Ways Citrus Growers Can up Their Defense Amid Stormy Skies

If normal winter weather tests rind durability in California’s Central Valley citrus, a potentially powerful El Niño could turn moisture management into a high-stakes fight to protect crops. Forecasts from the National Oceanic and Atmospheric Administration (NOAA) and private weather services such as AccuWeather have raised concerns about a strong El Niño bringing wetter winter conditions to California.

Growers know that tule fog, high humidity, and erratic swings between cool, moisture-laden conditions and unseasonably warm spells can contribute to rind browning, decay, and premature fruit drop.

Proactive orchard management is a grower’s first line defense against heightened disease pressure, said Ryan McCoon, technical sales agronomist for Northern California at Cultiva, a Las Vegas-based agricultural technology and crop solutions company.

Because prolonged moisture creates favorable conditions for infection, timing is critical. Fungicides are generally more effective when applied before disease development rather than used reactively after prolonged wet conditions. That requires preparation with the orchard management team about what an effective fungicide program looks like, the complementary products available, and the timely routine to support it.

“Before the weather comes is always the best-case scenario,” McCoon said. “Start having real-time conversations now about those fall and winter programs.”

 Orchard Defense

A resilient defense begins before the first winter storm, with practices that support orchard health and reduce disease risk.

McCoon recommends balanced plant nutrition and effective canopy management to help citrus orchards withstand prolonged moisture and heightened disease pressure. Opening the canopy improves airflow, accelerates drying, and allows foliar treatments and fungicides to reach more of the tree.

Effective disease control also depends on careful fungicide stewardship, McCoon said. Proper placement and timing, along with adherence to Fungicide Resistance Action Committee (FRAC) guidelines help to minimize the development of resistance.

While ongoing research and new chemistries remain important, McCoon emphasizes that disciplined resistance management and precise application timings are essential to protecting orchard health under challenging weather conditions.

“More than anything, [this] is probably the best course of action in mitigating potential issues with what would be a comprehensive program,” McCoon said.

Supplemental Protection

Plant cuticle supplements may offer another layer of protection by reinforcing fruit surfaces and repelling water.

These supplements can form a water-repellent barrier over fruit and foliage, potentially supporting fruit retention and complementing conventional disease management programs. Reinforcing the natural cuticle may help protect microfractures where fungi can colonize, while supporting carbon dioxide exchange, chlorophyll production, and epidermal durability.

Together, these effects could help preserve rind quality and reduce weather-related damage.

“When you talk about the rigors that come with this specific type of weather, all those are added benefits that can help keep fruit rind health and quality at a premium, and stave off some of the detrimental impacts that an El Niño could bring,” McCoon said.

Growers caught off guard by an early storm or prolonged wet conditions may still benefit from supplemental treatments and fungicide applications. Although preventative applications offer the best opportunity to limit damage, midseason treatments may also help manage ongoing disease pressure.

McCoon advises growers to assess conditions and determine where additional applications can provide meaningful protection as wet weather persists.

“The value proposition is fairly different at that point,” he said. “You risk exposure, but still there’s the upside and continued protection of these methods as that weather persists.”

While reactive treatments may help preserve fruit quality and limit further losses, McCoon maintains that proactive management offers the best chance of effective disease control and stronger economic returns.