ISA Board Certified Master Arborist (BCMA)

A mature oak shows interveinal chlorosis on the youngest leaves while the veins remain green, and a soil test reveals a pH of 8.1 on a calcareous urban fill. Which abiotic disorder is the most likely cause?

• ANitrogen deficiency with uniform yellowing of older leaves first
• BIron (Fe) deficiency induced by high soil pH
• CPotassium deficiency with marginal scorch on older foliage
• DMagnesium deficiency with interveinal chlorosis on older leaves

Girdling roots that wrap around the base of a tree most directly cause decline by which mechanism?

• AReleasing toxic exudates into the surrounding rhizosphere
• BCompressing vascular tissue and restricting water transport
• CLowering soil pH throughout the confined root zone
• DIncreasing mycorrhizal colonization at the root flare

A street tree planted in a 1.2 m (4 ft) wide tree pit surrounded by pavement shows progressive crown dieback over several years with no pathogen present. The MOST probable abiotic stressor is:

• AExcessive available phosphorus limiting root elongation
• BRestricted rooting volume and compaction limiting water and oxygen
• CExcessive organic mulch depth suffocating the root flare
• DOverhead wire clearance conflicts limiting crown development

Frost cracks (radial bark splits) on the southwest side of thin-barked trees in winter are best explained by:

• AFungal cankers expanding in bark during cold periods
• BRapid temperature differential causing differential wood contraction
• CSalt spray accumulation on bark during winter storms
• DBoring insect galleries weakening the southwest trunk face

Marginal leaf scorch with a sharp boundary between green and brown tissue, appearing first on the windward and upper crown during a hot dry spell, most strongly indicates:

• ABacterial leaf scorch with progressive branch-by-branch decline
• BAbiotic drought and high evaporative demand on exposed crown
• CNitrogen toxicity from recent high-rate fertilizer application
• DRoot rot fungi blocking xylem throughout the crown

In secondary growth, the vascular cambium produces:

• ACork outside and phellem inside from the phellogen
• BSecondary xylem inside and secondary phloem outside
• CPhloem to the inside and xylem to the outside
• DOnly xylem production with no secondary phloem

According to Alex Shigo's CODIT model, the wall that resists vertical (axial) spread of decay above and below a wound is generally the:

• AStrongest wall (Wall 4 / the barrier zone)
• BWeakest wall (Wall 1) resisting vertical spread
• CWall 2 resisting inward radial spread via latewood
• DWall 3 resisting lateral tangential spread via rays

Reaction wood that forms on the UPPER side of a leaning branch and pushes the stem upright is characteristic of which tree group and is called:

• AConifers forming tension wood on the upper stem side
• BHardwoods forming tension wood on the upper stem side
• CConifers forming compression wood on the lower stem side
• DHardwoods forming compression wood on the upper stem side

During photosynthesis, the light-independent (Calvin) reactions primarily:

• ASplitting water to release oxygen in the thylakoids
• BFixing CO2 into sugar using ATP and NADPH from light reactions
• CGenerating the proton gradient across thylakoid membranes
• DAbsorbing photons via chlorophyll in the light-dependent reactions

Adventitious roots that emerge from a buried trunk after a tree is planted too deeply are problematic primarily because they:

• AAlways improving trunk anchorage in deeply planted holes
• BGrowing as girdling roots in low-oxygen buried bark tissue
• CIncreasing mycorrhizal diversity along the buried trunk
• DConverting phloem tissue into functional xylem vessels

Apical dominance in a tree is maintained primarily by which plant hormone produced in the terminal bud?

• ACytokinin from lateral buds maintaining apical dominance
• BAuxin (IAA) from the terminal bud suppressing laterals
• CAbscisic acid governing dormancy in the terminal bud
• DEthylene regulating abscission at the terminal bud

A diagnostic distinction between Dutch elm disease (DED) and elm yellows (phloem necrosis) is that elm yellows typically shows:

• ABrown streaking in sapwood with rapid one-branch flagging
• BDiffuse crown yellowing with butterscotch-odored phloem
• CNo vascular discoloration or crown symptoms of any kind
• DWhite mycelial fans under bark at the root collar

Emerald ash borer (Agrilus planipennis) larvae kill ash trees primarily by:

• ADefoliating the entire canopy during larval development
• BTunneling in phloem and cambium, girdling the vascular system
• CInjecting a systemic toxin into the root system from the soil
• DFeeding on flowers and reducing seed set on ash trees

Armillaria root disease is most reliably identified beneath the bark at the root collar by:

• AOrange spore horns erupting from bark cankers on the trunk
• BWhite fan-shaped mycelial plaques with dark rhizomorphs
• CSunken target cankers with concentric bark rings
• DPitch tubes and boring dust at the base of conifers

A fungal conk (perennial bracket) of Ganoderma at the base of a trunk is significant to a risk assessor mainly because it indicates:

• AHealthy heartwood formation strengthening the buttress zone
• BActive decay of structural root and butt wood reducing capacity
• CRecent high-nitrogen fertilization stimulating new heartwood
• DNitrogen fixation by bacteria colonizing the root zone

The botanical name Quercus rubra refers to which species, and what does the binomial structure tell you?

• AA genus name only with no specific epithet provided
• BNorthern red oak: Quercus genus and rubra specific epithet
• CA cultivar trade name Rubra without a species epithet
• DA family-level taxonomic grouping of all oak species

When selecting a tree for a confined urban planting strip beneath utility lines, the single most important selection criterion is usually:

• ASelecting species for maximum mature height and spread
• BMatching mature size and form to available above- and below-ground space
• CChoosing species with the showiest flower color for the site
• DPrioritizing the fastest growth rate regardless of mature size

A planting plan calls for a species diversity guideline to reduce catastrophic pest loss across an urban forest. The commonly cited Santamour 10-20-30 rule recommends no more than:

• A10% of any species, 20% of any genus, 30% of any family
• B30% of any species, 20% of any genus, 10% of any family
• C10% of any family, 20% of any genus, 30% of any species
• DEqual thirds of conifers, hardwoods, and palms in the canopy

Opposite, palmately compound leaves with five to seven leaflets and stout twigs are most consistent with which genus?

• AFraxinus with opposite pinnately compound leaves
• BAesculus with opposite palmately compound leaves
• CAcer with opposite simple palmately lobed leaves
• DCarya with alternate pinnately compound leaves

USDA Plant Hardiness Zones are based primarily on:

• AAverage annual rainfall across the region
• BAverage annual extreme minimum winter temperature
• CSoil pH ranges typical of the local parent material
• DMaximum number of summer days above 32 °C (90 °F)

A soil with approximately equal influence of sand, silt, and clay so that no single fraction dominates its properties is classified texturally as a:

• ASand-dominated soil with rapid drainage and low water holding
• BLoam with balanced sand, silt, and clay contributions
• CPure clay soil with poor drainage and aeration
• DPeat soil defined by high undecomposed organic matter

Cation exchange capacity (CEC) is best described as:

• AThe soil's ability to drain water rapidly through macropores
• BCapacity to hold and exchange cations on colloid surfaces
• CPercentage of organic matter that has fully decomposed
• DRate of microbial respiration in the aerobic root zone

Most tree fine (absorbing) roots and beneficial mycorrhizae are concentrated:

• ASeveral meters deep in the subsoil below the clay layer
• BIn the upper ~30 cm where oxygen and organic matter are highest
• COnly directly beneath the trunk within the root flare
• DExclusively within the dripline and nowhere beyond it

Soil compaction harms trees mainly because it:

• AIncreases macropore space and oxygen in the root zone
• BReduces macropore space, limiting gas exchange and infiltration
• CRaises soil pH to toxic levels throughout the profile
• DAdds excess nitrogen from microbial mineralization of organic matter