AZ garden problem finder

• Defoliation overnight — whole branches stripped down to stems.
• Large green caterpillar (3–4") with a horn on its rear.
• Dark green pellet droppings on leaves below the damage.

Larvae of the sphinx moth. Lays eggs on undersides of leaves in spring and again after monsoon.

• Hand-pick at dawn or dusk — they're easiest to spot when feeding.
• Spot-spray Bt (Bacillus thuringiensis) on remaining caterpillars.
• Leave any hornworm covered in white rice-grain eggs — those are parasitic wasp larvae; the wasps are your free pest control.

• Till the bed in spring to expose overwintering pupae.
• Interplant with dill or basil to attract parasitic wasps.

• Clusters of small green, black, or grey insects on new shoots.
• Sticky honeydew coating leaves; black sooty mold follows.
• Curled, distorted new growth.

Sap-sucking insects that explode in numbers during mild AZ spring weather.

• Blast off with a strong jet of water — knocks them off and most don't return.
• Spray insecticidal soap or 1% horticultural oil at dusk; repeat in 5 days.
• Skip broad-spectrum insecticides — they kill the lacewings and ladybugs that eat aphids.

• Avoid excess nitrogen — soft, lush growth is what aphids prefer.
• Encourage beneficials by leaving a flowering border (yarrow, alyssum, dill flowers).

• Tiny white flies erupt in clouds when a leaf is disturbed.
• Yellowing and sticky honeydew on undersides of leaves.
• Black sooty mold growth.

Population builds through hot months; worst in dense, poorly-ventilated plantings.

• Yellow sticky traps placed at canopy height — catches adults.
• Insecticidal soap or neem oil on the undersides of leaves at dusk; repeat every 5–7 days.
• Remove and destroy the worst-infested leaves.

• Don't crowd plants — airflow matters more than spacing rules suggest in AZ.
• Reflective mulch (silver) confuses them.

• Fine stippling / bronze cast on leaves.
• Webbing on undersides of leaves and between stems.
• Plants look thirsty even when watered.

Heat-and-dust loving mites. Explode in hot, dry, dusty conditions.

• Rinse foliage at dawn or dusk every 2–3 days for a week — moisture is the #1 control.
• Spray with a 1% horticultural oil at dusk if rinsing isn't enough.
• Avoid sulfur — burns AZ leaves over 90°F.

• Mulch heavily to reduce dust.
• Maintain consistent watering — drought-stressed plants are spider mite magnets.

• Water-soaked dark sunken patch on the bottom of the fruit.
• Patch enlarges and turns leathery brown to black.
• Otherwise healthy foliage.

Calcium not reaching the developing fruit — almost always caused by inconsistent watering, not soil calcium deficiency.

• Even out watering: deep soak 2–3× per week, not shallow daily.
• Mulch heavily to buffer soil moisture.
• Remove affected fruit so the plant can redirect resources.

• Steady moisture is the #1 prevention.
• Avoid heavy nitrogen — pushes leafy growth at the expense of calcium translocation.

• Pale yellow then white-papery patch on the sun-facing side of fruit or bark.
• Affected tissue collapses or cracks; secondary fungal infection follows.
• Often appears after defoliation (pruning, hornworm damage, heat stress).

Direct intense AZ sun on tissue that was previously shaded.

• Don't remove damaged tissue from trunks — let it harden off.
• Pick badly scalded fruit so the plant focuses on protected fruit.

• Shade cloth (30–40%) over fruiting vegetables from late May through September.
• Whitewash young tree trunks (50/50 latex paint and water).
• Prune lightly in summer — never bare a sun-facing limb.

• White-grey dusty coating on leaves, starting on undersides.
• Affected leaves yellow, brown, and die back.
• Plant slowly loses vigor.

Fungal disease that prefers warm days and cool nights — peaks during monsoon and early fall.

• Spray potassium bicarbonate or 1:10 milk-to-water at the first sign.
• Remove the worst leaves to improve airflow.
• Severe cases: pull and replant after a month-long break.

• Water at the base — never overhead.
• Space plants for airflow.
• Pick mildew-resistant varieties when possible.

• Yellow leaves with green veins (interveinal chlorosis).
• New growth shows it first.
• Severe cases turn leaves nearly white with brown edges.

AZ's high-pH alkaline soil binds iron and makes it unavailable, even when the soil contains plenty of it.

• Apply chelated iron — EDDHA form is the only chelate that stays available above pH 7.5.
• Spray foliar iron for fast green-up while soil chelate takes effect.
• Add 1–2" compost top-dressing to lower the soil pH slightly over time.

• Mulch heavily — soil biology helps free bound iron.
• Use acidifying fertilizers (ammonium sulfate) on iron-prone plants.

• Uniform yellowing of older (lower) leaves.
• Stunted, pale, slow growth.
• Lawn turns yellow-green and grows slowly.

AZ soil is naturally low in organic matter and nitrogen, especially in new construction.

• Side-dress with blood meal, fish emulsion, or balanced organic fertilizer.
• For fast results: water-soluble fish emulsion at half strength.

• Maintain a steady compost top-dressing routine.
• Follow the fertilizer schedule for the plant category.

• Leaves wilt midday even when soil is wet.
• Leaf edges curl upward.
• New growth halts.

Transpiration outpaces water uptake when air temperatures exceed ~105°F.

• Do NOT water more in response to midday wilt — check soil first; if moist, the plant is heat-stressed not thirsty.
• Provide 30–40% shade cloth over vegetables.
• Mulch 3" deep to keep soil cooler.

• Pick heat-tolerant varieties (Heatmaster tomato, Anaheim pepper, Armenian cucumber).
• Shift planting windows: warm-season crops go in by late March, fall warm crops in early August.