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FL Lawn & Ornamental practice questions

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Question 1Pest identification and biology of turf and ornamental pests

A Florida lawn shows irregular dead patches with brown, rotted roots and dark mycelium at the soil line. Which pathogen group is most likely responsible?

  1. Mole crickets
  2. Fungi such as Rhizoctonia or Pythium Correct answer.
  3. Grass-feeding nematodes
  4. Chinch bug adults

Explanation

Root and crown rots with visible mycelium and dark lesions are fungal in origin. Pythium and Rhizoctonia are common pathogens of Florida turf. Nematodes and insects cause damage but do not produce mycelium.

Question 2Pest identification and biology of turf and ornamental pests

A white grub found in a Florida turf sample has a distinct C-shaped body and a raster pattern used for identification. Which pest stage is this?

  1. Adult scarab beetle
  2. Larva of a scarab beetle Correct answer.
  3. Pupa of a scarab beetle
  4. Egg of a scarab beetle

Explanation

White grubs are the C-shaped larvae of scarab beetles. They live in the soil and feed on turf roots. Adults are winged beetles and pupae are not actively feeding.

Question 3Pest identification and biology of turf and ornamental pests

Chinch bug damage in St. Augustinegrass typically first appears in which pattern?

  1. Yellowing patches in full sun, often near curbs and driveways Correct answer.
  2. Random circular spots across the whole lawn
  3. Brown streaks following mowing lines
  4. Dark green rings around trees

Explanation

Chinch bugs aggregate in hot, sunny, drought-stressed areas, so damage often begins near pavement. The grass yellows and dies in expanding patches. This pattern helps distinguish chinch bugs from disease.

Question 4Pest identification and biology of turf and ornamental pests

Which feature best distinguishes adult mole crickets from other turf insects in Florida?

  1. Bright red and black coloration
  2. Broad shovel-like front legs adapted for digging Correct answer.
  3. Long antennae longer than the body
  4. Wings held vertically over the back

Explanation

Mole crickets have enlarged, clawed front legs modified for burrowing through soil. This is their most diagnostic feature. They also tunnel near the surface, loosening turf.

Question 5Pest identification and biology of turf and ornamental pests

A turf sample shows small, pale, wormlike larvae inside the grass stems, causing dead central shoots. Which pest is most likely?

  1. Tropical sod webworm
  2. Billbug larvae Correct answer.
  3. Chinch bug
  4. Fall armyworm

Explanation

Billbug larvae feed inside stems and crowns, producing dead central shoots called deadhearts. They are legless, white larvae found within the plant tissue. Surface-feeding caterpillars and chinch bugs do not bore into stems this way.

Question 6Pest identification and biology of turf and ornamental pests

Which life stage of the tropical sod webworm causes the most visible turf damage?

  1. Larva Correct answer.
  2. Pupa
  3. Adult moth
  4. Egg

Explanation

Sod webworm larvae chew grass blades and create notched, thinning turf. Adults are harmless moths that fly at dusk. Eggs and pupae do not feed on turf.

Question 7Pest identification and biology of turf and ornamental pests

A lawn near a Florida lake develops brown patches that spread rapidly in hot, humid weather with drainage problems. Which disease is most likely?

  1. Pythium blight Correct answer.
  2. Gray leaf spot
  3. Dollar spot
  4. Take-all root rot

Explanation

Pythium blight thrives in hot, wet, poorly drained areas and can spread rapidly. It causes greasy brown patches and often follows drainage patterns. Other diseases progress more slowly or appear in different conditions.

Question 8Pest identification and biology of turf and ornamental pests

Which organism causes large dead patches of turf with white, cottony mycelium and sclerotia in the thatch during warm, wet weather?

  1. Puccinia graminis
  2. Rhizoctonia solani
  3. Sclerotium rolfsii Correct answer.
  4. Bipolaris sorokiniana

Explanation

Sclerotium rolfsii causes southern blight, producing white mycelium and round sclerotia. These structures help identify the pathogen. Rhizoctonia causes brown patch but does not form sclerotia in this way.

Question 9Pest identification and biology of turf and ornamental pests

Small, pale spots with dark borders on grass blades that enlarge and coalesce are most consistent with which problem?

  1. Leaf spot disease Correct answer.
  2. Drought stress
  3. Thatch accumulation
  4. Chinch bug feeding

Explanation

Leaf spot diseases produce distinct lesions with dark margins on blades. Multiple spots can merge and blight the leaf. Insect feeding and abiotic stress cause different symptoms.

Question 10Pest identification and biology of turf and ornamental pests

A landscape shrub shows mottled yellow stippling on leaves and fine webbing on the undersides. Which pest is most likely?

  1. Whiteflies
  2. Spider mites Correct answer.
  3. Aphids
  4. Scale insects

Explanation

Spider mites pierce leaf cells, causing pale stippling, and produce fine silk webbing. These signs are diagnostic. Aphids, whiteflies, and scales do not make webbing.

Question 11Pest identification and biology of turf and ornamental pests

A colony of small, soft-bodied insects clusters on new growth of an ornamental and secretes sticky honeydew. Which pest is most likely?

  1. Leafminers
  2. Aphids Correct answer.
  3. Bagworms
  4. Thrips

Explanation

Aphids are small, soft-bodied insects that cluster on tender new growth and excrete honeydew. The honeydew often leads to sooty mold. The other pests have different habits and appearances.

Question 12Pest identification and biology of turf and ornamental pests

Serpentine tunnels inside the leaves of an ornamental shrub with no webbing are most characteristic of which pest?

  1. Spider mites
  2. Thrips
  3. Aphids
  4. Leafminers Correct answer.

Explanation

Leafminer larvae feed between leaf surfaces, creating winding tunnels. The damage is internal and distinct from surface feeding. Mites and thrips feed on leaf surfaces.

Question 13Pest identification and biology of turf and ornamental pests

Which characteristic best identifies armored scales on an ornamental plant?

  1. A cottony secretion covering the colony
  2. Legs visible at all stages
  3. A waxy cover that can be removed from the insect beneath Correct answer.
  4. A soft body that never forms a cover

Explanation

Armored scales secrete a waxy cover separate from the body, which can be lifted off. Soft scales do not have a removable cover. This distinction matters for control decisions.

Question 14Pest identification and biology of turf and ornamental pests

A caterpillar pest of ornamentals constructs a silk bag covered with plant fragments and hangs it from branches. Which pest is this?

  1. Fall webworm
  2. Bagworm Correct answer.
  3. Eastern tent caterpillar
  4. Sod webworm

Explanation

Bagworm larvae build portable cases from silk and plant material. They carry the bag while feeding. The other caterpillars form tents or webs but not portable bags.

Question 15Pest identification and biology of turf and ornamental pests

An ornamental tree shows wilting and dieback, and a cross-section of the trunk reveals dark streaking in the outer sapwood. Which type of pathogen is most likely involved?

  1. Powdery mildew fungus
  2. Root-knot nematode
  3. Rust fungus
  4. Vascular wilt fungus Correct answer.

Explanation

Dark vascular streaking with wilting indicates a vascular wilt pathogen. The fungus colonizes water-conducting tissue and disrupts flow. Powdery mildew and rust affect leaf surfaces.

Question 16Pest identification and biology of turf and ornamental pests

White powdery growth on the upper leaf surface of a crape myrtle is most consistent with which disease?

  1. Downy mildew
  2. Sooty mold
  3. Bacterial leaf spot
  4. Powdery mildew Correct answer.

Explanation

Powdery mildew appears as white, dust-like fungal growth on leaf surfaces. It is favored by moderate temperatures and humidity. Sooty mold is black and grows on honeydew.

Question 17Pest identification and biology of turf and ornamental pests

Black, soot-like coating on leaves and branches of an ornamental is most directly associated with which condition?

  1. Fungal root rot
  2. Drought stress
  3. Herbicide injury
  4. Honeydew from sap-feeding insects Correct answer.

Explanation

Sooty mold fungi grow on sugary honeydew excreted by aphids, scales, and whiteflies. Controlling the insects reduces the mold. Root rot and abiotic stress do not produce honeydew.

Question 18Pest identification and biology of turf and ornamental pests

Which symptom pattern is most characteristic of nematode damage to turf roots?

  1. Yellow stippling on leaf blades
  2. Notched grass blades
  3. Generalized thinning and decline with shortened, stubby roots Correct answer.
  4. Distinct circular patches with white mycelium

Explanation

Plant-parasitic nematodes feed on roots, causing stunting and decline. Affected roots are shortened and lack fine branching. The damage is below ground and generalized, not patchy with mycelium.

Question 19Pest identification and biology of turf and ornamental pests

Fire ant mounds in a Florida lawn are best identified by which feature?

  1. Domed mounds of loose soil with no central entrance hole Correct answer.
  2. Large craters surrounded by excavated soil
  3. Flat tunnels with a visible entrance at the center
  4. Small holes with silk lining

Explanation

Imported fire ants build dome-shaped mounds of fluffy soil without a central opening. The ants enter through lateral tunnels. This distinguishes them from other ant species and from mole cricket tunnels.

Question 20Pest identification and biology of turf and ornamental pests

A turf area shows small dirt mounds and raised, loosened soil trails near the surface. Which insect is most likely responsible?

  1. Chinch bugs
  2. Sod webworms
  3. White grubs
  4. Mole crickets Correct answer.

Explanation

Mole crickets tunnel near the soil surface, pushing up soil and loosening turf. Their activity creates raised trails and small mounds. The other pests feed differently and do not create surface tunnels.

Question 21Pest identification and biology of turf and ornamental pests

Which environmental condition most favors development of brown patch disease in Florida lawns?

  1. Bright sun with low nitrogen only
  2. Cold soils with frost
  3. Warm temperatures with high humidity and extended leaf wetness Correct answer.
  4. Cool, dry weather with low humidity

Explanation

Brown patch is favored by warm, humid conditions and prolonged leaf wetness. These conditions support Rhizoctonia growth and infection. Cool, dry weather suppresses the disease.

Question 22Pest identification and biology of turf and ornamental pests

A gardener observes that a caterpillar pest feeds at night and hides in the thatch during the day, causing thinning turf. Which monitoring method is most appropriate?

  1. Daytime visual search of blades only
  2. Soil core sampling for grubs
  3. Pheromone traps for adults only
  4. Soap flush or nighttime inspection Correct answer.

Explanation

Nocturnal caterpillars such as sod webworms hide during the day, so daytime searches miss them. Soap flushes irritate larvae to the surface, and nighttime inspection reveals feeding activity.

Question 23Pest identification and biology of turf and ornamental pests

Which feature distinguishes thrips damage from mite damage on ornamental foliage?

  1. Serpentine tunnels inside leaves
  2. Silvery scarring and distorted growth with black fecal specks Correct answer.
  3. Sticky honeydew and sooty mold
  4. Fine webbing covering leaf undersides

Explanation

Thrips rasp leaf surfaces, causing silvery scarring and distortion, and leave dark fecal specks. Mites cause stippling and webbing. Honeydew and mines indicate other pests.

Question 24Pest identification and biology of turf and ornamental pests

A shrub's leaves are curled and distorted with colonies of tiny insects and sticky residue. Which insect order does this pest belong to?

  1. Hemiptera (true bugs and aphids) Correct answer.
  2. Coleoptera (beetles)
  3. Lepidoptera (moths and butterflies)
  4. Diptera (flies)

Explanation

Aphids are in the order Hemiptera, which includes many sap-feeding insects. Their piercing-sucking mouthparts cause curling and honeydew production. Moths, beetles, and flies have different feeding habits.

Question 25Pest identification and biology of turf and ornamental pests

A turfgrass sample shows irregular brown patches with a dark, rotted crown and no insect pests present. Which step best supports a diagnosis?

  1. Submit a sample to a diagnostic lab for pathogen isolation Correct answer.
  2. Increase irrigation without testing
  3. Mow lower and remove clippings
  4. Apply an insecticide immediately

Explanation

When symptoms suggest disease and insects are absent, laboratory isolation confirms the pathogen. This guides appropriate fungicide or cultural control. Applying insecticide without evidence is wasteful and ineffective.

Question 26Pest identification and biology of turf and ornamental pests

Chinch bug damage to Florida St. Augustinegrass is most reliably diagnosed by which field sign at the base of the turf?

  1. A yellowish, wilted patch that pulls up easily and reveals white root hairs chewed to stubs Correct answer.
  2. A dry, hollow thatch layer with no live roots below it
  3. A spongy, water-soaked rot at the soil line with a sour odor
  4. Fine silk webbing spun over the grass blades and thatch

Explanation

Chinch bugs suck sap from the crown and stolons, so damaged turf wilts, yellows, and lifts away from the soil with little resistance. The roots and lower stems show chewed, stubby remnants rather than rot or webbing, and the patch expands outward from a sunny, stressed area.

Question 27Pest identification and biology of turf and ornamental pests

A Florida lawn shows expanding irregular patches of blighted grass, and close inspection of the affected blades in early morning reveals a grayish, water-soaked lesion with a dark margin. Which pathogen group is most consistent with this presentation?

  1. Puccinia species, a rust fungus
  2. Rhizoctonia solani, the brown patch fungus Correct answer.
  3. Bipolaris species, a leaf spot fungus
  4. Pythium species, the cottony blight organism

Explanation

Brown patch caused by Rhizoctonia solani produces irregular blighted patches with lesions that appear water-soaked early and dry to a tan center with a dark border. It favors warm, humid nights and heavy nitrogen, and the pattern spreads from a center rather than appearing as scattered leaf spots.

Question 28Pest identification and biology of turf and ornamental pests

Which feature separates damage by the hunting billbug from damage by white grubs in a Florida lawn?

  1. Billbug larvae are legless and feed on roots underground, causing the turf to roll back like carpet
  2. Billbug larvae are C-shaped and feed only on thatch, leaving roots intact
  3. Billbug adults chew irregular notches along leaf edges, which is the only reliable sign
  4. Billbug larvae lack legs and feed inside stems and crowns, so turf pulls up with stems hollowed out Correct answer.

Explanation

Billbug larvae are legless, plump grubs that tunnel inside stems and crowns, so affected tillers break off and the stem interior is hollowed and packed with frass. White grubs are C-shaped, have legs, and feed on roots below the surface, so the turf can be rolled back like a carpet.

Question 29Pest identification and biology of turf and ornamental pests

A St. Augustinegrass lawn in full sun shows irregular dead patches in late spring, and pulling on the dead grass reveals stems cut off just below the soil surface with small, dark, seed-like objects nearby. Which pest is most likely responsible?

  1. Mole crickets Correct answer.
  2. Southern chinch bugs
  3. Mole crickets' relative, the tawny mole cricket
  4. Tropical sod webworms

Explanation

Mole crickets tunnel near the surface and sever stems and roots, so damaged turf lifts easily and shows cut stems plus small soil mounds. Their presence is confirmed by the tunnels and by the insects themselves, which are large and velvety brown with shovel-like front legs.

Question 30Pest identification and biology of turf and ornamental pests

Which symptom on an ornamental shrub is most characteristic of feeding by lace bugs rather than by spider mites?

  1. Large ragged holes chewed through the leaf margins
  2. Fine stippling with copious silk webbing on leaf undersides
  3. Sticky honeydew coating leaves with a black sooty mold growth
  4. Upper-surface chlorotic stippling with black, varnish-like fecal spots on the leaf underside Correct answer.

Explanation

Lace bugs feed on leaf undersides and deposit dark, tar-like fecal spots there, while the upper surface shows pale stippling. Spider mites also cause stippling but produce fine webbing and no varnish-like spots, which is the key separation in the field.

Question 31Pest identification and biology of turf and ornamental pests

A palm in a Florida landscape shows new fronds emerging small, crinkled, and distorted while older fronds look normal. Which pest or disorder should be investigated first?

  1. Ganoderma butt rot infecting the lower trunk
  2. Lethal bronzing phytoplasma in the phloem
  3. Palmetto weevil larvae boring in the trunk
  4. A micronutrient deficiency or an infestation of palm aphids on the spear Correct answer.

Explanation

Damage confined to newly emerging fronds points to a problem at the bud or spear, such as a boron or manganese deficiency or aphids feeding on the unopened spear. Trunk borers and vascular diseases typically cause wilting, decline, or collapse of the whole canopy rather than distortion limited to new growth.

Question 32Pest identification and biology of turf and ornamental pests

Which observation best confirms that a thinning turf area is caused by tropical sod webworm rather than by drought stress?

  1. Small green pellets of frass and silk-lined tunnels appear in the thatch near chewed blades Correct answer.
  2. The turf recovers within hours after irrigation
  3. The soil is dry several inches down and the blades fold lengthwise
  4. The grass blades show grayish streaks along the midrib

Explanation

Sod webworm larvae feed at night and rest in silk-lined tunnels in the thatch, leaving green frass pellets and chewed blade edges. Drought stress produces folded blades and dry soil without frass or silk, and it reverses after watering rather than persisting.

Question 33Pest identification and biology of turf and ornamental pests

A crape myrtle hedge develops white, waxy bumps clustered on twigs, and the leaves below are sticky and coated with black mold. Which pest group is most likely?

  1. Armored scales, which do not produce honeydew
  2. Leafminers, which tunnel inside leaves
  3. Soft scales, which excrete honeydew Correct answer.
  4. Spider mites, which produce webbing

Explanation

Soft scales such as the crape myrtle bark scale produce honeydew that coats lower leaves and supports sooty mold. Armored scales lack the honeydew-producing mechanism, so sticky residue with black mold points to soft scales, aphids, or whiteflies.

Question 34Pest identification and biology of turf and ornamental pests

An ornamental tree dies suddenly, and the trunk cross-section shows discoloration in the outer sapwood that forms a distinct ring. Which problem does this pattern most suggest?

  1. A canker pathogen confined to the bark surface
  2. A vascular wilt pathogen spreading through the xylem Correct answer.
  3. A defoliating caterpillar removed the leaves
  4. A root rot fungus decayed the inner heartwood first

Explanation

Vascular wilt pathogens colonize and plug the water-conducting xylem, producing streaking or a ring of discolored sapwood when the trunk is cut. The pattern follows the vascular ring rather than being confined to bark or heartwood, which helps separate wilt from canker and root rot.

Question 35Pest identification and biology of turf and ornamental pests

Which description correctly matches the life cycle of white grubs in Florida turf?

  1. Adults lay eggs in soil, larvae feed on roots for months, and pupation occurs in the soil Correct answer.
  2. Eggs are laid on leaves, and larvae bore into stems to pupate
  3. Larvae feed on foliage at night and pupate in the thatch
  4. Larvae overwinter in leaf litter and feed only on decaying organic matter

Explanation

White grubs are scarab beetle larvae that live in the soil, where females lay eggs and the larvae feed on turf roots before pupating in earthen cells. Root feeding reduces the plant's ability to take up water, so damage appears as wilting patches that lift easily.

Question 36Pest identification and biology of turf and ornamental pests

A Florida lawn shows small, scattered, circular dead spots a few inches across that enlarge slowly and have a frog-eye appearance with a lighter center. Which disease is most consistent with this pattern?

  1. Pythium blight
  2. Gray leaf spot
  3. Take-all root rot
  4. Dollar spot Correct answer.

Explanation

Dollar spot produces small, circular, sunken spots roughly the size of a silver dollar that can merge into larger blighted areas, often with a bleached center. It is favored by warm days, cool nights, and low nitrogen, and the small spot size separates it from large patch diseases.

Question 37Pest identification and biology of turf and ornamental pests

Which feature distinguishes damage by the azalea caterpillar from damage by the azalea lace bug?

  1. Lace bugs chew holes along leaf margins
  2. Lace bugs produce copious silk webbing over the shrub
  3. Caterpillars cause stippling on the leaf underside
  4. Caterpillars chew entire leaves and leave frass, while lace bugs cause pale stippling on the upper surface Correct answer.

Explanation

Azalea caterpillars are chewing insects that consume leaf tissue and leave frass, so damage appears as missing leaf area. Lace bugs are piercing-sucking insects that remove cell contents, producing pale stippling visible on the upper leaf surface with dark fecal spots below.

Question 38Pest identification and biology of turf and ornamental pests

A container-grown ornamental develops wilting that does not respond to watering, and the roots show dark, mushy tissue with a distinct margin between healthy and rotted tissue. Which problem is most likely?

  1. Herbicide injury from a growth regulator
  2. Spider mite feeding on the leaves
  3. Aphid feeding on the foliage
  4. A root and crown rot pathogen favored by poor drainage Correct answer.

Explanation

Dark, mushy roots with a clear margin between healthy and diseased tissue indicate a soilborne root rot pathogen, which is favored by saturated media and poor drainage. Wilting that persists despite watering reflects lost root function rather than a water deficit.

Question 39Pest identification and biology of turf and ornamental pests

Which characteristic best separates damage by the two-lined spittlebug from damage by chinch bugs on St. Augustinegrass?

  1. Spittlebugs cause fine silk webbing over the turf
  2. Chinch bugs produce frothy spittle masses on stems
  3. Spittlebugs feed only on roots below the soil surface
  4. Spittlebug nymphs produce frothy spittle masses on stems, and adults cause yellowing, while chinch bugs cause wilt without spittle Correct answer.

Explanation

Spittlebug nymphs are recognized by the frothy spittle masses they produce on stems and leaf sheaths, and heavy feeding causes yellowing and decline. Chinch bugs feed without producing spittle and cause wilting and yellowing that spreads from sunny, stressed areas.

Question 40Pest identification and biology of turf and ornamental pests

Which combination of signs most reliably identifies an infestation of the rugose spiraling whitefly on an ornamental?

  1. Fine stippling with no honeydew and no wax
  2. Chewed leaf margins with green frass pellets
  3. Dark, sunken lesions on stems with gumming
  4. Spiraling white waxy trails on leaf undersides with honeydew and sooty mold Correct answer.

Explanation

Rugose spiraling whitefly nymphs and egg masses produce spiraling white waxy deposits on leaf undersides, and the insects excrete honeydew that supports sooty mold. The wax trails plus honeydew separate this whitefly from mites, caterpillars, and canker diseases.

Question 41Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A St. Augustinegrass lawn in full sun shows yellow-green blades with the oldest mowed leaves yellowing first while new growth stays greener. Which nutrient deficiency is most consistent with this pattern?

  1. Calcium deficiency
  2. Potassium deficiency
  3. Iron deficiency
  4. Nitrogen deficiency Correct answer.

Explanation

Nitrogen is mobile in the plant, so a deficiency appears first on the older leaves while the newest growth stays green. Iron is immobile, so iron chlorosis shows on the youngest leaves first. Potassium deficiency typically shows marginal yellowing and leaf-tip scorch rather than uniform yellowing of older blades.

Question 42Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A homeowner waters a lawn every evening for ten minutes. The turf is shallow-rooted and wilts quickly between irrigations. Which irrigation practice best addresses the underlying problem?

  1. Switch to sprinklers that deliver finer droplets
  2. Water more frequently to keep the surface wet
  3. Reduce mowing height to lower water demand
  4. Water longer and less often to wet the root zone Correct answer.

Explanation

Shallow, frequent irrigation keeps only the top of the root zone moist, so roots stay shallow and the turf wilts quickly. Applying enough water to wet the root zone and then letting the surface dry between cycles encourages deeper rooting. Frequency should be reduced while depth per irrigation is increased.

Question 43Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A turf sample shows circular patches of blighted grass in the morning that appear tied with a dark thread-like growth when the grass is wet, and the symptoms fade as the leaves dry. What is the most likely cause?

  1. Pythium blight Correct answer.
  2. Take-all root rot
  3. Dollar spot
  4. Gray leaf spot

Explanation

Pythium blight produces the characteristic dark, thread-like mycelium on wet turf in the morning, and the visible signs disappear as the canopy dries. It is favored by warm, wet weather and poor drainage. Dollar spot and gray leaf spot do not form this cottony or thread-like growth.

Question 44Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A landscape bed shows stunted plants with pale lower leaves, and a soil test reports a very low cation exchange capacity with low magnesium. Which amendment most directly addresses the magnesium deficiency?

  1. Elemental sulfur
  2. Ammonium nitrate
  3. Dolomitic limestone Correct answer.
  4. Calcitic limestone

Explanation

Dolomitic limestone supplies both calcium and magnesium carbonate, so it raises pH while correcting magnesium deficiency. Calcitic limestone supplies calcium but little magnesium. Elemental sulfur lowers pH and does not supply magnesium.

Question 45Diagnosis of plant and turf disorders, including abiotic and nutritional problems

Ornamental shrubs in a bed near a concrete sidewalk develop yellowing between the veins of the newest leaves while the veins remain green. A soil test shows high pH. Which diagnosis is most likely?

  1. Nitrogen deficiency
  2. Salt burn
  3. Herbicide injury
  4. Iron chlorosis Correct answer.

Explanation

High soil pH reduces iron availability, and iron is immobile, so interveinal chlorosis appears on the youngest leaves with green veins. Nitrogen deficiency yellows older leaves uniformly. Salt burn typically causes marginal necrosis, not interveinal chlorosis of new growth.

Question 46Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A newly installed tree shows wilting despite moist soil, and the root ball is dry inside while the surrounding backfill is wet. What is the most likely explanation?

  1. The tree has a vascular wilt pathogen
  2. The root ball is not absorbing water from surrounding soil Correct answer.
  3. The tree is suffering from herbicide drift
  4. The soil pH is too low

Explanation

When the root ball dries out while surrounding soil stays moist, water does not move readily into the root ball, so the tree wilts even though the backfill feels wet. The fix is to water the root ball directly and check moisture inside it. Vascular wilt and herbicide injury would not explain the moisture difference between root ball and backfill.

Question 47Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A turf area in heavy shade thins out and the remaining blades are etiolated and pale. Which management change is most appropriate?

  1. Increase irrigation frequency
  2. Reduce mowing height and increase nitrogen
  3. Select a shade-tolerant species and reduce traffic Correct answer.
  4. Apply a broadleaf herbicide

Explanation

Shade reduces photosynthesis, so turf thins and becomes elongated and pale. The durable fix is to use a species or cultivar adapted to shade and to reduce traffic and competition. Raising nitrogen or irrigation does not create more light and can increase stress.

Question 48Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A lawn shows irregular grayish-brown patches with a smoky ring at the margin, and the grass blades have lesions with tan centers and dark borders. Which disease is most consistent with this description?

  1. Large patch
  2. Brown patch
  3. Fairy ring
  4. Gray leaf spot Correct answer.

Explanation

Gray leaf spot produces tan-centered lesions with dark margins and can blight patches of turf, often with a grayish cast. Brown patch and large patch cause blighted patches but do not produce the same distinctive leaf lesions. Fairy rings appear as rings of darker grass or mushrooms without these lesions.

Question 49Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A landscape plant shows cupped, twisted new growth with parallel veins and a strapped appearance after a lawn herbicide application nearby. Which herbicide class most likely caused this?

  1. Dinitroanilines such as pendimethalin
  2. Synthetic auxins such as 2,4-D or dicamba Correct answer.
  3. Photosystem II inhibitors such as atrazine
  4. Glyphosate

Explanation

Synthetic auxin herbicides cause epinasty, cupping, twisting, and strapping of new growth in sensitive broadleaf plants. Glyphosate injury is more often chlorosis and stunting of growing points. Dinitroanilines affect root and shoot development, and atrazine injury appears as chlorosis and necrosis.

Question 50Diagnosis of plant and turf disorders, including abiotic and nutritional problems

A turf sample has dark brown to black roots with a rotted appearance, and the turf declines in irregular patches with a dark ring at the edge. Which condition is most likely?

  1. Pythium blight
  2. Dollar spot
  3. Rust
  4. Take-all root rot Correct answer.

Explanation

Take-all root rot causes dark, rotted roots and patchy decline, and it often shows a dark ring at the patch margin. Dollar spot affects leaves, Pythium blight causes rapid blighting with mycelium, and rust produces orange pustules on blades.