (Paratanus exitiosus) ‘‘‘ 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. The best forms of control include using resistant cultivars, applying insecticides, and avoid planting in infested areas. (Insects and Arthropods -- Leaf and Crown Feeders)


ZINC DEFICIENCY

‘‘‘Zinc Deficiency: ‘‘‘ A light green color on the larger leaves near the center of the plant is the first apparent symptom of zinc deficiency. As the yellowing becomes more intense, small pits develop between the veins on the upper surface of the blades. These pits enlarge in an irregular pattern as more tissue collapses. (Nutritional Disorder)