With bloom around the corner, pistachio growers have disease protection in mind. UPL Technical Service Manager, Emily Smith said that one of the most substantial diseases growers can encounter is botryosphaeria. The rains that recently came through California were enough to potentially spread spores in the orchard. With warmer weather on the horizon, those spores have the potential to create infection in orchards.
“When temperatures start to warm up in early summer botryosphaeria becomes a really big issue in pistachios,” Smith explained. “Spores will spread and then when it warms up, they will activate and they can kill growing tissue. Then it will put that out of production for the following year. So, it is a pretty serious disease that needs to be controlled early on.”
Botryosphaeria can be a constant pressure for pistachio growers. The disease can be extremely difficult to control, especially if it is allowed to increase and spread over multiple years. The first treatments for the disease will generally go out in early summer and late spring, depending on the weather. Smith said that generally when temperatures begin to hit the high 70s, that is a good time to start treating for botryosphaeria. While organic producers may have limited options available for disease protection, conventional growers have several effective options.
“We have PH-D, which is Polyoxin D zinc salt, and it is a knockdown product. It also has a little bit of preventative action as well and it can kill any of the pathogen that’s out in the field. So, it is a great, really good treatment for earlier prevention of botryosphaeria infection,” said Smith. “It is a biological, but it’s registered as a conventional product. The PHI is zero days and then it has a really short reentry interval as well.”
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