Currant

Seasonal Pest & Disease Calendar

Pest & Disease Guide (Homeowner-Friendly)

1. Currant Blister Aphids

Symptoms

• Raised blisters, puckering, or curled leaves (often red/yellow patches)
• Sticky honeydew; ants may be present

Treatment

• Strong water spray to knock aphids off
• Prune off the worst distorted tips early
• Systemics only if severe and repeated (often cosmetic)

2. Currant Sawfly

Symptoms

• Rapid “skeletonizing” or stripping of leaves
• Green caterpillar-like larvae (they’re sawfly larvae, not moth caterpillars)

Treatment

• Hand-pick larvae early (fast and effective)
• Treat early when larvae are small if defoliation is starting
• Repeated defoliation = real stress (this one can matter)

3. Spider Mites

Symptoms

• Fine yellow stippling; leaves look dusty/dull
• Sometimes light webbing in hot, dry weather

Treatment

• Strong hose spray (especially undersides) during heat
• Avoid drought stress—deep water
• Miticides only if severe

4. Powdery Mildew

Symptoms

• White/gray “powder” on leaves and sometimes fruit
• Most common mid–late summer

Treatment

• Thin canopy for airflow; avoid overhead watering
• Fungicides optional if fruit/appearance matters
• Often manageable with pruning + site conditions

5. Leaf Spot / Anthracnose

Symptoms

• Small dark spots that can merge into blotches
• Premature leaf drop later in summer

Treatment

• Rake/remove fallen leaves (biggest improvement)
• Water at soil level; reduce leaf wetness
• Fungicides rarely needed for homeowners

6. Cane Dieback

Symptoms

• One or more canes fail to leaf out well, then decline
• Tip dieback or entire cane dieback (often after stress)

Treatment

• Prune dead canes to the base (remove/haul off)
• Improve watering and drainage; mulch (not against stems)
• No single “magic spray”—reduce stress and renew canes

7. Winter Dieback / Desiccation

Symptoms

• Tips or entire canes dead after winter; delayed leaf-out
• Worse on exposed/windy sites with dry soil

Treatment

• Winter watering during warm dry spells
• Mulch 2–3" (keep off crowns/stems)
• Spring pruning to remove dead tips/canes

Treatment Timing Calendar – Currant (Colorado Front Range)

March–Early April ( )

• Prune out dead/weak canes; open the center
• Check for overwintered stress and early aphid activity
• Water during dry spring weeks

Late April–May ( )

• Watch for sawfly larvae and early aphid blistering
• Treat sawfly early (small larvae) if defoliation begins
• Pinch/prune worst aphid-distorted tips if needed

June ( )

• Monitor for continued sawfly (if it repeats) and early mites
• Deep watering as heat ramps up

July–August ( )

• Powdery mildew + leaf spot/anthracnose show up
• Fungicides only if fruit/appearance is important
• Avoid heavy pruning during peak heat

September–October ( )

• Rake and remove leaves (best disease prevention)
• Water before ground freezes

Winter ( )

• Winter watering during warm dry spells
• No pesticide treatments needed

When to Worry vs. When It’s Cosmetic

When to Worry (Action Needed)

• Repeated or heavy defoliation (sawfly)
• Significant cane dieback year over year
• Early, repeated leaf drop from spotting diseases

Mostly Cosmetic (Monitor Only)

• Light blister aphids
• Mild powdery mildew late summer
• Minor late-season leaf spotting