Fungicide Mix Key to Almond Disease Management

Strategic fungicide application at bloom is key to almond disease management.

With warm and wet weather predicted for the West Coast this spring following a mild winter, growers will require effective almond disease management programs. The valuable crop likely will need early and more frequent protection from diseases including scab and Alternaria leaf spot.

With increased disease threat, growers can’t afford to simply react to conditions in their orchards, says Jeff Pacheco, technical sales agronomist, DuPont Crop Protection. “They will need a season-long almond disease management game plan that includes a combination of fungicides and an application rotation to minimize resistance development.”

Plan to Combat Resistance

Resistance to Qol (strobilurin) fungicides (FRAC group 11) and SDHI fungicides (FRAC group 7) has been documented in some orchards, yet these two groups contain some of the most effective options for controlling scab and Alternaria, says Pacheco. “The key is to use them in a planned rotation that includes fungicides with various modes of action and to consider all your product options.”

Qol resistance has been more widespread, while SDHI resistance has been more localized, says Jim Adaskaveg, professor and plant pathologist, University of California, Riverside. “To develop an effective plan, start with a grove’s disease history. If resistance has already been a problem, rotate fungicide modes of action and limit use of fungicides with a single mode of action to one or two applications per season. It’s also important to use full labeled rates.”

While fungicide premixes offer convenience, they sometimes contain reduced product rates, which can reduce effectiveness, notes Carl Bannon, technical sales agronomist, DuPont Crop Protection. “Or they might contain an active ingredient that’s not effective on the target disease.

“DuPont™ Fontelis® fungicide offers flexibility for almond disease control plans,” he says. “With a single mode of action (FRAC group 7), it can be tank-mixed with other modes of action, at a range of rates, for more customized control at an affordable price.”

Stay Ahead of Alternaria and Scab

University of California field trials in Colusa County compared a variety of fungicide treatments to control Alternaria leaf spot. “In 2015 trials, a tank mix of Fontelis® and Tebucon (FRAC group 3) was rated highly effective in controlling Alternaria leaf spot on Carmel and Monterey varieties,” says Adaskaveg. “That tank-mix combination provides two modes of action and would be a relatively cost-effective option in a season-long rotation.”

In other 2015 trials conducted at the University of California Kearney Research and Extension Center near Parlier, San Joaquin County Cooperative Extension Director Brent Holtz and colleagues evaluated sequential treatments of several fungicides for scab control on the variety Carmel. Despite last season’s dry conditions, researchers were able to induce scab development with frequent micro irrigation. “Trees treated with Fontelis®, applied by itself and in several tank-mix combinations, had fairly low scab incidence and severity ratings,” says Holtz. (Fontelis® is labeled for suppression of scab.)

“If more frequent fungicide applications are needed this spring, it’s worth considering rotating a product such as Fontelis® as part of a tank mix in a rotation for scab control, as well as some older multiple mode-of-action products and even micronized sulfur,” he adds. “We need to use all the control options we have, in well-planned rotation, to help them work the best and last the longest.”

Good Fit for Almonds

Fontelis® is an excellent fit for an almond production program because it delivers these qualities:

  • Preventive and curative properties
  • Reliable control of brown rot, anthracnose, Botrytis rots and shot hole
  • Can be used after bloom period in rotational strategies to control rust, powdery mildew, Alternaria leaf spot and scab (suppression)
  • Single SDHI fungicide active ingredient, penthiopyrad (FRAC group 7)
  • Can be used in rotation or tank-mixed with other modes of action to improve control and help manage fungicide resistance
  • Rainfast within one hour

DuPont Fontelis® is not available in all states. See your local DuPont sales representative or retailer for details on availability.
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