Following Blight, Botrytis now becomes the main threat — act early to avoid compounding issues.

By Stefan Vogrincic

Energy costs are currently a major burden for greenhouse growers. As a result, many are forced to make difficult decisions about how much energy to invest in climate control. However, reducing energy input significantly compromises the ability to manage diseases like Botrytis, often leading to increased reliance on fungicides. Striking the right balance between energy use and disease prevention is essential to avoid long-term crop losses and chemical dependency.

🌡️ Energy & Environmental Control tips:

• Dry Air = Lower Risk: Minimize greenhouse humidity and avoid condensation.
• Heat Smart: Use P-bands or maximum vent settings to stabilize temps while managing RH. Avoid sharp temperature swings.
• Energy Budgeting: Less energy = more fungicides. Weigh this trade-off carefully.

💧 Irrigation Discipline:

• No Excess Water: Control irrigation volumes. Avoid encouraging unnecessary uptake.
• Daily Checks: Strictly monitor EC, pH, and water uptake — especially during winter harvest.
• Fertiliser Recipe: have a sample analyzed and checked.

🌱 Plant Load & Handling:

• Avoid Overbearing: Don’t push fruit load – we’re just past the shortest day.
• De-leaf with Caution: Avoid wet days and late cuts. Always sanitize tools to avoid spreading spores.
• Remove Infected Tissue: Carefully collect infected leaves into sealed plastic bags — never drop them.

🧪 Preventive Measures:

• Spray Proactively: If you can’t run an ideal climate, your preventive regime becomes even more critical.

🌬️ Fans – Use With Caution:

• Before Problem = Yes,
  After Spores Present = Risky.
  Make a case-by-case judgment on circulation fans — they can help or hurt.

For tailored advice, please don’t hesitate to give me a call. Let’s discuss practical options to reduce the impact of Botrytis and help protect your income during this critical period—especially while market supply remains tight.

📸 Images above: Stem and Leaf Botrytis
When removing infected leaves, always carry a large enough plastic bag to immediately place the discarded material inside. Do not drop infected tissue on the ground—this only spreads spores and worsens the problem.

For more advice contact stefan@grower2grower.co.nz