Almond Orchards Prevail in Battle with Phytophthora

Losing crops is a reality of farming, especially when you’re battling weather, new pests and emerging diseases. Seeing a few acres of your life’s work perish is tough, but the threat of losing your entire operation is a different type of sting. One California almond grower shares how soil health improvements made his orchards vulnerable to disease and how he was able to bring them back from the brink of total devastation.

Trees Lost to Unusually Wet Weather Worsened by Soil Prep

Whole orchard recycling is a process to reincorporate an outgoing orchard in preparation for planting a new one. Mature trees are felled and ground into woodchips, which are then spread and incorporated into the soil. The University of California found that this process can help improve water retention. The issue for John Fassler, a California pest advisor who went through whole orchard recycling, was that the moist soil and greater-than-normal rainfall turned his orchards into the perfect breeding ground for oomycete pathogens like Phytophthora.

Fassler has consulted at Braden Farms where they used whole orchard recycling as a way to prepare for planting a new orchard. “This is a fairly new process, which means we’re learning as we go,” he says. “Some issues we’ve seen have been a rise in fungal diseases, such as Phytophthora and other replant diseases.”

Mother Nature hasn’t helped the fungal disease risk, especially at the beginning of the 2023 growing season. California experienced greater than average annual precipitation in 2023, breaking numerous records and ending three years of persistent drought, according to the California Nevada River Forecast Center.

“We’ve had significant rainfall in California the last two years, so this has really intensified the battle with Phytophthora in some spots,” says Ashley Bandoni, Syngenta sales representative and California almond grower.

Fassler experienced devastation due to those heavy rains. One of his orchards was completely submerged, worsening the orchard’s Phytophthora issues.

“We lost about 500 trees on this block due to Phytophthora and replant disease,” says Fassler. “Phytophthora is becoming more and more of an issue in these wetter years.”

Phytophthora Overtakes Young Almond Trees

Many California growers and crop consultants have been battling fungal disease challenges.

Ethan Nicol, an independent pest control advisor and crop consultant for Balanced Agronomics, helped one of his customers manage extreme Phytophthora in a young almond orchard.

Planted in the fall of 2021, Nicol began seeing early symptoms of Phytophthora infections the following spring. Young trees like the ones in the orchard Nicol manages tend to be more susceptible to disease because their root systems and crown areas are smaller compared to those of mature trees, according to the University of California Department of Agriculture.

“In that first 2022 season, we observed maybe 30 percent of the orchard was infected,” says Nicol. “By mid-August, we had really grown to realize the significance of the issue.”

Coming Back from Orchard Devastation

For both Nicol and Fassler, almond yield potential was on the line and devastation was just over the horizon. They both had a tough decision to make.

“As far as doing our research going into it, usually we have the Syngenta reps come in to help us decide if the product will be a good fit for us,” says Fassler. “We also ask about how the product differentiates itself from what we’ve already been doing.”

After discussions with their local Syngenta experts, Fassler and Nicol decided to apply Orondis^® fungicide to help save their orchards. Fassler says his flooded orchard plot turned around.

“My experience with Orondis changed up our program,” says Fassler. “We’ve been able to work it into our program really well and we didn’t lose one tree this year.”

Nicol’s experience with Orondis was also nothing short of extraordinary. Before application, Nicol was working with the grower to continuously remove and replant dead trees. They lost roughly 600 almond trees — six ranches — to Phytophthora. Once Orondis was applied in 2023, Nicol observed a noticeable decline in newly infected trees.

“We were confident in the success that we were seeing by the replants taking and growing strongly, and the existing trees continuing to grow and not develop signs of Phytophthora,” says Nicol. “Going into 2024, just as a precaution and to help protect this investment, we made an additional Orondis application. There’s been almost no sign of infected trees this season.”

Growers Also Need Care

If Fassler and Nicol didn’t have the guidance and support of their Syngenta representatives, their almond orchards might have been lost.

“I’ve worked with Syngenta for probably about the last 20 years, and through the years we’ve had many different experiences,” says Fassler. “Syngenta has always been there to help us through and guide us through what needed to be done.”