Advanced Crop Observation & Diagnostic Reasoning — Formative Check
Answer each item before opening its rationale. Use missed items to identify which lesson evidence you should revisit.
1. A feed sheet matches the target recipe, but plants show a pattern consistent with uptake stress. What should the technician conclude?
- Correct formulation does not prove correct uptake; root-zone, water, environment and plant-health evidence still require evaluation.
- Nutrient causes are impossible.
- The recipe must be changed immediately.
- The symptom is definitely genetic.
Check answer and rationale
Answer: A. Correct formulation does not prove correct uptake; root-zone, water, environment and plant-health evidence still require evaluation.
Nutrients may be present while root-zone or environmental conditions limit uptake; diagnosis must include system context.
2. A pest is detected on a trap in another zone, while the symptomatic crop has no pest signs. What is the strongest interpretation?
- The pest automatically explains all symptoms facility-wide.
- The detection raises pest plausibility but does not prove it caused the symptomatic crop; inspect and compare evidence in the affected zone.
- Pests can be ruled out because they were not seen on the first plant.
- Apply treatment to the symptomatic crop without authorization or confirmation.
Check answer and rationale
Answer: B. The detection raises pest plausibility but does not prove it caused the symptomatic crop; inspect and compare evidence in the affected zone.
Facility detection is relevant context, but diagnosis still requires evidence linking the causal agent to the affected crop.
3. After two hypotheses remain equally plausible, which next step is strongest?
- Repeat a measurement both hypotheses predict identically.
- Pick the hypothesis with the more familiar name.
- Choose an observation or test expected to produce different predictions under the two hypotheses.
- Change multiple systems and see what happens.
Check answer and rationale
Answer: C. Choose an observation or test expected to produce different predictions under the two hypotheses.
A discriminating test is designed to change the relative support for competing hypotheses.
4. A crop block develops interveinal chlorosis on older leaves while root-zone EC has risen across several irrigations. Tissue results are not yet available. Which next step best strengthens the nutrient differential?
- Diagnose magnesium deficiency from leaf color alone.
- Ignore root-zone history because visual symptoms identify nutrient causes.
- Increase every fertilizer element at the next irrigation.
- Compare root-zone EC, pH, moisture trend and matched unaffected plants before deciding whether nutrient supply, uptake or water balance best fits the evidence.
Check answer and rationale
Answer: D. Compare root-zone EC, pH, moisture trend and matched unaffected plants before deciding whether nutrient supply, uptake or water balance best fits the evidence.
Nutrient-related symptoms can overlap with root-zone and water-balance problems. Comparing root-zone trends and unaffected plants strengthens the differential without treating leaf appearance as proof of one deficiency.
5. Leaf-edge injury appears soon after an environmental setpoint change, and scouting finds no insects, webbing, frass, sporulation or characteristic lesions. What is the strongest initial interpretation?
- Treat the condition as a confirmed fungal disease.
- Treat the condition as a confirmed nutrient deficiency.
- Keep abiotic stress and biotic causes in the differential, verify timing and distribution, and look for discriminating signs before assigning a cause.
- Apply a pesticide because direct signs are unnecessary when leaves are damaged.
Check answer and rationale
Answer: C. Keep abiotic stress and biotic causes in the differential, verify timing and distribution, and look for discriminating signs before assigning a cause.
Plant injury can have overlapping biotic and abiotic appearances. Timing, spatial pattern and direct signs help separate hypotheses before a high-consequence diagnosis or control decision is made.
6. Within one cultivar, upper nodes show clear reproductive development while shaded lower nodes are less advanced. What should be checked before labeling the lower-node development abnormal?
- Only the number of days since the photoperiod change.
- Position in the canopy, local light environment, whole-plant morphology and the cultivar's developmental pattern.
- Whether another cultivar in a different room flowers at the same speed.
- Whether fertilizer concentration can be increased immediately.
Check answer and rationale
Answer: B. Position in the canopy, local light environment, whole-plant morphology and the cultivar's developmental pattern.
Developmental interpretation should use plant morphology and local crop context. Node position, canopy conditions and cultivar response can produce normal within-plant differences that a calendar date alone cannot classify.
7. After an irrigation-system change, similar stress appears first on plants at the end of one line across two cultivars, while the same cultivars elsewhere remain unaffected. Which observation would best discriminate a local process problem from a cultivar effect?
- Compare delivery, root-zone moisture and symptom timing at affected end-of-line plants with matched unaffected plants elsewhere.
- Compare only the cultivar names on the plant tags.
- Assume both cultivars developed the same genetic defect at once.
- Wait until every plant in the room shows the same symptom.
Check answer and rationale
Answer: A. Compare delivery, root-zone moisture and symptom timing at affected end-of-line plants with matched unaffected plants elsewhere.
A repeated location pattern across cultivars points to a potentially local process factor. Matched affected-versus-unaffected comparisons and chronology provide stronger discriminating evidence than cultivar labels alone.
8. Formative diagnostic check 8: A supervisor asks for the “confirmed cause” while two leading hypotheses remain plausible. What should the technician report?
- Choose the more familiar diagnosis so the report is decisive.
- Call both causes confirmed.
- Remove the weaker hypothesis from the record without explanation.
- State the leading hypotheses, confidence, evidence for and against each, and the next discriminating check.
Check answer and rationale
Answer: D. State the leading hypotheses, confidence, evidence for and against each, and the next discriminating check.
Diagnostic reporting should match certainty to evidence and preserve unresolved alternatives.
9. Two canopy sensors agree through most of the light period but diverge whenever a nearby dehumidifier cycles, while a reference sensor sits outside that airflow zone. What should be verified before treating the difference as a room-wide event?
- Sensor placement, local airflow/equipment effects, sensor condition and comparison with representative locations.
- Only the room-average setpoint shown on the controller.
- Whether the highest reading can replace every other sensor value.
- Whether all sensors can be moved beside the dehumidifier.
Check answer and rationale
Answer: A. Sensor placement, local airflow/equipment effects, sensor condition and comparison with representative locations.
A measurement can be real but locally unrepresentative. Verifying placement, equipment-linked airflow, sensor condition and representative comparison points helps distinguish a local microenvironment from a room-wide environmental event.
10. Two cultivation beds have the same programmed irrigation volume, but one shows slower dryback and consistently higher runoff EC. Which evidence set best tests whether their root-zone behavior is actually different?
- Programmed irrigation volume alone.
- Delivered volume, drainage/runoff, moisture trend, root-zone pH and EC, root observations and a matched comparison over time.
- The fertilizer product name and label color.
- One room-temperature reading taken after irrigation.
Check answer and rationale
Answer: B. Delivered volume, drainage/runoff, moisture trend, root-zone pH and EC, root observations and a matched comparison over time.
Programmed inputs do not prove equivalent root-zone conditions. Comparing delivered water, drainage, moisture dynamics, chemistry and root observations over time provides evidence about whether the two beds are behaving differently.
11. Formative diagnostic check 11: Why is a one-factor nutrient explanation often weak when several mineral inputs changed together?
- Plants cannot respond to individual nutrients.
- All mineral deficiencies have identical symptoms.
- Nutrients can interact, so plant response may depend on combinations rather than one input acting independently.
- EC identifies every ion concentration separately.
Check answer and rationale
Answer: C. Nutrients can interact, so plant response may depend on combinations rather than one input acting independently.
Cannabis response-surface work found interaction effects among N, P and K on multiple growth attributes.
12. Scouting finds scattered chlorotic spots but no direct pathogen sign. A confirmatory sample can be collected, although poor handling could spread contamination. What is the best next step?
- Move symptomatic leaves through several rooms so more staff can inspect them.
- Call the condition a confirmed disease and begin treatment immediately.
- Discard the observation because visual symptoms are never useful.
- Follow the containment and sampling procedure, document representative evidence, and escalate for appropriate confirmation before making major crop decisions.
Check answer and rationale
Answer: D. Follow the containment and sampling procedure, document representative evidence, and escalate for appropriate confirmation before making major crop decisions.
When disease is plausible but unconfirmed, evidence collection should preserve biosecurity and support consequence-proportional confirmation. Controlled sampling and escalation are stronger than diagnosis from appearance alone.