Yellow Leaves with Holes: Insects, Watering, and the Two-Knuckle Test

Diane's rose has yellow leaves with holes. Two separate issues likely.

Holes = Insects

Chewed edges = caterpillars, beetles, sawfly larvae. Tiny holes = flea beetles. Skeletonized = rose slugs (sawfly larvae). Inspect leaf undersides at dawn/dusk. Treat with Bacillus thuringiensis (caterpillars), spinosad (beetles/slugs), or insecticidal soap (aphids/mites).

Yellow Leaves: Water or Food?

Two-knuckle test: Insert finger 2 inches deep. Moist = don't water. Dry = water deeply. Overwatering suffocates roots → yellowing. Underwatering → stress yellowing.

Yellow + green veins = iron deficiency (high pH). Yellow uniformly = nitrogen deficiency. Fertilize with balanced rose food containing micronutrients.

Yellow + Black Spots = Black Spot

Fungal. Spray fungicide weekly, remove fallen leaves, water at base, ensure sun/airflow.

Integrated Routine

Scout weekly. Water by finger test. Feed monthly in growing season. Spray preventatively in humid weather. Mulch 2–3 inches.