Cytokinins at Budburst: The Smart Shortcut to Better and Crunchy Seedless Grapes 🍇
- Stefano Franchini
- Oct 20
- 3 min read
Why Use Cytokinins at Budburst?
Budburst sets the tone for your entire season. It’s when the vine decides:
How many buds will actually shoot
How many will carry fruit
How balanced and uniform the canopy will be
For seedless grapes varieties like Crimson, Thompson and Sugraone, using cytokinins early can help to:
Reduce uneven budbreak
Encourage fruitful shoots instead of empty tendrils
Set up more even clusters and larger, crunchier berries later on
Two Ways to Apply Cytokinins
1️⃣ Natural Cytokinins – Seaweed Power
Seaweed extracts (like Ecklonia maxima or Ascophyllum nodosum) provide natural cytokinin compounds that boost early growth and balance.
When to apply:
From cotton bud to 5–10 cm shoot length
Again before flowering
Typical plan:
Budburst: 2.5–3 L/ha foliar
+10–14 days later: 2.5 L/ha
Pre-flowering: 2.5 L/ha (often with Zn + B foliar spray)
Goal: Uniform shoot growth and more fruitful buds.
2️⃣ Synthetic Cytokinins – Precision Tools
6-BAP (6-Benzylaminopurine): Used to improve bud fertility and help the vine form more flower clusters.
When: Late spring / early summer (during flower formation or after uneven budburst)
Rate: 5–10 ppm on test rows
Effect: More inflorescences, fewer sterile tendrils
CPPU (Forchlorfenuron):Used to increase berry size and firmness.
When: After flowering, when berries are 3–6 mm
Rate: 5–10 ppm, 1–2 sprays every 7–10 days
Effect: +15–25 % berry weight and firmer pulp
Note: Can delay colour and sugar development by 1–2 weeks — open up the canopy for better colour.
The “Cytokinin Triangle” – Getting the Best Results
Cytokinins only work properly when three things are balanced:
💧 Water: No stress from budburst to flowering. Regular, light irrigations keep the hormones moving through the vine.
🧪 Nutrition:
Nitrogen available but not excessive
Zinc + Boron before flowering
Calcium from fruit-set onwards
☀️ Light:
Upright, spaced shoots
Gentle leaf removal for sunlight on bunches
Better light = better fruit set and colour
Quick Field Plans for Seedless Grapes Varieties
Goal A – Uniform Growth & Bud Fertility
Budburst: Seaweed 2.5–3 L/ha
+10 days: Seaweed 2.5 L/ha
Pre-flowering: Seaweed + Zn + B foliar
(Optional) 6-BAP 5–10 ppm in late spring to set up next season’s fertility
Goal B – Berry Size & Crunch
Pre-flowering: Seaweed 2.5 L/ha
Post-set (3–6 mm berries): CPPU 5–10 ppm
+7–10 days later: repeat at low rate if needed
Add Calcium foliar regularly after set
Lightly defoliate red varieties to help colour
Common Mistakes and How to Avoid Them
🚫 One big CPPU dose: Causes compact, green bunches — split it into smaller doses and watch maturity.
🚫 Only one seaweed spray: Too weak — aim for 2–3 sprays before flowering.
🚫 6-BAP too late: Won’t work — apply during the flower formation stage.
🚫 Skipping micros (Zn–B): Leads to poor fruit set.
🚫 Dry soil after spraying: Reduces response — always irrigate before and after hormone use.
Pre-Spray Checklist
✅ Soil moist 20–30 cm deep
✅ Irrigation system checked
✅ Zn + B foliar scheduled before bloom
✅ Shoots trained and light reaching clusters
✅ Test rows marked (treated vs control)
✅ Harvest window flexible by +7–14 days if using CPPU
What to Expect
✔️ More active shoots and fewer blind buds
✔️ More clusters per cane
✔️ Bigger, firmer berries with better shelf-life
✔️ More even canopy and harvest window
Final Take
Cytokinins aren’t magic — but when paired with good irrigation, balanced nutrition and sunlight, they can transform your vineyard.They’re one of the smartest early-season tools for building uniformity, fertility and fruit quality in Mildura’s seedless table grape blocks.
Start small, keep records, and fine-tune your timing — that’s how you turn plant hormones into profit.
At GrapeCare, we specialise in vineyard Agronomy.
Our experienced team can help you with tangible tools & tips to help your vineyard thrive.
Book your consultation today!
📞 Contact us today or visit grapecare.au to learn more.
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