CATS Tree Nutrition and Fertilization 2 — Questions and Answers
Question 1: What is the best time of year to apply fertilizer to deciduous trees in the Albuquerque area to maximize uptake?
- Midsummer during peak heat
- Late fall after leaf drop or early spring before bud break (Correct answer)
- During drought stress periods
- Immediately after heavy pruning
Correct answer: Late fall after leaf drop or early spring before bud break
Late fall or early spring is optimal because trees are actively storing or mobilizing nutrients, and cooler temperatures reduce volatilization and runoff losses.
Question 2: A soil test in an Albuquerque urban landscape reveals pH of 8.2. What amendment would an arborist most likely recommend to improve micronutrient availability?
- Lime (calcium carbonate)
- Elemental sulfur (Correct answer)
- Potassium chloride
- Superphosphate
Correct answer: Elemental sulfur
Elemental sulfur acidifies alkaline soils by being oxidized to sulfuric acid by soil bacteria, lowering pH and improving micronutrient availability.
Question 3: Which nutrient is classified as a secondary macronutrient and plays a critical role in cell wall structure and root tip development?
- Iron
- Manganese
- Calcium (Correct answer)
- Zinc
Correct answer: Calcium
Calcium is a secondary macronutrient essential for cell wall structure and meristematic (growing) tissue development, including root tips.
Question 4: When conducting a foliar nutrient spray for iron deficiency in Albuquerque, which iron chelate formulation performs best in high-pH soils?
- FeEDTA
- FeDTPA
- FeEDDHA (Correct answer)
- FeCitrate
Correct answer: FeEDDHA
FeEDDHA is the most effective iron chelate in high-pH soils (above 7.5) because it remains stable and plant-available at alkaline pH levels.
Question 5: What does the N-P-K ratio on a fertilizer label represent?
- Nitrogen, Phosphorus, Potassium percentages by weight (Correct answer)
- Number of applications, pH, and Kilogram weight
- Net nutrients, plant-available portion, and known compounds
- Nitrogen, Potassium, and Phosphate molecular weights
Correct answer: Nitrogen, Phosphorus, Potassium percentages by weight
The N-P-K ratio shows the percentage by weight of nitrogen (N), phosphate (P₂O₅), and potash (K₂O) in the fertilizer formulation.
Question 6: Which fertilization method is most appropriate for a large mature oak tree on a property with a well-maintained lawn where surface disturbance must be minimized?
- Broadcast granular fertilizer over the lawn surface
- Deep root liquid injection outside the drip line (Correct answer)
- Trunk implant capsules
- No fertilization is needed for mature trees
Correct answer: Deep root liquid injection outside the drip line
Deep root liquid injection outside the drip line delivers nutrients to feeder roots without disturbing the surface, making it ideal when lawn disturbance is a concern.
Question 7: Over-fertilizing a tree with excessive nitrogen can lead to which of the following negative outcomes?
- Increased drought tolerance
- Stimulated excessive soft growth susceptible to pests and disease (Correct answer)
- Improved root-to-shoot ratio
- Enhanced fruit and seed production
Correct answer: Stimulated excessive soft growth susceptible to pests and disease
Excessive nitrogen stimulates rapid, soft vegetative growth that is more susceptible to insect attack, fungal diseases, and environmental stress.
CATS Tree Nutrition and Fertilization 2
What is the best time of year to apply fertilizer to deciduous trees in the Albuquerque area to maximize uptake?